Originally Posted by penngray
Your last statement is so true and THX should be taking with a grain of salt. I have never found THX certified speakers to be better then Danley, JBL, Mark Seaton or any DIY speaker designs so in the end its all just user specific.
But it can be useful for J6P who doesn't want to learn enough to make his own decisions, to simply buy THX stuff in his price range and have a warm fuzzy... not so much for me, however...
I have high end sealed DIY speakers that roll off naturally at 70Hz...I have never read about a recommended min of 60 Hz being set in stone if the sub system does up to atleast 80Hz very well.
Well, "recommended min" and "set in stone" are two different things. Bottom line is that if the speaker starts adding it's own rolloff to that of the crossover at a frequency where the the output of that speaker is still required to make the crossover smooth, it's easy to see that that there will be a little dip... whether or not it's audible will depend on the person, the sub, the room, the material etc... OTOH, if we're talking DIY, you can have a speaker with a 1st order rolloff, and crossover with a first order rolloff on the speaker side but a second order rolloff on the sub side where a -3db point of 80Hz on the speaker would be just peachy, and then anything else would cause dips or bumps... like you said above, it all depends... rules of thumb...
I guess my main point is that anyone hung up on THX specs, THX speakers are the people that need to understand a little more about overall audio performance. THX label and standards has nothing over some of the best systems I have heard...Heck some THX label stuff is not what I consider good at all when compared to custom HT systems.
I happen to agree with you there, but some of that comes from misunderstanding their different logos. Some equipment carries a THX logo indicating that they license certain technology from THX, such as Re-Eq or BGC or the like, and have nothing to do with being THX certified... except for that particular circuit meeting THX's requirements for that particular circuit. Also, what's THX certififed for one environment may not sound very good in another environment, but the different classes are very ambiguous except for anyone who does some homework. I blame THX for this. At a min, they need to do a better job marketing themselves to the public.