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Author Topic: THX amps? Amanda Mundin Expert Film Handler Posts: 122 From: Belper, Derbyshire, UK Registered: Sep 2005 posted 11-30-2005 12:15 PM                     Does anyone know how amps and speakers are judged to be upto THX spec? and in what way are the THX models better than the non-THX models?  |  IP: Logged Pete Naples Phenomenal Film Handler Posts: 1565 From: Dunfermline, Scotland Registered: Feb 2001 posted 11-30-2005 01:03 PM                     They aren't necessarily better in any way, they just bear the badge THX means next to nothing in the UK now, none of the major chains are bothering with it. A well designed, specified and insatlled theatre and projection/sound system can easily match or exceed THX.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 11-30-2005 02:23 PM                        This was not true when Tom Holman set up the program; but it is true now. To answer your question; I have found by experience that the very best amplifiers have one thing in common: they are RATED into a 2 ohm load. Louis  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 11-30-2005 10:32 PM                     Typically a THX approved device will do what the spec sheet claims it will how it is then used is upto the system design engineer  |  IP: Logged Jonathan Worthing Master Film Handler Posts: 384 From: Hereford, UK Registered: Apr 2001 posted 12-01-2005 10:35 AM                     quote: Pete Naples They aren't necessarily better in any way, they just bear the badge And what a price for a badge  |  IP: Logged Ben Wales Jedi Master Film Handler Posts: 602 From: Southampton. England Registered: Jul 99 posted 12-01-2005 05:56 PM                     THX means next to nothing in the UK now......... I wonder what Andy Summers will have to say about that!  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 12-01-2005 06:15 PM                  Yeah Ben, I wonder what Andy would have to say about it too...especially since I totally agree with Pete and Jonathan. THX certification is just another horseshit marketing thing that really has NO advantage that 99% of the theatre-going masses can recognize...BUTT! Think they can! OBTW: Don't forget to use "Monster Cable" for EVERYTHING! It's just ANOTHER hype for the theatre owners to pay the $$$ so they can have the "privilege" to screw the patrons outta more $$$. HERE is the "official" approved equipment list. (pdf) (Which just goes to show that shit equip is "approved" right along with the "good" stuff!)  |  IP: Logged Daryl C. W. O'Shea Film God Posts: 3977 From: Midland Ontario Canada (where Panavision & IMAX lenses come from) Registered: Jun 2002 posted 12-01-2005 11:01 PM                        Don't you be knockin' Monster Cable. I just rewired a 2000 car space drive-in's AM system with Monster Cable and it definitely rocks. Well worth the $6,000,000 it cost.  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 12-02-2005 02:59 AM                  OK, OK, OK, Daryl! I'll endorse Monster Cable for the AM transmitter interconnects for drive-ins with a capacity of 1500 or more cars. BTW: Was that cost in US or Canadian dollars?  |  IP: Logged Daryl C. W. O'Shea Film God Posts: 3977 From: Midland Ontario Canada (where Panavision & IMAX lenses come from) Registered: Jun 2002 posted 12-02-2005 05:25 AM                        Canadian of course. Didn't you hear that American money isn't worth anything anymore?  |  IP: Logged John Walsh Film God Posts: 2490 From: Connecticut, USA, Earth, Milky Way Registered: Oct 1999 posted 12-02-2005 08:50 AM                     Given two similar pieces of equipment, I'd buy the THX rated one. It probably doesn't cost any significant amount extra anyway. I agree that the "THX approved" nameplate doesn't mean much today, but I'd like to point out Louis's remark. 20 years ago, few products had as much hyperbole as audio equipment. Manufacturers routinely fudged specifications, ratings, etc. in almost any way possible to make their product look better (anyone remember the stupid IHF ratings?) RTA's, wow and flutter meters, good filters, etc. were expensive in the late 1970's, so it was somewhat difficult for the average person to see for themselves the real specs of a piece of equipment. This was the state of the industry when THX started rating equipment. As Gordon said, with a THX rating, at least the equipment will do what the spec sheet says. So if you want to say THX rated equipment doesn't mean much today, well, OK. But to say it's a waste is like saying mag striping on release prints was a waste; you are using modern eyes to judge an old problem. THX raised the bar for motion picture audio and just about everyone has benefited. It too bad George just bailed on the whole idea 'quality' for theaters.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 12-02-2005 12:28 PM                        John: the words you want to say are "SOLD OUT!" I was one of the very first of the TAP engineers; back in-the-day. The others included Bill Purdy. All were the best at that time. Over the years deals were made until THX literally meant nothing. I personally heard 5 movies at the same time in one large chain auditorium that was "self certified." Other chains were not allowed to self certify and sometimes were held to a much higher tolerance. The outcome for me is that we built all auditoriums to THX specs, used the same equipment (except crossover) and no one could tell the difference between certified or not. Untimately that chain removed the THX since no one could tell the difference; and, since it was not on all screens, they could not reliably promote THX to the public. (need any "like new" dbx card frames?) Louis  |  IP: Logged Frank Dubrois Jedi Master Film Handler Posts: 896 From: Cleveland, OH Registered: Mar 2005 posted 12-02-2005 04:39 PM                    quote: Gordon McLeod Typically a THX approved device will do what the spec sheet claims it will how it is then used is upto the system design engineer Exactly.....but thats not worth anything??? C'mon people. I think THX really started quality control in the theater / home theater business. Perhaps a lot of manufacturers are stepping up to the plate and making good equiptment now BECAUSE THX was so popular. I'd bet a lot of theaters / equiptment manufacturers used or still use THX specs to build their equipment..possibly take it even further and exceed THX standards. It pisses me off when people say THX is because its not. It may not be the ULTIMATE standard that it once was...but its not . I'd pay more for a THX certified AMP or speakers because I know its going to sound great and DO exactly what its supposed to. THX is good.  |  IP: Logged Richard Hamilton Phenomenal Film Handler Posts: 1341 From: Evansville, Indiana Registered: Jan 2000 posted 12-02-2005 07:01 PM                     quote: Gordon McLeod Typically a THX approved device will do what the spec sheet claims it will how it is then used is upto the system design engineer Exactly, as are all similar devices. About 10 years ago, I installed an 8 plex using Hafler amps, Smart ModIV's and JBLs, a single mic and a Goldline. THX was called in by a sub that was responsible for the sound insulation between the auditoriums. The THX tech set up his R2 to analyze everything, and asked me who set up the sound system because it was right on. I agree alot has to do with the equipment, but the design and install play a major factor in the whole outcome. Who really cares about the name brand? Does the average paying customer think about THX? I think they worry more about if the concession has Coke or Pepsi, or coconut or canola oil! Oh, and free refills!! The fact is a well designed theater can get just as good results as a theater that has all THX approved equipment. In my opinion THX did not set any standards, the new technology and the competition between theaters has made the experience what it is today. my 2 cents, Rick  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 12-03-2005 11:07 AM                     quote: Louis Bornwasser To answer your question; I have found by experience that the very best amplifiers have one thing in common: they are RATED into a 2 ohm load. That may be partially true of the more reliable amplifiers but, and this is a big BUT, The most important contribution to sound quality that an amplifier should posess is very low odd harmonic distortion levels..... The human ear is far more sensitive to odd harmonics than it is even harmonics..... The next most important thing is having a large....no, huge power supply reserve, sometimes refered to as head room but its not just headroom that matters here.... the power supply capacity(large power cord, transformer, bridge rectifier(high speed rectifiers or just the 10 cent variety), and filter capacitors.... have alot to do with the reliability AND the overall sound of an amplifier. Just about 95% of the amplifiers we all install in cinemas are WAY underbuilt in the power supply department, thats how the manufacturers are able to afford all those lavish full page ads in national magazines! There are other factors that weigh in with other things that really matter a great deal as what type of output devices are used right down to brand and type... some sound way better than others, are the emitter resistors inductive or non-inductive... inductive=cheap and they sound bad, this is what 95% of the commercial amps have, Mode of operation... class B, Class AB, or Class A, Is there an indictor in series at the output of each channel(really bad!), etc. Personally, even though I dislike all digital cinema processors I do look forword to the new breed of Class D Digital power amps comming to use in cinemas in the near future. You can attain huge power levels.... easily 2-350 RMS into 8 ohms easily in a 12 pound package with little to no heat sinking! They typically run at 90+% efficiency. Many of the "consumer versions" of these amps sound phenominal and the radiated RF energy from them is now well under control. Reliability is as good or better than a standard power amp because of sophisticated byult in protection circuitry... parts count per channel is also way less. Complete 2 chan 300 watt RMS @ 8 ohms Class D power amp less power supply. Power supply is +/- 60 vdc. Mark  |  IP: Logged

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