| jarkaa |
Hello,
I just finished a lm3886 gainclone with an inverting t-net topology.
There is no humming at the output and dc-offset is 7mV and 21mV. The Amp sounds pretty sweet but I get quite a bit of hissing HF noise.
There might be little oscillation because the chips get a bit warm without source signal.
Can any of you experts tell how to get rid of the problem?
I am using PMA:s audio buffer as preamp.
I have build several gainclones before and this is the first time I have problems with HF noise.
PSU is snubbericerad aŽla Carlos but the snubbers are located directly on the chip pins with 100nF bypass caps. |
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| toque_101 |
I have a similar problem with my lm3886 GC... although, my HF interference seems to be in the form of radio stations :) This only happens with my input cable connected, however.
I have posted about this problem before, one thing that was suggested was a LP filter on the input with a 470 ohm resistor and 1nf cap just before the decoupling capacitor (if you use one). I tried it and found it didn't really help but also didn't hurt, so its worth a try. For me, the next thing to try is better sheilding as I have an open air amp and no sheilding on the interconnects.
my .02
-steve |
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