Sovtek Midget 50H Info?

[batsong]

Hi. I'm posting as there seems some people here familiar with the Sovtek Midget 50H.
I think the one I have has been repaired possibly not to original spec. What I am seeing is 2x 220uF (correct) 1x 80uF (?) and 2x 100uF (?) IC electrolytics. The one's in question I can't find in the schematic.
What I am hearing is very stiff, but nice pretty clean tones, harsh high gain tones in both the power and pre sections, lots of crunch but non of the saturated high gain it seems others get from these amps.
I've biased the Sovtek 6L6's to almost the melting point which warmed up the amp a little, and added a NFB switch (which I happen to prefer it with stock NFB).
Thinking of adding some sag resistors and maybe lowering the filtering.
Would really like to get this amp sounding warmer, open and less stiff. I usually play a modded JTM-45 which is very smooth, open and likes to breathe.
Any help will be appreciated.

-Gabe

[batsong]

Added some sag resistors, and re-biased. This seemed to loosen the amp up. The 2x 100uF caps look like they were originally supposed to be 47uF, still can't see where the 80uF cap comes in by searching the schematic. I like the clean tones this amp gets, and it is becoming quite versatile too.

[soundmasterg]

I had one of these that I bought new and it was completely stock when I sold it. These are the best made of the Sovtek amps. The circuit is basically a JCM800 2204 running 6L6's with some minor tweaks that people often do to the Marshalls also. I too thought the amp was harsh, but it was ok for what I was doing with it.

Greg

[kleuck]

MIGs are not hi-gain amps, you need a booster to enter this territory.

[batsong]

Hi Greg. I'm in Oregon too. I'm working on getting this amp warm up a bit. I want to make it work because a guy in Roseburg had built it into a neat little pine 2x10 combo. I'm getting some tone out of it, but can't seem to get the (excessive) glassiness to go away.

kleuck, I guess that may be true, though I've read a few claims to the large amount of gain on these master volume 50H's. Not really looking for tons of gain, just a little smoother breakup.

This seems to be a very stable amp (until I switch off the feedback). Maybe lowering the filtering back to stock will help with the sensitivity of the amp, but what would help to tame the bite?

Thanks.

[kleuck]

You're right actually, the "Midget" version has a lot of gain according to the schematic, i was thinking of the regular one (i used to have a MIG 60)
Something must be wrong, old tube ?
To tame the brightness, you can remove the "Marshall cap" in // with a 470K resistor just before the gain pot, or modify the tonestack (TSC) or try a Zobel across the 8 ohms output.

[batsong]

Was missing the 15pF cap on plate and grid of first tube. Things seem to be a little more under control now. Little by little, getting this thing into true form...

[soundmasterg]

Yah the Midget is basically a tweaked JCM 800, as in all the differences between that and a Marshall JCM 800 are the typical mods that people do to the Marshalls. The MIG-50H has lots of gain and is more of a metal amp than the MIG 50 ('59 Bassman clone) or MIG 60 (Plexi clone with a bit more gain and voltages that are WAY too high). Since the MIG-50H is based on the JCM800 I always thought it would sound better with EL34's but never got around to trying them before I sold the amp.

I would suggest to reduce the voltages to the preamp and maybe the phase inverter stages. That will reduce the highs and reduce gain, though the amp will break up more when you do this. you might also have to reduce gain on some of the stages to compensate. With lower voltages, the amp will sag a little more and be more touch responsive. You may also reduce the negative feedback, though this will increase gain and could be too much.

Cool that you're in Oregon...where abouts? I'm in Cornelius myself.

Greg

[batsong]

Hi Greg. I'm in Sweet Home, near Corvallis.
Gonna have to figure how to implement the changes you described. Sounds like what I am looking for.

-Gabe

[soundmasterg]

Hi Gabe,

If I can locate my schematic for that amp and get a chance to look at it, I can give some recommendations as far as which parts to change....

Sweet Home isn't that far away...couple hours.

Greg

[batsong]

Hi Gabe,

If I can locate my schematic for that amp and get a chance to look at it, I can give some recommendations as far as which parts to change....

Sweet Home isn't that far away...couple hours.

Greg

Wow. Thanks, Greg.