Gorilla Glasses clipping pot no effect

[fontoponto]

Hi everyone,

I finished a GCI Gorilla Glasses and it seems to have no audible effect to turn the Clip pot.
I can't hear any difference. On an oscilloscope it make more difference to cough at the gain pot than to turn the clip pot.
The pot is fine and changing resistance up to 5k. The dmm shows a forward voltage drop of 0,195V in circuit for each 1N5818.
The led is a small green one...
The continuity tester tells me that the connections are fine.

What could be wrong?

According to the warp control explanation it’s a volume control for the harmonics

AMZ Warp Controls

Circuits for producing asymmetrical clipping in guitar distortion pedals.

www.muzique.com

Unfortunately there are no sound clips or videos out there to listen to how the pedal should sound like. There is one interview of Kurt where he is demoing the ape eye but that does not have a clip control.

The whole project:

https://kurtballou.com/docs/GOD%20CITY%20INSTRUMENTS%20%E2%80%93%20Gorilla%20Glasses%20V1.0%20Build%20guide.pdf

The clip part:

 

[fontoponto]

It seems to be doing something. On the oscilloscope I can see a very slight shift on the y axis towards the positive with only a few millivolts at the end of the pot turn.

 

[BuddytheReow]

Does every other control work as it should? I’ve tried the warp controls from AMZ on a breadboard and most of them are more subtle than I wanted. Your clip control is a blend between on and off for lack of a better description. Do you hear clipping or no clipping?

 

[fontoponto]

Yes the other controls are fine.
Yes it clips. I will cut lug 3 and see what happens. Maybe add a switch as mentioned in the build document and throw other diods in there.

From AMZ:

One could speculate that the reason this type of control is not often used in commercial boxes is that the change in sound is noticeable but subtle. It is not a drastic enough that the added cost, complexity and extra control knob space can be justified.

So my ears are not suitable for subtle

 

[temol]

Make sure that R13 is 4k7 not 47R. There shoud be visible difference on the oscilloscope between min and max pot setting.
What's the signal level between C15 and R13? Did you measure clipping level with maxed gain?

 

[fontoponto]

The resistors all have the correct value.
Volume and tone at noon, gain max, clip min.
Yellow Ch1 is on clip pin3, blue Ch2 is on pin1.

When I turn the pot on max both are of course equal (no screenshot...).

C15&R13
Other voltage scale than above but you can see the difference in waveform

 

[DailyDovetails]

Does the LED flash when you play hard with it turned up and not flash when you turn it down? Many of the pedals with clipping LEDs I have done you can see when it clips. My guess is it sounds subtle also. I recently built a pedal that pans between 5817 and green LEDs and unless you are playing with it fairly clean the difference is subtle.

 

[temol]

Here's the output signal with clipping pot @ min and max:

1. Ltsice simulation.


2. Circuit on breadboard.
Pot @ max


pot @ min


Check connection between diodes and GND and also diodes and clipping pot. Inspect the PCB. Maybe there's an error on a PCB? Missing track?

 

[fontoponto]

Does the LED flash when you play hard with it turned up and not flash when you turn it down? Many of the pedals with clipping LEDs I have done you can see when it clips. My guess is it sounds subtle also. I recently built a pedal that pans between 5817 and green LEDs and unless you are playing with it fairly clean the difference is subtle.

Until now I thought that a square pad means - (cathode, negative, ground etc) but I was wrong.
The led was soldered the other way around. Of course should the led light up as in every other pedal!!!!!

Here's the output signal with clipping pot @ min and max:
Check connection between diodes and GND and also diodes and clipping pot. Inspect the PCB. Maybe there's an error on a PCB? Missing track?

Min


Max


And the clipping is not subtle. The subtleness vanishes after the pot is at noon. It turns it into a blackest black metal pedal.

I want to punish myself for not questioning the measured voltage dropt in the wrong direction when I measured it in circuit.
Sorry but I can't select both answeres as solution.

Thank you guys!

There will be an info to Kurt about this

 

[fontoponto]

Learned: flat side of the printed led is the cathode.