Im glad Theta is back in a big way. I owned them a few years back, but was talked into switching to another manufacturer when Theta seemed to be in trouble. I think I will give them another try. I have some questions for you guys about Theta.
1) How much influence does ATI have on Theta. My concern would be that A DNIII would be mainly an ATI influenced amp, while the DNII would be the classic Theta sound and design. What do you guys think about this.
2) Also, I have some questions about some of the reviews reviewers have given some Theta amps. Mostly the measurements they find that they attribute to the lack of negative feedback. For example, Stereophile claimed of the Intrepid on page 2 of their measurements . . .
the amplifier meets its specified 100W output into 8 ohms at 2% THD rather than the usual 1%. Into 4 ohms, the clipping point had to be further relaxed to 3% THD+N for the Intrepid to meet its 200W specification, even though just one channel was driven for this measurement.
The THD seemed to be in a 3rd harmonic only, and the reviewer said the amp sounded very good despite the THD measurements. I know the Intrepid is discontinued and a budget item, but in the review of the DNII, Ultimate AV claims in their measurements of the amp . . .
Into an 8ohms load, with five channels driven, the Dreadnaught II clipped (1% THD+noise) at 192W per channel at 20Hz and at 189Wpc at 1kHz (215Wpc with two channels driven at 1kHz into 8ohms). Into a 4ohms load, five channels driven, clipping occurred at 228Wpc at 20Hz and at 227Wpc at 1kHz (255Wpc with two channels driven at 1kHz into 4ohms).
The DNII is supposed to be 225 per channel into 8ohms, and about 500 into 4ohms, but the measurement says the THD is 1% at 192 watts and 228 watts? I owned this amp, and thought is sounded great, blowing away the competition but these numbers don't make any sense. TJ Nelson reviewed the amp for Ultimate AV and said it sounded great too. The DNII is also discontinued, but the Enterprise is not. Stereophile reviewed the Enterprise, and we all know that the review isn't useful, but the measurements seem to show lots of THD too. Their review measurments show . . .
the Theta doesn't quite meet its specified output power at the usual 1% THD clipping point: 280W (24.5dBW) instead of 300W (24.8dBW). (I note that the Enterprise's power output appears to be specified at 1.75% THD.) The 0.3dB shortfall will not be audibly significant, but relaxing the clipping point to 3% THD does allow the Enterprise to give out 452W into 8 ohms (26.6dBW) and 580W into 4 ohms (24.6dBW). But only 215W are available into 2 ohms at 1% THD (17.3dBW), meaning that the amplifier is really best used into speakers of 4 ohms and above.
Again, I know the amp sounds great, but what can be made of the high THD? Even the mighty Citadel suffers the same measurements. Stereophile measured the following in their review . . .
An amplifier's clipping point is usually defined as 1% THD+noise, at which point the waveform, viewed on an oscilloscope, is visibly squared-off. The Citadel failed to meet its specified output power of 400W into 8 ohms at the 1% clip point, raising just 250W (24dBW). It did deliver 400W into this load (26dBW) when the specified clipping point was relaxed to 2% THD+N, as specified by Theta.
But the reviewer raved about the amp, and the reviewer at Ultimate AV bought the amps and said they were the best he had ever heard.
Can someone please sort out the odd measurements and how they can be there yet the amps sound very good. My main concern is about the amp clipping (defined as 1% THD+noise) and damaging the speakers.