Development of a "reference" class D starting point

[Bricolo]

Please, let's not start with a "experienced users only" discussion

this is a starting point thread, maybe we should first explain and define class D, the parts needed, the topology, the theory. I'm new in class D and I begin to get lost with your technical discussion

[classd4sure]

Originally posted by Bricolo
In fact I asked for a basic schematic. No power/THD defined in it.

BTW, could we define here what UcD is?

In fact, here is one

http://www.diyaudio.com/forums/attac...&postid=418321

I'll take the blame for it. Don't trust those values, but it should give you the idea of it.

UCD is simply a hysteresis free phase modulator with a dual purpose single feedback loop which is taken after the filter coil. Circuit shown is right off the patent and is excellent if done right.

Much of it can be replaced by a single differential comparator.

Chris

[Bricolo]

Originally posted by classd4sure


I'll take the blame for it. Don't trust those values, but it should give you the idea of it.

I even have difficulties to guess the part symbols, so don't worry about the values, I won't trust them since they are too small

Does this qualify as UcD?
But In fact I wanted to see something more simple, with block diagrams (integrator, comparator...) no discrete for the momment

[phase_accurate]

Does this qualify as UcD?

It's even using the original circuit from the UcD patent !

Regards

Charles

[Jan-Peter]

A nice starting to understand how Class-D Amplifiers work is to read this tutorial from IRF;

http://www.irf.com/product-info/audi...sdtutorial.pdf

Regards,

Jan-Peter

www.hypex.nl

[Bricolo]

Originally posted by phase_accurate


It's even using the original circuit from the UcD patent !

Regards

Charles

Nice

But take care, I remember (with some PASS patents) that patent text and schematics aren't really made to help people (and DIYers ) to understand the principe. Most of the time it's quite the opposite. And the patent's schematics aren't "optimal integration of the theory" not "ready to work" circuits.

But since we have the inventor here, maybe things will be easier

[classd4sure]

Hi,

Originally posted by Bricolo
Please, let's not start with a "experienced users only" discussion

this is a starting point thread, maybe we should first explain and define class D, the parts needed, the topology, the theory. I'm new in class D and I begin to get lost with your technical discussion

Originally this was a starting point thread (I thought), but it seems people need at least 100 watts with great quality..that's not starting point anymore.

Had you been happy with say 20watts, you could be listening to it play really bad in about ten minutes flat, probably for under 10$, learn all about the how's and the why's....and move on to bigger and better things. That's what a reference is after all.

The way this has turned now, It doesnt' seem anyone has any concern over that, and want a good "this is how it's done right" design.

Whatever the end result winds up being I've no doubt will be documented sufficiently.

Things like "what is class d" probably shoulnd't be covered in more than a sentence or two, see google.

Try looking for "phase shift oscillator", same sort of idea. I can link you to the patent it's got the block diagrams and that but....I'm too burnt to dig it up right now, will get it for you later.

Personally, I'm still all for keeping this a class d beginners ideal circuit (cheap, quick, kind of works, learn a heck of alot!)

Once you decide you like it or not, you can decide to start spending more time and money on it....but someone wanted 100w
Regards,
Chris Crashed

[Bricolo]

Originally posted by Jan-Peter
A nice starting to understand how Class-D Amplifiers work is to read this tutorial from IRF;

http://www.irf.com/product-info/audi...sdtutorial.pdf

Regards,

Jan-Peter

www.hypex.nl

Yes, I read this one.
That's why I asked about the full bridge, in thus tutorial they seem quite elogious about this

[Bricolo]

Originally posted by classd4sure
Hi,


Originally this was a starting point thread (I thought), but it seems people need at least 100 watts with great quality..that's not starting point anymore.

Had you been happy with say 20watts, you could be listening to it play really bad in about ten minutes flat, probably for under 10$, learn all about the how's and the why's....and move on to bigger and better things. That's what a reference is after all.

The way this has turned now, It doesnt' seem anyone has any concern over that, and want a good "this is how it's done right" design.

Whatever the end result winds up being I've no doubt will be documented sufficiently.

Things like "what is class d" probably shoulnd't be covered in more than a sentence or two, see google.

Try looking for "phase shift oscillator", same sort of idea. I can link you to the patent it's got the block diagrams and that but....I'm too burnt to dig it up right now, will get it for you later.

Personally, I'm still all for keeping this a class d beginners ideal circuit (cheap, quick, kind of works, learn a heck of alot!)

Once you decide you like it or not, you can decide to start spending more time and money on it....but someone wanted 100w
Regards,
Chris Crashed

Here's the patent
http://l2.espacenet.com/espacenet/vi...h&LG=en&DB=EPD


What I want, is to understand how what I build works. That's all... (maybe that's not as easy as it seems)

As for the power, can't we simply agree on a design, and adapt the PS rails (and the output mosfets) for more or less power?

[classd4sure]

Originally posted by Bruno Putzeys

Quite precisely. That's why I think the most important thing is getting the comp/PS/filter done right. The control loop can be saved for last. You could even consider not placing the modulator on the same PCB with the power stage so you have a Universal Test Mule to try anything you like.

An excellent Idea!