DC offset adj in JE990 - diyAudio
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Old 2nd December 2012, 10:37 PM   #1
robmil is offline robmil  United Kingdom
diyAudio Member
Join Date: Jun 2004
Location: London
Default DC offset adj in JE990

Hi all

I'm putting together a 2 channel mic preamp based on the Jensen mic pre.
I have made 6 x JE990 opamps and the DC offsets are all so different. I haven't matched any of the components but am using some LM394s which I have had for a couple of years and thought I'd use them on this project.

My question is can I adjust R5 in the diagram (replace it with a 500ohm pot maybe) to be able to adjust my DC offset to below 50mV. At present I am getting any where between 400mV and 100mV on all 6 JE990s I have made.
Will putting a pot here upset anything else in the circuit - noise etc.

Thanks for this guys.

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