Electronic – Simulated inductor for guitar use

gyratorinductoroperational-amplifierotasimulated

Edit: Sorry! Please bear with me, this is my first post! Well, it seems that placing a buffer before certain fuzzes can chance their sound. However, placing an inductor after the buffer cancels this effect ("unbuffers"): http://www.muzique.com/lab/pickups.htm Sure, ditching the buffer would too but sometimes you can't or don't want to: http://www.muzique.com/lab/imp.htm . I wonder if a simulated inductor has the same effect, this could be useful for resonance adjustment and guitar synths.
OLD: I would like to use a floating active inductor to "unbuffer" a guitar signal before a fuzz, made from off-the-shelf parts.
After an exhaustive web search, the models I found either requires custom parts or is too technical. Eventually I heard of a "3-OTA conventional simulated inductor", but I could't access the schematic.
So, does anyone know any circuits for this purpose? Low noise and ajustability would be nice.

Best Answer

I'll take a stab at this. Most fuzzes rely on BJT's of some sort, which are current driven devices -- for "musical" reasons, guitarists tend to like the sound of fuzzes when driven by high impedance sources (such as guitar pickups); that is, not capable of providing much current. Driving them with a low impedance source provides far more current, changing the behavior of the BJT amplifiers, subjectively to the detriment of the sound. I imagine you're hoping to place your fuzz after a buffered effect, such as a tuner or a not "true bypass" effect, rather than at the front of your signal chain. That, or you have active (buffered) pickups.

In your linked page, the point of the RLC circuit is not to "unbuffer" the circuit per se, but rather to provide an impedance and frequency response that roughly approximates a generic guitar pickup when driven by a low impedance, high(er) bandwidth source. This can be useful when you have a nice bench signal generator, but that's not the case here.

You are interested in "debuffering", or raising the output impedance of the preceding stage. This does not in any way require an inductor or capacitor, "simulated" or otherwise. Just putting a resistance in series with the input should increase the impedance "seen" by the BJT. This could take the form of a single resistor enable by a switch, a bank of resistors with a rotary switch, or a variable resistor in the form of a potentiometer.