Asymmetrical Octaver Effect

In a previous post, I told how I made an EQD Tentacle Clon in a 1590 Enclosure. I took the layout from and made some minor changes:

  • I used NPN transistors with a high beta (>400), I think they will give higher input gain and more output gain in the final stage.
  • I had a very anoying noise in this circuit from a cheap power supply. Added a 56 Ohms resistor between supply 9V and circuit and the noise disappeared completely. It seems that the 100uF capacitor was not enough and needed a little resistor to absorb the noise.
  • Ommited the two bottom rows with no function.

Yesterday a made a new, more drastical change: I swapped one of the two rectifier diodes (1N4148, Vf = 0.7V) with a BAT46 Schottky diode, with Vf = 0.3V, just to experiment with this component.

The electrical result is an asymmetrical rectification of the input signal, as can be seen in the oscilloscope:

input signal below, output signal above

The audible result is a more natural sounding octave effect. Usually octavers have to be combined with overdrives or fuzzes in order to be bearable. Otherwise they sound too robotic and are unusable, at least for me. With this change, even if visually does not seem to be very different from its symmetrical counterpart, at least for my ears it sounds like a very dynamic distortion, and of course gets improved with some kind of light distortion after it.


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