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Class D Switching Power Amplifiers and Power D/A conversion

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Old 19th October 2005, 02:58 PM   #11
Pierre is offline Pierre  France
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Mmmm. I must be missing something.
Lars, were you talking about the supply in the photo? If so, you said ETD14 instead of RM14
Where are the rest of the components of the supply (mosfets, output diodes...)? Isn't it a flyback design? (Just can't see the voltage divider capacitors or an AC coupling one)

I am also waiting for you to post more details...
Best regards,

Pierre
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Old 19th October 2005, 05:18 PM   #12
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Pierre: Absolutely right about the RM14. My mistake.

It is a push pull type smps with a coupling capacitor. This way i can avoid the smps' regulation loop to be 'visible' to the audio section. Also a push pull layout is the one that makes the most efficient use of the transformer size.
(Most power per copper and Ferrite).

In the first attempt i was using a rather special driver circuit, that is very simple and safe. But unfortunately the MOSFET's are now so powerful (20A) that they have a bit too high capacitances for the simple driver circuit. That is why i am going to switch to another well proven solution, that i will be posting soon.
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Old 19th October 2005, 06:56 PM   #13
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Yves Smolders: Actually i would prefer it if you would not use my switchmode for your JP modules.

You will end up getting a sound that is lacking dynamic perfomance, and a messy soundstage. I am sure JP will quickly convince you that the problem is not his modules, but the smps. (hmm for obvious reasons). Well as you know the above problems IMO does not come from the power supply, as any power supply you can think of will give these results.

However using the proposed smps with ZAP modules will give you a highly dynamic, open sound performance with a perfect soundstage. Those are the ones i have been designing the smps for, so i know how it works.
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Old 19th October 2005, 10:28 PM   #14
KLe is offline KLe  Australia
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Quote:
Originally posted by Lars Clausen
However using the proposed smps with ZAP modules will give you a highly dynamic, open sound performance with a perfect soundstage. Those are the ones i have been designing the smps for, so i know how it works.
Thankyou Lars: Looks fantastic and I look forward to using it with my ZP2.3SE modules.

What do you see as the pros and cons of your SMPS over a traditional large transformer PS?
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Old 20th October 2005, 02:05 PM   #15
Pierre is offline Pierre  France
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A simple question for Lars...
Why did you choose push-pull topology instead of half-bridge?
If I am not wrong, each mosfet has to withstand twice the rectified bus voltage. That's around 2x320V here, in europe.
It is not easy to find fast and powerful mosfets rated at around 750-1000V, is it?
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Old 20th October 2005, 02:08 PM   #16
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Pierre: Maybe there is some topology confusion.

Actually it is a half bridge, which runs the transformer in push pull mode. And i am using 550 V MOSFET's from ST. They seem to have the best ones in this voltage range.
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Old 20th October 2005, 02:12 PM   #17
Pierre is offline Pierre  France
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Ah, ok. Then you have a half-bridge, with a big bus capacitor (400V rated, I suppose) and then a 1uF or similar capacitor, from one of the primaries to bus GND. The other primary terminal to the mosfet bridge. Is that correct?

It was very strange to me that you were making a push-pull! Best of luck with that design. Hope you publish it soon ;-)

Pierre
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Old 20th October 2005, 02:43 PM   #18
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D*** you are good !!

The relay is for soft start purpose.
Attached Images
File Type: gif smps1.gif (11.2 KB, 714 views)
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Old 20th October 2005, 03:06 PM   #19
Pierre is offline Pierre  France
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Ok, Lars.
You have kept it the simple way, haven't you? No output inductor, only two rectifier diodes, no feedback... I assume you run at near full duty cycle all the time. But... isn't that electrolytic 400V capacitor a bit small for around 400W? (with no regulation, as your bus will sag badly under heavy loading, your output will do the same).
Anyway, that will happen as well with a toroid and linear supply!

We are all waiting to see the rest of the circuit.

Best regards,
Pierre
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Old 20th October 2005, 03:12 PM   #20
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Pierre: I have a feeling that you might have some good ideas to contribute here. Since none of us are going to make a product out of this, and it's just for fun, why not pitch in?
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