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PostPosted: Wed Oct 17, 2007 3:15 pm 
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Sheep

Joined: Wed Oct 17, 2007 6:30 am
Posts: 19
:hello: :wave:

Anyone here ever worked with delta sigma modulation ? I tried this but could never defeat the hiss it produced, i nailed the idle hiss but still had some hissing on low freqs and some high freqs, this was a clocked one with a quantizer clocked by a crystal oscillator, that i promptly blew up when changing to a transformer for power supply and forgot the ground wire.

Now i am unsure what i wanna do next, i did pwm amps before that worked descent but looked alot worse.
I did a quick and dirty self oscillating amp with a gate driver for output 2 days ago and it sound descent but gets gets very hot, i use a TL074 whicj is the best opamp i have around until i get some goods i bought on ebay.

Which is a good one to continue with, self oscillator or a clocked, half or full bridge ? :scratch:
Is IRFP450 any usable for class d or should i hunt for something different ?


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PostPosted: Thu Oct 18, 2007 10:29 pm 
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Sheep

Joined: Wed Oct 17, 2007 6:30 am
Posts: 19
I´ve built an amp today and measurements show that its extremely good for beeing a simple circuit on a breadboard.
Heres a schematic: http://diymania.hv4all.com/selfosc%20classd/d-amp.PNG

The measurements: http://diymania.hv4all.com/selfosc%20cl ... surements/


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PostPosted: Sat Oct 20, 2007 5:15 pm 
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Account disabled on owner's request

Joined: Wed Dec 29, 2004 8:31 pm
Posts: 899
Hi,

If you're hard up for parts and don't mind the possibility of high quality sound for little complexity I'd think about a discrete self oscillating half bridge with post filter feedback like ucd.

I wouldn't bother with IRFP450 other than for blowing up those first few required to settle the gate drivers in.

Look for low Cout, gate charge, qrr, trr.. dont' use one with a much higher voltage rating than required it will be slower won't switch as clean.


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PostPosted: Sun Oct 21, 2007 8:07 am 
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Sheep

Joined: Wed Oct 17, 2007 6:30 am
Posts: 19
I´m currently working on this:

http://diymania.hv4all.com/selfosc%20classd/D-Amp2.png
http://diymania.hv4all.com/selfosc%20cl ... mp2brd.png
http://diymania.hv4all.com/selfosc%20classd/board/


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