Russian detector diode types

[thelonious]

For our uses in pedals (clipping, stabilizing Ge transistors, etc.), are there any substantial differences between the different types of Russian detector diodes? I remember several people talking about the D9E version. The others (D9B, D9J, and D9L are the others I've seen for sale, specifically) have different numbers for forward current and reverse voltage, but is forward voltage still around .27?

D9B has a low max reverse voltage (10V). Would that ever be problematic in a clipping configuration? Does only DC voltage difference across the diode count toward that?

Lotsa questions. Gracias in advance...

[teemuk]

is forward voltage still around .27

I don't know the spec for that specific diode but in general it's just a threshold. The differences between clipping a 1.2Vp signal with a diode that has forward voltage of 0.6V and 0.6Vp signal with a diode that has forward voltage of 0.3V are quite small so overall most forward voltage levels can be "homogenized" by plain matching of input sensitivity vs. forward voltage. Knee characteristics you can easily alter with series resistances. I personally wouldn't obsess too much about this.

D9B has a low max reverse voltage (10V). Would that ever be problematic in a clipping configuration?

Not neccessarily problematic but it does introduce certain issues you need to consider in design.

Does only DC voltage difference across the diode count toward that?

No, the rating applies to both AC and DC. With that in mind, the low reverse voltage rating naturally isn't an issue as long as it isn't exceeded. If you use clipping schemes where each halfwave is clipped at least below 10 volts the forward conducting diode will always limit the reverse voltage seen by the reverse biased diode. It's only the asymetric circuits where >10Vp swings at one of the halfwaves affect at the diode terminal.

[thelonious]

If you use clipping schemes where each halfwave is clipped at least below 10 volts the forward conducting diode will always limit the reverse voltage seen by the reverse biased diode. It's only the asymetric circuits where >10Vp swings at one of the halfwaves affect at the diode terminal.

Thanks, teemuk! That is exactly what I was wondering.