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Class D Switching Power Amplifiers and Power D/A conversion

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Old 5th February 2006, 10:22 PM   #1
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Location: West Coast of Norway
Default Regulated PSU for Class D?

Has anyone tried?
Came across this sceme regarding a regulated PSU for a GainClone. Would be interesting to adopt it to a hmm, lets see a zappulse project for instance.
Click the image to open in full size.

Is this doable with transformers with 42v secondaries?
The regulators have to be be changed, but are there regulators that can do this job with 800va-2*42 V secondaries?
Just wondering.
I have a couple of zappulse monoblocks, but want to change them into the 700xe version and rebuild my PSU. Therefore I am looking for a really good, maybe ultimate PSU for the modules.
I am not that into this, and maye a regulated PSU is not the way to go with Class D amplifiers at all.
Do yo diy guys have any other Hi End Psu alternatives to share?

Best Regards
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Old 6th February 2006, 12:08 AM   #2
BWRX is offline BWRX  United States
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Location: Pennsylvania
If you're looking to use linear regulators you'll want to find ones with good load transient response because the class d output stage sources and sinks quick bursts of current from the supply rails. Some LT1083s in parallel per rail could do the job but who knows how it would sound. They're expensive regulators too, and that money could be put towards larger/better filter caps in an unregulated supply.
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Old 6th February 2006, 12:14 AM   #3
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It seems to only make sense using something like that for the low voltage input stage/driver supply, and if you really want to a smps for the output stage, not the simplest thing to do though.
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Old 6th February 2006, 03:13 AM   #4
ghemink is offline ghemink  Netherlands
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Location: Japan
Default Re: Regulated PSU for Class D?

Quote:
Originally posted by bambadoo
Has anyone tried?
Came across this sceme regarding a regulated PSU for a GainClone. Would be interesting to adopt it to a hmm, lets see a zappulse project for instance.
Click the image to open in full size.

Is this doable with transformers with 42v secondaries?
The regulators have to be be changed, but are there regulators that can do this job with 800va-2*42 V secondaries?
Just wondering.
I have a couple of zappulse monoblocks, but want to change them into the 700xe version and rebuild my PSU. Therefore I am looking for a really good, maybe ultimate PSU for the modules.
I am not that into this, and maye a regulated PSU is not the way to go with Class D amplifiers at all.
Do yo diy guys have any other Hi End Psu alternatives to share?

Best Regards

You need more (bigger) caps after the regulator to avoid/reduce power supply pumping I would say.

Gertjan
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Old 6th February 2006, 05:25 PM   #5
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Join Date: Feb 2006
Location: Portland, OR
Default simple but good

Has anyone ever just tried a good old emitter follower as a power supply regulator?

My experience with regulators for audio is that its darn hard to beat a emitter follower loaded with a current source.

The input to the follower can get as complex as you wish, the simplist just being a voltage divider bypassed by a cap, a capacitance multiplier.

I suspect this would be done with a darlington like configuration given the currents. each loaded with its own current source.

They are
1)very wide band
2)have decently low output impedance.
3)no global feedback, well, that debatable, but they are just rock solid stable from a stability standpoint.
4)Nothing to overload, and need to recover from.

I think i'd put lots of output cap on the output still though.

What they don't have is super tight DC tolerence.
They also do droop a bit with load, but not very much, and they loop bandwidth is wide, like the UCD.
An IC reg will have better DC and PSSR at low frequencies because of high DC loop gain, but usually cause more damage than good at high frequencies.

I just ordered my Ucd400's and thought to maybe try this with the monoblock cases that already have nice bipolar high current transistors mounted on them ;>)

It will be a good experiement.

Best Regards,
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Old 6th February 2006, 05:30 PM   #6
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Join Date: Feb 2006
Location: Portland, OR
Default Mr moderator help me!

Hi,

Kind of hope this doesn't get posted.

I find it rely hard to search for info I know is in here becuase the search returns a thread that might have 100's of entries.

Am I missing something.

Like for example, I want to know what the dead time of the UcD400 is. I'm sure I'm not the first guy to ask, but I get a thread in response that is over 1000 entries?

Am I missing some method.
Got any Faq for me?

Thanks

Portland Mike
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Old 9th February 2006, 12:17 PM   #7
ghemink is offline ghemink  Netherlands
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Join Date: Jun 2004
Location: Japan
Default Re: simple but good

Quote:
Originally posted by Portlandmike
Has anyone ever just tried a good old emitter follower as a power supply regulator?

My experience with regulators for audio is that its darn hard to beat a emitter follower loaded with a current source.

The input to the follower can get as complex as you wish, the simplist just being a voltage divider bypassed by a cap, a capacitance multiplier.

I suspect this would be done with a darlington like configuration given the currents. each loaded with its own current source.

They are
1)very wide band
2)have decently low output impedance.
3)no global feedback, well, that debatable, but they are just rock solid stable from a stability standpoint.
4)Nothing to overload, and need to recover from.

I think i'd put lots of output cap on the output still though.

What they don't have is super tight DC tolerence.
They also do droop a bit with load, but not very much, and they loop bandwidth is wide, like the UCD.
An IC reg will have better DC and PSSR at low frequencies because of high DC loop gain, but usually cause more damage than good at high frequencies.

I just ordered my Ucd400's and thought to maybe try this with the monoblock cases that already have nice bipolar high current transistors mounted on them ;>)

It will be a good experiement.

Best Regards,

Yes, I believe a capacitance multiplier should work, in fact I have two at home (from white noise audio). Plan to modify them a bit and may then use them for some of my amps. The only thing you have to do when you use them for class D amps is to add extra caps at the output to prevent the supply pumping as those emitter followers will not absorb any current back from the amp (as occurs in Class D).

The advantage of using an capacitance multiplier is that you burn less power as the voltage drop over the emitter follower is less than when a fully regulated supply is used. And yes, they should be super stable (in terms of not senstive to oscillations) as there is no feedback, well in fact there is of course as it is an emitter follower, however, it ill react very fast and probably not easy to get it oscillating.

Gertjan
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