# Solid State Yamaha amp



## marcos (Jan 13, 2009)

Anyone know how to get my 70's Yamaha amp to have a more warmer sound? I have tried a few different speakers and thats not working. Anything you can do internally to make it less trebly? I have a small Fender Champion SS amp that sounds fantastic and trying to find out what can be done to the transisitors or pots to make it sound a bit warmer.
Thanks


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## bw66 (Dec 17, 2009)

I have a G30-112 from that era. In general I love the amp, but, while I don't find it too trebly, there are days when I would like it to be warmer. I know of nothing internally, to warm it up, though you can always use a pre-amp, or emulator to round out the sound - but you probably knew that.


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## greco (Jul 15, 2007)

Which model Yamaha amp is it? ...knowing this information might be helpful.

Have you tried an EQ pedal or similar?

Cheers

Dave


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## marcos (Jan 13, 2009)

Dave, its the Fifty 112 model. Not tried any EQ pedals.


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## mhammer (Nov 30, 2007)

Looking at *A* schematic of the G50-112 (yours could be a slightly different issue). http://elektrotanya.com/yamaha_g50-112_guitar_amplifier_sch.pdf/download.html

One thing I would suggest is downloading the Duncan Tonestack Calculator: http://www.duncanamps.com/tsc/ The tonestack is of the standard Fender topography. You can punch in the values for your amp, as shown in the schematic, and see what sort of frequency response to expect from the unit. The plug in some alternate values, and see how that might come closer to the sort of response you want.

So, for instance, maybe the tonestack imposes a big midscoop, so as to emphasize the highs and lows, but gutting the lower mids you need. A change to the right component values might be able to repair things.

The other thing I'll note is that the distortion circuit in the amp has precious little lowpass filtering to "round off" the clipped sound, and unfortunately the tonestack comes before the clipping section, so you can't use the treble control properly to smooth out the clipped sound.

In which case, you will want to either run a small-value cap (I would estimate, something between 4700pf and .1uf; season to taste) in parallel with the pair of 1S1555 diodes, or a similar cap to ground from the junction of the two resistors and 1uf cap after the diodes. That will "warm up" the clipped sound but have no effect on the EQ-ing in general.


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## marcos (Jan 13, 2009)

mhammer said:


> Looking at *A* schematic of the G50-112 (yours could be a slightly different issue). http://elektrotanya.com/yamaha_g50-112_guitar_amplifier_sch.pdf/download.html
> 
> One thing I would suggest is downloading the Duncan Tonestack Calculator: http://www.duncanamps.com/tsc/ The tonestack is of the standard Fender topography. You can punch in the values for your amp, as shown in the schematic, and see what sort of frequency response to expect from the unit. The plug in some alternate values, and see how that might come closer to the sort of response you want.
> 
> ...


Thank you Mark.


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## mhammer (Nov 30, 2007)

My pleasure.

If you do try some of the things I suggested, certainly let us know how it turned out. If a little more coaching is needed, fine. And if it was a case of tried-it-but-it-wasn't-what-I-really-needed, tell us too.

Describing the gap between what you're hearing, and what you _want_ to be hearing, can be a tricky thing. No great surprise that many "helpful suggestions" can end up being red herrings as a result. So don't be shy about saying it was not the panacea you were hoping for.


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