CLASS D MONO AMPS buy ATMASPHERE MUSIC SYSTEMS

There are many sources of distortion in class d amps, not only those you have mentioned, but also in the output filter. Do you use post filter feedback?

Yes.

Please share some measurements of the frequency response with load, THD+N with power and frequency, FFT's and IM. Also, can you share the switching frequency used? Lots of claims made here (not all by you) so it would be enlightening to see a more complete picture of how this amp performs in actuality, not how it sounds to those who haven’t heard it yet.

The frequency response is load invariant within 1/10db from 20-20KHz, with 0 degrees phase shift at 20Hz and less than 1 degree at 20KHz. The invariance due to the output impedance being a few milliOhms, the low phase shift due to the feedback value, which allows the amp to correct for phase shift at the bandwidth extremes.

THD from 20Hz- 20KHz  is < 0.1% at full power (200 W into 4 Ohms) and about 0.005% at 1 watt. We think it might be lower but finding a decent filter to knock out the residual has been tricky during the pandemic. We  found one about a week ago and are interested to see how things differ once its integrated into our test setup. The distortion is lower into 16 Ohms.

The switching frequency is just shy of 500KHz, depending on load. The input is entirely direct-coupled.

The filter I mentioned is an Audio Precision device and is used to knock out the residual to prevent it messing with the distortion analysis. If I got this right its 8th order(!) and puts the residual down about 60dB... This is why we've not posted any more distortion data since the residual throws the readings off.

@kuribo No. Purifi is last year's news, even if he is now working on a higher powered module, and Hypex... well.  GaN is state of the art--and not the generic stuff being put out by Peachtree and LSA.

And @noske, I disagree and would maintain my point.  As regards proprietary modules, power output, and price, the two products are directly comparable.  The fact that one is housed in two cases is secondary.  The Audions are nice but not only considerably more expensive but also less powerful than the Tempo di Gan.  My proposed comparison seems to me to offer the levelest of playing fields.

The frequency response is load invariant within 1/10db from 20-20KHz, with 0 degrees phase shift at 20Hz and less than 1 degree at 20KHz. The invariance due to the output impedance being a few milliOhms, the low phase shift due to the feedback value, which allows the amp to correct for phase shift at the bandwidth extremes.

THD from 20Hz- 20KHz  is < 0.1% at full power (200 W into 4 Ohms) and about 0.005% at 1 watt. We think it might be lower but finding a decent filter to knock out the residual has been tricky during the pandemic. We  found one about a week ago and are interested to see how things differ once its integrated into our test setup. The distortion is lower into 16 Ohms.

The switching frequency is just shy of 500KHz, depending on load. The input is entirely direct-coupled.

The filter I mentioned is an Audio Precision device and is used to knock out the residual to prevent it messing with the distortion analysis. If I got this right its 8th order(!) and puts the residual down about 60dB... This is why we've not posted any more distortion data since the residual throws the readings off.

 

I look forward to plots once you get your filter worked out.

At only 500Khz, what is the advantage of using GaN? None of your specs appear to be anything not already achieved or bettered by amps using good old fashioned mosfets.

Thanks for the info.

@kuribo No. Purifi is last year's news, even if he is now working on a higher powered module, and Hypex... well.  GaN is state of the art--and not the generic stuff being put out by Peachtree and LSA.

Until bettered, ncore and purifi are still the peak of class d design and performance.

GaN is a state of the art device but has yet to be implemented in a class d amp in a way that improves upon what has been already done by ncore and purifi using mosfets. Maybe some day, but not yet.

I was a scientist and for a long-time I had myself convinced that I could find better equipment by knowing more facts about the gear I might buy. And sure, I still think some audio facts can be a useful guide. At some point, however, you’ve just got to kick the tires and see how it sings.

Glad to see some people are loving the new amps Ralph.  Congrats.