Does anyone recognize this schematic?

[pineapples10]

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.

 

[pineapples10]

Here is a picture of the power supply schematic as well...

 

[Apheared]

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.

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!

 

[pineapples10]

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

 

[rickcr42]

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

 

[pineapples10]

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