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JRC 4556AD based amp noise floor too high, how to reduce?

post #1 of 3
2/3/10 at 1:16am
Thread Starter 
My JRC 4556AD based portable amp has a very high noise floor (I can hear quite a bit of hiss). Can I reduce this somehow or this inherent to this particular Opamp.

Schematic similar to the following, too lazy to draw the exact schmatic I made for this thing.

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post #2 of 3
2/3/10 at 1:49am
First, depending on your headphones, you may have too much gain.
Second, those resistor values surrounding the opamp are way too high, which leads to high noise. Reduce the values all around (including the volume pot) by about 10x and you should get a nice improvement in noise floor.
Third, JRC4556 is not as low in noise as some of the more modern opamps.
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post #3 of 3
2/4/10 at 2:41am
Thread Starter 
Thanks Ti. Yeah I guess the resitors are pretty high in value. By my calculations the closed loop gain should be around 4.73, with my setup (ipod and cheap iems) I'm happy with the gain. On the JRC, I don't know how other opamps compare but so far it sounds decent and some what neutral.
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