View Full Version : THX
panosxgr
08-07-2006, 14:38
Εϊμαι σχετικά νέος στο χώρο του ήχου και θα ήθελα την άποψή σας στο παρακάτω θέμα.
Διαβάζω για ενισχυτές και παρατηρώ ότι τα ακριβά μοντέλα γνωστών εταιριών είναι πιστοποιημένα με το σήμα της LUCAS ARTS (THX). Παίζει τελικά τόσο μεγάλο ρόλο στον ήχο να αγοράσει κανείς έναν ενισχυτή αυτού του είδους? Γιατί έχω βρει κι άλλους ενισχυτές (7.1) που δεν έχουν το σήμα πάνω τους. Αυτό σημαίνει ότι δεν θα έχω κινηματογραφική απόλαυση στο σπίτι μου με ένα τέτοιο ενισχυτή?
Σας ευχαριστώ -bye-
Νανόπουλος Γιάννης
08-07-2006, 17:18
Σιγά μη δεν έχεις κινηματογραφική ατμόσφαιρα και απόλαυση στο σπίτι σου με ενισχυτή που είναι 7.1 αλά δεν έχει την στάμπα T.H.X....μη τρελλαθούμε τώρα.
Ακουσε 7.1 χωρίς και με Τ.Η.Χ στάμπα, και άμα καταλάβεις διαφορά σε χώρους που δεν είναι φτειαγμένοι με προδιαγραφές Τ.Η.Χ(δηλαδή σε όλλους!!!) εμένα γράψε μου!!!
panosxgr
08-07-2006, 17:22
Αυτό πιστεύω κι εγώ Γιάννη. Αλλά επειδή ακουώ πολλά, ξέρεις τώρα, οι πολλοί πορωμένοι του αθλήματος, κι επειδή είμαι και λίγο αδαής όσον αφορά τον ήχο, για αυτό και ρωτάω.
panosxgr
08-07-2006, 17:28
Μια άλλη μου απορεία είναι σχετικά με την τοποθέτηση των ηχείων, κυρίως των περιφερειακών. Πρέπει η απόσταση που έχει ο θεατής από τα 2 μπροστινα ηχεία και το κεντρικό να είναι η ίδια με αυτή που θα έχουν τα περιφερειακά? Αν είναι μικρότερη δηλαδή (π.χ. κάθομαι πιο κοντά στα περιφερειακά), αυτό φτιάχνεται μέσω ρυθμίσεων/καλιμπραρίσματος του ήχου από τον ενισχυτή?:chinscratch:
Νανόπουλος Γιάννης
08-07-2006, 17:34
Για αυτό υπάρχουν οι ρυθμοί καθυστέρησεις και μέτρων στους ενισχυτές.
Κανονικά πρέπει να υπάρχουν ίδιες αποστάσεις των πίσω ηχείων με τα υπόλοιπα, εκτός των περιπτώσεων εκείνων που αφορούν δίπολα ηχεία.
panosxgr
08-07-2006, 17:51
Τι γίνεται στην περίπτωση των δίπολων? Γιατί τέτοια θέλω να βάλω για πλαϊνά περιφερειακά.
Απο προσωπικη εμπειρια υπαρχει διαφορα κυριως στο μπασο και στον τροπο που το αποδιδει το σαμπ. Πχ η ιδια σκηνη ενος εργου με ενα αποτομο μπασο (πχ μια εκρηξη) ακουγεται τελειως διαφορετικα εαν το THX mode ειναι στο on απο το απλο Dolby Digital. Αυτη ειναι η προσωπικη εμπειρια με εναν Denon AVC-10se και ενα Yamaha 800sw. Οσο για τα διπολα που ρωτας εξαρταται απο το χωρο σου. Εμενα για παραδειγμα μου ελυσαν τα χερια γιατι μπορεσα και τα τοποθετησα ακρβως πανω απο τα αυτια των ακροατων (γιατι απλα δεν υπηρχε χωροταξικα αλλη δυνατοτητα) χωρις να χασω πολυ σε αισθηση περιβαλοντος ηχου. Σιγουρα περιβαλουν τη θεση ακροασης πολυ καλυτερα απο ενα μονοπολο ηχειο. Σε αυτό το σημειο ομως να τονισω οτι πιστευω οτι ενα σωστα τοποθετημενο μονοπολο ηχειο σαν περιφεριακο θα απεδιδε καλυτερα απο ενα διπολο.
panosxgr
08-07-2006, 17:55
Απο προσωπικη εμπειρια υπαρχει διαφορα κυριως στο μπασο και στον τροπο που το αποδιδει το σαμπ. Πχ η ιδια σκηνη ενος εργου με ενα αποτομο μπασο (πχ μια εκρηξη) ακουγεται τελειως διαφορετικα εαν το THX mode ειναι στο on απο το απλο Dolby Digital. Αυτη ειναι η προσωπικη εμπειρια με εναν Denon AVC-10se και ενα Yamaha 800sw.
Το θέμα είναι ότι δεν θα μπορώ να το έχω και στη διαπασών! Γιατί το subwoofer, αν είναι δυνατά, θα έχουμε πρόβλημα και με τους γείτονες! Αυτό που με ενδιαφέρει περισσότερο είναι σε ικανοποιητική ένταση να έχω καλή απόδοση στα χαμηλά (sub) αλλά περισσότερο με ενδιαφέρει η απόδοση των περιφερειακών, γιατί αυτά είναι που δίνουν τελικά τη μαγεία στο χώρο! :music-smiley-005:
vipcinemas
08-07-2006, 23:49
Loipon,
ta peri THX:
Otan enas enisxutis einai THX simainei oti exei perasei kapoia test sta grafeia tis THX, oson afora isxu, paramorfoseis, processing, etc.
Auti i diadikasia einai xronovora, kostizei, kai gia na sas doso na katalavete, grafetai mia anafora 300 selidon, prokeimenou na dothei auti i poistopoiisi.
Oloi oi enisxutes apotuxanoun to test, kai xreiazetai na ginoun kapoies diorthoseis mexri na ginoun THX. Sunithos einai firmware diorthoseis.
Enas THX enusxitis exei tetoio menu, oste na mporei na ginei kalo rithmisma tou sustimatos, kurios me delays, crossovers. etc. Xereis oti o enisxutis den tha einai 7x100 me 20% paramorfosi, kai oti ola ta THX modes tha einai apsoga.
Oson afora to mpaso, to mono pou sou dinei to THX, einai oti to crossover paei sta 80HZ. Exoun aplopoiisei tin katastasi, oste me THX ixeia kai THX enisxuti, ta crossover pane automata sta 80HZ. Tipota parapano
Dimitris
Νανόπουλος Γιάννης
09-07-2006, 01:54
Τι γίνεται στην περίπτωση των δίπολων? Γιατί τέτοια θέλω να βάλω για πλαϊνά περιφερειακά.
Tα δίπολα ηχεία τοποθετούνται απέναντι απο την θέση ακρόασης η λίγο πιό πίσω απο αυτην με την προυπόθεση να υπάρχει αρκετός αέρας απο τον πίσω τοίχο και ύψος απο το δάπεδο περίπου 1,30 μέτρων.
Μελίδης Μιχάλης
09-07-2006, 08:57
O ενισχυτής μου είναι με ΤΗΧ αλλά δεν το χρησιμοποιώ ποτέ. Δεν μου αρέσει ο ήχος έτσι, γίνεται πιο μαλακός και προτιμώ απενεργοποιημένο το ΤΗΧ.
Σε τελική ανάλυση δεν θέλω να εξομοιώσω τον χώρο μου με αυτόν μιας αίθουσας κινηματογράφου. Ούτε στην εικόνα ούτε στον ήχο. Προτιμώ τον άμεσο καθαρό ήχο χωρίς εξομοίωση των αντανακλάσεων ενός μεγάλου χώρου. Και ποιός σας είπε ότι είναι καλύτερα να ακούς σαν να είσαι σε τεράστια αίθουσα ενώ είσαι σε 15 - 20 τετραγωνικά? Με τεχνητές καθυστερήσεις ήχου και μαλακή εικόνα πλησιάζεις το σινεμά αλλά δεν είναι και ότι καλύτερο.
Δεν έχω ευχαριστηθεί εικόνα σε σινεμά και τώρα ούτως ή άλλως δεν πάω πλέον πάνω από δύο φορές το χρόνο. ¶σε τα πανάκριβα ποκ κόρν.
panosxgr
09-07-2006, 13:11
Δηλαδή τελικά για να καταλάβω καλύτερα, για το σπίτι δεν αξίζει να δώσεις τόσα λεφτά απλά και μόνο για να έχεις την πιστοποίηση του THX στον ενισχυτή σου, γιατί δεν πρόκειται να δεις και μεγάλη διαφορά, ιδίως αν ο χώρος σου είναι περιορισμένος σε τετραγωνικά. Σωστά?
vipcinemas
10-07-2006, 03:40
Δηλαδή τελικά για να καταλάβω καλύτερα, για το σπίτι δεν αξίζει να δώσεις τόσα λεφτά απλά και μόνο για να έχεις την πιστοποίηση του THX στον ενισχυτή σου, γιατί δεν πρόκειται να δεις και μεγάλη διαφορά, ιδίως αν ο χώρος σου είναι περιορισμένος σε τετραγωνικά. Σωστά?
THX simainei oti o enisxutis tirei kapoies prodiagrafes,kai me to patima enos koumpiou sunergazetai me alla THX proionta.
Ean den se endiaferei auto, tote pare to ftino.
To thema einai oti oloi oi THX einai pio akrivoi. Einai omos genikotera pio akrives ulopoiiseis, eite paizeis se THX, eite se Dolby Digital.
H diafora tou Yamaha pou eixa, me tou Lexicon, einai mera me ti nuxta...
Vgale sumperasma monos sou...
Μελίδης Μιχάλης
10-07-2006, 08:44
Ρε παιδιά που πήγε το μήνυμά μου που έγραψα εχθές;
Andronidis Akis
10-07-2006, 09:23
Γιατι εγω παλι πιστευω οτι ειναι κυριως θεμα marketing.
Σάββας Σ.
10-07-2006, 10:03
Καλημερα στα παιδια του forum.
Οσον αφορα το ΤΗΧ ειναι μια καινοτομια που επινοηθηκε απο τα κινηματογραφικα στουντιο GEORGE LUCAS FILMS και αφορα την βελτιστοποιηση της εικονας και ειδικα του ηχου.Πρωτοξεκινησε για τις αιθουσες του σινεμα και τωρα διαμορφωθηκε και για τα σπιτια μας.Εγω προσωπικα δεν διαθετω ενισχυτη με ΤΗΧ,αλλα με dolby digital,dts κτλ.
Τουλαχιστον εγω οπως και εσεις θα εχετε προσεξει οτι δεν υπαρχουν παρα πολλα εργα που να ειναι γραμμενα με ηχο ΤΗΧ.Περαν του 90% των εργων που υπαρχουν για ενοικιαση ειναι γραμμενα με ηχο dolby digital.Γι αυτο παιδια και ειδικα ο φιλος panosxgr που ενδιαφερεται να μην ανησυχειται γιατι δεν ειναι κατι πολυ σημαντικο.Επισης φιλε panosxgr για τα διπολα ηχεια που ενδιαφερεσαι να σου πω οτι εχω και εγω διπολα πισω ακριβως επειδη ειχα προβλημα χωρου.Βασικα ηταν λυση αναγκης.Πρεπει ομως να σου πω οτι ειναι πολυ καλα για τους σκοπους του home cinema.Εκει που μπορει να υστερουν λιγο ειναι στην ακροαση μουσικης.Ελπιζω να βοηθησα λιγο.
Πιο κατω παραθετω ενα κειμενο σχετικο για το ΤΗΧ
THX has been called by one British
journalist "... possibly the best thing to
happen to home cinema since microwave
popcorn." Nice words. It's taken almost
20 years to earn them. As a filmmaker
who scrutinised every aspect of
production and post-production, George
Lucas was not satisfied with the sound he
heard in most movie theatres. He noted
that each theatre was different and very
few reached the highest professional
standards So, in 1980, Lucas set out to
develop and implement a set of quality
control criteria for theatres. His goal was
to ensure that his films, as well as those of
other filmmakers, would be accurately
reproduced for moviegoers for whom
sound was an important part of their
overall film enjoyment.
Three years later THX, named after Lucas'
first feature film, THX 1138, had been
developed and THX systems were
installed in two theatres for the premiere
of RETURN OF THE JEDI. Today, more
than 2000 theatres and dubbing stages
around the world meet THX requirements.
As a further boost to film presentation
quality, the THX Theatre Alignment
Program (TAP) was created in 1983 as a
service to filmmakers and studios. TAP is
the industry's most comprehensive quality
assurance program whose services
include reviewing release prints for image
and soundtrack quality, distribution to
theatres of technical facts about a film and
proper equipment alignment, on-site
equipment alignment, and a toll-free
phone number and web site that theatre
patrons can contact to report presentation
problems.
Lucasfilm began research on the Home
THX audio system in 1986; it would take
four years of work before the Home THX
Program would be introduced. Today,
there are more than 45 licensed
manufacturers producing THX Certified
components for Home Theatre.
THX also certifies home video software
through the THX Digital Mastering
Program, ensuring that DVD software,
laser discs and VHS videotapes provide
the best image and sound quality possible
through the use of patented THX
technology and our unique quality control
expertise.
Based in Marin County, California,
Lucasfilm Ltd. is now one of the leading
film and entertainment companies in the
world, with a list of all-time movie favourites
that includes the STAR WARS and
INDIANA JONES trilogies. Combined,
these features have won 16 Oscars and
garnered many more Academy Award
nominations. 1982
George Lucas requests a
state-of-the-art post production
facility. After extensive research,
Lucasfilm engineers develop the
ideal environment for mixing rooms,
from which the THX System is
developed. First THX mixing room
opens at Lucasfilm.
1983
THX Division of Lucasfilm, Ltd is
created. THX System is unveiled to,
and adopted by, the Hollywood
community. Two THX theatres open
in time for the release of RETURN
OF THE JEDI.
1990
Home THX Program is introduced;
Lucasfilm engineers work with
leading A/V manufacturers to
incorporate Home THX technologies
into consumer equipment.
1993
THX Laser Disc Program is created;
quality control services are offered to
studios for films during video disc
production.
1994
Complete Home THX System
demonstrates the 5.1 digital format at
the Winter Consumer Electronics
Show.
1996
Laser Disc Program expands to
include videotape and DVD. Name is
changed to THX Digital Mastering
Program.
1997
More than 1,600 certified movie
theatres and mixing rooms are
created around the world; some 250
certified Home THX products appear
on the market.
1998
THX announces certification standard
for DVD players
Για να έχεις ΤΗΧ σύστημα πρέπει όλα να είναι ΤΗΧ.Από ενισχυτή μέχρι και τα ηχεία.Έχω ακούσει σύστημα με krell και ηχεία μόνο για σινεμά jamo thx ultra2 και μου έχουν ξεκολλήσει τα αυτιά.Αλλά όταν άκουσα μουσική με τα ίδια ηχεία έβαλα τα γέλια.Δεν μπορείς να τα έχεις όλα,και πόσο μάλλον μέσα σε ένα σαλόνι.Ο δικός μου ενισχυτής (ΑΧ10 PIONEER THX ULTRA2) παίζει καλύτερα με ΤΗΧ όταν και το δισκάκι είναι επεξεργασμένο έτσι.Αλλιώς DD.Όμως και πάλι δεν έχει καμία σχέση με ΚRELL η LEXICON.¶ρα ότι πληρώνεις παίρνεις.:grandpa:
panosxgr
11-07-2006, 00:37
Παιδιά, σας ευχαριστώ καταρχήν όλους για την βοήθειά σας και τις απόψεις σας. Αυτό που θέλω είναι να έχω έναν ικανοποιητικό ήχο home cinema μέσα στο σπίτι. Δεν ζητάω και τα πιο advanced, που σαφώς είναι και πιο ακριβά. Απλά ρωτάω αν τελικά κάνει τόση μεγάλη διαφορά ένας ενισχυτής προδιαγραφών THX ή όχι? Γιατί δεν θέλω να δώσω 400-600 ευρώ παραπάνω και στο τέλος ίσα-ίσα που λέει ο λόγος να καταλαβαίνω μια μικρή διαφορά στην ακουστικη!!! Και τέλος με ενδιαφέρει περισσότερο ενισχυτής για home cinema κι όχι τόσο για ακρόαση μουσικής.
Μελίδης Μιχάλης
11-07-2006, 08:34
Ψηφίζω όχι ΤΗΧ. Σκέτο Dolby Digital και DTS.
Και ακούς καλά και γλυτώνεις λεφτά.
ΒΛΑΣΙΔΗΣ
11-07-2006, 08:35
Vipcinemas μπορείς να γράφεις χρησιμοποιώντας ελληνικό πληκτρολόγιο ή όχι; Αν ναι, θα σε παρακαλούσα να το κάνεις, διότι τα greeklish είναι πολύ δυσανάγνωστα και κουράζουν.
Συγγνώμη, το σκεπτικό είναι αν αξίζει ή όχι να δώσεις παραπάνω λεφτά κατά βάση για THX; Ούτε να το σκέφτεσαι (κατά τη γνώμη μου). Για μεγαλύτερη ισχύ ή κάποιες χρήσιμες λειτουργίες να πω, αλλά για το THX μόνο... δε λέει! Όπως επίσης δε λέει (και πάλι κατά τη γνώμη μου) να επιλέξεις μεταξύ δύο ενισχυτών αντίστοιχης κατηγορίας τιμής βάσει του αν ο ενισχυτής είναι THX certified ή όχι (αν υποθέσουμε ότι ο ένας δεν είναι).
Σάββας Σ.
11-07-2006, 19:26
Συμφωνω με τον Μιχαλη.
Panosxgr να παρεις ενα καλο ενισχυτη που να εχει dolby digital και dts και θα εισαι μια χαρα.Σε αυτη την κατηγορια υπαρχουν καλοι ενισχυτες και φτηνοι.Οπως ανεφερα και στο προηγουμενο post τα πλειστα εργα που βρισκεις για ενοικιαση ο ηχος ειναι γραμμενος σε dolby digital.
Μελίδης Μιχάλης
11-07-2006, 20:51
¶λλωστε σε λίγο με τα BLUE-RAY και HD-DVD που θα έχουν 8 κανάλια συνολικά, πάλι θα αλλάζουμε ενισχυτές, όχι υποχρεωτικά όλοι, αλλά εγώ π.χ. θα αλλάξω
panosxgr
11-07-2006, 22:30
Παιδιά σας ευχαριστώ και πάλι όλους για το χρόνο σας και τις πολύτιμες πληροφορίες σας. ΑΠό ότι βλέπω συμφωνούμε οι περιοσσότεροι ότι δεν είναι ανάγκη να πάρεις έναν ενισχυτή μόνο και μόνο επειδή είναι προδιαγραφής THX. Την ίδια καλή δουλειά μπορεί να σου κάνει κι ένας άλλος, πιο φθηνός σαφώς και στην μισή τιμή περίπου. :grandpa:
Τέλος θα συμφωνήσω και με τον Μιχάλη ότι επειδή η συγκεκριμένη περίοδος είναι περίεργη, όσον αφορά τα formats (Blue Ray ή HD-DVD) και θα έχουμε τότε 8-κάναλο ήχο, δεν συμφέρει και τόσο σε μια πολυέξοδη αγορά ενός ενισχυτή. :music-smiley-005:
ακομα ενα προιον απο τον λουκα ,που αποτελει συνολο υπηρεσιων
πληροφοριες www.thx.com
για τα νεα φορμα
τα πισω πλεον απομακρινονται μιας και δεν παιζουν μονοφωνικο σημα
http://www.thx.com/home/setup/speakers/dolby.html
απλα τα αναφερω
http://www.thx.com/products/home/tests/pow_testing.html
http://www.hometheaterhifi.com/volume_13_1/feature-article-thx-1-2006-part-1.html
επειδη ειναι κακο να νομιζουμε
εδω αρκετα θεματα περι thx και δισκων με σταμπα
http://www.hometheaterhifi.com/features/technical-topics/thx-certification.html
επειδη ειναι κακο να νομιζουμε
εδω αρκετα θεματα περι thx και δισκων με σταμπα
http://www.hometheaterhifi.com/features/technical-topics/thx-certification.html
Αργύρη ότι και να πεις, όλοι νομίζουν ότι το THX είναι μια απλή στάμπα ποιότητας, το έχω αναφέρει πολλές φορές, ιδίως στους ενισχυτές υπάρχουν εξαρτήματα που διαφοροποιούν τον ήχο!!!!!
το τι νομιζει ο κεθενας εχει να κανει με τις γνωσεις του
ο λουκας ειναι ο μονος που παιζει επεξεργασια ηχου εκτος απο τα dolby-dts
σφραγιζοντας συσκευες με την επεξεργασια thx ultra 2 cinema
αλλος μεχρι τωρα δεν
Technical Articles
THX-Certification
Written by Brian Florian
Saturday, 31 December 2005 16:00
Article Index
THX-Certification
Part II
Part III
Part IV
Part V
Part VI
All Pages
Introduction
THX is almost a quarter century old, and its Consumer Branch has been around since 1990, yet people still do not have a proper understanding of THX. Maybe that's THX's fault, maybe it's ours (the press), maybe it's the sales people's at the local A/V store. Probably, it is a combination of all three, so we're going to at least do our part and tender to you, our readers, this explanatory article.
We will try and dispel the myths, reiterate the truths, and of course give you our slant on the whole thing as well. If you think you know THX, you might be surprised at what you read here. We're in for quite a ride, so let's get comfortable.
In the Beginning . . .
There is now an urban legend that George Lucas walked into a small town movie theater one day and watched Star Wars. The sound system was so poor and so out of alignment that no one could understand the dialogue and the picture was a mess. He decided then and there to found THX, a company which would push out to the world a standards based certification program for movie theaters so that artists could have confidence that their work was being presented as they had crafted it.
True story? In essence at least, if not in fact. Regardless, it's a cute fable which makes for a nice ice breaker.
No, THX grew out of the development of Skywalker Sound, the state of the art post production facility that George Lucas created with the profits from the first Star Wars. Skywalker was to be (and to this day is) the high water mark for facilities of its kind. In developing the the various setups for Skywalker, Tomlinson Holman and the Lucasfilm engineers, through experience and research, defined the ideal standard for mixing rooms, incorporating all the existing international standards set down by SMPTE, ITU, etc. These became the very first THX standards. The year was 1982. When the word got about about just how good things were at Skywalker, the other studios in California asked if their facilities could be upgraded to the same standard. The concept of being "THX-Certified" was born.
Once they started bringing other professional facilities up to their standard, THX realized that what they were doing could be "pushed out" to the local movie theaters, creating an end-to-end consistency in the way movies are crafted and then presented. Everything from the light level on the screen, the background noise level in the room, the quality of the theater and all its equipment, even the quality of the prints and the consistency thereof come under the THX TAP, or Theater Alignment Program. In 1983, the AVCO cinema in Los Angeles was the first theater to receive THX certification.
In the years to come, Tom Holman was not idle. While listening to master tapes of film sound elements at home on top quality hi-fi gear, he and the sound designers and mixers weren’t happy, because the same tapes played in both spaces didn't "translate" accurately. This led Tom to the first set of specifications for THX consumer gear, which we will talk about at length in a moment, and the subsequent launch of the first THX home controller in 1991 (the Technics SH-THX10).
Myth: "THX DVDs have THX sound on them which requires THX equipment to play."
Reality: A THX DVD is one which has been mastered under their supervision to the industries highest standards. There is no proprietary format or content.As VHS, LaserDisc, and the whole home theater concept began to take hold, THX was approached to monitor the transfer of film to video. In 1993 the THX Digital Mastering program was launched, providing the service of consistently applying the technologies and specifications of best-practice telecine processes (transferring the image from one medium to another: film to film, film to tape, film to computer, etc.)
A DVD which is THX Digitally Mastered is not technologically different from any other. You do not need THX equipment to play the disc or realize some special feature on it. THX Digitally Mastered simply means that the film has been transferred under technically correct and consistent processes. In virtually every case the film's director, art director, or sound designer (or all three) are present and are free to make artistic choices, with THX's role being one of supervision, ensuring that those choices are being made under the correct circumstances and that they translate as the artist intended to end audience at home.
Quick sidebar: In the time before DVD I had bought the VHS of James Cameron's Titanic. It did not take long to realize the audio on the tape was reversed left to right. I e-mailed THX and within a day I got a phone call asking if they could send FedEX to pick up the tape and drop off a replacement (along with a T-Shirt). Being a THX Digitally Mastered title, they wanted the tape so that they could figure out exactly which duplication machine it was made on and correct it. True story!
THX at Home
THX Home Cinema is fundamentally about one thing: The technically competent and correct reproduction of a piece of audio/video work. Period. THX is able to achieve this through a very precise, defined specification for hardware which goes well beyond conventional metrics, as well as the incorporation of proprietary technologies and processes that are integral to the system. Their intention is to offer the consumer a system with baseline performance which closely replicates the monitoring environment in the studio. Once that baseline is in place, the consumer can change things any way they like knowing that they can always go back to a baseline that's pretty darn close to the original recording environment.
You may have read the usual diatribe about the goals of THX being:
Intelligible dialogue
Pin-point localization
Enveloping surround
Accurate frequency response
Generous dynamics, soft as well as loud
Accurate coverage ("Every seat is a good seat.")
Yawn! That's all well and good, but frankly that should be the goal of ANY product which makes any sort of "hi-fi" claim (though achieved by few). Performance metrics are obviously the heart and soul of THX certification, but the real benefit of THX for the consumer is exactly how these standards and design elements were arrived at. Holman knew that the source tracks sounded different in a home space, despite him listening to them over absolute state of the art home systems of the time. It would have been easy to say "lets just do the same thing we do at Skywalker sound", but that is utterly unrealistic, even for the very wealthy (and I don't know if this was on George's mind, but technically competent and correct presentation of movies should not have to be the province of millionaires alone).
So in addition to simply drawing on the technologies and specs already developed at SkyWalker for professional facilities, THX Home Cinema did something more: They addressed the REALITIES of the consumer market. They realized that consumers would not put wall-to-wall acoustical treatments in their home, or install an array of 12 surround speakers. They realized that for the most part, home theater is "living room theater". Even so called "dedicated" home theaters have more in common with living rooms than they do with Stage C at Skywalker. As we'll see, everything about a THX piece goes back to this fundamental.
A few words on "Reference Level"
Before we start talking about the pieces and parts, we first need to take a quick refresher on the concept of "Reference Level", as you are going to be hearing that term quite a bit in the coming paragraphs. Simply stated, Reference Level is a standard, known, predictable and reproducible playback volume level. When movie sound tracks are crafted, they are done so on systems which are locked at this level. The sound artist does not play around with a big volume knob when doing his/her work. If the sound artist wants something to be loud, they make that sound loud within the sound track. When they want something to be soft, they make that element soft within the sound track. Movie theaters set their playback level by the exact same rules, so when the movie is shown, you hear EXACTLY what the sound artist heard when they were making the piece. Loud, soft, in-between, it's all there, and no one touches the master volume knob over the course of a two-hour movie.
To achieve THX certification, components must play at this reference level without breaking, distorting, buzzing, rattling or any other distracting effects.
Reference level is by any definition, objective or subjective, quite loud. It basically mirrors the dynamic range of the studio system, which in the case of all movie sound tracks, is 105 dB. Any single channel of the system is calibrated to play 0 dB FSD (the loudest sound the sound track can contain) at 105 dB (115 dB for the LFE channel). While that is really, REALLY loud, its important to remember that there is 105 dB of dynamic range and the artist can put a sound at any level they want. So while a system's volume may be set to reference level, dialogue within the sound track can, and most often is, at a normal, natural level. Reference level, with the dynamic range available, permits a movie to have that normal, natural dialogue, and then suddenly a spectacular, loud car chase without anyone touching the volume control. Every element in the sound track comes out as it should.
Now, having said all that, watching a movie at reference level in a home theater is almost never done. It can be extremely loud to begin with, but the close spaces typical of home theaters make it perceptibly even more so. Reference level is still very important in home theater though for several reasons. Because it is the absolute loudest a sound track should ever be played, its fairly intuitive that its a good idea to have a system that can competently go that loud. It gives you a sort of "safe maximum" volume level, even though you may never push it that high. Even more important though is knowing what volume you are at RELATIVE to reference level because if we go too low, we literally lose the quietest sounds since they are pushed below the audible threshold, surrounds lose their presence, the perceived spectral distribution of the track is altered, and dialogue intelligibility suffers.
The THX Controller
Metrics Tested on THX Controllers:
Reference Output Voltage
Voltage Gain
Input Impedance
Gain Control Range
Gain Tracking of the Master Gain Control
Overload Source Voltage
D.C. Bias Current at the Input
Maximum Output Voltage of Low-Level Outputs
Output Source Impedance
Polarity
D.C. Offset at the Output
Frequency Response Deviation
Signal Time Delay
Noise Output Voltage
Input Level Indicator (Clipping Indicator)
Video Path Switching
Video Level
Sync Level
Bar Tilt
Pulse/Bar Ration
K-Factor (K-2T)
Frequency Response Amplitude (0.5 to 4.2 MHz)
Group delay (0.5 to 4.2 MHz)
Chroma Gain
Chroma Delay
Differential Gain
Differential Phase
Noise
Video Conversion
Harmonic Distortion and Noise
Difference-Frequency Distortion
Dynamic Range
Digital Data Sampling Rate Support
Input Mode Control and User Interface Design
Input Mode Switching
Automatic Detection of Data Types
Output Modes and Post Processing
Equalization and Tone Controls
Signal Headroom
Bass Management
Filter Characteristics
LFE Channel Level Scaling
Loudspeaker Position Time Synchronization
Auto Calibration
Auto Setup
Output Levels
Dialogue Normalization
We refer to the THX controller as both dedicated surround sound processor/preamplifiers, and the processing section of integrated receivers.
There are two distinct halves to the certification of a THX Controller. The first is the actual performance metrics, shown in the table at right. As you can see, it goes well beyond any review you've ever read, including our own best. What is absolutely key here is that these are not simply "minimums" a product must meet, but many are actually design considerations. For example, the line level outputs must not only meet a certain voltage capability, but their output voltage must be a certain level relative to an input signal, be it analog or digital.
Things like this are important because not only must each THX piece be excellent at what it does, but it must also work in concert with the other pieces to create a synergistic whole. By predetermining the output voltage for a reference level signal, as well as the output impedance, the amplifiers (which we'll talk about in a minute) can be designed and spec'ed in anticipation of that output, and the S/N performance of the WHOLE system is assured, without any "matching" effort required by you, the end user. THX controllers are a perfect match for THX amplifiers, end of story. You can think of this in terms of dynamic range windows: when they all line up, you get maximum performance all the way through.
The second, somewhat distinct aspect of certification of a THX Controller is the inclusion and implementation of various design features, including the THX Post-Processes. Here we are starting to get into what I was previously saying about THX addressing the realities of home theater.
All THX Controllers include one or more THX modes which are NOT surround sound decoding schemes or codecs. When engaged, the THX modes apply a set of processes or filters to the soundtrack AFTER it has been Pro Logic, Dolby Digital, or DTS decoded.
The most basic THX mode is called simply "THX Cinema". This mode includes:
Myth: "Re-Eq is required because movies are mixed for theaters which are aligned to the X-Curve and have perforated screens which attenuate the high frequencies."
Reality: Re-Eq is a simple, rational filter to address the fact that home theaters rarely will have proper acoustical treatments.Re-Eq, or ReEqualization. Ironically this is the best known, and the single most misunderstood element of a THX processor. Remember we said that Tom Holman found sound tracks sounded different in the home-style rooms? One of the reasons was that they were coming across as too bright, which is a fancy way of saying there is too much treble. Why? The equipment was excellent, high fidelity stuff. The "culprit" if you will, was the room itself. Lacking the extensive acoustical treatments of professional sound and production rooms, high frequency energy is bounced around and sustained. At elevated playback levels (at or close to reference) it gets subjectively worse and you start to squint. Here is the very first example of what THX does to address the realities of the consumer market: THX knew that no one would be talked into turning their family's living room into a sound studio. Instead, Re-Eq simply applies a rational, mild roll-off of the high frequencies. It's that simple.
Everything you have read about movie sound tracks themselves having too much high frequency energy, including what THX's own marketing department has put out there, is inaccurate. The treble is not exaggerated by the sound artist to overcome the perforated screens at the theater (the theater does its own EQ to address that). The tracks do not have too much treble because movie theaters are aligned to something called the X-Curve. We have an entire article on the history of cinema sound system curves which discusses the relevance of the X-Curve, and why it has absolutely nothing to do with why sound tracks sound too bright in a home. Please feel free to digest it when you are done here.
Another quick sidebar: For many years, my living room was my home theater. As a reviewer, I had the privilege of playing with some very nice amps, preamps, and more speakers than I care to remember, but regardless of the caliber of equipment, movies just sounded harsh without a THX controller and Re-Eq. As soon as I created a serious screening room complete with extensive acoustical treatments, I found Re-Eq necessary only at the absolute loudest output levels. Go figure. This is why our Secrets SSP Benchmark specifications require that THX controllers offer the option of turning Re-Eq off independently.
Myth: "THX's De-Correlation was made obsolete by the discreet surrounds of Dolby Digital."
Reality: For Dolby Digital and other 5.1 formats, De-Correlation became Adaptive De-Correlation, intelligently applying itself when discreet surrounds contain mono content.Adaptive De-Correlation / De-Correlation. The THX Home Theater program was launched in 1991 at a time when Dolby Pro Logic, the consumer equivalent of Dolby Stereo, was the only thing going in surround sound. While virtually all surround sound configurations used two surround speakers, Pro Logic decoding yields only one surround channel, meaning both speakers get the exact same signal. This can cause the sound to be "in your head" instead of pleasantly surrounding you as it should, or if seated off center, can cause the surround sound to collapse to the speaker nearest you. THX's De-Correlation very subtlety alters the phase and time relationship of the two rear speakers so that they don't sound absolutely identical, maintaining the spacious nature the surrounds are suppose to have.
When Dolby Digital hit the consumer market, De-Correlation was NOT made obsolete by the 5.1 format's two discrete surround channels. Many, many surround sound effects in sound tracks are still input equally to both surround channels so that it fills the surround space, and as such, the system can suffer the same pitfalls as Pro Logic's mono surround channel.
De-Correlation was updated to Adaptive De-Correlation, which, as the name suggests, adapts to the incoming signal. Content which is identical in both channels undergoes De-Correlation, the rest of the sounds intentionally steered to one side of the other remain as such.
Timbre Matching. A given sound in front of us sounds different if sourced behind us. That's because of the shape of our outer ear and is part of how we can tell where a sound is coming from (the other is the relative amplitude in our two ears). In home theater though, sounds which are panned from the front of the room to the back, or vice versa, can lose continuity because of this auditory reality, since halfway from rear to front the panned sound is actually coming at us from BOTH in front and behind. Timbre Matching applies a generic HRTF (Head Related Transfer Function) to reshape the surround sound speakers' sound so that it is a closer match to what we hear from the front channels, closing the "seam" between the front of the room and the rear.
Also, part of the THX Cinema mode, and indeed any THX mode (we'll talk about some of the others later), is that it "overrides" any superfluous alterations of the program. For example, if bass or treble controls have been engaged, or an alteration made to the level of a speaker (outside of the master calibration), any such "impurities" are zeroed out whenever the THX button is pressed, assuring you that the movie is in fact being presented as it should.
In 1999, a new THX mode was added to the repertoire: THX Surround EX. It includes all the aforementioned processes, and simply puts them on top of Dolby Digital Surround EX decoding, so its not really a separate THX mode, but we mention it here because THX actually co-developed Surround EX.
Dolby Digital Surround EX, as it is called in movie theaters, was jointly developed by Dolby and THX. It applies a Dolby matrix decoder to the two surround channels, and decodes a third channel between them (the center-surround or rear channel as it is sometimes called) yielding a "6.1" configuration (though the 6th channel is not actually discrete). Soundtracks encoded in this format became available on DVD, and the first consumer systems to decode them were THX units with THX Surround EX (the EX decoding later became available on non-THX equipment under the name of Dolby Digital EX).
One major design consideration of the THX Controller is the bass management system. While some form of bass management is now common in consumer electronics components, THX designed into their program a very specific bass management system right from the start, back in 1991 when the phrase "bass management" was not even well known. We're going to talk more about it in the speakers section of this article, but suffice it to say for now that the THX Controller has to implement bass management in a very specific way, using a specific set of slopes, to accommodate and make the most of the speaker system. The THX Controller may also provide a bass peak limiter, a feature which allows you to set a maximum signal level sent to the sub. Again, knowing the realities of home theater and that not every situation would permit a subwoofer to be placed in the best spot with maximum loading, THX knew that even a THX sub could be overdriven. The Bass Peak Limiter allows you to "protect" a subwoofer in such situations, taking away the fear you may have of pushing your volume a little closer to reference level. While at one time required by THX, this feature is now an option implemented at the manufacturers discretion because, by and large, powered subwoofers have their own limiter/protection.
Another key element that THX requires for receivers and SSPs is the reference setting for volume control. When a system is calibrated according to the manufacturer’s instructions, "0.0 dB" on the volume control corresponds to reference level playback. In turning the volume down, the volume level is expressed in -dB, or how many dB below reference level you are.
Metrics Tested on THX Amplifiers:
Reference Output Voltage
Voltage Gain
Output Current
Output Source Impedance
Overload Restoring Time
Stability with Capacitive Load
Harmonic Distortion and Noise
Modulation Distortion
Difference-Frequency Distortion
Noise Output Voltage
Phase Response
D.C. Offset at the Output
Hum
Crosstalk
Acoustic Noise Level
Mechanical Noise
Input Sensitivity
Input Impedance
Output Impedance
Load Impedance Range
Voltage Output Capability
Current Output Capability
Transient Output Capability
Transient Overload Recovery Time
Asymmetrical Clipping
Frequency Response
Phase Response
Phase Margin
Time
Total Harmonic Distortion
Intermodulation Distortions
SMPTE IM Distortion
IHF IM Distortion
DIM 30 Distortion
Noise
Hum
Radiated Interference
Conducted Interference
CrosstalkSeparate Amplifiers and the Amplifiers in Receivers
It's too easy for people, including us here at Secrets, to say "get as much power as you can", "you should have at least 100 watts per channel", and so on. While having more power than you need, even lots more, is not a bad thing and in fact is much preferred by speaker manufacturers (in that more speakers are damaged from underpowered amps driven to clipping, than ones which were fed too much power), the reality is that power, REAL power, is expensive. The question is, how much is needed to drive a reasonably efficient speaker in a reasonably sized room to reference level and still have adequate headroom left over?
THX has done something which, to my knowledge, no one else in the industry has done, at least on the scale which they have done it: They have logged the dynamic content of virtually every piece of finished sound track they can get their hands on (we're talking hundreds of sound tracks here) and from that developed a practical "dynamic" requirement for multi-channel power amplification.
All of the THX amplifier tests use bursts in various combinations at various frequencies, at various lengths of time, repeated cycles and combinations of speaker loads. This enables THX to uniquely qualify an amplifier, particularly a receiver, as capable of playing sound tracks to reference level (given of course a certain speaker efficiency and room size limit).
Make no mistake: THX Ultra power amplifiers tend to be very powerful. We've never seen one with less than 100 watts/channel continuous RMS, full band, all channels driven, BUT because of the "practical sum" THX has defined for themselves, even seemingly modest receivers under $1,000 can get THX Select2 certification and provide a satisfying experience for a lot of people who can't afford a stack of THX Ultra power amps (we'll talk about Select- vs. Ultra-Certification a little later).
But it's not all about raw power. As we mentioned when talking about the THX Controller, the input and output levels and impedances of everything "THX" are within a certain tolerance so that all pieces "talk" to each other synergistically. One can see from the metrics list above that everything down to the hum of the power supply transformer must be in check to be THX certified. Yikes!
Speakers and Subwoofers
Metrics Tested on THX Speakers:
Axial Frequency Response Analysis
Directional Characteristics
Sensitivity
Impedance
Harmonic Distortion
Low Frequency Cut Off
Phase Angle
Stray Magnetic Flux
Maximum Output Level
Acoustic Noise Level
PolarityBack once again to the realties of the consumer market, and once again knowing that a living room will remain a living room, much of what makes THX speakers unique and special has to do with addressing this fundamental tenet.
Starting with the more pedestrian facets of speaker performance, it almost goes without saying that THX speakers must have no compromise in terms of neutral frequency response, power handling, output capability, and the often overlooked dynamic, or transient, response.
Any good speaker should be able to make such claims. THX speakers are designed as such and can, without hesitation, be driven (by a THX amplifier) to reference level. However, THX speakers go beyond this by designing in certain features and characteristics which put them in a position, as a system, to excel at faithfully reproducing the program in that "living room home theater" we keep talking about.
Main/Front Channel Speakers
Myth: "THX speakers only sound good for one person in the room"
Reality: The opposite is true: while THX speakers must have a narrow listening window in the vertical to attenuate reflections from the floor and ceiling, they must simultaneously provide a VERY wide horizontal listening window, ensuring good sound for everyone in the room.THX Speakers have to meet very specific design goals in terms of their radiation pattern: In the horizontal, they must have a very, VERY wide listening window so that everyone across the couch hears good sound. At the same time they must have a limited, or narrow, listening window in the vertical because reflections off the floor and ceiling can smear and distort the sound in the time domain.
Again, back to THX realizing people will not likely acoustically treat their ceilings so that conventional speakers can be used, recently (as of Ultra2) these requirements have changed in terms of emphasis (less on vertical roll-off, more on off-axis linearity), but we'll talk about that when we cover Ultra2 a little later.
The other major design characteristic of a THX speaker is that it is a dedicated satellite speaker which REQUIRES the support of a subwoofer. The THX speaker system therefore is categorically a sub/sat system.
Full-range speakers are nice. I love full-range speakers, but they have no place in a multi-channel sound system if we want to have any chance of realizing a flat, uniform reproduction. Again, this goes back to acoustics: it is very difficult to get a similar low end response from five speakers spread out through a room, or even just three across the front of it, even if all the speakers are identical, because their different physical positions in the room are going to result in different acoustical loading (i.e., the bass response will not be the same from speaker to speaker). By summing all the bass in the sound track and sending it to a subwoofer, or set of subwoofers (all getting the same signal), the system's reproduction of bass from each channel will be uniform.
The other benefit of a sub/sat system, known by experts such as Ken Kreisel long before THX and home theater, is dynamics. By asking one amp and speaker to cover the upper audible range (the main speaker) and a completely different one the bottom, both do a better job than either could if it was trying to do the whole shebang.
Remember we said bass management was integral to the THX controller, long before a time when it was common in consumer equipment? Now we're getting to the heart of that. These days, all processors and receivers offer bass management, but what slopes do they use? What crossover frequencies are offered? Will it all work with your speakers? If you have a THX Controller with THX speaker, you don't have to worry about this. Your stuff will work together famously because it was designed as such from the ground up.
For you Techies:
The THX crossover consists of an 80 Hz, 4th order Linkwitz/Riley filter alignment, and it was not chosen lightly or without serious consideration. As the crossover frequency increases, it becomes harder to blend the subwoofer with a satellite, and the subwoofer becomes more difficult to audibly "hide". At the same time, as the crossover frequency increases, distortion from the satellite decreases, the total dynamic range increases, and loading the room for the flattest response becomes much easier. The logic of the 80 Hz crossover point is that it's high enough to ease demands on the speakers and amplifier, but low enough to make the whole setup work without a tremendous headache. The 4th order (24dB/octave roll-off, 6dB/octave/pole) Linkwitz/Riley alignment not only offers a steep slope, but one that immediately transitions to that slope, maximizing the benefits of that slope near the crossover point. The high-pass side minimizes excursion and power requirements, while the low-pass minimizes more localizable content at higher frequencies.
To correctly achieve this, THX satellite speakers are sealed systems with an 80 Hz –3 dB low frequency cutoff (preferably with a Qtc of 0.71). The electronic high-pass filter applied to them is an 80 Hz, 2nd order (12dB/octave) Butterworth alignment. The speaker and the filter sum to a 4th order Linkwitz/Riley roll-off which matches the electronic filter applied to the subwoofer, and an excellent crossover is achieved.
Surround Channel Speakers
Myth: "Di-Pole surround speakers were used because of Dolby Pro Logic's mono surround channel and are obsolete with Dolby Digital 5.1."
Reality: Di-poles are used to emulate the multi-speaker arrays of movie theaters. It is Adaptive De-Correlation (see THX Controller section above) which addresses mono surround channel issues.The surround channels in movie theaters are reproduced by arrays of speakers, anywhere from four to sixteen speakers on either side and the same again across the back. What is the best way to reproduce that surround sound effect at home? The answer would be to use twelve or more surround speakers of course! THX knew that no one would even entertain such a suggestion so for their surround speakers they mandate a dipole design.
A dipole, or dipolar speaker is one which fires sound from two opposing sides, or poles, where each pole is out of phase with the other (meaning that while one side is moving outward, the other is moving inward). In a home theater, they are generally placed to the side of the main listening area with the poles firing to the front and back of the room, never directly at the listener. The result is that the sound bounces off the walls of the room, successfully emulating the speaker arrays of the movie theater.
Movie theaters and large dubbing stages use speaker arrays for uniform, enveloping surround sound. Dipoles in a home theater do an admiral job of emulating that sound field using just two properly placed speakers.
THX dipoles must meet a strict requirement of flat total power output, which means the sum of the sound coming spherically from all around the speaker must be smooth, as opposed to the sound coming from just one of the poles. This is not easy for a designer to do, and there are plenty of examples of poorly designed dipoles (none of which are THX-Certified).
In general no one will deny that dipoles do an admirable job of emulating the multi-speaker arrays of movie theaters, but many a journalist has gone on record as saying they are not suitable for multi-channel music and that monopole (a.k.a. conventional) speakers must be used.
Myth: "THX Surround speakers are ok for movies but not music"
Reality: THX Surround speakers, with their flat total power response, provide excellent, pleasing results for BOTH movies and music.Research done by Tom Holman in 1986 (involving both technically savvy audio engineers as well as laypeople) revealed that while some sound engineers preferred mono-poles in certain situations only for their ability to "expose" defects such as pops and dropouts, when it comes to actually listening, all persons showed a clear preference for a diffuse ambient surround sound field when the test involved properly designed dipoles level matched to the monopoles they were being compared to. The "bad-rap" dipoles get is often due to evaluations clouded by the use of improperly designed dipoles and a failure to level-match them with monopole counterparts.
There are many ways of getting diffuse sound, including strategically positioned and angled monopoles, but dipoles are simply the most practical solution for a consumer (once again, THX is dealing with the realities of the market).
Ultimately, the argument of monopole vs. dipole surrounds is one of inevitable compromise, with THX and others selecting the dipoles as the preferable of the two. These days, THX certifies mono, di and bipole surrounds, recognizing that each has its appropriate use. To achieve that elusive balance of envelopment with some directionality of special effects or game sounds in wildly different rooms, it's necessary to choose the design that works best. THX still puts dipoles first as great problem solvers in many typical rooms, but they acknowledge that other designs have their uses.
Subwoofers
THX-Certified subwoofers embody the usual tenets of bass, which is both high in output and low in distortion. Back to Reference Level, a THX subwoofer has to be able to reproduce the bass from all the channels of a sound track at Reference Level (within a room size limitation) without distress or calling undue attention to itself. Beyond that, like regular power amplifiers, the built-in amplifiers of THX subwoofers must conform to an I/O spec that matches the THX controller. In particular, voltage levels are much higher than for the other line-level signals, several times higher in fact! This gives the subwoofer the 20 dB headroom it needs over any other channel (because it carries the bass from all channels, plus the LFE channel, all summed together).
In terms of depth, THX subwoofers are traditionally anechoically flat to 35 Hz with a shallow roll-off thereafter, allowing room-gain to make up the difference for a perceived flat in-room response. That has changed somewhat with Ultra2, which we'll get to in a moment.
Projection Screens and Other Things
THX also has a specification and certification for perforated, acoustically transparent screens, which obviously involves ensuring they really are acoustically transparent, or at least that the loss incurred is predictable and uniform such that it can be easily compensated for. Light loss must also be minimized.
Although of little interest now, THX at one time had certification of LaserDisc players.
Rane and AudioControl had THX-Certified equalizers, which are still prized pieces.
THX Select vs. Ultra
In 1999, THX launched THX Select, and renamed what had previously been called just THX to THX Ultra.
Whereas THX/THX Ultra was specified and designed for rooms "up to" 3000 ft3, THX Select took that requirement down to 2000 ft3. Both the requirements of the amplification and the output of the speakers were scaled back appropriately, placing THX in the hands of a whole new audience who could not have otherwise afforded it.
When it comes to amplification, continuous output tests are run on up to one, four, and five channels (simultaneously) of an Ultra product, but only one at a time on Select. With all products, the dynamic amplifier tests are done on up to all available channels. Ultra amplifiers must be stable on all channels to 3.2 ohms and swing an 18A peak, while Select products must be stable into 4 ohms (front channel) and 8 ohms (surrounds), and swing peaks of 12.5A and 6.2A respectively.
So, right off the bat, Select amplifiers have a lower bar to reach, but ultimately in meeting it, they will still cleanly drive any reasonably designed speaker to reference level in a Select-size room. What we are talking about here is the idea that the lower powered equipment can get a THX certification that will assure consumers that the really affordable stuff has met certain standards like the high-end equipment.
The THX Controller section features are no different between Select and Ultra, which is why you'll never see a Select preamp/processor (SSP), only Select Receivers.
THX Select speakers, other than having reduced output requirements as compared to Ultra, do not have the same requirement for a narrow vertical listening window, because in a Select-size room you are apt to be close to the speakers and floor/ceiling reflections are that much less of an issue. While THX Select surround speakers are still recommended to be dipole in design, conventional monopole designs are permitted for a few reasons, the main being that dipoles are, by their nature, expensive (having twice as many drivers as a conventional monopole), which goes against Select's mandate for a more affordable system.
Select subwoofers of course have reduced output requirements as compared to Ultra.
Ultra 2: The Second Age
In 2001 THX revamped their Ultra program into Ultra2.
Ultra 2 Processing
One of the catalysts of the revamp was the enthusiastic consumer embrace of THX Surround EX and the 7.1 speaker layout that it implies, but Surround EX decoding only "works" well if the sound track was implicitly encoded for it, otherwise the surround sound filed tends to collapse to the center surrounds. At the same time, multi-channel music was becoming more of a presence in the market, and speaker arrangements for music vs. movies were at odds with each other, with movies favoring a very diffuse sound field produced from the sides, and music favoring more in-your-face surround, with the source being more "behind" you.
With Ultra2, THX came up with a single system and speaker configuration which would work for everything.
Whereas THX Surround EX simply called for two more surround speakers at the back of the room for the then new sixth channel, Ultra2 replaced them with a pair of monopole speakers specifically placed right next to each other. Somewhat like the way two-channel stereo can "position" sounds between two speakers, THX with their new process they call ASA, or Advanced Speaker Array, is able to "position" virtual surround speakers between the side surround speaker and the corresponding rear speaker (it's not really that simple, but it is the best way to visualize it). So while Ultra2 controllers still offer THX Cinema and THX Surround EX modes, THX introduced three new THX modes with Ultra2 which use ASA:
THX Ultra2 Cinema. This mode is identical to THX Cinema, except it does a "soft EX decoding", giving us some output from the rear, but does not allow the sound to collapse there. Surround sound predominantly comes from the side dipole speakers.
THX Music. This mode differs from the above in two ways. First, using ASA, the surrounds are virtually positioned between the side and corresponding rear speaker, a position usually favored by multi-channel music setups. This mode also disengages Re-Eq because music tends to be enjoyed at a lower median level than movies, and as such does not need it.
THX Game. This mode basically puts all surround speakers on full duty, giving you a very lively, "exciting" sound experience which is what people want when playing an active video game.
The THX Ultra2 Layout For THX Surround EX, ASA places "virtual" speakers in the requisite position.
For Ultra2 Cinema, ASA "softens" the rear channel, keeping it active, while eliminating the "collapse" associated with Surround EX decoding of non-EX encoded material. For Ultra2 Music, ASA places "virtual" speakers in the location favored by multi-channel music enthusiasts, while maintaining an overall spacious surround space.
Its important to note that the Ultra2 controller has a setting for the distance between the two rear speakers, the default being <1ft as depicted above, yielding the most spacious sound field. The alternate setting of 1-4 ft can be used to "favor" the music playback mode. By moving the physical rear speakers apart, there is less of a "virtual speaker", with more of the surround sound in Music mode coming from the monopole rear speakers.
Ultra2 Hardware
THX Ultra2 also raised the bar for speaker performance. While output, sensitivity, and distortion requirements stayed the same, off-axis performance requirements changed dramatically. THX also changed how they measure the performance.
Smoothness of off-axis performance is now emphasized rather than attenuation as called for in Ultra. Recent research makes it clear that speakers with off-axis performance which is completely free of peaks and dips in amplitude response sound better that those with peaks and dips (even if attenuated). If a room has unacceptably strong ceiling and floor reflections, it is possible to correct that with acoustical treatments (something more and more consumers are willing to do), but poor off-axis linearity is something you can't fix after the fact.
They've also broken up the linearity requirement with Ultra2 into three bands of the audible frequency spectrum: Low, mid, and high. The ± dB window is quite tight in the mid-band, with greater variation allowed for the low and high. This requires that a speaker be quite accurate in the critical mid-band while still giving the designer enough latitude to keep their company’s signature "voicing". Frankly, we find this last item a little disappointing, since we are somewhat opposed to the notion that a speaker should ever have any sort of unique "character". THX's answer is that they realize no speaker is absolutely 100% perfect in this respect, and their banding of the spectrum simply forces a manufacturer to concentrate the greatest effort on the band that matters most.
In addition, subwoofers now need to be anechoically flat to 20 Hz. THX did this because their research shows it give them a better match with the rolled-off energy from the satellite speaker. Because these new subs may get shoved into a corner and end up with TOO MUCH at the bottom end, THX Ultra2 controllers include a Boundary Gain Compensation which, when selected during set-up, rolls-off the bottom end of the subwoofer signal to compensate if an Ultra2 sub is getting too much help from the room itself.
Select2
In 2005, THX Select was revamped to Select2. Intuitively, Select2 inherits from Ultra2 the ASA (Advanced Speaker Array) along with the modes that use it: THX Select2 Cinema, THX Music, and THX Game. As such, support for 7.1 speaker configuration is no longer optional as it was with Select (products can include only five channels of amplification, but they must provide the full 7.1 line-level output).
The S/N (signal to noise) requirement was increased 9 dB with Select2. THX tells us that while, at first, some manufacturers grumbled at the extra design work that would take, all certified products have managed to meet the new requirement.
Some Things We're Not Crazy About
Metrics Tested on THX DVD Players:
Video Level
Sync Level
Bar Tilt
2T K Factor
Pulse/Bar Ratio
Sin x/x Response
Sin x/x Group Delay
Chroma Level
Composite and Y/C Chroma Delay
Chroma Differential Gain
Chroma Differential Phase
Burst Amplitude Differential
Flesh Tone Phase Error
Luminance Linearity
AM Chroma Noise
PM Chroma Noise
Chroma Correlated Noise (IM)
Chroma Burst Frequency Leakage in Y
Chroma Burst Frequency
H Sync TimingIn 1998, THX launched certification for DVD Players, and we were a little disappointed to say the least. While on paper their goals for DVD Player design are first rate (see metrics list at right), they quickly brought their testing and certification integrity to question with the very first Certified DVD Players such as the Pionner DV-09. More recent offerings from the likes of Denon fair much better, but we would be remiss if we were to not mention this "sour" launch and there are still models which fall well short of our own Benchmark.
Another THX product which leaves us scratching our heads is cables, and that's NOT a reflection on THX. It's no secret cables are a high margin item, but the THX cables we've seen take it to a whole new level. It's important to remember that THX doesn't tell people how to price or market their products. If a cable or wire passes the signal for which it is intended with acceptable integrity, THX will give it a license to use their name. They can't help it if the licensee goes on to position and price the product as something it is not. In fact, some of the THX interconnects we've played with employ ridiculously tight RCAs which only give a false impression of superior connection while introducing the risk of breaking your equipment from the force required to plug or unplug them.
One nice thing about THX and cables, however, and indeed the I/O jacks on THX equipment, is that they have a comprehensive color coding scheme. Unfortunately, THX has not pushed it as hard as they should have, and most products either fail to use the color coding scheme, or don't use it comprehensively. Another nice THX cable thing that THX let go of was their standard for a single DB-25 multi-channel connection. My 10 year old Rotel five-channel THX amplifier has this input. If I had a THX controller with the corresponding output, I would have only one cable between them, not five. THX tells us it fell by the wayside because no one was willing to put it on their product for fear of it being seen (incorrectly) as a "degraded signal path".
As far as THX DVD titles, every one we've come across has exquisite sound, but on occasion perfection in the video quality is debatable. It might be excellent, but not exquisite. Some titles exhibit the all too common halo/ringing artifact, but further investigation is warranted before we pass final judgment (it has been suggested that, at least in the case of Lucasfilm's own Star Wars Episode I, it was an artifact of the green screen process which "crept through" to the hi-def master).
THX-like Settings
Myth: "THX equipment only works with other THX equipment."
Reality: Any THX piece can be used with non-THX equipment, though in certain situations you may end up loosing some of the benefits. For example, using THX speakers with a non-THX crossover will result in a less than perfect subwoofer/speaker splice.You can get some of the THX benefits without actually having THX-certified equipment.
Many non-THX receivers are using the same combination of bass management crossover slopes as THX, and simply using a THX speaker set, or a non-THX set with the same FR alignment, will net you the same perfect crossover. Although difficult to find and identify, there are properly designed dipole speakers which are not THX-Certified (Paradigm models come to mind).
There are many examples of excellent, non-THX high power amplifiers which will fit right in with the rest of the THX pieces, though if you are picky, you'll want to do your homework to make sure it mates perfectly with the rest of your stuff.
We've already mentioned not worrying about THX-Certified cables. And, you can look at our own DVD Player Benchmark to find out what you need to know when picking a player.
You could (and should!) acoustically treat your room, and as a result be able to accommodate a wider variety of speakers, maybe even negate the benefits of Re-Eq, but even in that situation, THX equipment can't hurt, so you might as well put some on your shopping list.
The Certification Process
As romantic as it sounds, manufacturers do not simply submit a product to THX for testing and then get a yea or nay. A THX product starts with the manufacturer purchasing the expensive and confidential THX Design Manual for the product in question. THX products are designed to be THX products. The manufacturer knows what they have to do from square one. Once they have a working sample, it is sent to THX where it is tested, for a fee, and either checks out and a license granted, or it is sent back with a report on what needs to be addressed. THX tells us that they have yet to receive a product which got everything 100% right on the first try.
Licensees then pay a small per-unit license fee for the manufactured product.
I hope everyone can appreciate why, to this day, the particulars of THX's criteria are not public. They are a business like any other and they need to protect their intellectual property. If everything was out in the open, people could just say, "It meets or beats the THX criteria", and THX would get nothing. They'd fold, and we'd never get all the benefits they've brought this industry over the years.
Myth: "THX restricts manufacturers in terms of their design creativity."
Reality: Nothing could be further from the truth! See text at left.When asked why their product is not THX certified, some manufacturers have told us its because they "wanted to do things THX does not allow". In terms of speakers, there is indeed not a whole lot of latitude (no full-range models for example), but when it comes to electronics, that's nonsense. THX requires that a piece perform to their spec (or exceed it) and that it do what it is supposed to do when the THX mode is engaged. Manufacturers are free to offer exotic decoding schemes, try innovative things like room EQ (such as the Audyssey system in some recent THX receivers), or offer crossover options other than the standard THX (because not every customer is going to have THX speakers). Lack of THX certification in higher-end electronics (where cost is supposed to be no object) may be an indication that the manufacturer is not willing to make a competent product, or that they just don't feel their customer is interested in certification.
Nick Platsis from Anthem Audio Video:
"The THX Ultra2 spec has tougher standards compared to the other licensing bodies, for example higher output swings are required, especially for the subwoofer channel. On the video side, no one else tests it. It's good that someone does, for example some manufacturers may take the bandwidth of a video switch and try to pass that on as the bandwidth of the whole circuit from input jack to output jack. Regardless, it's not difficult to meet any of these standards unless attempting to do it on the cheap or there's an element of laziness somewhere.
The challenge is integrating every single option that THX, Dolby, and DTS have to offer while maintaining user friendly operation and preventing conflicts between the various requirements. Then, when more processing options appear on the scene, it starts all over. Luckily, the people at THX are great to work with."
Other Areas of Interest
In recent years, THX has branched out into other markets as well as continually revitalizing existing ones.
On the professional side, THX has implemented PM3, their Professional Multi-channel Mixing and Monitoring program.
THX has also become active in the PC Computer market. While the THX Computer was something of a flop, THX PC Speakers are very well respected. There isn't really an industry standard for PC sound like their is for movie sound, so what THX is doing with PC speakers is basically saying that at a given price, a product is as good as it can be, basically giving you some assurance you're not being ripped off, and it takes away your need to try and decipher specs (which in the PC Speaker market are practically useless).
Perhaps more interestingly, THX has gotten involved with computer/PC Game development. The production values of computer and console games have risen tremendously in recent years, in some cases rivaling Hollywood, but the industry at large has grown up largely without the benefits of standards. It has taken THX to come in and infuse the industry with the concept of consistent and performance-oriented presentation. For the first time, the person doing the raw art, sound bites, 3D environments, or what have you, can be assured that the effort they put into their work will be realized right to the end because everybody's workstations, environments, and equipment are all set up to the same consistent standards. Room acoustics, background noise, room lighting, every piece of audio and video equipment, all must meet certain THX performance requirements.
THX has also been contracted to design Car Audio systems for Lincoln. The pieces and bits are manufactured to THX design and spec by Ford sub-contractors. They have a full time staff in Detroit to handle this project with several THX home office engineers working on auto projects as needed.
Looking Forward
We are assured that THX is very busy with new projects, and there are aspects of the industry we know could use their help.
In the works is a program which makes it possible to have a home theater itself THX certified (as opposed to just the equipment in it), which although the province of only the most wealthy, is an awfully cool notion. If you have a spare $250,000 or so, a THX Reference theater can be yours in about 12 months. Standard theaters should come in in the $50,000 range and will be possible in about 18 months. These theaters require THX gear (d'uh!) and must be built to THX-approved plans and tested to meet THX performance minimums for both audio and video. The big difference between reference and standard will be in video requirements and sound isolation, both of which get quite expensive quite fast.
Conclusions
I would be remiss if anyone came away from this essay with the impression that Secrets endorses everything THX does or that we feel anything non-THX is intrinsically inferior.
I do hope we've given you a better understanding of THX, enabling you to decide if THX is for you. I cannot stress enough that it never "hurts" for a piece to be THX-certified, except that it sometime may costs a little more. Shopping for a system "from scratch" is an excellent time to consider THX because virtually all of the guesswork as to what will work with what and how it will work together has been taken care of for you. At the same time, there is nothing stopping you from integrating a couple THX pieces, the ones that make the most sense to you, into an existing system that has non-THX-Certified components.
THX guarantees a lot of very useful features, and if you get a THX system, then simply plug everything in and press Play, you're going to get results that are pretty close to acceptable. If you actually then further calibrate and position speakers properly, it'll almost certainly be excellent. Buying non-THX, most importantly, means that you have far less of an idea about what you're getting without some homework.
I would like the thank John Dahl of THX for his time and assistance in the writing of this article.
μια λειτουργια στο remote που συνηθως αγνοουμε
μιας και το ολο θεμα εχει φτιαχτει ωστε να φτανουν τα πριμα και στις πιο μακρινες αποστασεις , ακουγονται υπερλαμπρα
το re eq ερχεται να κουρεψει τα ενοχητικα ψηλα
κατι που ισχυει για χωρους μεχρι 70 τ.μ
--------------------------------------------------------------------------------
Re-equalisation™: This function compensates the fact that all films are mixed with more treble than one hears in the cinema. Effectively, in the movie theatre, the main speakers are found just behind a screen which absorbs many of the high frequencies.
Εδω μπορουμε να δουμε το πως και τα πρεπει κατα λουκα το home cinema.
Aφορα αποκλειστικα της οικιακη χρηση.http://thx.com/library/pdf/THX_HT101-011906.pdf
Το πιο ευκολο για καποιον κατασκευαστη ειναι να ειρωνευεται το thx .Το θεμα ειναι γιατι καποιοι επιμενουν να ξοδευουν λεφτα και χρονο για κατι που στο ματι του ανυποψιαστου πελατη δεν ειναι τιποτα περισοτερο απο μια σφραγιδα?
Εδω η λιστα με ολα τα προιονταπου μπορουν να πιστοποιηθουν: http://thx.com/library/index.html .
Και κατι ακομα ΟΛΑ τα κορυφαια προιοντα σχεδον απο ολες τις εταιριες σφραγιζονται, τυχαια?
Εδω μια εξαιρετικη αναφορα απο γνωστο ιντερνετικο περιοδικο.http://www.hometheaterhifi.com/volume_13_1/feature-article-thx-1-2006-part-1.html
Ξεκαθαριζει πολλα πραματα, ισως η καλυτερη αναφορα που εχω διαβασει .
Δημήτρης Θ.
11-09-2009, 18:40
ΠΧ, το 800D της B&W δεν το βλέπω στην λίστα, αλλά βλέπω το FCM 8
Δηλαδη η λογικη ειναι το πιο φτηνο ηχειο της teufel ας πουμε επειδη δεν εχει σταμπα παιζει καλυτερα απο το ακριβοτερο που τυχαινει να εχει σταμπα?
Μην ψαχνουμε ευχες ή καταρες στο thx .Ευτυχως ή δυστυχως ειναι ο μονος που πρωτοασχοληθηκε με τον ηχο - εικοναστον κινηματογραφο και αναγνωριστηκε απο Ιαπωνια μεχρι Αμερικα
Δημήτρης Θ.
11-09-2009, 18:53
Είπα κάτι τέτοιο?
Απλά, αυτό που πιστεύω (βάσει εμπειρίας ατομικής) είναι ότι η στάμπα είναι marketing και τίποτα παραπάνω.
Αν ασχοληθεις περισοτερο θα δεις οτι ειναι πολυ περισοτερα, αυτο σαν αγοραστης .
Ακομα μια αναφορα αυτη την φορα απο το audioholics, αξιζει καποιος να ακουσει σωστα thx επεξεργασια .Αλλα ας δουμε την αναφορα http://www.audioholics.com/education/audio-formats-technology/thx-select-and-thx-ultra2-certification-general-questions
Και μια ωραια παρομοιωση
"THX beats the rest
"What’s the best between THX and Dolby Digital?" To this relatively frequent question, there is no answer: In fact THX on its own is nothing, having imperatively to be associated with something else.
In this precise case, it is a sound standard or norm. This question is in fact like comparing a car and a turbo… You can use a car by itself, but you can’t do much with a turbo all on its own! On the other hand, it’s better to have a turbo in your car. Let’s say that here, the car is represented by an audio standard, such as Dolby Surround, Dolby Digital or DTS, and the turbo is represented by THX.
Και για να μην μπερδευομαστε.Επειδη καποιοι βλεπουν προιοντα οπως τα ηχεια του pc και ευκολα βγαζουν συμπερασματα .Αλλες οι απαιτησεις σε καθε τι για home cinema ή cinema και αλλες για pc.
Πολυ ωραιο Argi ,σαν αρχαριος το βρισκω πολυ χρησιμο
Πριν 2 μηνες περιπου γνωστος ριβιουερ που εχει ακουσει το συστημα μου πολλες φορες περασε για ακροαση (ευκαιρια να τον μπερδεψω λεω). Και ξεκιναω με reign of fire σε μπλε.Η απαντηση του ηταν οπτι το συστημα μου εγινε θαμπο , (σωστη η παρατηρηση του σκεφτομαι)
Του βαζω την ιδια ταινια σε dvd και ολα στρωνουν.(δεν μενει αφωνος γιατι εχει ξαναζησει παρομοιες καταστασεις).Επομενη ταινια xmen2 σε μπλε παντα.
Η παρατηρηση πολυ λαμπρο ειναι , δεν μου αρεσει λεει.
Αργύρη να ρωτήσω και εγώ μπρε εδώ είπες ότι το dvd παίζει καλύτερα από το μπλε εντάξει? Μήπως γίνετε και το ίδιο βρε Αργύρη μου με το απλό μου LG και το THX μην ξοδεύομε άδικα για Prologic IIx-z και THX? Τι να κάνω δεν κατέχω αυτά τα μηχανήματα του διαβόλου.. βοήθεια μπρε!
Στη συγκεκριμενη περιπτωση φταιει η μεταφορα σε μπλε δισκακι .Δεν φταιει το πλειερ.Δυστυχως ολες οι περιπτωσεις δεν ειναι ιδιες.
Μια νεα τεχνολογια απο τον λουκα παρουσιαστηκε στην cedia, αφορα μεγαλους χωρους,ελαχιστη αποσταση απο την οθονη 6 μετρα , ηχεια με διπλοκαλωδιωση ,και ερχεται να γεφυρωσει την κονσουμεραδικη και επαγγελματικη σειρα του thx lab.Πληροφοριες εδω.
Last week at CEDIA EXPO 2009, THX Ltd. introduced its “Big Room” product design and certification concept that brings professional audio quality and performance to “prosumer” amplifiers, pre-amps, and loudspeakers. The program was created to bridge the gap between the consumer and professional audio worlds, offering custom installers more hardware choices for designing large, multi-row media rooms, and home theaters.
THX showcased its new THX Certified concept products at CEDIA EXPO 2009, showcasing products from Snell Acoustics, Parasound, Diodes Zetex Semiconductor, and Integra.
According to THX, Big Room certification builds upon the THX Ultra2 Plus program, ensuring speakers, amplifiers and preamps are designed with the performance necessary to deliver studio Reference Level volume (85dB) and headroom in large home theaters where the viewing distance from the screen is 20 feet and beyond—rooms 660 square feet or 8,000 cubic feet in size.
“The THX Big Room concept is bringing together premium audio brands from the professional and consumer worlds to fill a critical need in the custom install market,” THX director of consumer technology, Warren Mansfield, said. “THX is setting a design and performance benchmark for audio products in the large room category, providing CEDIA professionals a wider portfolio of products for their most challenging installations.”
Snell’s chief engineer, Joseph D'Appolito, noted that Snell has always wanted to design an audiophile product that would set a new precedent for audio performance in large room applications. “We’re thrilled to be part of the Big Room project with THX and look forward to bringing custom installation professionals the tools they need to create truly astounding large-room home theater audio systems,” he noted.
Most consumer-grade speakers and receivers are designed for average sized residential home theaters and living rooms of 1,000 to 3,000 cubic feet. When used in rooms that exceed this size, consumer components are often overdriven, causing clipping, distortion, and physical damage to loudspeakers. THX Big Room systems include at least two rows of monopole/bipole side surround speakers and four individually calibrated and delay-adjustable subwoofer outputs to ensure enveloping coverage throughout the seating area.
Sponsored Link
“With the vast number of large, private screening rooms that we have been designing over the years, we are very excited to now have the choice of fully THX Certified ‘Big Room’ systems,” PMI president and Residential Systems columnist, Anthony Grimani, said. “These products will be a great complement for our new generation of large-screen PMI 2.0 venues.”
THX Big Room systems require higher power transducers and speaker bi-amplification. This provides the maximum flexibility to speaker designers, as well as protects the speaker drivers from damaging harmonics when driven hard. The crossover and amplification can be either internal or external, allowing for self-powered or externally powered systems.
At CEDIA EXPO, Snell Acoustics demonstrated the first prototypes of THX Big Room LCR speaker systems. These bi-amplified loudspeakers are powered externally with an active crossover and equalizer. The high power and high sensitivity design uses compression driver horns.
Parasound showed the world’s first THX Big Room power amplifiers. The concepts shown at CEDIA featured variable gain design, higher voltage rails, and higher power than traditional consumer amplifiers. This provides the amplification necessary to fill large home theaters with high impact sound.
Integra has a new pre-amplifier that follows the Big Room requirements, featuring lower noise and additional side surround and subwoofer channels.
Diodes Zetex Semiconductors provided the bi-amping frequency division and equalization in a crossover processor. This is achieved using their ZXCZEVB80DAC multi-channel DAC and digital preamplifier demonstration board using the Zetex Direct Digital Feedback Amplifier (DDFATM) chipset. The chipset is available to hardware manufacturers on an OEM basis for implementation into audio video.
Ακομα ενα κειμενακι , αυτη την φορα απο την orion.http://www.orionstudios.com/D5/THX.htm
ΔημήτρηςΤοπ.
12-10-2009, 18:11
ναι καλα...αντε να δεσεις σωστα 4 γουφερ στον ιδιο χωρο χωρις ισοσταθμηση .ειχα δυο και ... περα δωθε ...
ασε που εχουν ξεπεραστει ποια οι 80 κυκλοι...εγω τους ακουω με κατευθυνση...αν δε κοψεις 70 και κατω δουλεια δε γινετε...γνωμη μου...
Νανόπουλος Γιάννης
12-10-2009, 20:14
Παιδιά...προσέξτε την υπερβολή μπάσων στον χώρο σας σε σχέση με το υπόλοιπο σύστημα.Είναι εντελώς παράτερο μεγάλος ήχος,μεγάλο μπάσο με μιά οθονίτσα μιά σταλιά!!!
ναι καλα...αντε να δεσεις σωστα 4 γουφερ στον ιδιο χωρο χωρις ισοσταθμηση .ειχα δυο και ... περα δωθε ...
αν παρακολουθουσες το σαιτ του thx θα εβλεπες οτι μεχρι πριν 1 χρονο και κατι υπηρχαν και πιστοποιημενα εκουαλαιζερ.Αν εχεις την δυνατοτητα για 4 σαμπ εχεις και για εκουαλαιζερ
ασε που εχουν ξεπεραστει ποια οι 80 κυκλοι...εγω τους ακουω με κατευθυνση...αν δε κοψεις 70 και κατω δουλεια δε γινετε...γνωμη μου...
ξερεις ποσο ευκολα αρπα ενα πηνειο σε ενα γουφερ ?
οσο για την αποκοπη εξαρταται απο πολλα , οποτε να λεμε οτι οι 80 και οι καθε 80 ειναι ξεπερασμενοι δεν ειναι και τοσο επικαιρο.
Παιδιά...προσέξτε την υπερβολή μπάσω στον χώρο σας σε σχέση με το υπόλοιπο σύστημα.Είναι εντελώς παράτερο μεγάλος ήχος,μεγάλο μπάσο με μιά οθονίτσα μιά σταλιά!!!
γιαννη η δικη σου υπερβολη ειναι η χαρα καποιου αλλου, οσο για το αν εννοεις 4 σαμπ σε μικρο χωρο και αυτο γινεται.Αρκει καποιος να μπορει να σκεφτει πως.
ΔημήτρηςΤοπ.
12-10-2009, 20:56
οσο για το αν εννοεις 4 σαμπ σε μικρο χωρο και αυτο γινεται.Αρκει καποιος να μπορει να σκεφτει πως.
τι ενοεις με αυτο αργυρη?
με συνδεσεις γραμμης?
να συμπληρωνει το ενα με τα αλλα τις ατελειες του χωρου ?
Με δυο οντισι σαμπ , τα βαζεις ανα ζευγος στα οντισι, και σε ισες αποστασεις απο την θεση ακροασης.Τωρα αν καποιος σκεφτει οτι ειναι υπερβολικο ας σκεφτει οτι δεν μιλαμε για 18ιντσα σε μικρο χωρο αλλα για αναλογες ιντσες με τον χωρο και σε σωστες εντασεις ρυθμισμενα.
Και ακομα λιγες πληροφοριες.
Type Privately held company
Founded 1981
Headquarters San Rafael, California, United States
Key people Tomlinson Holman, Developer
David Pierce, General Manager
Richard Dean, VP Technology
Robert Hewitt, VP Sales
Industry Audio
Products Digital Audio Certifications
Digital Audio and Video Mastering Technologies
Website www.THX.com
Οπως βλεπουμε ασχολουνται με Digital Audio and Video Mastering Technologies οποτε αν θελουμε μπορουμε να κοροιδευουμε τον παπα της ενοριας μας , το φουρναρη και το thx αλλα επειδη ειναι συγκεκριμενο προιον καλο θα ειναι να εχουμε να αντιπροτεινουμε ενα προιον δικο μας παγκοσμια αναγνωρισμενο απο τον Αη Ραφαηλ μεχρι το Τοκυο.Μιας και τα προιντα του επιλεγονται απο ακρη σε ακρη του πλανητη.
Kαι κατι απο το χρονοντουλαπο της ιστοριας.Ο πρωτος nad με σφραγιδα THX , αν θυμαμαι καλα κυκλοφορησε στο τελος του 1996 και ειχε αρχισει το πηγαινε ελα (για να παρει την πιστοποιηση σχεδον ενα χρονο πισω) εξου και το lucas film audio
¶στα Αργύρη, εδώ κοροιδεύουμε ακόμη τους Ιταλούς, οτι δεν ξέρουν να φτιάχνουν αυτοκίνητα!!!!!!!!!!!!
toliskot
18-04-2012, 13:02
Μπορεί κάποιος να μου πεί ποιές ρυθμίσεις πρέπει να κάνω στον AV και στο Sub, ώστε να ακούω σύμφωνα με την προδιαγραφή THX ?
78933
usherades
18-04-2012, 13:15
Καλησπέρα και χρόνια πολλά. Κατ'αρχας πρέπει ο ενισχυτής σου να φέρει πιστοποίηση THX, από κει και πέρα δε μπορείς να κάνεις κάτι άλλο.
toliskot
18-04-2012, 14:30
Το THX δεν συμπεριλαμβάνει προδιαγραφές έντασης, αποκοπής συχνοτήτων κτλ. ?
Αν βρω αυτές τις προδιαγραφές και με τη βοήθεια του γενικού setup και του parametric equalizer τις περάσω στον AV, δεν θα ακούω σύμφωνα με το THX ?
kblachos
18-04-2012, 14:50
THX:
- Ολα τα ηχεία δηλωμένα small, και συχνότητα αποκοπής στο υπογούφερ στα 80Hz.
- Master Volume κατά την αναπαραγωγή στα 0dB (αν δεν έχεις θέμα με τους γείτονες).
- Επιλογή του κατάλληλου ΤΗΧ mode απ' το menu του ενισχυτή.
toliskot
18-04-2012, 15:28
THX:
- Ολα τα ηχεία δηλωμένα small, και συχνότητα αποκοπής στο υπογούφερ στα 80Hz.
- Master Volume κατά την αναπαραγωγή στα 0dB (αν δεν έχεις θέμα με τους γείτονες).
- Επιλογή του κατάλληλου ΤΗΧ mode απ' το menu του ενισχυτή.
Εάν τα δηλώσω ως small, όταν χρησιμοποιώ τον AV (Yamaha Z7) για στερεοφωνική ακρόαση σε Pure Direct mode, το παρακάμπτει αυτό ή πρέπει κάθε φορά να τα αλλάζω σε Large ?
Σύμφωνα με το manual τις λειτουργίες treble, bass και parametric equalizer τις παρακάμπτει. Για το συγκεκριμένο δεν αναφέρει κάτι.
Αυτό που λέει ο Κώστας είναι η βασική προϋπόθεση της ΤΗΧ, ανάλογα βέβαια τον όγκο του δωματίου. Thx Ultra, select κλπ.
Από εκεί και πέρα αν ακούς stereo θα έλεγα να δηλωθούν large, εκτός κι αν θέλεις όλες οι χαμηλές να περνάνε μόνο από το υπογούφερ.
toliskot
18-04-2012, 17:31
Δεν το καταλαβαίνω αυτό. Το κανάλι του sub είναι ένα ξεχωριστό κανάλι με ξεχωριστή πληροφορία από τα υπόλοιπα. Δηλαδή ο υπεύθυνος ήχου κάθε ταινίας έχει επιλέξει πότε θα ενεργοποιείτε και πότε όχι. Γιατί λοιπόν εγώ να το μπερδέψω και να του στείλω σήμα και από τα κυρίως ηχεία από τα 80 Hz και κάτω τη στιγμή που από μόνα τους μπορούν να κατέβουν άνετα μέχρι και 50 Hz ?
Portioli
18-04-2012, 18:15
Δεν το καταλαβαίνω αυτό. Το κανάλι του sub είναι ένα ξεχωριστό κανάλι με ξεχωριστή πληροφορία από τα υπόλοιπα. Δηλαδή ο υπεύθυνος ήχου κάθε ταινίας έχει επιλέξει πότε θα ενεργοποιείτε και πότε όχι. Γιατί λοιπόν εγώ να το μπερδέψω και να του στείλω σήμα και από τα κυρίως ηχεία από τα 80 Hz και κάτω τη στιγμή που από μόνα τους μπορούν να κατέβουν άνετα μέχρι και 50 Hz ?
Το αυτί δεν καταλαβαίνει από που προέρχονται οι ηχοι κάτω των 80 Hz.
Για αυτό και δεν εχει νοημα απο που θα έρχεται ο ήχος.
Για χαμηλές συχνότητες που συνανταμε στις ταινίες και όχι στα μουσικά κομάτια, θελουμε μεγάλα drive (= πολλές ιντσες)
Οσο πιο πολλές, τοσο πιο ευκολο ειναι για το ηχείο να κατέβει σε συχνότητες.
Απο την αλλη οσο πιο μικρή είναι η συχνοτητα ενός ηχου ( χαμηλά Hz) τόσο μεγαλύτερο το μήκος κυματος
άρα και μεγαλύτερος κίνδυνος για στάσιμα κύματα.
Δηλαδή ανομοιογένεια των χαμηλών συχνοτήτων στο χώρο.
Σε κάποια σημεία εχεις μπουμαρίσματα και σε κάποια σημεία κενά ήχου (δεν ακους μπασο).
Για να μην εχουμε προβλημα με τα στασιμα κύματα οι περισσότεροι μηχανικοί ήχου
έχουν καταλήξει οτι η καλύτερη συχνότητα αποκοπής των χαμηλών συχνοτήτων είναι τα 80Ηz.
Γενικότερα το LFE αμα παρατηρήσεις είναι ένα μονοφωνικό, φτωχο σε πληροφορία και χαμηλό σε ενταση κανάλι.
Το σωστό όπως προτεινει η THX, η audyssey Κι ο kblachos :) είναι όλα τα ηχεία small και οι χαμηλές
μαζί με το LFE στο sub-woofer.
Αυτο που μας βολεύει στην συγκερκιμένη ρυθμιση έιναι η τοποθέτηση.
Aυτός ειναι ο κύριος λόγος.
Περνεις ενα μεγαλο καλώδιο και φερνεις γυρα όλο το χώρο σου , μέχρι να βρεις το καταλλήλότερο μέρος
για να βάλεις το sub-woofer.
Τα τρια κύρια ηχεία έχουν παντα πολυ συγκεκριμένη θεση.
Το sub λογω της ιδιαιτερότητας του αυτιου να μην αναγνωρίζει απο που έρχονται οι χαμηλές δεν έχει τέτοιο πρόβλημα.
Εν ολίγοις... όλα αυτά γίνονται για να μοιραστούν οι χαμηλές συχνότητες σωστα.
toliskot
18-04-2012, 18:36
Σε ευχαριστώ για όλες αυτές τις πληροφορίες.
Αν δηλώσω λοιπόν όλα τα ηχεία small , και στο setup του AV για το Sub ρυθμίσω την αποκοπή στα 80 Hz, το Crossover του Sub που να το ρυθμίσω ? Να το ανοίξω τέρμα στα 200 Hz?
kblachos
18-04-2012, 19:41
Δεν το καταλαβαίνω αυτό. Το κανάλι του sub είναι ένα ξεχωριστό κανάλι με ξεχωριστή πληροφορία από τα υπόλοιπα. Δηλαδή ο υπεύθυνος ήχου κάθε ταινίας έχει επιλέξει πότε θα ενεργοποιείτε και πότε όχι. Γιατί λοιπόν εγώ να το μπερδέψω και να του στείλω σήμα και από τα κυρίως ηχεία από τα 80 Hz και κάτω τη στιγμή που από μόνα τους μπορούν να κατέβουν άνετα μέχρι και 50 Hz ?
Για τους Lucas - Holman δεν έχει καμία απολύτως σημασία ποια είναι τα ηχεία σου και ποια η ικανότητά τους να αναπαράγουν χαμηλές συχνότητες. Και τα TAD-R1 των 150kg με frequency range 20Hz - 100KHz να έχεις για L-R, σύμφωνα με την ΤΗΧ θα πρέπει να τα δηλώσεις small.
Σε ευχαριστώ για όλες αυτές τις πληροφορίες.
Αν δηλώσω λοιπόν όλα τα ηχεία small , και στο setup του AV για το Sub ρυθμίσω την αποκοπή στα 80 Hz, το Crossover του Sub που να το ρυθμίσω ? Να το ανοίξω τέρμα στα 200 Hz?
Aκριβώς....
@Portioli
@Kblachos
Συμφωνώ με όλα αυτά που λέτε και όπως έγραψα παραπάνω είναι η βασική προϋπόθεση της ΤΗΧ αλλά θα ήθελα να παρατηρήσω το εξής.
Ο Holman βέβαια (δεν θυμάμαι το μικρό του) ήταν ο διευθυντής της Lucas films και από εκεί πήρε και την ονομασία THX (Τ ..το μικρό του, Holman, eXperiment).
Η THX δεν αναιρεί ότι δεν μπορούν να γίνουν και άλλες ρυθμίσεις όπως για π.χ όλα large, όλα small ή μπροστινά L/R large και υπόλοιπα small. Η ΤΗΧ βέβαια μιλάει για περισσότερα του ενός γούφερ για να έχουμε καλύτερα αποτελέσματα.
Όταν διαθέτεις κύρια ηχεία με μπάσο (από αυτά που γνωρίζω και έχω καταλάβει) τα ορίζεις large στα 80hz ενώ στα ηχεία κολώνες ορίζεις 120-150hz
Η ρύθμιση στα 120hz εξασφαλίζει καλύτερη απόδοση στο γούφερ και προσφέρει μεγαλύτερη ευκολία στην τοποθέτση του σε διάφορα σημεία μέσα στο χώρο.
Η ρύθμιση στα 150 εξασφαλίζει μεγαλύτερη ισχύ με την προϋπόθεση το γούφερ να είναι κοντά στα ηχεία.
Στα 200hz δεν γνωρίζω τι γίνεται ή αν έχει κάποια ακουστική διαφορά.
kblachos
19-04-2012, 11:46
Ο Holman βέβαια (δεν θυμάμαι το μικρό του) ήταν ο διευθυντής της Lucas films και από εκεί πήρε και την ονομασία THX (Τ ..το μικρό του, Holman, eXperiment).
Tomlinson Holman...
Εάν τα δηλώσω ως small, όταν χρησιμοποιώ τον AV (Yamaha Z7) για στερεοφωνική ακρόαση σε Pure Direct mode, το παρακάμπτει αυτό ή πρέπει κάθε φορά να τα αλλάζω σε Large ?
Σύμφωνα με το manual τις λειτουργίες treble, bass και parametric equalizer τις παρακάμπτει. Για το συγκεκριμένο δεν αναφέρει κάτι.
Είναι απλό. Βάλε ένα στερεοφωνικό πρόγραμμα, ένα CD για παράδειγμα και δες αν παίζει το sub σε Pure Direct mode. Αν παίζει δεν παρακάμπτει. Αν δεν παίζει τα παρακάμπτει. Υποτίθεται ότι αυτά τα modes παρακάμπτουν οποιαδήποτε επεξεργασία και παίζουν αυτό που παίρνουν από την πηγή είτε δικάναλο είτε πολυκάναλο.
Tomlinson Holman...
Σωστός..:music-smiley-005:
toliskot
19-04-2012, 12:33
Πειραματίστηκα εχτές με το setup του AV (Yamaha Z7). Τα ηχεία μου (B&W CM9) τα είχα πάντα Large δηλωμένα. Όταν τα έβαλα σε small εμφανίστηκε μια επιπλέον επιλογή όπου ρυθμίζω την συχνότητα αποκοπής. Δεν συμβαίνει όμως το ίδιο και με το sub. Ο ενισχυτής δεν μου δίνει επιλογή ρύθμισης αποκοπής του Sub.
kblachos
19-04-2012, 12:43
Μία είναι η συχνότητα αποκοπής. Αν δηλώσεις αποκοπή (συχνότητα cross) στα 80Hz, τότε οι υψηλότερες απ' αυτό το νούμερο συχνότητες κατευθύνονται στα ηχεία, και οι χαμηλότερες στο υπογούφερ.
toliskot
19-04-2012, 13:46
Δηλαδή ο AV στέλνει αυτόματα τις χαμηλότερες από 80 Hz στο Sub ? Ρωτάω αυτό γιατί ενώ μου έχει συχνότητες αποκοπής για όλα τα ηχεία, μπροστά και πίσω, στο menu που αφορά το Sub δεν μου δίνει καμία ρύθμιση αποκοπής.
Δηλαδή ο AV στέλνει αυτόματα τις χαμηλότερες από 80 Hz στο Sub ? Ρωτάω αυτό γιατί ενώ μου έχει συχνότητες αποκοπής για όλα τα ηχεία, μπροστά και πίσω, στο menu που αφορά το Sub δεν μου δίνει καμία ρύθμιση αποκοπής.
Σωστά.
Εγώ έχω τα jamo D6 THX τα οποία είναι δηλωμένα small, συχνότητα του sub 200 Hz και του AV στα 80 Hz
Δηλαδή ο AV στέλνει αυτόματα τις χαμηλότερες από 80 Hz στο Sub ? Ρωτάω αυτό γιατί ενώ μου έχει συχνότητες αποκοπής για όλα τα ηχεία, μπροστά και πίσω, στο menu που αφορά το Sub δεν μου δίνει καμία ρύθμιση αποκοπής.
Όπως σου είπε και ο Κώστας "Μία είναι η συχνότητα αποκοπής". Αν καταλαβαίνω σωστά (δεν ξέρω καλά τους yamaha) έχεις πάει στις ειδικές ρυθμίσεις του κάθε ηχείου ξεχωριστά. Αν θέλεις μπορείς να το κάνεις αλλά για μένα δεν χρειάζεται.
Όταν δηλώνεις small λογικά ο av σε πάει στα 120 ή 150 ανάλογα. Θα πρέπει λοιπόν χειροκίνητα να βάλεις crossover στα 80Hz ...αλλά δεν θα ακούσεις διαφορές αφού είναι small. Η άποψή μου λοιπόν είναι: L/R Large και τα υπόλοιπα Small με crossover στα 80Hz. Κάνε αν θέλεις κάποιες δοκιμές σε ταινίες πολυκάναλες ή μουσική πολυκάναλη και σε stereo ακούσματα (βινύλιο, cd ) και κάνε εναλλαγή μεταξύ αυτού που έγραψα παραπάνω και της περίπτωσης όλα Small στα 120 και μετά αποφάσισε αυτό που σου αρέσει καλύτερα.
...Και φαντάζομαι εκτός των ηχείων, γούφερ κλπ πρέπει και ο ενισχυτής (και όχι μόνο) να είναι THX αλλιώς δεν θα έχουν νόημα όλα αυτά. Για ένα καλό και σωστό Thx θέλει δουλειά πολύ. Κι εγώ έχω π.χ ηχεία και γούφερ Thx αλλά όχι ενισχυτή. Οπότε το δικό μου είναι μαϊμού!! :antlers:
Εγώ πάλι έχω ανάποδη μαιμού. Ενισχυτή THX αλλά ηχεία όχι THX.
Παρ' όλα αυτά βρίσκω πολύ ωραίο το mode ΤΗΧ Select 2 όταν το επιλέγω.
Αναφορικά με το σημείο αποκοπής. Υπάρχουν περιπτώσεις που ρυθμίζεται το HPF ξεχωριστά από το LPF. Αλλά για λόγους ευκολίας το σημείο αποκοπής είναι ένα. Σε εμένα γράφει HPF/LPF και είναι μία ρύθμιση. Όταν στο μενού βάλω ότι έχω ηχεία THX τότε όλα αυτόματα πάνε small και το HPF/LPF στα 80Hz.
Για την ιστορία ο A/V μου είναι ένας Marantz SR8002.
Μήπως και ο χώρος μας πρέπει να πληροί κάποιες προδιαγραφές? Όπως και οι κινηματογραφικές αίθουσες που φέρουν την πιστοποίηση ΤΗΧ.
Το παρατράβηξα ε? -bye-
Μήπως και ο χώρος μας πρέπει να πληροί κάποιες προδιαγραφές? Όπως και οι κινηματογραφικές αίθουσες που φέρουν την πιστοποίηση ΤΗΧ.
Το παρατράβηξα ε? -bye-
H λογική της στάμπας στα μηχανάκια βγήκε έτσι. Αφού δεν μπορείς να πιστοποιήσεις το χώρο με προδιαγραφές στο σπίτι, πιστοποιείς τα μηχανάκια. Έτσι λέει η ΤΗΧ.
H λογική της στάμπας στα μηχανάκια βγήκε έτσι. Αφού δεν μπορείς να πιστοποιήσεις το χώρο με προδιαγραφές στο σπίτι, πιστοποιείς τα μηχανάκια. Έτσι λέει η ΤΗΧ.
Δεν θυμάμαι που………… σε ποιο Σαιτ…………. Και όμως ……….. κάπου έχω δει home cinema κατά ΤΗΧ.
Δεν μπορώ να θυμηθώ τώρα…. :damnyou:
Στο site της THX προφανώς
http://www.thx.com/professional/cinema-certification/
toliskot
20-04-2012, 09:12
...Και φαντάζομαι εκτός των ηχείων, γούφερ κλπ πρέπει και ο ενισχυτής (και όχι μόνο) να είναι THX αλλιώς δεν θα έχουν νόημα όλα αυτά. Για ένα καλό και σωστό Thx θέλει δουλειά πολύ. Κι εγώ έχω π.χ ηχεία και γούφερ Thx αλλά όχι ενισχυτή. Οπότε το δικό μου είναι μαϊμού!! :antlers:
Κανένα από τα μηχανήματα μου δεν έχει τη στάμπα THX. Απλός σκέφτηκα ότι αν ρυθμίσω τον AV σύμφωνα με τις προδιαγραφές του THX, θα πλησιάσω αρκετά στη συγκεκριμένη ακουστική.
Κανένα από τα μηχανήματα μου δεν έχει τη στάμπα THX. Απλός σκέφτηκα ότι αν ρυθμίσω τον AV σύμφωνα με τις προδιαγραφές του THX, θα πλησιάσω αρκετά στη συγκεκριμένη ακουστική.
Μακάρι να ήταν έτσι, αλλά...
Εντάξει είναι μια πιστοποίηση που προϋοποθέτει κάποιες σεβαστές παραμέτρους, αλλά δεν είναι και θέσφατο.
Κανένα από τα μηχανήματα μου δεν έχει τη στάμπα THX. Απλός σκέφτηκα ότι αν ρυθμίσω τον AV σύμφωνα με τις προδιαγραφές του THX, θα πλησιάσω αρκετά στη συγκεκριμένη ακουστική.
Όχι ακριβώς.
Ότι φέρει την πιστοποίηση ΤΗΧ, είναι μια σειρά από προδιαγραφές που θέλουν οι εμπνευστές τις εταιρείας.
Από ένα καλώδιο έως μια αίθουσα.
toliskot
20-04-2012, 10:52
Ωραία..... με τα μηχανήματα κατάλαβα τι παίζει.... Τι γίνεται όμως με τις ταινίες ? Υπάρχουν κάποιες οι οποίες στην πίσω μεριά του κουτιού υπάρχει το λογότυπο. Επίσης και όταν ξεκινάει η ταινία. Αυτό σημαίνει ότι ο ήχος της ταινίας έχει τις προδιαγραφές THX ? Μήπως για να ακούσω σωστά το THX πρέπει και τα μηχανήματα και τα ηχεία αλλά και η ταινία να έχουν το λογότυπο ?
Τι μου θυμίζεις τώρα…………..
Πριν τα DVD υπήρχαν τα περίφημα Laser Disc.
Πολλά από αυτά αν όχι όλα έφεραν την στάμπα ΠΟΙΟΤΗΤΑΣ ΤΗΧ. Έτσι έγραφαν τα περιοδικά τότε.
Ναι λοιπόν ακόμα και στα σημερινά DVD η εγγραφή κατά ΤΗΧ έχει διαφορά σε σχέση με τις απλές.
Βέβαια μην σε μπερδεύει με τον ήχο Dolby Digital η Dts.
Ένα DVD μπορεί να έχει πολυκάναλο ήχο Dolby Digital και Dts και να φέρει και την προδιαγραφή ΤΗΧ.
Αυτό σημαίνει ότι ο ήχος της ταινίας έχει τις προδιαγραφές THX όπως σωστά αναφέρεις και εσύ.
Για να ακούσεις σωστά δεν παίζει ρόλο η στάμπα.
Χιλιάδες home cinema παίζουν περίφημα χωρίς την στάμπα ΤΗΧ
Η στάμπα απλά μας λέει ότι φέρει την συγκεκριμένη προδιαγραφή, Και καλό θα είναι αν θέλουμε να έχουμε την προδιαγραφή ΤΗΧ, ότι μηχάνημα έχουμε να είναι κατά ΤΗΧ.
kblachos
20-04-2012, 12:50
Εδώ ένα κατατοπιστικό άρθρο για το ΤΗΧ απ' τον Δ. Σταματάκο και το avmentor:
Κάποιοι εξόχως κυνικοί τύποι, θα έλεγαν ότι το καλύτερο που έχει να κάνει ο George Lucas θα ήταν να ασχολείται περισσότερο με τα σενάρια των ταινιών Star Wars τα οποία πηγαίνουν από το χειρότερο στο ακόμη χειρότερο αντί να ασχολείται με την τεχνολογία του κινηματογραφικού ήχου. Κάποιοι άλλοι, θα μιλούσαν για την μεγαλύτερη και πιο καλά στημένη «αρπαχτή» στην ιστορία της τεχνολογίας του ήχου ή ακόμη και για «παράγκα» στην βιομηχανία της 7ης τέχνης. Από την άλλη, αν και τα «THX approved» καλώδια είναι ίσως υπερβολή που δικαιώνει όλους τους παραπάνω, μία προσπάθεια για ομογενοποίηση των προδιαγραφών και των δυνατοτήτων δεν θα έβλαπτε κανέναν.
Αυτό που με βεβαιότητα μπορεί να πεί κανείς είναι ότι το THX δεν αποτελεί βασική τεχνολογία κινηματογραφικού ήχου όπως το Dolby Digital και το DTS, αλλά περισσότερο μία συλλογή απόψεων, προθέσεων, και περιφερειακών τεχνολογιών ενός συγκεκριμένου φορέα, οι οποίες καταλήγουν σε μία δέσμη προδιαγραφών για τις συσκευές που απαρτίζουν ένα σύστημα κινηματογραφικού ήχου και θεσμοθετούνται από μία διαδικασία αξιολόγησης μέσα από την οποία ένα προιόν αποκτά την σφραγίδα «THX» και το δικαίωμα να φέρει υπερήφανα τον σχετικό λογότυπο στην πρόσοψη. H αρχική ιδέα, αφορούσε στην δημιουργία μίας ομάδας προδιαγραφών για τις ίδιες τις κινηματογραφικές αίθουσες (σε θέματα διαστάσεων, ακουστικής και εγκαταστάσεων) ώστε τα όλο και πιο πολύπλοκα soundtracks με τα ειδικά εφέ και τα πολλά κανάλια να ακούγονται όπως υποτίθεται θα έπρεπε να ακούγονται.
Η ιδέα, όπως ήταν επόμενο, πέρασε και στα οικιακά συστήματα με τον Lucas να δηλώνει ότι ένα σύστημα THX εξασφαλίζει τις βέλτιστες συνθήκες μεταφοράς του soundtrack στο σπίτι. Η προδιαγραφή THX είναι εξαιρετικά λεπτομερής και περιλαμβάνει «απαιτήσεις» για κάθε -σχεδόν- παράμετρο των συσκευών τις oποίες αφορά. Προβλέπει επίσης μία σειρά από επεμβάσεις στο σήμα κυρίως με την μορφή ισοστάθμισης και ψηφιακής επεξεργασίας που έχουν σαν στόχο την βελτιστοποίηση της αναπαραγωγής (Re-equalization, Timbre Matching, Adaptive Decorrelation, Bass Management Electronic Crossover, Bass Peak Level Manager, Loudspeaker Position Time Synchronization, κ.λπ, κ.λπ).
Στις προδιαγραφές επίσης περιλαμβάνονται απαιτήσεις για την κατευθυντικότητα και την πολική απόκριση των ηχείων, την απόκριση των υπογούφερ κ.λπ. Είναι σημαντικό, να γίνει κατανοητό ότι οι προδιαγραφές THX δεν είναι αυτονόητα και καθολικά αποδεκτές (για παράδειγμα πολλοί κατασκευαστές κορυφαίων συσκευών δεν τις πιστοποιούν για THX) καθώς επίσης και το γεγονός ότι ένα σύστημα «είναι THX» μόνον και μόνον όταν ΟΛΕΣ οι συσκευές του είναι THX.
Τούτων λεχθέντων, ας δούμε μερικές παραλλαγές της ιδέας το THX Surround EX και το THX Ultra-2:
To THX Surround ΕΧ αποτελεί ένα προσάρτημα των προδιαγραφών THX ειδικά σχεδιασμένο για συστήματα 6.1. Προσφέρει bass management για το οπίσθιο κανάλι ώστε να μεταφέρονται οι πληροφορίες χαμηλών συχνοτήτων στο υπογούφερ και προβλέπει την εφαρμογή της ειδικής ιστοστάθμισης (Re-equalization) σε αυτό. Επίσης, επιτρέπει την ρύθμιση των περιφερειακών καναλιών (στάθμης και φασική) ώστε να προσαρμόζονται στον χώρο και στην θέση του ακροατή και επιτρέπει την δρομολόγηση μονοφωνικών σημάτων surround στα περιεφερειακά ηχεία και όχι στο οπίσθιο κεντρικό.
Το ΤΗΧ-Ultra2 αποτελεί μία ομάδα προδιαγραφών που επιτρέπουν την χρήση ενός πολυκαναλικού συστήματος για κινηματογραφικό ήχο και για πολυκαναλικό ήχο υψηλής ανάλυσης (από SACD ή DVD-A). Χρησιμοποιείται μία συγκεκριμένη γεωμετρία 7.1 για την τοποθέτηση των ηχείων, απαιτούνται ειδικές «έξυπνες» είσοδοι που αντιλαμβάνονται το είδος του σήματος και επιτρέπουν την προσαρμογή του συστήματος και απαιτούνται -επίσης- υπογούφερ που κατεβαίνουν μέχρι τα 20Hz και ηχεία που μπορούν να αποδώσουν στάθμες 105dB σε χώρους 3.000 κυβικών ποδών (περίπου 80 κυβικών μέτρων).
http://avmentor.gr/downloads/cinema_sound.pdf
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