Theta CB3HD -2012 Diric Live, Digital Out Card, DTS Neo X 11.1 - Page 2

http://www.soundandvisionmag.com/pho...s-2012?image=9 Appears the info I orginally posted was accurate. Oh, 'cause we want them to look pretty.

"Theta’s known for the Dreadnaught, an exotic tower-style amplifier that uses no global negative feedback and sure sounded awesome when I tested one about 10 years ago. But the high distortion of the no-global-feedback design just didn’t fly with Morris Kessler, the man who bought Theta in 2007 and is best known as founder of ATI and co-founder of SAE. So for Theta’s new Prometheus amp, Kessler used a new Class D topology called N-Core; the Prometheus represents the first use of N-Core in a consumer product. The amp uses a conventional linear power supply designed by Theta. The $6,000-each 250-watt monoblock has a claimed A-weighted signal-to-noise ratio of 128 dB and distortion rated at less than 0.01%."

Quote from Brent Butterworth, Sound and Vision mag, last January.


N-Core sounds like something from Star Trek. "Nanite" Core! "NtiMatter" Core?

Actually, its:

http://www.hypex.nl/index.php?option...=article&id=89

As any consolation the DIY has been able to get their hands on a modified version of the ncore (discrete input comparitor) and are in love with the thing, I have yet to hear a negative comment about the amp.

I saw that. Amazing no negatives . Theta is using the NC1200 module. I think the DIY is NC400? Less power?

yes. The NC400 is the only one available to the DIY community. Bruno says that no manufacture wants to buy an OEM that a DIY can get (the need to be special). So he came out with the NC400 which is a lower powered version and the input stage is all discrete components.

I plan to build several of these units some time next year when I move into a house and completely replace my current HT gear.

Looking at the specs, Theta is showing 250/500/1000 watts into 8/4/2 ohms. The module specs 350/650/1200 watts. My guess Is that Theta is doing the typical and underrating the watts into 8ohms to make the amp appear to double in output as impedance is halved. I hope so.

The new amps use A LOT of negative feedback and are not fully balanced like all past Theta designs. I am not sure the feedback is a detriment to sound quality. The specs are high so being fully balanced may not matter either. I will note that the designs of David Riech and Charles Hansen before him are more highly regarded than any amps from SAE or ATI. I guess in the end we will judge the method by the result. The results so far appear to be pleasing.

Very possible BUT more likely the power is limited by the power supply. I am willing to bet they went with a regulated design (how else do you justify the price?) which will limit the output current. The designer has mentioned himself that you don't need a super clean supply because of the high PSRR but I have to admit that Theta knows exactly what their customers want and is going to give it to them.



A class D amp has to use feedback, this is just how they work. Bruno has some interesting white papers on his site if you are interested to know why the ncore is different from other class D amps. I won't get into the whole audiophile myth of feedback being evil. Like anything in design its more about how its implemented then black or white.

I read them. I also wondered about the power supply being a factor in output. Yeah Theta knows what we want and SMPS is not it.

Still I am almost certain the amp will beat the specs because the specs show the power doubling.

Sometimes engineering has to take a backseat to marketing Regardless they should be great amps .... I hope so because Ill have like 7+ of them (ncore not Theta).

Not sure about that. Ayre stuff is really good and uses the same philosophies. Maybe this will be it but so far I have never heard a Class D amp approach Theta,Ayre. Or BAT.

For roughly $600-700 you can build a monoblock ncore and judge for yourself. Easy to get rid of if you dont like it.

We're talking wooden enclosure or maple board and SMPS? At any rate it's not enough power for me. My amps clip at over 700 watts into 8 ohms. The replacements at 850 into 8ohms. 250 wattle? I need man power and that's girl power. I note that Theta invited such price comparisons when they decided to turn from their in-house designer. It's likely that many companies will offer Amos with the same modules.

Just saw this on FB.

Wish I was in the area.

"I read them. I also wondered about the power supply being a factor in output. Yeah Theta knows what we want and SMPS is not it."

Probably why they are "A" weighting the SNR. It would "improve" the SNR of a linear PS at 60hz by 28dB.

Shawn

Who the heck is Bruno? Who makes a NC1200 module or NC400 module?

Bruno Putzys is the head designer at http://www.hypex.nl/

Why does the lower powered module still spec at 124db SNR even with SMPS?

What makes you think the SNR is a function of output power ? The SNR is independent of the supply noise ... that is the very definition.

I don't think that which is why I am asking Shawn to clarify. It seems the implication is that the amp would measure SNR of 100db without A weighing?