Oxide / Mostortion clipping switch question

[eh la bas ma]

Hello,

I am finishing the Oxide build. I did a clipping switch, and I wonder if it's allright ?





Green (on D2-) rings with R9, blue (D4-) rings with IC1.1. and Drive's pin 3.

I connected 1 red led+ to an other red led-

https://docs.pedalpcb.com/project/OxideDistortion.pdf

I can't really hear the usual volume gap, it sounds like something is happening when i use the switch, but not much though.

I don't know this circuit, but i feel something is wrong... like it's not really clipping.

Did I forgot something ?



Every help is welcome !

[Mark Hammer]

I've built a few Mostortions, with 3260 and 3240 chips.  There is an audible difference between the two, but I can't say I like one better than the other.  They both sound great.  The real secret to this little beast is the use of a 2+2 diode complement (just like a Timmy) and the terrific 3-band EQ.  Personally, I don't feel it benefits from mods.  I say "Enjoy it as is" and leave the diode switching to someone else.

[eh la bas ma]

Thanks for your reply !

I understand. No mods.

Ouch ! I already have the extra hole....

Before I forget all about it, I would like to try and see if I can get it working.

So there is no obvious mistake here ?



Edit: I'll try this instead

[idy]

What you have drawn is OK, but...
You are leaving the "stock" diodes, 2 pairs of 1n4148s.
If the diodes you want to use are, for example, LEDs, they have a higher turn-on voltage, you will never hear them.

So the highest "forward voltage" diodes need to be the ones that are "hardwired" in with lower vf pairs on the toggle.

You could use one, and a pair, of Germanium diodes on your switch...or one and/or pair of single Si....

[eh la bas ma]

What you have drawn is OK, but...
You are leaving the "stock" diodes, 2 pairs of 1n4148s.
If the diodes you want to use are, for example, LEDs, they have a higher turn-on voltage, you will never hear them.

So the highest "forward voltage" diodes need to be the ones that are "hardwired" in with lower vf pairs on the toggle.

You could use one, and a pair, of Germanium diodes on your switch...or one and/or pair of single Si....

I am not sure I understand...

You mean I should only use one led ? Like this ?


Edit : Ah! You mean leave D1 and D2 soldered on the pcb, then add the switch with D3, D4 on one side, and a single led on the other ?

[eh la bas ma]

Thanks a lot !

I left 2 diodes on the pcb. The led on the switch doesn't light up,  but that's probably to be expected.

I can hear a beautiful distortion now, and I have the possibility to soften the clipping a bit.

I used 1n914 instead of 1n4148, but i guess the difference is negligeable, if there is one.

Now, let's play with this thing....

[antonis]

I'm not sure what you've done now but in your initial wiring you always had asymmetrical clipping..
(either 2 LEDs in series or 4 diodes in series..)

You should have wired antiparallel LEDs between switch lugs 1 & 4 and antiparallel series diode pairs between lugs 3 & 6..
(to switch between Si diodes and LED clipping..)

[eh la bas ma]

Thanks you for your help !

I did what is described in reply #4 : "leave D1 and D2 soldered on the pcb, then add the switch with D3, D4 on one side, and a single led on the other "

I used 1n914 diodes and a 5mm red led.

From what I understand from Idy's answer, a pair of led alone won't clip the signal in an audible way, because of forward voltage considerations.
If i am correct, he suggested to use germanium or silicon diodes before the led, so the led can be put to good use, but I may have misunderstood what Idy meant...

Right now I can hear 2 different clipping options with the switch, but I can't say if the led does anything at all. Maybe I am just hearing 4x1n914 versus 2x1n914.

I guess i will desolder the led on the switch, to see if i notice any change. Then the diodes on the pcb, to try your idea and report.

[antonis]

From what I understand from Idy's answer, a pair of led alone won't clip the signal in an audible way, because of forward voltage considerations.
If i am correct, he suggested to use germanium or silicon diodes before the led, so the led can be put to good use, but I may have misunderstood what Idy meant..

Without speaking on behalf of @idy:
I think he told you that a pair of Si diodes permanently connected in parallel with LEDs (like D1/D2 left on PCB) will never result into LED clipping..
Also, any kind of diode in series (either before or after) the LED will further raise clipping threshold..

Summary:
What @idy proposed you is to have LEDs permanently hardwired (always into the circuit) and toggle between LEDs // Si/Ge diodes (SW Closed)  or LEDS  ONLY (SW Open)..



P.S.
You can implement any Si/Ge diodes combination you like as long as their total series forward voltage drop is lower than LED's one..