OP rolling

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yayage

Member
Joined 2011
Hi,

I want to change the OPs in my vintage Kenwood PreAmp .
Some Modifikations were discussed here years ago.

The goal is to place good sounding OPs with less DC-Offset at the outputs.
I guess i have to choose low input bias current types.

In the schematic Output there is a JRC 5532DD which causes 150mV Offset.

Is there OPA2132 / OPA 2134 a good choice ?
Or maybe a LM4562? The input current is higher, but about 20mV Offset would be acceptable.

The input buffers are JRC4580DD with 100mV Offset and a very low slew rate.
Maybe there are the LM4562 a good choice too ?

Jay
 

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Mooly

Mooly

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Joined 2007
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The offset is not a problem in that design, and if anything I would say it defines a known and stable small voltage across the coupling caps.

The OPA's would generate near zero offset but as mentioned that isn't an issue anyway.

The LM4562 is possible replacement for the 5532 but I would advise that whatever you fit that you check any residual offset and reposition the coupling caps accordingly to suit any change in polarity of offset.
 
Mooly

Mooly

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Joined 2007
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100mv offset and its polarity makes a difference to electrolytic coupling caps and I would rather have 100mv with correct polarity across such a cap than have it reversed.

Any DC offset in an AC coupled circuit has no impact on audio quality whatsoever.
 
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