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Chip Amps Amplifiers based on integrated circuits

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Old 14th January 2004, 11:37 PM   #1
soneil is offline soneil  United States
diyAudio Member
Join Date: Jan 2004
Location: Michigan
Default My first, um, thing

Well, I guess not technically my first, because I had built a headphone amp that I followed some designs for before this which gave me the idea. I saw a passive preamp design by HarryHaller, and wanted to put one of those alongside a headphone amp inside a box with some more inputs, but after some problems (which I asked about on the solid state forums ) I just played around with it until it worked.

Please note, this is more of a product of trial and error than anything else hence the rediculously long signal path runs. I had to put the resistors on the dvd input to ground to keep it clipping and distorting into oblivion. Correct me if I am wrong here, my dvd player probably has around a 2V RMS (I havent looked it up to find out), and since I am only running +/- 9v into the opamp with a gain of 11 it would need +/- 22V in order not to clip? Also, I'm not sure how to figure out the input/output impedances, and what they should be, any good links I could learn about this from?

It sounds quite good to my ears (not saying much), and doesnt distort anywhere on the volume control scale, which was my greatest accomplishment with it. I havent tried it with a phono input, I am doubting it will work due to the amount of amplification required. Also I plan on trying the audio control used in ESP's project01.

Anyway, just looking for comments on how I could improve the next one, or comments on obvios flaws.

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Old 15th January 2004, 02:57 AM   #2
soneil is offline soneil  United States
diyAudio Member
Join Date: Jan 2004
Location: Michigan
Here's a schematic of (the majority) of the insides. Sorry it's a little rough, I made it in Sodipodi. What do all you guys use for drawing stuff, anyway? Is there anything good for Linux?
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Old 15th January 2004, 04:16 AM   #3
paulb is offline paulb  Canada
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Join Date: Jun 2001
Location: Calgary
Default Looks good

What's your next project?

There's a free CAD package out there that may be available for Linux. Forget the name.
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Old 15th January 2004, 04:37 AM   #4
soneil is offline soneil  United States
diyAudio Member
Join Date: Jan 2004
Location: Michigan
Next is a gainclone. I have the chips (LM3875TF) on the way, I need to get some more money so I can order the rest of the parts. And a fair bit more reading is in order too... get a little more comfortable with how the PSU works before I zap myself. I also found a better version headphone amp I'm looking at too - headwize .

I've some more pics on my webpage (under audio) ...
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