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Bryston: THX for 2 ch - a good thing or not?

Several Bryston amps are available with THX certification and badging at extra cost. Is this a good thing for 2 ch setups?
I recently had an email exchange with an Audiogon seller of a Bryston 8B ST amp. I told him I was also looking at two Bryston 8B ST THXs on eBay. He related to me an opinion he had heard that the ST THX versions were somehow inferior to the ST versions. Was he just hyping his amp or is there something to this allegation?
I googled this issue every which way without much satisfaction. One source mentioned that the THX stardard required expanded dynamic headroom, which sounds like a good thing, but doesn't the ST version also meet this requirement?
I spoke to a Bryston designer at the factory in Peterborough some months ago, before the current question became an issue for me. I got the impression from him that the THX versions were just the ST/SST versions with THX certification and badging, for which Bryston had to pay Lucas for the priviledge. Therefore, amps were certificed as THX compliant more for marketing reasons than due to any design modifications, except perhaps for some features (like a different input gain for the THXs).
Bottom line, is there any reason I should avoid THX versions for 2 ch listening? Are they better, worse, or just about the same?
russelllondon

Showing 3 responses by russelllondon

russelllondon OP
4 posts
 
I agree with Sailfishben, Mcfavre4 & Sdcampbell. Whether THX or not, it's not worth worrying about if ST/SST versions are in fact exactly the same as the THXs.
However, have a look at the following from an Audiogo.com item currently for sale as "Bryston 4BST - Thx
RE: THX certification taken from Bryston website....

New Standards of Accuracy:The Bryston THX amplifiers incorporate the use of an innovative gain stage topology, which yields the quietest possible noise floor through the use of low-impedance pathways within the amplifier. This approach also has strong advantages in improving overall distortion performance. Bryston's computer-controlled distortion analyzers confirm intermodulation distortion levels less than 10 parts per million (below 0.0009%) are typical for this new circuitry."
Doesn't that imply that this THX amp is superior to a 4BST without THX? It's totally misleading if everything claimed for the THX also applies to the 4BST. So why would, or should, anyone pay a premium price to get the THX badge on their amp? I agree that they shouldn't, but I still have an open mind on the topic if anyone out there has evidence to the contrary.
BTW Mcfavre4 I tried Audiocirles.com but it doesn't seem to be an active site.
russelllondon OP
4 posts
 
Mcfavre4: I found the site at audiocircle.com (w/o the plural "s" and certainly not my mispelled "audiocirles"), but haven't found Tanner's comments on THX. Thanks for the suggestion. I am very impressed that Bryston and Tanner are so supportive of the Bryston owners' community.
russelllondon OP
4 posts
 
Bryston's online manual for the 3/4/5/7/8B STs includes drawings of the rear of the units, which indicate that the 5/8B STs have the power on/off function, whereas the 3/4/7B STs don't, and the 8B ST THX does.
The manual also refers to this function as being optional, so I suspect you could order it on a non-THX ST version.
A Bryston brochure also says "All ST amplifiers are available in THX version, include remote power on/off function."
The implication of this to me, as someone searching eBay, Audiogon, etc. for a Bryston power amp, is to make sure I ask the seller of non-THX versions if this feature is present or not. I have a Bryston pre-amp with it, so I would definitely want it.
The upshot is it seems I don't have to be concerned that the THX versions contain any design trade offs to comply with the THX standard that would effect my listening experience in 2 ch listening.
BTW I recall a posting on one of the forums where Tanner (Bryston VP) was commenting on a similar issue: the difference between base and pro versions. He said (in my own words from memory, since I can't find that posting right now) there was no fundamental difference, other than the pro version having a feature to attenuate the incoming signals to facilitate matching amp gains. He cautioned those who prefer a purer signal path (w/o attenuation electronics/switches) should stay with the non-pro version.
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