Friedman schematics

[roseblood11]

I'm looking for schematics of Friedman amps, especially the Runt 20 and Runt 50.

[pompeiisneaks]

Generally it is quite hard, if not near impossible to get schematics on current run amps.  If you're a tech with access, you often sign agreements you'll only use them for repair work etc.  Therefore, it may be a bit of a stretch.  I've seen a few pictures out on the interwebs of someone reverse engineering the Dirty Shirley if I recall, but otherwise, it's not going to be easy.  OTOH, from what I gather, the Friedman amps are just heavily modded Marshall amps, same basic design, just tweaks of specific areas to give a different tone etc.

~Phil

[roseblood11]

I think the BE 100 is the most complex circuit. Many of his other amps might be simplified variations. So, the Runt's distortion channel might be close to the"BE" setting (only 4 triodes), as that amp only has 3 preamp tubes. The clean channel in the Runt 20 might just be the first triode. But the Runt 50 has a separate tone stack for the clean channel, which should need an additional gain stage after it. But the Runt 50 also has only 3 12ax7.
http://music-electronics-forum.com/attachments/39789d1467770843-be100-v2-rev1.5.png
Maybe the Pink Taco is closer, but it doesn't have a clean channel.

[roseblood11]

Pink Taco
http://www.tube-town.de/ttforum/index.php?action=dlattach;topic=21032.0;attach=50953;image

Small Box 50
http://www.tube-town.de/ttforum/index.php?action=dlattach;topic=21032.0;attach=49804;image

[Ledzepp007]

Reviving this dead topic. I just ordered a Runt 20. I’m curious as to how the circuit deviates from the Pink Taco/BE100. I’m particularly interested to see if the Runt has a plate bypass cap/resistor (I don’t think that it does) that may be contributing to its brightness vs the PT. If that’s the case, a simple mod would make the circuits identical.

Should be able to reverse engineer the circuit, if that’s kosher and if people are interested.

[Ledzepp007]

Well, got the Runt. Extremely nice amp. Absolutely slays. It’s like a high-ish gain, perfectly voiced Marshall.

Poked around inside. Initial thoughts are this: decent work, very little slop. They made a mistake and had to replace a resistor and were a little messy. I was somewhat surprised to find that the amp is cathode biased (with a 120R). DC supply filtering seems to be four nodes of 47uF. Effects loop circuitry is located on the main board. I had time to check out the first gain stage before my wife asked me to do something else. It was consistent with my BE100 schematic with one exception. The 2.2nf coupling cap was 22nf in the Runt. I may just be talking to myself here, but I will continue to investigate.

[hweeden0708]

I am very interested in what else you find comparing the two.

[Ledzepp007]

I am very interested in what else you find comparing the two.

I may have some time this week to crack it open again

[Shack]

Im still interested in what the actual circuit details that make these amps sound so good.

[Dc10]

Anyone come up with a Schematic for the Runt 50?

[Bantam]

I know it's a dead topic but I'm interested to see what has come up... What I would add to this is I've had luck by changing my search engines. if I refine my search with one and I can't find what I want, changing search engines can help.

[Johnny Hulst]

by no response deleted my question...