Sony MXP300 Opamp rebuild questions:

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Jed

Well-known member
Joined
Jun 6, 2006
Messages
97
Location
Portland, OR - USA
This is a carry over from here: http://www.groupdiy.com/index.php?topic=26154

I’m trying to mock up a replacement mxp3000 “green blob” to test out my mic pres and get them running again. I’ve got most of the needed parts lying around except for the transistors used in the originals.

Gltech’s schematic specifies “d786” transistors. I’m assuming this is the, now obsolete, 2SD786? Can anyone suggest a common replacement?

I’ve been looking at the 2SC3329. You can get them at http://www.acme-sales.net but it insults my sensibilities to pay $12 in shipping and handling for $4 worth of transistors. Especially when I already need to order something from Digikey. Anybody have a suggestion that digikey stocks?

Also, what kind of capacitors should I be trying out in this circuit? Metal film? Polys?

If I get this working properly I might try swapping some different opamps to see how they sound, and or throw a little pcb together to make this easy.
 
I'll put these up for now -- I assume no one has a problem with having them up. Gltech, if you *don't* want them shown, let me know and I'm happy to remove them.

Sony_T94124211BoardWCircuitOverlay.jpg

Sony_T94124211Schematic.JPG
 
There are no "common replacements" for the various low-noise Japanese transistors. A 2N4401 is your best bet, note that the pinout is different though. If there's space you might parallel a pair to get closer to the original noise figure.

Samuel
 
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