Roland JC120 too bright

[DrGonz78]

Could even be fresh solder connection on the signal path helped out a bit too. You just never know sometimes when it comes to solder connections. Honestly all of these tiny caps in the signal path are basically all cheap parts but if they measure right then they work.... Well sometimes lol. As I recall checking ESR on very small caps 0.1uf and smaller always prove impossible on my blue ESR meter. I will have to check that out again though no doubt.

[DrGonz78]

Actually my ESR meter does read even those small signal coupling caps  :duh. I think the thing with those caps is that I am not testing them as much for ESR. Mostly I am tracing signal and the signal does not come out the other side so I just pull it out and toss it aside.  :trouble I find the ESR meter really comes in handy when I am testing for bad electros. So if you measure a 0.1uf cap and it say 10-80 on the ESR scale it is probably good still. However, if i measure way higher than that then it is definitely a bad one. I will have to start testing those bad coupling caps soon for sure.  :dbtu:

[gbono]

X5R for a small value ceramic capacitor - I don't think so - try C0G. X5R has a really nasty voltage coefficient and is microphonic due to the piezo effect. Do you have the BOM for this amp design?

Maybe it is easier to listen with one's eyes.

[cejay825]

Got the amp sounding great BUT this chorus thing is driving me crazy. With the chorus off it sounds just like it should but when the chorus is engaged, the right speaker/channel (looking at the front of the amp) has a volume drop....I would say in the order of around 25-30%. I'm assuming this is the dry signal channel because you can plainly hear the chorus effect in the left channel. The chorus works and sounds great but theres the slight volume drop. Is this normal ? This would be a great hindrance when playing live.....

[Enzo]

I wouldn't call that normal.

One thing that occurred to me earlier.  if the amp sounded overly bright, as in the lower range sounded less than optimal by comparison.  And now one side sounds weak.  Try reversing the speaker wires on that weak side, just as a test.  Any difference?

The amp in clean mode - ie no chorus - should send the same signal to both channels.  In chorus mode, it turns off clean to one side and runs the chorused signal there, keeping the other side dry.  I can see some element in the routing circuit could be resistive or otherwise attenuating.   Good place to use a signal tracer.

[cejay825]

I'll try a speaker lead swap test. By the schematic, isn't the chorus being injected into the ("Power Amp R") right channel ?

[Enzo]

I don't have the schematic open.  One side has chorus only (no dry) while the other side has dry only (and always).  CHorus working against dry makes a much better chorus effect than the wet/dry mix from something like a chorus pedal.