EgoDriver clipping (05.2012 version)

[Loztboy]

Hi. I finally got some time to build a pedal again.
I have a question about the clipping mod.
I can hear a difference when I toggle the clipping switch from normal to diode clipping, but when the switch is in diode mode I can't hear the difference from when D3 and D4 are empty and when I put LED's in them. When the leds are in, they light up when playing, but they don't seem to affect the sound.

I have tried 5mm red diffused, 3mm clear blue and 5mm clear green.
I tried some D9E's, they are the only ones that have affected the sound so far in the form of a volume drop.
Is this normal? Is the clipping effect so subtle that I can't hear it`?

[Loztboy]

I can't seem to figure this one out. I built it according to BOM. But after I discovered that it squeals like a pig in HP mode with gain on full and volume on about 60% I changed the volume pot to 100K, it still squeals
It's not boxed up, but the oscillations are so strong that I don't think the box will stop the squealing.
Here is a photo:


I have checked for solder bridges over and over.

Does anyone have a EgoDriver with LEDs in sockets? if so, would you do me a favor and check if you hear the difference with and without the LEDs in the socket (in LED clipping mode)?

[Loztboy]

I think I figured out the squealing part, Grounding input helps a lot.

The LED clipping part is still unclear for me.

[rullywowr]

Without diodes you will get a large volume boost. With diodes you will get clipping of different varieties.

[Loztboy]

Yes that's what I thought, but it does not happen on my build. The clipping mode is more gainy than the normal mode but the LEDs have no effect.

[Loztboy]

Can someone with a EgoDriver (05.2012 version) with LEDs in sockets please confirm that there is a audible difference with and without LEDs (when the clipping switch is in LED-clipping mode)? and what kind of LEDs did you use. I'm going nuts

[Ludo15]

I'll look into it today.
Cheers,
Ludo

[mgwhit]

How sure are you that it's the May 2012 board?  The version 5 board from September 2011 has an error in the PCB regarding the LED clipping.  You can easily check this by testing the top-most pads of the LED clipping diodes for continuity to ground.  The 2012 board should not have continuity to ground at those points, but should have continuity to a VB point (like the positive leg of C10).  I don't know if that would even cause your problem, but it's worth testing.

[Loztboy]

I'm 100% sure. The 2011 board have a little different layout than the 2012 board.

[Ludo15]

I just past some time with my egodriver, here's what i got:

My leds (3mm red diffused Vf=1.8V) light up when playing and there is a difference between both clipping modes (normal and led).

But when I remove the leds I see absolutely no difference with or without them (did it for a couple minutes using a looper pedal). The gain and tone knobs are all the way up, and HP mode on the OCD.

Found that weird, so I've put silicon diodes instead of the leds and did the same test. There was a big difference when removing them, both in volume and harmonic content.

Is it possible that the Vf of leds is to high in that circuit?

[Loztboy]

Thanks a lot for doing the test Ludo15, that's exactly what I experience. Now I feel a little better.
I will try to experiment with some silicon diodes, what diodes did you try, and was there a volume drop or boost with the Si's

[Ludo15]

No problem Loztboy.

I used 1n914s:
There was a slight volume drop between normal mode and silicon (silicon being slightly lower), the harmonic content between the two was different (preferred normal mode).

When I removed the silicons diodes, there was a big volume increase (as expected).