THX doesn't officially release their specs, which is an annoyance to many of us. So when the recently released Monster Cable Subwoofer received THX Select certification, I attempted to reverse engineer the specs from the approved products list.

The attached file shows all the subwoofers approved by THX for Select certification. I gathered data from internet sources, using company website information where available.

As can be seen, Sonance The Sub has the weakest specs at 12"/150 watt driver/amp combination. Sonance The Sub has been phased out and the sub that replaces it (The SUB 12-250) has a 12"/250 watt driver/amp.

Excluding this one 'outlier', a 12"/200 watt driver/amp is the minimim standard to receive THX Select certification.* So what does THX Select mean for performance? Not much. What does the Monster Cable Subwoofer have? The minimum of course. :rolleyes:

*Revealing is the fact that *two* Crystal Acoustics 1x10"/120 watt are required for THX Select, while a single 1x12"/200 watt (with the same frequency response) is THX Select.

don't you have anything better to do? ;)

Apparently I don't either, since I looked at your charts. It seems certification doesn't impose much to me, the worse sub has a measely 35Hz extension. I think the spec must impose a minimum SPL for a small-medium room, which isn't very hard to meet even with a $250 sub

based on the approved sub list, I think anything except the bose bass module could get thx certification

based on the approved sub list, I think anything except the bose bass module could get thx certification

yeah, kind of revealing, huh?

I think what they should do here is make a product that can work in all environments rather than beating around the bush. I use THX select and thou I use separate amplification with a loudspeaker management crossover system, need I say anymore.

I use a cinema type design sub for reproduction of LFE.1 the JBL 4645 18” which serves very well for all types of DVD or laserdisc, now then.

I think what they should do here is make a product that can work in all environments rather than beating around the bush. I use THX select and thou I use separate amplification with a loudspeaker management crossover system, need I say anymore.

I use a cinema type design sub for reproduction of LFE.1 the JBL 4645 18” which serves very well for all types of DVD or laserdisc, now then.

Does that mean that not unlike a movie theater you have a separate sub for the LFE channel and a separate sub for the rest of the summed (i.e. bass managed) 5 channels?

I personally don't care about THX specifications. A subwoofer that can extend to 105 dB's (which I've been told is the "holy grail" for THX is a meaningless figure.

105 dB's at what frequency ? At 1 m ? At the listening position ? What distortion level is acceptable for THX requirements at this level ? 20 % THD ? 50 % ? More ?

Reference level playback demands output levels in excess of 120 dB's at the listening position with bass management engaged which far exceeds THX "spec".

Extension to 20 hz which is the goal of THX subwoofers is another meaningless metric because in order for you to justify the 20 hz extension you need to produce enough sound pressure at that frequency to perceive it.

A case in point is the Onkyo all-in-one THX system. It apparently conforms to THX specs. Subwoofer is THX certified. Yet there is no physical law permitting that would allow this thing to extend to 20 hz at usable levels. No physical way.

THX specs are very inconsistent from one product to another. It's just a minimum set of requirements set by THX engineers to achieve a good ("good" is inherently subjective and is meaningless in the grand scheme of things) level of performance for movie playback.

--Regards,

I have experienced THX demos that were highly impressive. I also know that the first THX receiver under the Technics brand wasn't very good. Snell, Klipsch, and others make some first rate THX gear. Not only that, there are different levels of THX certification. Ultra II is usually pretty good, almost regardless of what you think "good" is.

For those who really need Reference Level, the THX spec might not mean much. A lot of people use the Klipsch KW-120 THX with a 1,000 watt dedicated amp.

I personally don't care about THX specifications. A subwoofer that can extend to 105 dB's (which I've been told is the "holy grail" for THX is a meaningless figure.

105 dB's at what frequency ? At 1 m ? At the listening position ? What distortion level is acceptable for THX requirements at this level ? 20 % THD ? 50 % ? More ?

Reference level playback demands output levels in excess of 120 dB's at the listening position with bass management engaged which far exceeds THX "spec".

Extension to 20 hz which is the goal of THX subwoofers is another meaningless metric because in order for you to justify the 20 hz extension you need to produce enough sound pressure at that frequency to perceive it.

A case in point is the Onkyo all-in-one THX system. It apparently conforms to THX specs. Subwoofer is THX certified. Yet there is no physical law permitting that would allow this thing to extend to 20 hz at usable levels. No physical way.

THX specs are very inconsistent from one product to another. It's just a minimum set of requirements set by THX engineers to achieve a good ("good" is inherently subjective and is meaningless in the grand scheme of things) level of performance for movie playback.

--Regards,



I tend to agree. When it comes to subwoofers, I don't believe that THX specifications have much merit, since this industry has no real standard of measurement. It's the actual performance of a sub that really means anything.

Ian

Now this isn't to say that there are no "good" THX subwoofers. There are. But the THX certification in and of itself is not a prerequisite to attain "good" performance.

Flat, clean, loud, low and linear. Ed Mullens list of "good" performance criteria also happen to fulfill my ideals. :D

Cheers !

--Regards,

I think the outdated THX cert was important back when HT was just getting started and there were almost no decent equipment, including subwoofers. So, at one time it was a big deal to meet all of the requirements and a great marketing tool for those that did.

Of course, now it is almost meaningless now that a $200 sub can meet those specs as well as correspondingly cheap receivers, etc. Most companies don't even bother with it regardless because it is an expensive proposition with little or no value in today's HT.

aren't there different levels of thx certification?

In the case of system components, THX Home Cinema offers two main levels of certification - 'Select' and 'Ultra', which are further sub-divided according to the category of the different system components, while a third type of certification is also available for multimedia products.

good article
http://www.hometheaterhifi.com/volume_13_1/feature-article-thx-1-2006-part-4.html

aren't there different levels of thx certification?

yes. this analysis was just for the "select" level. since that is what the new monster cables subwoofer is rated for, that is what i chose to look at.