Basic C2 opamp upgrade?

jmitchnh

Active Member
I recently picked-up a beautiful Basic C2 preamp that I cannot wait to listen to. In doing some on-line research, I found that a common problem/fix is to replace the factory opamps (NJM4560) with a different model (NE5532). Just wanted to run it by all the Kenwood fans to see if this is a legit upgrade and if so, is it a drop-in swap or is it much more involved than that?
Thanks!
 
Perhaps you should listen to the amp before starting to change things out.

If you did not know what op-amp was in there would you care as long as it sounded good?

EDIT: What is this problem that is being fixed? ...Is there a real problem or is it just somebody on the internet wanting to put in the worlds fastest op-amp to cure an imaginary problem.?
 
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Stock opamps are being overvolted. A NE5532, OPA2604, or a LME49860 would not be, were they in their place.
 
Perhaps you should listen to the amp before starting to change things out.

As the owner of a C2 in excellent original condition, I concur with the above. Give it a listen first, and you may be very happy. Unless you have an abnormal love of soldering or something. :) Seriously, it's a quiet preamp with a big soundstage and a terrific phono section.
 
I was looking at the schematic. It looks like there is +/-18.6V listed next to an emitter on those rails.

.6V is not that much and it is not uncommon for there to be enough of a voltage drop by the time it reaches the IC to bring it to +/-18V or below.

If you measure +/-18V or less on the pins of the op-amp it should be fine. Also be sure to keep in mind small errors in your voltage meter and adjust for that.

EDIT: If the rail voltages are beyond that carefully check the voltages around D11, 12, 13 and 14. That is where the voltage rails are regulated.

C2 schematic.
http://elektrotanya.com/kenwood_c2.pdf/download.html
 
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I did pickup a C2 last month...Will be getting to this in Jan.

My Recap/Op-Amp upgrade for Onkyo P-304:
http://www.audiokarma.org/forums/showthread.php?t=495735

When the Specs allow...These are my goto Op-Amp..LME49860

Please post a thread (and a link to said thread) when you do this. I'm thinking of recapping my Basic C2 and figure I might as well do the op-amps as well if I'm there...

Are you going all LME49860 or are you mixing it up a bit (for example, a pair of LT1115 with adapters for the EQ IC1)?

-D
 
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