Why do more diodes = louder?

[nbabmf]

I thought there was a voltage DROP across them.   :idk:

My 808 clone is louder when the switch is on asymmetrical clipping (3 diodes) than it is on symmetrical (2 diodes).  I used a Tonepad PCB.

http://www.tonepad.com/getFile.asp?id=81

I mean, I don't really care because it sounds awesome... but I am just puzzled.

[Paul Marossy]

Try reading this: http://www.diystompboxes.com/pedals/diodes.html

[davidallancole]

There is more output voltage going to the amplifier.  The 2 diodes clamp the output voltage swing to ~+-0.7 volts, where as a 3 diode setup will clamp the output to ~+0.7 to -1.4 volts.  Thus there is more output voltage going to the amplifier.  That means if the volume control on the amplifier hasn't been changed once you switch to the 3 diode setup, that extra voltage out gets amplified more than the 2 diode setup.

[brett]

Hi

There is more output voltage going to the amplifier.

If, and only if, you have the volume control maxxed. ( Usually, the easiest way to drive an amp harder is to turn up the volume.)

Otherwise, extra diodes can change the shape of the waveform a little, and if they are present in unequal numbers in each direction, they create please harmonic distortion ("asymetric clipping").
cheers

[nbabmf]

Try reading this: http://www.diystompboxes.com/pedals/diodes.html

"The clipping threshold set by diodes is additive, meaning that if you were to put two Ge diodes of the same orientation in series, in parallel with two other Ge's of the opposite orientation, you would have symmetrical clipping, with Ge quality, but with a higher clipping threshold (double, or roughly 500mv). Similarly, stick a Ge and Si in series, and the threshold (for that half cycle) is now 500+250=750mv. You will sometimes see circuits that use pairs of 2 and 3 diodes in series."

Now it makes sense.  I have two 1N914 diodes in parallel with one 1N914 diode.  The one side of the waveform affected by the pair is actually being clipped LESS than that of the single diode.  Very interesting!  Thanks, guys.

[davidallancole]

Brett,

What I was getting at but did not clearly explain, is that if you do not change any gain or volume controls, but switch the diodes from 2 to 3, the voltage out from the op-amp will increase, thus increasing the volume out of the speaker.