Build Your Own Clone Message Board

So I had a functioning Opticomp... and then I had to go and mess with it.

I added the Release mod and the LED Compression indicator according to this thread (already had the attack switch mod), and now I'm getting some weird behavior. Sometimes it sputters (compression goes back and forth as the note dies out, almost tremolo effect) and I can see the sputtering with the LED indicator, and sometimes I'm getting a weird effect where the first strum gets compression and a "pop" noise, the but I won't get compression on any other strums until the first one has completely died out. So if I strum a regular rhythm, on certain settings I'll get an effect where every 2nd or 3rd strum gets the "pop" and compression, and the others don't seem to have any effect.

I'm wondering if this is just the LED compression indicator that's causing this. The Opto-isolator has a common node for the two LDR's, so could the LED be sucking current off the signal path causing the problem? Has anyone else implemented that mod successfully? It's a pretty cool feature (especially with the various attack/release mod combos, so you can actually see what's happening), so I'd like to keep it, but I'm not sure if there's another way to implement it that doesn't share that common portion or doesn't suck as much current off the signal path.

It does sound like a voltage issue. Are the LED wires properly isolated?

Isolated as in not touching anything else? Yes, I trimmed the leads short and soldered wires to them, and then put heat shrink over the connections. Grounded one side to the output jack, connected the other to the open leg of the Opto-Isolator.

Yep, sounds like you did a good job with the LED. Pictures? Maybe you're missing something obvious. Doesn't it always end up being the obvious thing??

I have done the mod on a couple of opti-comps and have never had an issue like the one you are describing. I have read some others that say they have a "heartbeat" noise if the compression is really high but I haven't had that one either.

pics?

If nothing else is wrong then you could always remove the LED mod and see if that clears up the problem. That would isolate the problem to that mod.

Hello
I'm new to this board. I've build so far the Armstrong Twin, the Tribooster und the Opticomp. Very Cool Stuff! Then I did the attack mod and the release mod to the OptiCompand they where fine. so I thought it would be a good idea to have this control LED and I did the case drilling and this mod. Now I have the same issues as discribed by NQbass7 in his first post It's even worse: If I play with my PRS Hollowbody there is a big amount of distortion, when the control light lits up. With a Strat or a Tele it's as discribed by NQbass7.

If I disconnect the LED from the Optocoupler, everything is fine again... And yes, I've isolated everything with heat shrinks.

Is there a solution to this problem? Or do I have now a hole to much in my enclosure?

With kindly regards

Is the release set low when you have the sputtering issue? Maybe in combination with a lot of compression and hot pickups. I know there is a similar problem with hot pickups and a lot of compression, heavy inconsistent tremolo sounding. Maybe try turning down the volume pot on your guitar with your current settings and see if the problem continues. If problem goes away, reconfigure, because comp pedal input is to sensitive. To raise the threshold of that sensitivity in the pedal use a higher voltage power supply. No higher than 18volts. I use 18volts with my Les Paul because of the hot humbucker output of the guitar, demanding more headroom from the opticomp.

thank you for responding.
I've tested with 9 and 12V but it dosn't matter. when the release and the attack is low it's worse. but the problem exists with every setting and diffrent guitars( PRS hollowbody, strat, tele, les paul with P90). If I disconnect the LED it is working. but I've tested now more intensly and there are some strange things also without the control LED.
for example: if I run the optocomp after the OCD, it ampilfies the signal very much and don't compress... none af my others compressors do that. I like to have the optocomp as the last stage in my chain, because of it's very transparent sound, but so it is unusable.

so I think the optocoupler or one of the transistors failed. can anybody measure with a DMM the voltage between the LED minus leg of the optocoupler and the + when one strumming a guitar hard? thanks a lot

Also make sure your PCB board is totally clean. Use Flux Off or some type of flux wash and a very small firm brush for cleaning boards, or toothbrush I guess. Make sure that no flux from one solder point to another is in contact. I was once so frustrated with a circuit and as it turned out it was just flux residue shorting me out.