Diode clipping question

[Luke51411]

In an set of anti parallel diodes to ground hard clipping set up what happens if you add in a parallel set of diodes to ground with a different fv? Will it clip at the lowest threshold and the higher fv diodes have no impact on the sound?

[jubal81]

Yep. Exactly right.

[Luke51411]

Thanks. I was pretty sure that was the case just couldn't find an answer confirming it.

[midwayfair]

Actually, it will make a difference. The resistance across the diodes will divide in parallel, the knee will change, and the Fv will also divide a little.

Totally unscientific, but I'm not the only one who's noticed it: Lucifer's Trip did a contest entry once that used six Ge diodes in parallel.

[Luke51411]

Actually, it will make a difference. The resistance across the diodes will divide in parallel, the knee will change, and the Fv will also divide a little.

Totally unscientific, but I'm not the only one who's noticed it: Lucifer's Trip did a contest entry once that used six Ge diodes in parallel.

Hmm ok I'll have to try it out. I'm actually planning on having 2 or 3 spst switches for different clipping options so if all settings are a bit different,  that would work out well anyway. I'll plan on doing a fair amount of testing to determine it myself.

[mgwhit]

I'm actually planning on having 2 or 3 spst switches for different clipping options so if all settings are a bit different,  that would work out well anyway.

The formerly-available Lavache circuit used a switch to "override" one or both of the stock 1n914 clipping diodes with lower forward voltage BAT46s.  One switch setting used a pair of antiparallel BAT46s to completely circumvent the 1n914s, the other just used a single BAT46 for slightly asymmetrical clipping with with one of the 1n914s.  Might be worth looking at.

[RobA]

I'm actually planning on having 2 or 3 spst switches for different clipping options so if all settings are a bit different,  that would work out well anyway.

The formerly-available Lavache circuit used a switch to "override" one or both of the stock 1n914 clipping diodes with lower forward voltage BAT46s.  One switch setting used a pair of antiparallel BAT46s to completely circumvent the 1n914s, the other just used a single BAT46 for slightly asymmetrical clipping with with one of the 1n914s.  Might be worth looking at.

That's where I lifted the hard clipping section from for the scramjet. I did quite a bit of playing with the circuit with various different kinds of clippers at the time. There's a lot of possibilities in that really simple design. The one thing I thought was consistently true is that you need the clippers on the switch to be somewhat close to the forward voltage of the main clipper -- less than but close.

In the scramjet circuit it certainly sounds different to me to have the MOSFET clipping section in when the parallel LED's are also in than when just the parallel LED's are there. The MOSFET may be an atypical case because of the knee of the clipping from it, but I do think that you will see similar things with other clippers in the always on position -- especially if their Fv are close.

[Luke51411]

Actually, it will make a difference. The resistance across the diodes will divide in parallel, the knee will change, and the Fv will also divide a little.

Totally unscientific, but I'm not the only one who's noticed it: Lucifer's Trip did a contest entry once that used six Ge diodes in parallel.

Ok, I'm confirming this point again. On my chimaera I had two anti parallel unknown germ diodes and then added on more parallel to that set and it changed the tone. I then had an asymmetrical clipping arrangement with the same germs and added the parallel diode and it changed it as well. I'm going to try some other diodes now.

[deafbutpicky]

Diodes don't just clip the signal they have some parasitic capacity too, especially germanium.
I don't stock them really but my two handfuls of different types have a range between 100p - 600p.
This is what gives them a tonal character too in this setting as they don't have to add actively to the
clipping to change the sound this way.

[Luke51411]

I haven't really played around with diodes a whole lot as I previously was not into too many circuits with diode clipping but it's kind of fun to play around with. I added anti parallel LEDs and a set of anti parallel germs I don't think there was much difference with the LEDs in or out of the circuit but I thought maybe it seemed like the edge was a bit harder or something, maybe I was just perceiving a difference because I changed something... For this particular project I think I'll have LEDs always in and then the option to place symmetrical and asymmetrical germs on top (I'm using 2 spst switches for style reasons, that will be clear when I post my build report.)