Class D is just Dandy!

Ha! Thanks for the vote of confidence, Erik.

Kdude - I'm only jealous that people get to hear all these amazing pieces of equipment. I'm curious, more than anything. But when I choose a piece of gear, I tend to stick with it for years. I am a content human. Messing around with my system is fun, but I certainly do not have upgrade-itis. Thank Buddha!

The Ghents replaced a crown xls 1500, which replaced a NAD integrated. Can't remember which one, unfortunately. I'll look next time I'm at its current home.

Any amp after these will probably be some kind of class d kit..

Wait, didn't we have a manufacturer participate in this thread?

I tried going to their web site but it seems down?


http://www.iceh2oaudio.com/index_htm.html

Just a few of the industry's heavy hitters of hi-end design give their opinion on the merits of Class-D in a round table discussion with Absolute Sounds.

http://www.stereo.net.au/forums/topic/110007-switching-noise-in-class-d-amps/?do=findComment&com...

Cheers George

@georgehifi

Interesting article, full of inaccuracies. One I may have helped propagate.

Class D vs. Digital Amplification

The article claims, erroneously, that Class D amps all have an A/D converter at the front. They do not.  It is actually more of an Analog to Analog converter with a switching voltage amplifier in the middle. :) Somewhere there is an article or paper by Bruno Putzeyes chafing at the use of "Digital" to describe his amps, which I can't find right now. Worth a read if you can find it

Class D amps (ICEPower/Hypex) generally rely on feedback to control the switching, which uses a linear comparator. There's no A/D conversion in the chain, it's not needed.

Here is a good short article on the subject:

https://en.wikipedia.org/wiki/Class-D_amplifier

Interestingly, George, the Technics Class-D amp you are looking forward to IS more of a digital amp than most Class D in that it DOES have an A/D front end, followed by a DSP engine to do the calibration and frequency/phase adjustments to the original signal before feeding the amplifier section. You are really trusting the amplifier with a great deal, because it will chew the signal up and digest it before spitting it out again. This is an approach not entirely unlike Theta and Meridian have undertaken.

Best,

E

So, to those confused by Class D vs. Digital, to be "digital" you have to convert or have the signal as an integer to describe the waveform. Like the digits in a CD track. This is "digitization" or converting an analog signal into a series of digits.

Class D does NOT do this conversion, but the amplifier IS switched on and off. :)

It’s confusing because what happens is that the comparator keeps the switch ON or OFF more or less in proportion to the incoming signal. This is why feedback is so important and completely different in a Class D amp vs. linear. The feedback IS essentially the only way the amp has to control the output signal, however this feedback takes different shapes. The more global the feedback, the more accurate the output.

It’s a subtle but important distinction.

Here is a list of Bruno's papers, I encourage you to read them, as I am sure I made mistakes, and the guy is one of the celebrated Class D amp designers of our time.

https://www.diyclassd.com/p/application-notes-white-papers/

Best,

E