Tone Difference between Silicon & Germanium Diodes?

[Gearjoneser]

I'm no expert on pedals....OD, Dist, Fuzz to be exact, but can anyone shed some light on the tonal differences of silicon and germanium diodes in an OD circuit? And, what effect on tone would there be if you were to swap one for the other in a OD/Fuzz pedal?

[ArtieToo]

Re: Tone Difference between Silicon & Germanium Diodes?

Its the voltage turn-on point. A diode, in a fuzz circuit, serves the same basic function as a capacitor in a guitars tone circuit. It just takes a certain amount of the voltage, and redirects it to ground. Whereas a capacitor/potentiometer combo vary this amount, with a diode, its predetermined. Thats where the difference comes in. Modern diodes have a turn-on voltage around 650 - 750 millivolts, the older germaniums turned on at around 350 millivolts.

That, of course, meant that they came into play at a much lower volume.
Thats the difference.

Edit: Ooops . . . left out part of my explanation. While a cap redirects some degree of the high-frequency's to ground, a diode sends the top of the waveform, or amplitude, to ground, causing controlled clipping. (Like an overdriven tube, or transistor.)

[Blue Dream]

Re: Tone Difference between Silicon & Germanium Diodes?

Just read an article about this recently, the Germanium transistors will have a shorter life span due to "leaking" (electrons flowing in both directions=bad), this would lead to tone deterioration.

Silicon transistors are supposed to be more robust and capable of handling the rough physical and electronic conditions associated with guitar playing.
I guess that explains the difference in tone between pedals with Germanium.

[some_dude]

Re: Tone Difference between Silicon & Germanium Diodes?

If I'm correct, the silicone diodes have closer tolerances, and a cleaner sound.

Germanium has that less clean, bluesy, "brown-ish" sound going on.

The suggestion I was given by a modder friend of mine is to go for Metal Film in medium to high gain stuff to avoid mud, and germanium in low to medium gain stuff to avoid glassyness.

Germanium will colour your sound more.

[Gearjoneser]

Re: Tone Difference between Silicon & Germanium Diodes?

Thanks for the good info guys. I'm sure stratdeluxer97 has some experience swapping them in and out. He must have a life today. Ha Ha.

[Kent S.]

Re: Tone Difference between Silicon & Germanium Diodes?

The threshold difference between GE and SI is more or less well know, but the GE also (IIRC) have a bit of a non-linear response to frequency, as the higher frequency breech the turn on point faster than the lower frequencies do, resulting in more high harmonics, that's around the clip point though, SI are higher in threshold and bit more in sensitive to Fc.Per a given signal level the GE will clip sooner, and more than the SI. SI also has a faster forward/reverse bias changeover, when they clip they tend to do so a bit quicker and recover a bit quicker, in a sense being *harder*. The Ge are a bit laggy in their response .The Ge has bit more even ordered harmonics than the SI, which I find odd because the ge is a bit more sensitive to high frequencies ,while the SI is a bit more balanced as to even and odd harmonics. Of course the differences become hardly noticeable under high gain, and whether or not the diodes are arranged for symmetrical or asymmetrical clipping, and the mix of diode types further alters the harmonics.
That's if memory serves correctly, at high gain I feel they have a slightly different *feel* to them, as the tonal differences become very hard to notice.

[STRATDELUXER97]

Re: Tone Difference between Silicon & Germanium Diodes?

Thanks for the good info guys. I'm sure stratdeluxer97 has some experience swapping them in and out. He must have a life today. Ha Ha.

Hears what I hear...The silicon diode keeps tightness of tone and is a cleaner and more articulate tone...

The germanium diode seems to add more distortion and a softness or squishyness to the tone and isn't as tight in the crunch on chords..I Like to mix and match diodes,but on some pedals I Like to leave the pair or all 3 silicon diodes in place and soften the tone via a capacitor across the diodes...

John

[Jonnylane]

Re: Tone Difference between Silicon & Germanium Diodes?

I've made various fuzz pedal with both.

In the fuzz face circuit (the simplest of them all) I find the Si is tighter than the Ge, BUT, in the same breath I have to say that it's getting harder and harder to match Ge transistors for gain; my stockpile is severely depleted (and no I'm not selling any ) and it's got to the point where It's a lot more time efficient to use Si.

Plus, I personally prefer the sound of silicon