Is THX a con?


Active Member
I have a THX Ultra certified processor (Tag AV32R) and a THX Ultra 2 power amp (Arcam FMJ P7).

When I try to access THX post processing on my Tag I feel it sounds worse than normal Dolby Digital / DTS and certainly different.

Is this because my speakers are not THX certified or does everything from cables to DVD player/ DVD disc/ processor/ amp have to be THX certified to get the benefit?

I first thought it would be great to have THX badges but now I feel let down. I know that THX is a set of standards laid down by Lucas and that more expensive av equipment have these THX badges. They have to pay Lucas a licence.


I personally don't use THX post processing. All it does, to my ears, is dull the sound. Perhaps for a brighter sounding system at higher volumes it can be useful, maybe even necessary. My system is geared towards music above all else, thus movies are not presented with outright slam but as they were, I believe, intended to be heard. Thus the post processing is not necessary.

Having said that, I have not heard a THX certified end to end system (other than at the cinema) so I cannot comment on how it sounds with/without post processing.

It could be your system is not overly bright, thus the THX processing is not useful to you. As you have correctly indicated, THX is a set of standards, so you are reaping the benefits of those standards even if you don't use the processing aspect of it.


Active Member
Hi Sab
I found Thx proccessing very good with my M&KS which can get bright in the treble at ref levels as chris says its more than likely that its effect is better on different speaker systems.
Cheers Gonzo.


Well-known Member
As you've said,THX is just a set of standards,issued under licence.

There are plenty of amps etc which more than meet the standards,but due to various issues(age,manufacturer's willingness to have the logo etc)do not have THX "approval",and mine are a very good example of that...too old to have THX approval,being made well before THX!

As for post processing,whilst my processor does allow it to be used,I generally dont,as most soundtracks sound fine without it,but the occasional really abrasive track does benefit.....if you don't need it,or it sounds worse engaged,don't use it.

Peter Baker

Novice Member
I find myself switching between THX and non-THX on TV programs. Often the difference is small, but sometimes, the dialogue is a bit more intelligible with the THX processing on.
On films, it can tame the treble a little, and seems to bring dialogue a little higher in the mix. It can also flatten the soundstage.
I have to say all these differences are pretty minor.


Active Member
Sab: I'm at the other end with a THX Ultra speaker set on a non THX amp and I'm really happy with them. They're the most cohesive sounding HT speaker set I've ever had and I've had several.

THX isn't a con it's a 'standard' if you buy the whole system it will give you performance to that 'standard'. You may be able get better sounding systems or you may get worse than THX but THX will always be consistant. IMO THX is the processing and the speakers all the other stuff is optional.

If you listened with Processing left on for several days and then turn it off I bet you will find that the unprocessed sound now seems bright. It's whatever you're used to. YMMV

Peter Baker

Novice Member
After reading, and commenting within this thread, I was prompted to listen closely to a tv source with and without THX on Prologic (I don't have PrologicII).
On reflection I agree with chrisgeary, as I found the main impact of THX was a definite dulling of the dynamic, and a reduction in soundstage depth and space. With a very busy soundtrack this may serve to reduce distraction from the dialogue, and this is probably what I at first perceived.
I've now changed my default to be without THX, and believe the sound is better separated, and has more rear information. The difference is not enormous, but is worthwhile.
Thanks Chris



Novice Member
I feel that the set of standards are a good idea as it is a guarantee of a piece of equipments level of ability. But as for post processing I dont like it at all, as several of you have pointed out it just shaves off the top end making things sound dull. THX Ultra 2 was quite usefull when I first had it as in music mode it generates a good centre surround image without messing about with the HF response of the front speakers. But a soon as PL2x came out in december this enabled me to use this in combination with dolby 5.1 for the centre rears and is better than Ultra 2, so now I dont use any kind of THX post processing at all. It seams to me a bit pointless to produce THX certified speakers that sound too bright in the first place just so you can then apply post processing to dull them down?


Active Member
THX speakers aren't designed to be brighter than other speakers (mine certainly aren't) the soundtrack is.

A movie sound track is mixed with and for speakers behind the screen, as in a cinema. As the screen will absorb the HF the HF is boosted, this means the soundtrack tends to be bright in the home where the speakers aren't covered. The THX movie post processing rolls of the HF to compensate for this so if there never was any boost, makes the sound duller.

TV is probably mixed in a smaller studio and shouldn't IMO need any THX processing unless you like the sound it makes.

If you check out the THX site they're now certifying studio monitors and video game production so I don't know quite where that means THX home is going. Except maybe even more THX modes.


Novice Member
DVD soundtracks used to be mastered with no change from the cinema mix, but in my experience nowadays the vast majority of DVD releases are mixed specifically for the DVD release and have already been re-eq'd, so no THX re-eq is needed.


Novice Member
Originally posted by Thunder
DVD soundtracks used to be mastered with no change from the cinema mix, but in my experience nowadays the vast majority of DVD releases are mixed specifically for the DVD release and have already been re-eq'd, so no THX re-eq is needed.
Exactly. THX re-eq is much more relevant to laserdisc and early DVD than current DVDs. Does make it tricky though given the lack of info on the DVD - you can't exactly plug and play...
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