Diode Recommendation Needed

[Nick C.]

I have been messing with moding a SD-1 to get TS tone and beyond and need
help with diode clipping options. I have changed most of the tone path to TS
specs and it does replicate the TS nicely. I am planning on adding a dpdt to
get 2 clipping options. One will be 2x 1n4148 per side and looking for advice
on a very compressed, sustaining option. I have tried over 20 options already
and I'm starting to loose my mind and hearing things. I've tried various
combinations of 1n34a, 1n4148, 1n4004, leds. I have reads many many posts on
diodes, so I do understand prox to clip, knees points, symetry and such. I had hoped
that 1n34a's would do the trick but the output is too low even with up to 3
per side. By the way I'm using a Strat.

Getting back to the point, what would be the ultimate sustaining diode combo
for a TS or SD-1?

Thanks

[brett]

Hi

but the output is too low even with up to 3
per side.

You should get about as much out put with 3 x Ge diodes as one Si diode (aka standard tubescreamer), which is quite a lot.

what would be the ultimate sustaining diode combo

The diodes control the clipping, not the gain and sustain.  IIRC maximum gain is only 120 or so, whereas high-gain circuits give 400 to 800 (or more).  For more sustain, I suggest putting a simple booster in front, or changing to a high-gain pedal, like a big muff pi.

cheers

[newb]

ive never built a tube screamer so I dont really know what diodes to reccomend. lately ive been playing around with using 2/3 of a transistor in place of a clipping diode anything from jfets to germaniums.  i find i get sounds i wouldnt using the usual compliment of diodes.    Just an idea

Peace and Love
scott

[brett]

Yes, transistors are really just 2 diodes located close to one another.The base-collector one in Si transistors has particularly low leakage, and a smaller "knee" (in relative terms) than Ge or gold-doped diodes such as the 1N4148.  They like very much like the 1N400X diodes.  The base-emitter one has more leakage, but isn't going to sound much different.  Of course, diodes with high Vf let more voltage flow coz they clip at higher voltages, so if you want a big signal, go for coloured LEDs.  But it you want high gain (ex clipping) and a high slew rate, you need to increase the resistance in the feedback look.  You could add a 100k to 220k resistor.
cheers

[Nick C.]

I'm a little confused as to what's going on. I'm think I'm looking for compression to get sustain and a low Vf should get me more compression, but the output is way too low. Raising the Vf by adding more diodes or using leds is getting the output up but the result is more dynamics not compression. There must be a good compromise? One combination I tried from the "Fullclone" (1n4148 vs 1n400x+1n34a) sounds pretty good and I'll probably solder that in for awhile. For some reason I'm do feel like I'm getting more compression using 1n4004s instead of 1n4148s.

Does anyone know what "magic" diode combinations are used in some of the rectifier or Germanium mods out there, or what lurks under the goop of some fancy schmancy pedals.

At some point I would like to play with using fets for diodes but right know just looking to use typical diodes.

You should get about as much out put with 3 x Ge diodes as one Si diode (aka standard tubescreamer), which is quite a lot.

Funny thing in my case it doesn't. I've even tried 6 ge's vs 1 1n4148 and the output is still lower than stock. Maybe I should measure their Vf.

Thanks