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Old 11th September 1986, 02:59 PM   #1
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Default pc board pics

boards for another prototype of this amp...
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Old 11th September 2003, 09:25 AM   #2
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Default My recent power amp...

Hi guys,

Thought I share this amp to my fellow diyers. Not that hard to build but it sounds good enough for me.

I've tested it with an OPA134 but even an LM301AN will work. Outputs in the prototype are MJL21193/4 (TO-264) but I've tried/tested MJ15003/4, MJ15024/5 (TO-3) with good results. That means it will work with anything you have laying around .

Supply for the prototype is only +/-50V but has also been tested with a +/-70V. If you use the higher supply, better use a bigger heatsink.

Sound is, as I said, good enough for me. I'm planning on using this for mid-high applications but have also tried it for a 10" dual voice coil subwoofer.

JojoD
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Old 11th September 2003, 09:27 AM   #3
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Default small pic, sorry

a small picture of the prototype amp... I know the supply wires are too thin, they are just used for testing.
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Old 11th September 2003, 09:30 AM   #4
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Default forgot the pcb

here is the pcb in pdf only.
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Old 11th September 2003, 09:32 AM   #5
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Default sorry for the pic quality

another pic
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Old 11th September 2003, 09:33 AM   #6
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forgot to attach the pic
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Old 11th September 2003, 09:34 AM   #7
matth is offline matth  United Kingdom
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Congrats JojoD,

Nice work, I like the way the amps are sat on top of the heatsink with the drivers either side. Also the fact the the heatsink fins are verticle giving the best cooling. When ever I build an amp I always end up with the HS upsidedown or some such poor configuration.
With +-50v its should be good for approx 250Watts into 4 Ohms well within the capabilaties of two pairs of MLJ21193/94.

Happy lisening
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Old 11th September 2003, 09:38 AM   #8
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Default jean-paul

hi,

i was too excited to post the amp and forgot to edit the schematic. however, you can find the values of the resistors in the pcb parts placement guide. The values for the caps are at the schematic. Hope you guys don't get confused!

The amp is working and playing as I post this message, it has been four days and still no problem. Anyway, this is actually the second prototype.

Cheers
JojoD
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Old 11th September 2003, 09:41 AM   #9
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Did you try local feedback at the opamp and only a DC feedback for offset compensation ?

A long time ago I made amps like that and they sounded better than the conventional way but measured poorer.

Not negatively meant but I would always decouple supply lines with some caps and around the opamps I would place them very near the supply pins. With the more modern opamps a small cap ( 10 to 100 nF ) directly from + to - pins of the used opamp might be necessary.

Apart from that it looks cool.
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Old 11th September 2003, 09:44 AM   #10
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Default matth!

Hi matth,

Thanks! The amp was really "brutally" tested and yes, it can handle 4 ohms quite happily. The heatsink gets hot though, I guess that's what they are there for.

Regards,
JojoD
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