Tube Amp Archive

Totally agree the KOC master is over-promised and over-complicated. The normal pre-PI one works fine (if you aren't trying to get PI overdrive at low volumes). If you ignore the MV pot itself, think about what you've done by adding the 220K resistor between treble wiper/MV input lug and 1M to ground...

They’ve found a replacement:

https://www.tubesandmore.com/products/s ... position-0

You didn't say power or output transformer, but I'm guessing you meant output. Personally I think this is a fool's errand (no offense), and that changing a transformer out for one you already think sounds fine and is good quality is a lot of effort and expense for an imperceivable difference in soun...

Yeah, I agree it's unacceptable as well, but Friedman hasn't been a "factory" for that long, being a "boutique" modder/builder for many years. Circuit flaws in the boutique world is often see excused as "quirks" rather than what they really are - bad design.

The real amps do this too. It's a bad design tbh. Freidman changed later models to have a 2.2M in place of the 10M pull down resistor. There is also 10uF cap in series with a 100R resistor across the relay coil, which helps slow down the relay a little. I don't think you'll ever get rid of the pop c...

May be helpful if it was the same noise I was hearing. https://music-electronics-forum.com/forum/amplification/guitar-amps/theory-design/932727-strange-solution-to-ugly-distortion Also try removing the reverb tube just to rule out the reverb circuit causing it. If you search you’ll find it’s another...

Those Panasonic caps are more than okay, and many people do use them for tube amps. It's not that they are cheap, it's more that they are not overpriced

It’s normal for all Friedman amps - old school Fender/Marshall presence Control. It has a much better taper than the “new” type, and frequency breakpoint changes depending on setting (in a good way).

There are lots of good ways to do an effects loop. Even passively buffered ones (using a simple voltage divider to knock down the voltage and get a low-ish impedance) like in Cornford amps seem to do a fine job. If you have any volume control before the loop then it's acting like a send level contro...

I think the point you are missing is the recovery stage. You do need to drop the level way down to instrument level for FX pedals, but then you need to boost it back up to where it was (this can be done with a tube gain stage or more transparently with a transistor). The loop in the 800 reissue is g...

Just to play devils advocate, I think my approach would be a non expanding compressor pedal with a blend control before the amp or even in the effects loop. All these other methods are valid, but will only work when the amp is cooking at a certain level. I've had the best results control screen volt...

That's strange. 15 seconds seems more reasonable. There is DC until C2 charges up, which shouldn't be that long since C2/R1 are not too large.

Did you ever get this resolved?

Dr. Z asking is asking us for cheap schematic software recs? I am so confused.

xtian wrote: ↑Thu May 03, 2018 3:52 pm I just pulled two original Cliff jacks from an '83 JCM 800. Same issue--metal components were sliding out of place and not making contact with the plug tip.

In all fairness, those are 35 years old! Never had an issue with Cliff UK myself.