Class D is just Dandy!

It may not be, but it works totally differently.

In a digital amp the feedback affects the width of the "on" period.

First, I’m not sure that anyone has proven in a linear amplifier why moderate feedback is a bad thing. Second, in class D it is a couple of stages away from the output signal, so whatever arguments you might have made for a linear amp’s feedback I don’t know that they would work at all.

As I understand it, Technics is using more of a feed-forward loop. They analyze the errors with the output stage, and then digitally correct it ahead of time, before the actual power amplifier stage. Talk about a huge amount of processing and signal meddling though. :)

The Technics approach is VERY similar to digital EQ and phase correction if you were to limit the correction to purely electrical, it is identical in theory.

If you go that far, might as well include the acoustic output of the speakers as well and finish the job. :)



Best,

E

Using feedback to reduce distortion isn't a free lunch though, or is it?

From what is understood for years by the guru's of amp design, is that any amp should be designed for as little distortion, low output impedance ect., as possible without the use of feedback. Then to use just a little feedback if necessary to clean it up if need be.

Cheers George 

feed-forward loop

Feed forward was used in the old days, and it was resurrected again by Rogue in their M120 and I believe in their M150/180's.

Cheers George 

Hi George,

Feed forward in a linear amplifier is very different. :)

In this case, I’m using it more as an analogy or principle rather than a specific circuit design.

While most amplifiers have feedback at the output stage, the Technics does the correction mathematically at the input, pushing the error compensation from the front instead of the back.

For this reason, I think of this as a feed-forward idea, being the opposite of feed-backwards.

Best,

E

Curious if any of you have tried the Pioneer Elite AVRs and taken a serious listen to the D3 Amplifiers.  I am pretty sure Onkyo now owns them all.    I use them for 2-channel, it is musical, fatigue free, harmonically accurate to my ears.   I does lack the warmth and SLAM if my good Sim Audio separates on my main rig for audio.   But I have to say that in many respects it is more accurate in coherent at about 1/20th the price :).    I can listen to it all day long without issue.   Any other receiver I have owned doesn't come close.         It maybe just me, since I dont hear much about AVRs taken seriously for audio.