Diode questiong on pedal

[kostaz8]

I have a question about a guitar pedal on tonepad.com here http://www.tonepad.com/getFile.asp?id=31 the d2,d3,d4 are the 1n456? or anything else?

[Minion]

You can probably use any diodes with a different distortion effect .... I personally like the sound of red LED"s .....

[kostaz8]

you mean that if I put leds to these places it would work?

[Minion]

Yes leds would work or any Diode ... I haven"t seen that Particular Diode arrangement before but I believe they are used as Clippers to create the Overdrive/Distortion effect , what they do is clip the signal at 0.7v (1.5v for Leds) which creates the distortion effect , different diodes will sound differently ...

Cheers

[Enzo]

They are just general purpose switching diodes. The project part list even shows 1N4148 along with 1N456. You might find subtle differences between regular diodes, and of course LEDs have much higher voltage drops. But any general purpose diode will work.

[Minion]

one of the main reason why I like LED"s as clipping diodes is because they clip at 1.5v , with a regular 0.7v diode your output signal is limited at 0.7v (unless there is a makeup gain stage) so with LED"s you get twice the output signal .....

the drawback with Leds is if the Curcuit doesn"t have a lot of gain then you won"t get any clipping from the diode but luckily most distortion pedals are fairly high gain ....


Cheers

[PeteMcK]

Gain isn't everything, you need to consider the difference in tone between types of diodes:
http://www.diystompboxes.com/pedals/diodes.html

my preference is to use a single Ge diode

[MuthaFunk]

I second the Ge diodes. They give a lot warmer distortion. The MXR Distortion + and the Classic FuzzFace both run on Ge Diodes.

[PeteMcK]

I just tried a pair of mosfets in place of LEDs in my amp;
(2N7000, G&S tied together)
first impressions are good, they don't have the hard edge of the LEDs. & I think I like them more than the Ge diode..

[gain-wire]

Originally Posted by PeteMcK

Gain isn't everything, you need to consider the difference in tone between types of diodes:
http://www.diystompboxes.com/pedals/diodes.html

my preference is to use a single Ge diode

aha, the type of diode isn't everything either: consider the group delay of the frequencies passing through the diode. This affects the harmonic content of the signal and consequently has a direct impact on the ratio of even to odd harmonics, which we all know is the key to having tube-like overdrive. If one can slow down the electron flow in the said diode, one can more easily control the group delay effect. You probabaly need to convert the electric signal coming out of the diode into an optical signal then pass it through some kind of Bragg-grating filter, like a demultiplexer, and filter out chosen harmonic bands. Then multiplex it back and reconvert it to electric. It's really quite simple when you think about it. Just an idea. How exactly I donT' really know.

Maybe you should consider the ultra-conductivity theory: slow down the electron flow by bringing the diode to near absolute zero. You should probably invest in a cryogenic refrigeration unit to house the diode. How exactly you can control the group delay Idon't know. it needs studying still. This might affect your electricity bill.

That being said, it is time for my medication.