Build Your Own Clone Message Board

Hi everyone!
Before building this kit I'm already in the mood for some MODs!

So the LED to indicate compression MOD seems very cool, like on my EHX Black Finger, but as I have the 4 leads optocoupler, can I still do it? Can I connect the LED to the "closest" bottom leg of the VTL5C4?

Can I use a superbright LED for this?

thx!

EDIT: report of xperience below

Sorry, I actually haven't tried it with the 4 lead optocoupler. I don't know if it is possible. I don't have any of the 4 leads so you will have to experiment with it and see what you can find.

Ok I'll try and post results here, but the way I see it, I think it will have some influence to the audio circuit...

Maybe not the most adventurous advice, but I would say build it stock first and make sure it's working, then mod. Makes things a HELL of a lot easier to troubleshoot...

Looks like it's not possible...
The LED is doing a short circuit in the audio path, or it stays always on when connected to the other legs of the optocoupler.

It make sense with the 5 legs (dual element) device, as the second element is reacting to the signal the same way the first one does, but without doing anything to the audio path. With the 4 legs ones, we're messing with the audio by adding the LED, which's connected to the ground.

I've found this feature very handy in the EHX Black Finger: with low amount of compression you can see what you barely hear! But this big pedal is not pedalboard friendly, so I wanted the same feature with the opticomp.. maybe after doing the attack and release mods, I will buy a VTL5C4/2!

I did a little research on the 4 leg optocoupler and I decided that it wasn't going to work without that 5th leg.

Then I came hear and saw that you had already posted your last message. I should have checked here first I guess.

Anyway, I think you are right.

Hi again!
Here's my experience with this Mod.
As you probably figured out, I bought a 5 legs VTL5C4/2 so I can do the Mod, it works BUT.... It has some influence on the audio path!! There's more gain when the led is connected, and with a fairly hot output guitar (Seymour Duncan SH4) some distortion can be heard when played hard. This is the same problem as described here: http://www.buildyourownclone.com/board/viewtopic.php?f=19&t=25117 and I've tried 9 and 12V power.

My solution was adding a resistor between the optocoupler and the LED, and, it may seems silly, be carefull to choose where to solder the LED to the ground: soldering it on the output jack made things worse, on the pcb it sounds better. For the resistor I haven't a lot of values to try but 4.7K seems fine, almost no distortion and enough juice to light up the LED.

Off Topic: I've also tried a different IC, the OPA2604 and was disapointed: the sound is indeed clear but at the expense of the compression as the sensivity pot has no effect, as the attack switch.

thank you for reading!

Interesting. As I said, I have done this mod to a few opticomps, including 2 that I still have, and I have never had any distortion issues with any of them. I called a friend of mine who has one that I have done the mod on and he has never had any distortion issues either.

I play a PRS with a HFS Treble in the bridge which is a pretty hot pickup but I don't know what it's specs are since PRS won't post them for some reason.