Does anyone recognize this schematic?

Aug 18, 2001 at 7:44 PM Thread Starter Post #1 of 6

pineapples10

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Hi,
I went to my friends house recently, and found that he had built me a headphone amp. He gave me a sheet with schematics on it for one channel. It doesnt look like the Apheared or CMOy, maybe its something else. Anyway...it sounds great. Please take a look and see if you can identify it.
 
Aug 18, 2001 at 7:45 PM Post #2 of 6
Here is a picture of the power supply schematic as well...
 
Aug 18, 2001 at 9:11 PM Post #3 of 6
it's a inverting amp with a fair amount of gain (5) and it's close to a 47 in that it uses the other 3 opamp sections of each quad to provide a current boost (110/3 is the amp's output impedance)

It's very much like a CMoy 47 variant... technically we're all doing the exact same thing.
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The only real difference is that one is inverted instead of non-inverting... but whoop... most people can't tell. (not with ears anyway)

edit: sorry, I didn't answer your question! The amp design - it's textbook. (or maybe a datasheet example.) Then again, so's 90% of the stuff we do. Not only textbook, but 50 year old textbooks at that!
smily_headphones1.gif
 
Aug 18, 2001 at 9:58 PM Post #4 of 6
Thanks for your reply Apheared. He in fact did take it from a text book. What is the difference between this and your 47 amp? IT sounds great, except at high HIGH volumes where there is a large amount of hiss (any suggestions to get rid of this?). Will a CMOY with x-feed sound much different? Thanks
 
Aug 18, 2001 at 11:44 PM Post #5 of 6
what opamps are you using ?

If the ones shown in the schematic then you might want to improve the opamp quality.Maybe try bypassing the ops +/- with 0.1 caps RIGHT AT the supply pins

BTW-same circuit I have been using for a while,but not as many in parallel

Rick
smily_headphones1.gif
 
Aug 19, 2001 at 12:14 AM Post #6 of 6
The opamps he used I beleive are Two Quad OP Amps, number LM837N I found a site with some details about them http://www.national.com/pf/LM/LM837.html but I dont know what a lot of it means. Can anyone tell me if these are any good? Thanks
 

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