Avi Greengart is the Research Director for Consumer Devices at Current Analysis (Mobile Phones, Connected Devices, and Digital Home). He also regularly writes for Slashgear, sporadically blogs at Home Theater View and Tweets far too often as @greengartAvi's expertise lies in understanding consumer electronics marketing, consumer behavior, and technology adoption patterns: where new technologies meet the mass market. 



Avi Greengart is an expert on the convergence of technology and entertainment: video, audio, computing, and wireless, how these are coming together, and what's likely to survive long enough to make a difference in your life.

Everything You Wanted to Know About: THX


I’m looking for a new receiver.  Do I need one with THX to play THX DVDs?

AskAvi Replies: 


THX certified DVDs are not unique in any way; they’re simply discs which were authored following THX’s standards, which may or may not be better than anyone else’s standards.  For example, the THX-certified Toy Story discs are so good that they are often used as reference material for both audio and video.  However, Titanic, another THX certified disc, is not even enhanced for 16x9 televisions, and subsequently lacks visual detail.  Titanic’s sound is impressive; however, the disc defaults to stereo, not surround, unless you specifically select the correct soundtrack from the menu.

The THX program for home theater receivers has a lot more substance.  THX home theater products adhere to a set of standards, are certified to ensure that the product actually meets those standards, may include proprietary audio processing modes (that work in addition to the “regular” digital sound decoders), and include a healthy dose of home theater philosophy.  More on this later.

Some Background

Today, THX is a company with a series of licensing programs for commercial theaters, home theaters, video reproduction, multimedia, and even car audio – they’re constantly expanding, and I’m sure I’ve left something out.  It all started in 1977 when George Lucas first released Star Wars.  Back then, movie theaters generally had terrible sound capabilities, and few had the capability to play back Star Wars’ Dolby Surround soundtrack.  Based on rigorous acoustical principles and an enduring partnership with Dolby Labs, Lucas launched a new company, THX, to provide standards for movie theater sound.  Whether you like Lucas’ films or not,  moviegoers owe Lucas a huge debt of gratitude: THX almost single-handedly pushed  through the technical strides movie theaters have made since the late 1970’s.

The THX program for commercial theaters continues to this day.  But when “home theater” became a phrase, THX decided to expand it’s mandate to include it.  The Home THX program covers everything in the chain from media to your senses – players, processors, amplifiers, wires, speakers, and training for installers.  Video displays haven’t been certified… yet.  As a rule, complete Home THX systems are expensive, extremely well integrated, and can play clean and loud.

Home THX Philosophy

The Home THX program standards follow from a unique philosophy about home theater, including loud expected peak sound levels and a diffuse rear soundstage.  Amplifiers are expected to play clean even at extremely loud levels.  Speakers must reproduce sound cleanly even at those extremely loud levels.  Speaker systems are subwoofer-satellite designs with a strict 80Hz crossover – the main speakers should be relatively small and nearly identical, with a separate large subwoofer (or two) providing the bass.  Original THX specifications also included speakers that can strictly control where the sound is directed – not off the ceiling – and surround speakers were required to disperse sound in multiple directions.  Processors (or the processing portion of receivers) include modes for increasing the spaciousness of surround sound, and reducing the harsh treble on recordings mixed with commercial theaters in mind.*  What tends to confuse people is that unlike Dolby Digital, these processing modes are not essential – they are enhancements that work in addition to Dolby Digital or DTS.

THX, THX Ultra, THX Select, THX EX, THX Ultra2

THX has done a good job promoting their program, but the changes over the years are a bit hard to follow.  First, there was THX.  It assumed you had a big room and a lot of money.

Then, there was THX Ultra, which was a new name for the original program when THX introduced THX Select.  THX Select assumed you had a smaller room (lowered amplifier requirements) and less money (it allowed for less complicated surround speakers).

Then came THX EX – which confused everybody, because THX EX is just a fancy licensing name for Dolby Digital EX.**  You can have “EX” without “THX,” but since the THX folks helped develop the standard with Dolby, they got to use the name for a while before anyone else could.

With the popularity of home theater rising, THX revised the THX Ultra program and called it THX Ultra2.  They relaxed certain parts of the requirements (the vertical directivity of speakers was reduced to allow for better sound in the oddly-shaped living rooms of America), raised others (subwoofers now need to be able to reproduce the seriously low bass that appears on more and more DVD releases), and tried to accommodate multi-channel audio (by allowing flexibility in the type of surround speakers used, and providing processing modes to better use those speakers).

Does Anyone Need THX-Certified Gear?


A manufacturer could build gear to meet or exceed THX standards, and many do. However, while the basics are well known (subwoofer crossover frequencies, amplifier total harmonic distortion, speaker dispersion characteristics) the standards aren't published in the public domain - they're part of a licensing program. Even if our manufacturer did follow the same guidelines, they wouldn't be able to advertise that they've done so, because "THX" is a registered trademark.


Even if the manufacturer implied somehow that it met/exceeded THX standards (perhaps by posting a list of the standard specifications, and putting check marks next to each item), the consumer still wouldn't have independent verification that these claims are legitimate. THX actually tests a sample of the gear bearing their logo; our non-certified manufacturer has no independent third party ensuring that these specifications are, in fact, met.***

Proprietary Processing Modes

Sure, rear speaker de-correlation (broadening the surround sound) and treble roll-off (taming soundtrack brightness) are available on non-THX processors, but not THX's implementation of it.  While others may imitate the THX modes, and some may even provide more flexibility, the THX processing is still the reference they are judged against.


You may not agree with parts of the THX philosophy, or you may simply consider the THX logo, certification, and processing a poor value for the added cost (all licensing programs add to the cost of the product).  There are undoubtedly a lot of products out there that equal or exceed the quality of their THX-certified competitors.  Still, when you use THX-certified speakers with THX-certified processors, a lot of the interaction guesswork has been taken care of for you, and that can have a significant impact on the quality of your system.  If you have the budget, go for it.

None of this, however, should take away from the simple enjoyment of playing a DVD – THX certified or not – on your DVD player – THX certified or not – and listening to the ensuing surround sound through your receiver – THX certified or not – and your speakers – THX certified or not.



* DVDs with soundtracks specifically remixed for reproduction in a home environment might not need the THX processing, though some still do.  Most THX-certified receivers and processors allow you to selectively engage the processing as needed.

** Dolby Digital EX is one of several recent surround modes that adds one or two surround channels behind the listener.  Rear surround speakers in a typical home theater setup should actually be placed on the sides of the listener.  For full THX EX, Dolby Digital EX, and DTS-ES installations, the rear center speakers are placed directly behind the listener.

*** Just how independent is THX?  THX is not a manufacturer, so by definition, they are independent of the companies they license. Are they objective? Well, they are dependent on licensing revenues, so they can't reject absolutely everything, but their whole business is setting and licensing standards, so it isn't in their best interest to be overly lax.  Besides, what are your alternatives?

bulletYou could rely on magazines for objective advice, but magazines that accept advertising are beholden to their advertisers (some much more so than others). 
bulletYou could rely on online forums for objective advice, but while the folks online are beholden to no one, they tend towards close-minded groupthink, banding together and dismissing entire companies/products/concepts out of hand (for example, anything from Bose, Microsoft, or Monster, band-pass subs, music DSP modes, etc.).
bulletYou could rely on this column for objective advice, but how many equipment reviews can I possibly do?!

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