Hello, I have a LM4562 op amp circuit set up as shown in the microphone
preamplifier section of the data sheet in the following link
http://www.national.com/ds/LM/LM4562.pdf . The performance of the pre
is very good from 10 Hz to 50 kHz on a line input. But when connected
to a balanced microphone and set to a decent amount of gain from 40 dB
to 60 dB I get a 10 kHz peak about 20 dB above the noise floor. The
microphone is an industry standard shure SM-58. The power supply is
made of batteries so I don't think the source is the power supply.
There are no capacitors or inductors in any of the signal path section
to cause oscillation besides the microphone itself. Anyone have any
clue why an op amp circuit would have a peak at 10kHz. There are 47uF
caps on the power inputs to the op amps. Any other suggestions for
capacitor values I should try here? Any help is welcome thanks.
preamplifier section of the data sheet in the following link
http://www.national.com/ds/LM/LM4562.pdf . The performance of the pre
is very good from 10 Hz to 50 kHz on a line input. But when connected
to a balanced microphone and set to a decent amount of gain from 40 dB
to 60 dB I get a 10 kHz peak about 20 dB above the noise floor. The
microphone is an industry standard shure SM-58. The power supply is
made of batteries so I don't think the source is the power supply.
There are no capacitors or inductors in any of the signal path section
to cause oscillation besides the microphone itself. Anyone have any
clue why an op amp circuit would have a peak at 10kHz. There are 47uF
caps on the power inputs to the op amps. Any other suggestions for
capacitor values I should try here? Any help is welcome thanks.