Tonal difference in types of si diode clippers?

[suprleed]

Hi all.  I had a quick question for all the experienced builders on this great forum.  I'm currently in the middle of my first build, the Small Bear Tweak-O (waiting on a unibit so I can finish tooling the case), but I'm already planning my next project (yes, very addicting).  I'm thinking about modding my DS-1 and had a question about the sound differences in diode clippers (if any).  Is there a major tone difference in the various silicon diodes used for clippers?  e.g. are 1n4001's smoother/harsher than say 1n914's or 1n4148's.  I've read that LED's can give you more crunch but do they add grit or smoothness compared to the 1n4001's?  Or does the noticeable tonal differences only come into play between silicon vs. germanium diodes?  Just wondering what some your experiences have been with the sound of various types of silicon diodes and LED's.  I'm hoping to absorb some wisdom from the experts as I plan my future projects and mods.

Thanks and happy playing.   

[Mark Hammer]

Dear lord.

It's a fair question, not foolish at all, but an answer to that is a bit like answering the question "Could you tell me everything that has happened on The Bold and The Beautiful so far since the start of the show?"  You cannot begin to imagine the number of key presses devoted to that subject matter here.  I've probably logged at least 100,000.

Quick folks, give this welcome newbie a few tips on what should be used as suitable productive search terms to dig through the vast archives here.

[suprleed]

Sorry for the broad question.  Maybe the sound differences is more a product of the design of the clipping stage/feedback loop than the type of diode used.  I was just wondering if anyone had any general guidelines, e.g. 1n914 = rougher, 1n4001 = smoother, etc.

I'll go back into lurking mode and see if I can have better luck with my searches...

[Mark Hammer]

You will probably hear some opinions.  The trouble is that the behaviour of the diodes in question will always and forever be inextricably linked to the nature of the circuitry around it.

[demonstar]

Theres loads of good reading on the net. Here are some quick examples (I just searched and these are few I picked out so not necessarily the best threads just the lucky ones that were selected ) ...

"http://www.diystompboxes.com/pedals/diodes.html"

"http://privatewww.essex.ac.uk/~mpthak/Distortion/"

"http://www.diystompboxes.com/smfforum/index.php?topic=62010.0"

"http://www.diystompboxes.com/smfforum/index.php?topic=57927.0"

"http://www.diystompboxes.com/pedals/mhdistort.html"

"http://www.diystompboxes.com/smfforum/index.php?topic=26918.0"

I think a big part of what kind of distortion you get out comes from which part of the signal you're clipping eg. using a filter to clip only the low end or clipping the whole frequency range. Also how prominent the effect is, is altered by the position of the diodes in the circuit. For instance in the dist plus the diodes are at the rear of the circuit so the clipping is harsh and more pronounced than say positioning the the diodes in the feedback loop of the opamp which would produce soft clipping. There are some good oscilloscope pictures somewhere showing this very well. I think it might be at geofex or amz.

It must also be remembered that individual diodes of the same type can vary quite a bit as well. Even diodes from the same batch can vary in how they clip all be it subtlety.

Diodes can also be placed in different configurations. Don't be afraid to mix and match and experiment with different sorts. You can create asymmetrical clipping by using different diodes to clip the positive and the negative sides of the waveform.

As a general rule of thumb most people believe germanium diodes to produce a thicker, heavier but smoother distortion and silicon diodes to be harsher with more bite. People generally seem to avoid LEDs but some do try them and find they like them. That leads onto preference; it all depends on the individual. I'd suggest getting a lucky bag of diodes or a good mix and don't worry about exactly what each one is, just stick them them in and use your ears.

I personally found that the germanium diodes I have tried (1N34) I don't really care for as much as these other silicon ones I use. I'm sorry I don't even know what they are but they sound good!

Hope that gets you started and have fun! Try some searches on the areas I've touched on and you should find what your after.