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Author Topic: Yamaha 1280r need schematic diagram  (Read 7846 times)

J M Fahey

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Re: Yamaha 1280r need schematic diagram
« Reply #15 on: January 06, 2014, 09:37:27 PM »
The sound you describe is so much like what a Valvestate 8080 would sound like, that I fear it's just a straight clone, or at least *very* close.
Given that your amp works, the problem is one of taste, and it's practically impossible somebody can mod it to your liking, doubly so without schematic and not being able to hear it.
As of the lack of bass you notice, it's a normal design decision to minimize farting and very dirty and muddy distortion.

So in a nutshell:

1) if it were burnt/shorted, maybe we could help you detect and replace shorted power transistors, open emitter resistors, blown rectifiers, etc., which is what you'd probably find there ... but , best case, it would sound exactly as before.

2) if you don't like its sound, well, if neither Yamaha nor Marshall could make them sound the way you like, what can *we* do?

3) I insist on you making an external preamp is the only practical solution.
Name an 80W , 1 x 12"Celestion speaker SS amp you like and *maybe* we can help you clone its preamp.