Apparently my MIG-100 was all original. The plastic standby switch finally broke a few weeks ago, and I took it to Matt Weed of Atomium Amplification to replace both (the power switch was three-way for some reason). Here is what Matt has to say about them in his post.
Sovtek Mig-100, all original except for the new power/standby toggle switches I installed (the plastic originals are awful and break all the time). Not exactly a Marshall 2203 but very close. The distinctive sound of these amps mostly comes from the circuit tweaks Sovtek made to get more reliable operation from Russian military tetrodes – 2.2k screen resistors, for example, to limit screen dissipation. The B+ is 520V!
I love this amp, it’s loud, sounds great, and takes pedals well. Easily my favorite amp.
Remember how I played a Sovtek Mig100 in Berlin over the summer? I’ve been on the hunt for one at a good price ever since. I finally tracked one down.
Though I haven’t had a chance to really crank it, it’s extremely loud, clean, and warm sounding. Not brittle at all. It’s missing the back grate that protects the tubes, but I think I can make one fairly easily. The plastic jacks and switches are still there, so maybe soon I’ll get Matt Weed to replace them with metal ones. Or maybe I’ll wait until something breaks…
Now I have to decide which amp to sell – my Laney GH100L or two-channel Dual Rectifier.
Matt from Atomium Amplification posted about a custom distortion pedal he’s building for me (along with the modded SD-1 from the previous post). Take a look:
Basic volume/tone/gain setup with selectable symmetric/asymmetric clipping (really compression). The symmetric uses germanium 1N34As, the asymmetric uses a violet LED and 1N914s. Both sets use series resistors to make them act more like a compressor. Most of the actual clipping comes from overloading the 4580 opamp, which has no diodes in its feedback loop. The diode compressors give it more of a “touchy” vibe. It’s not a great design for low-gain, since it gets gainy really fast, but for high gain it’s got massive punch and manages to get both saturation and note separation.