Clean Boost circuit identification / possible mods?

[soundxplorer]

I recently purchased a pedal (used) that has distortion on one side and a clean boost on the other side. I've tried contacting the builder with a couple of questions, but they have not replied. I understand they might be busy, or maybe they aren't interested in supporting a second-hand purchase, that's fine.

Anyway, I'm hoping someone here might be able to answer a few questions based on the image I've posted below of the clean boost circuit. My main issue with it is that it isn't very "clean" at all. It's actually very crunchy, even when used on its own and set to the slightest bit of gain. I can see there are a pair of LEDs in the circuit, and they seem to be bridging two of the leads on pot. If it seems like there's a lot of wiring to and from the circuit in the pic, that's probably because there's a switch on the panel that moves this boost either pre- or post- the distortion side within the pedal.

1. Can anyone identify roughly what circuit this might be based on just by looking at the picture?
2. Do you think if I took those two LEDs out of the path it would clean up the sound?

Thanks in advance for any help.

[antonis]

Hard to say but, probably LEDs are part of distortion circuit, clipping between lug 3(pot input) & lug1(GND)..

Can't tell if they are permanently engaged (both for distortion and clean boost use) without the rest part of pedal..
Is that a Volume pot one for only clean boost or does it serve as common setting for both effects..??

[soundxplorer]

Hard to say but, probably LEDs are part of distortion circuit, clipping between lug 3(pot input) & lug1(GND)..

Can't tell if they are permanently engaged (both for distortion and clean boost use) without the rest part of pedal..
Is that a Volume pot one for only clean boost or does it serve as common setting for both effects..??

If I click the boost side off, that gain pot doesn't do anything. So I'm pretty sure the two sides are independent. The distortion half of the pedal has it's own clipping LEDs, and its own separate volume and gain controls.

I'm inclined to just experiment by removing those LEDs. I can put them back easy enough.
But I guess then my question is: if I remove them, should I bridge that path between lug3 and lug1 with a bare wire? Or should I just clip them and leave it hanging? My knowledge of circuit design is pretty much zilch, as you can probably tell.

Thanks!

[Plexi]

As antonis says: maybe that leds are for a light clipping.

Hmm...one transistor, 2 caps, 3 resistors (4k7 and 2M at the bottom? I don't see very clear that colors)... maybe some kind of EM-drive.. I guess?

If the caps are 100nf (104), it could be...

[soundxplorer]

maybe some kind of EM-drive.. I guess?
If the caps are 100nf (104), it could be...

Cool, thanks for the suggestion. I'll take a closer look at the components later tonight.

I aiming to get the boost side to be a little cleaner. So when I opened it up and saw the LEDs, my first thought was "Ah-ha, there's the culprit."

[Plexi]

you're welcome!
Sure, let us know about that.

If you want a cleaner boost, you'll have to check for another circuit there.
If it result in a EM-drive, will be a bit difficult to tweak it to "clean" a bit more.
Maybe with an input potentiometer (as in the EM-drive to crontol "gain"), or biasing the transistor.

[Zerikin]

The LED are likely clipping the signal. If they go directly to ground you'd want to leave the connection open and not replace it with a wire.

[soundxplorer]

maybe some kind of EM-drive.. I guess?
If the caps are 100nf (104), it could be...

Caps are indeed 104, so it definitely looks a lot like an EM Drive. Thanks again for your help!

[soundxplorer]

The LED are likely clipping the signal. If they go directly to ground you'd want to leave the connection open and not replace it with a wire.

Looks like they go ground. I'll try clipping them later, with an A/B sound comparison. Thanks for your help!

[duck_arse]

what is the transistor part number?

and, welcome to the forum.

[soundxplorer]

what is the transistor part number?

and, welcome to the forum.

Thanks!
Looks like: 2N3904 B331

[GGBB]

Component count and type matches up with an Electra Distortion variant using LED clippers. Whatever it is, it appears to be a pretty straightforward BJT boost into clippers arrangement. Remove the clippers and it will clean up. Raise the 470R to lower gain.

[antonis]

<The distortion half of the pedal has it's own clipping LEDs, and its own separate volume and gain controls. >

If so, the other half shouldn't be called "Clean Boost"...