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Class D Switching Power Amplifiers and Power D/A conversion

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Old 14th November 2006, 09:52 AM   #31
djQUAN is offline djQUAN  Philippines
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UPDATE!!!!!!!!!!!!!!

I was able to complete 90% of amp8 yesterday and have done a little bit of torture testing.

I'm not yet sure how much power I'm getting from the amp but my car's alternator and battery are starting to give up. It blew a 40A fuse like popcorn and the 60A is still holding up. though the amp cuts off some of the time due to low voltage most possibly due to the batt and alt sagging. I got a in dash voltmeter and I can see it drop to 12.4V (13.8V at no music) with the engine running at idle.

the main SMPS seems to be holding up well since the fets ,rectifier diodes and main toroids are berely getting warm.

I'm guessing it's putting up some power since my subs are beginning to smell after a minute or two. they are both dual 4 ohm coil wired in series to get 8 ohms per sub then two wired parallel to get 4 ohms. then they are bridged on the two channels so the amps are basically running at 2 ohms each.

the mosfet heatsinks are running hot but are still manageable. the driver chip stays the same temp at idle or at high output, the zobel resistors get burning hot (guessing about 60-70 degrees C) and also the toroids. the toroids are getting a bit too hot for my liking so I'm thinking of rewinding them again but I'm gonna have to make my own litz wire since I don't have enough left.

I'm gonna rewire the toroids with a bit more turns to lessen the residual at the outputs since this thing is already an EMI nightmare when a drum core inductor is connected to a scope to measure EMI radiation around it.
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Old 14th November 2006, 10:12 AM   #32
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No wonder if you are driving many hundreds of watts outta the amp, the op coils are not really meant to be handling these wattages continously.
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Old 14th November 2006, 10:20 AM   #33
djQUAN is offline djQUAN  Philippines
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well, I did notice they are getting warmer than desired even at idle so I was really expecting it to get hotter when pushing some power.
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Old 22nd November 2006, 12:07 PM   #34
djQUAN is offline djQUAN  Philippines
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hi y'all
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Old 22nd November 2006, 12:09 PM   #35
djQUAN is offline djQUAN  Philippines
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and behind the rear seats.......


I got more but I can't seem to shrink file size without losing detail with paint.
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Old 22nd November 2006, 12:11 PM   #36
djQUAN is offline djQUAN  Philippines
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and this is where they're all stuffed in.........
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Old 20th January 2007, 06:09 PM   #37
djQUAN is offline djQUAN  Philippines
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wow. amp8 pushed the subs really hard. got only 142.7db in car but I think that is good enough for a straight DIY system and by that, I mean all signal processing and amps are all DIY.
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Old 21st January 2007, 06:01 AM   #38
Danko is offline Danko  Hungary
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djQUAN!

HOw did you wound the toroids in the SMPS ? How did you arrange the windings?
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Old 21st January 2007, 06:55 AM   #39
djQUAN is offline djQUAN  Philippines
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i just wound the primary then the secondary over it. just went ahead and wrapped the whole core with the windings.
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Old 21st January 2007, 07:03 AM   #40
Danko is offline Danko  Hungary
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How did you "stack" the windings?
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