sahlomonic
Well-known member
Several years ago, I bought a modded JCA20H from a guy that used it as a base for all his mods for his business. I won't mention his name, but this amp was a complete POS when I got it. Ton of half-assed mods, most mods sounded like garbage, and the quality of work was appalling. Undersized components, daisy-chanied resistors (one part of the circuit had FIVE) instead of one resistor value, burned up PCB, cold solder joints, and smelled like the guy was a 2 pack a day sort of fella.
Anyway, after letting it sit for a couple years, I decided to bring it back to stock form. Yanked out a lot of worthless control pots, reduced the daisy chained resistors to one value, replaced a couple dead pots, retouched a lot of solder joints, etc. Got it running. Yay. Now time to put some real mods on it.
I also have a Friedman modded JCA20H I bought from a buddy for cheap ($400?). He keeps wanting to buy it back, and I eventually told him I'd sell it back if I can clone it on another amp. Well, here's the perfect opportunity.
Pulled the boards on both amps so see how Dave did the BE voicing mods, and a lot of it was pretty straight forward - only big change was moving the gain control to in between the 2nd and 3rd gain stages, the rest were mostly Marshall type values and adding bypass caps. Also added a SAT switch (Jose style diode clipping circuit). I had the BE100 schematic and a loose tutorial I found on Google that was close to mine but some parts of the circuit were off.
I don't have board pics or clips YET, but hopefully this weekend I'll have some time to show the guts, but it sounds MEAN. A/B'd with the host amp that Dave modded himself, and it's virtually identical.
Anyway, after letting it sit for a couple years, I decided to bring it back to stock form. Yanked out a lot of worthless control pots, reduced the daisy chained resistors to one value, replaced a couple dead pots, retouched a lot of solder joints, etc. Got it running. Yay. Now time to put some real mods on it.
I also have a Friedman modded JCA20H I bought from a buddy for cheap ($400?). He keeps wanting to buy it back, and I eventually told him I'd sell it back if I can clone it on another amp. Well, here's the perfect opportunity.
Pulled the boards on both amps so see how Dave did the BE voicing mods, and a lot of it was pretty straight forward - only big change was moving the gain control to in between the 2nd and 3rd gain stages, the rest were mostly Marshall type values and adding bypass caps. Also added a SAT switch (Jose style diode clipping circuit). I had the BE100 schematic and a loose tutorial I found on Google that was close to mine but some parts of the circuit were off.
I don't have board pics or clips YET, but hopefully this weekend I'll have some time to show the guts, but it sounds MEAN. A/B'd with the host amp that Dave modded himself, and it's virtually identical.
