2 vs. 4 diodes

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Mr. G.
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Post by Mr. G. »

In a TS style clipping section, what would be the difference between using 2 or 4 diodes/LEDs? Would one produce more gain than the other? Is there much, if any, difference in the overall tone/feel?

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modman
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Post by modman »

Mr. G. wrote:In a TS style clipping section, what would be the difference between using 2 or 4 diodes/LEDs? Would one produce more gain than the other? Is there much, if any, difference in the overall tone/feel?
They will not bring the gain down, but more diodes equals less output.
Overall tone/feel is very subjective, maybe what some would call 'more compressed' is for others 'very tight'

You should trust your own ears only. Experiment with sockets or breadboard!
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Post by Fuzzer »

The important thing is the forward voltage of the diodes, and how they sum up; the more voltage threshold there is, the less distortion the clipping scheme will give, because the signal has more space to go without getting clipped. That also affects the volume you get out of the circuit, because if you clip at too low a level, then you will have low output.

One thing to keep in mind is the conduction characteristic curve of the diode may have an influence in sound, germanium diodes turn on differently than silicon diodes in terms of current against voltage, so, in the same circuit, if you have a symmetric silicon diode pair with a threshold of 0.6 [V], it might not sound the same as a symetric arrangement of four germanium diodes with the same voltage threshold.
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Post by Mr. G. »

Here are the two clipping options I'm toying with. One is from a YATS and the other is from the CM PlexiTone. One more difference is one (not sure what the particular section is called) goes to ground and the other goes to Vr. Could someone elaborate on the differences between these two clipping sections?

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Post by earthtonesaudio »

modman wrote:
Mr. G. wrote:In a TS style clipping section, what would be the difference between using 2 or 4 diodes/LEDs? Would one produce more gain than the other? Is there much, if any, difference in the overall tone/feel?
They will not bring the gain down, but more diodes equals less output.
Overall tone/feel is very subjective, maybe what some would call 'more compressed' is for others 'very tight'

You should trust your own ears only. Experiment with sockets or breadboard!
If you arrange the "more" diodes like picture "B" you will get more output, less clipping.
Mr. G. wrote:Here are the two clipping options I'm toying with. One is from a YATS and the other is from the CM PlexiTone. One more difference is one (not sure what the particular section is called) goes to ground and the other goes to Vr. Could someone elaborate on the differences between these two clipping sections?

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Mr. G:
Clipping option "A" has several things going on which will affect the tone in a certain way.
-Obviously 2 LEDs clip at a lower voltage than 2 pairs of LEDs. I noticed one schem says "3mm" and the other "5mm" but more important is color. In the LED world, size really doesn't matter. :slap:
-Next biggest difference is the .22u/1k going to VR. This will create the traditional TS bass-cut at around 700Hz, but it's not a straight 6dB/octave, since the 1k resistor makes it a "shelving" type of rolloff. If VR is a voltage source, it behaves exactly like ground as far as AC signals are concerned.
-The most subtle difference is probably the 10k resistor in series with the Drive pot. This will limit the minimum amount of gain, and slightly raise the maximum amount of gain.

Clipping option "B" will have more bass and overall gain, but two LEDs in each direction will keep the amount of distortion down. Tying the cap to ground makes no difference for either effect, except if the cap fails (shorts), circuit "A" will keep working fairly normally.
rocklander wrote:hairsplitting and semantics aren't exactly the same thing though.. we may need two contests for that.

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Post by Mr. G. »

Thanks a lot! This is exactly the information that I was looking for. The LEDs that I'll be using are the clear red ones. I specified 3mm LEDs in option B just to save on board space.

I think I'm going to use option B in the circuit I'm toying with, and just socket the LEDs so I can see what I like best.

Thanks again! :thumbsup

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