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Author Topic: Yamaha 1280r need schematic diagram  (Read 7929 times)

Giulio

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Yamaha 1280r need schematic diagram
« on: December 23, 2013, 01:04:28 PM »
Yamaha 1280 solid state guitar amp with tube pre section ...Help me, i need schematic diagram or manual service. 
 :dbtu:

Thanks

J M Fahey

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Re: Yamaha 1280r need schematic diagram
« Reply #1 on: December 23, 2013, 02:25:23 PM »
Mystery amp, not even Yamaha mentions it in its own page.
What kind of problem do you have with it?

teemuk

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Re: Yamaha 1280r need schematic diagram
« Reply #2 on: December 23, 2013, 03:47:53 PM »
Quote
Mystery amp, not even Yamaha mentions it in its own page.

Yamaha has plenty of mystery amps in their sleeve.

Evidently they made a whole series of these hybrid amps in Italy.


Giulio

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Re: Yamaha 1280r need schematic diagram
« Reply #3 on: December 24, 2013, 04:54:18 AM »
Thanks for answers.
  I would like to make changes to the preamp to get a warmer sound.
In origin it is very harsh and metallic. (the tube is ok)
I tested an external preamplifier and the sound improves. direct entry into the "return"

http://en.audiofanzine.com/guitar-combo-amplifier/yamaha/1280r-tube-80w/medias/pictures/a.play,m.716654.html

http://en.audiofanzine.com/guitar-combo-amplifier/yamaha/1280r-tube-80w/medias/pictures/a.play,m.641318.html
« Last Edit: December 24, 2013, 05:09:35 AM by Giulio »

Roly

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Re: Yamaha 1280r need schematic diagram
« Reply #4 on: December 24, 2013, 06:07:27 AM »
Hi Giulio, welcome.


What is the valve/tube type in the preamp?

If it's a 12AX7 then there are several other twin triodes which are plug in substitutes with less gain that may make it sound less harsh, 12AT7, 12AY7, and the lowest 12AU7.  YMMV.
If you say theory and practice don't agree you haven't applied enough theory.

Giulio

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Re: Yamaha 1280r need schematic diagram
« Reply #5 on: December 25, 2013, 05:52:55 PM »
Hi Roly, Thank you!
 Original is a 12ax7w I tried with different types of valve-tube.
 noticed a change in volume, but the sound as transistors poor cheapest.  :-\

This amp model TU1280r has been proposed to the European market, probably in the U.S. is a different model code
« Last Edit: December 25, 2013, 06:04:23 PM by Giulio »

J M Fahey

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Re: Yamaha 1280r need schematic diagram
« Reply #6 on: December 26, 2013, 06:16:30 PM »
Maybe the best bet is to build an external preamp, Tube or SS, either inside a rack type cabinet or housed in a "big pedal" enclosure.
*There are* "pedals" which are actually preamps, such as MB VTwin and even Marshall Guv'nor/ShredMaster/Jackhammer "Distortion Pedals" which are actually a full preamp (some even have their own effects loop, go figure)

Giulio

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Re: Yamaha 1280r need schematic diagram
« Reply #7 on: December 28, 2013, 03:24:03 PM »
Yes, at the moment the best thing is to use an external preamp, but it is not convenient  :-\

J M Fahey

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Re: Yamaha 1280r need schematic diagram
« Reply #8 on: December 29, 2013, 04:32:35 AM »
Well, then you'll have to grab pencil, paper, a good light, and start drawing the schematic yourself :(
That's how all those "mystery amp/pedal" schematics eventually appear on Internet.

teemuk

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Re: Yamaha 1280r need schematic diagram
« Reply #9 on: December 29, 2013, 05:25:05 AM »
And of course an obvious question is: has Yamaha been contacted yet?

If they are not willing to share shcematics then it's pencil and paper time.

Giulio

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Re: Yamaha 1280r need schematic diagram
« Reply #10 on: December 31, 2013, 09:48:20 AM »
Yamaha has advised me to contact the service center. :trouble
But in fact it is not a fault but a natural characteristic of this amplifier.
A design schematic ? (the only pre-amp) .... I'll see you next year :cheesy:
« Last Edit: December 31, 2013, 09:49:50 AM by Giulio »

Roly

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Re: Yamaha 1280r need schematic diagram
« Reply #11 on: December 31, 2013, 10:46:06 AM »
 Keep plugging at them until you get it.   :trouble  :dbtu:
If you say theory and practice don't agree you haven't applied enough theory.

J M Fahey

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Re: Yamaha 1280r need schematic diagram
« Reply #12 on: January 01, 2014, 11:06:32 AM »
FWIW I don't think there's much room for "improvement" there, if any at all.
Yamaha are not fools or beginners, I bet they *already* got the best sound they could .... for that configuration anyway.
But it's probably, from what can be seen, a "Marshall Valvestate type" amplifier, a full SS amplifier with , at best, a lonely small tube thrown in for distortion ... and that's not enough for what I guess you want.
Don't expect miracles  :(
Usually most what can be done is to, say, add a small capacitor, killing some highs to make it *somewhat* less harsh ... usually making sound dull in the process .... or cutting some lows before distortion so it's less farty, or finding some stage where there's a little extra gain still unused, to give it a little more sustain (this alone opens a new can of worms).
All small tweaks, but which won't radically turn it into something else.
I repeat, Yamaha know their stuff, I bet it already sounds as good as it can, or very close to it.
And by the way, I don't think it sounds *that* bad, play it loud and most of the little problems disappear.
Now, at lower volume in a bedroom or something, yes, most amps (even a few good ones), sound buzzy and harsh.

J M Fahey

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Re: Yamaha 1280r need schematic diagram
« Reply #13 on: January 01, 2014, 11:14:50 AM »
Hey !!! Just found this:
http://youtu.be/zBjsitYZGG4
It sounds VERY good !!!!!!!  (as I suspected).
You just need a good distortion pedal (your choice) .
« Last Edit: January 01, 2014, 11:16:45 AM by J M Fahey »

Giulio

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Re: Yamaha 1280r need schematic diagram
« Reply #14 on: January 06, 2014, 02:08:33 PM »
To be or not to be this is problem,
the sound is   :duh  "acid" in clean channel... in lead channel, the "distortion" is without bass tone, 4-5-6th strings is same "sounding" of 1-2-3th-strings  :'(