Pass Class D

[Nelson Pass]

About 40 years ago I was inspired to make a switching amp, and the
result was a modest 20 watt/ch unit that worked quite well.

I've been asked about this several times in the last couple weeks about
the existence of a Threshold Class D amplifier, and I was inspired to
haul it out of storage and fire it up. It still measures decently if not
to the standard that Bruno has developed, but it sounded good - I
recall that Gordon Holt liked it.

Anyway, here are some pics.

 

[chrisb]

So the kits will be available at DIY Audio store when? 😆

 

[Loudthud]

Eight PCBs ?

 

[Mark Johnson]

It's pretty impressive that the only (visible) heatsink, is on a bridge rectifier. Very smooth!

 

[kevinkr]

That is a very tidy prototype build. 🙂 The fact that it still works says a lot.

 

[skunark]

Eight PCBs ?

There might be nine…

 

[ripblade]

Where was the audio switching done?

 

[eriksquires]

Very nice!! I am curious just how "Class D" it is though? Does the topology have much resemblance to the Wikipedia article, with a triangular wave generator, etc??

 

[twitchie]

Is this going to make a guest appearance at BAF?

 

[Jacruzer787]

You know Pa, those were your heretic days.... back in those old days, you still played with bipolars and Class D amps.

That must have been a traumatic period in your life, and for that reason, it would not be fair for you to hold on to that amp.

Fine, I'll take the bullet, I will take it from you so that your mental health will not suffer, and before Zen Mod gets his greedy hands on it!

Also if people keep asking you about your class D amp, you can tell them that a Florida man has it!

Best,
Jose

 

[kevinkr]

I'd love to hear the story of that amp, and the technical details. It would be historically interesting and it might just make a good project for some of the crowd if it meets your threshold of performance. 😆

 

[Zen Mod]

 

[Zen Mod]

 

[davidkou]

How about a 'DSD amplifier', which could impedance match a line DSD 'digital' signal from the output of a DSD DAC directly into a speaker load, with perhaps any appropriate LP + DC offset filter?

 

[yetis]

Nice, that would pair nicely with the DA (D1) you briefly made..

 

[drjlo]

So...not tpa3255 😉

 

[Nelson Pass]

How about a 'DSD amplifier', which could impedance match a line DSD 'digital' signal from the output of a DSD DAC directly into a speaker load, with perhaps any appropriate LP + DC offset filter?

That would be for Wayne to do...

 

[EUVL]

For those who are interested in how it works, this is an excellent article from Bruno :

https://www.diyclassd.com/media/5c/19/2e/1682341812/Simple self-oscillating class D amplifier.pdf


Patrick

 

[savan]

How about a 'DSD amplifier', which could impedance match a line DSD 'digital' signal from the output of a DSD DAC directly into a speaker load, with perhaps any appropriate LP + DC offset filter?

Here you go -> DDPD

 

[Sidsmith]

Well a DIY class D amp design that has the same sonic signature than the ACA minus the heat, I would be interested !