Class D

Please show what you’ve done in solid state amp design, that can even come anywhere near close to Cyril Hammer’s Soulution range of power amps. You should at least believe him about Class-D switching frequency if not me.

I will state again for the slow kids at the back of the room, Soulutions "talent" is

When Audiolabor went under, Cyrill and Roland hired its chief designer Christoph Schürmann to develop their own series of amps, preamps, and CD players. Costs were no object; bullet-proof sonic excellence was. What the boys from Dulliken were after was the inherent musicality and low time-related distortion of tubes combined with the high current/drive capability and low THD of solid-state. What they wanted, in a nutshell, was an amp with all the virtues and none of the vices of both technologies. What they wanted was an amp with no pronounced sonic signature of its own.

It took Schürmann better than half a decade to pull off this little trick.

The comment about GHz switching was not made by their "talent", it was made by a person with technical background, but ultimately the business manager.

I will state again for the slow kids at the back of the room

There's only one slow one here, that's you sunshine. 

I don't see anything in Cyrill Hammer's bio that would suggest the extensive knowledge in signal processing or advanced control theory or even ultra high speed switching for analog reconstruction that would make his opinion any more valid than many many others, and perhaps less. That GHz comment really makes me suspect his depth of knowledge on the topic is really quite weak.

It makes more sense that his comments are that of marketing rather than an engineering background. Obviously George missed my debunking of his use of Cyril's comments earlier on this page. The idea that you need GHz switching speed in a class D amp is rubbish. I'm sure the guy that designed the Soulution amp is cringing at that bit of marketing hype!


I'm going to deal with the Technics issue that George keeps bringing up; not to take them down (I've heard their amp and its pretty good) but to debunk some of the things George says about it (that no other class D amp has); to wit: that because of its higher switching frequency, it has no phase shift because its output filter is set higher.


This is true, but there is an important distinction here! The Technics website claims that the Technics amp is **zero feedback**. When any amp has no feedback (we've been making zero feedback amps for decades), wide bandwidth is required in order to minimize phase shift. That is why Technics opted for a higher switching speed. Its also quite likely that they were wary of Bruno Putzeys' patents in the field of self-oscillating class D amplifiers.


So here we see that there are in fact two methods of preventing phase shift at audio frequencies. The first is the old school accepted method of wide bandwidth (this is the means we have used for 45 years in our OTLs). The other means is to apply so much feedback that even though you don't have bandwidth much past the audio passband, the phase shift is nevertheless controlled to the same degree.

George missed my debunking of his use of Cyril’s comments earlier on this page.

You are good with tubes granted, but sales for them, especially OTL are waning, you need to shill for you Class-D, you are nothing compared to Cyril Hamer for solid state design. And here the story ends.

The idea that you need GHz switching speed in a class D amp is rubbish.

And that’s another twisted furphy of yours. That statement of his say mhz for now as Technics have done with the SE-R1.
And the the ghz reference said by him is looking into the future of Class-D.
  
Can you or the other one see the forest for the trees, or is something like the mighty $$$ stopping you?
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