A FET preamp inspired by the Orange OTR-120 amplifier.
The idea originally was given to me by a friend guitarist that was experimenting with various pre-amps. As a fan of the OTR-120 he suggested that it would be a nice option to have a transistor based reproduction of the OTR's pre-amp in a pedal footprint. And... here it is!
While many builders tend to call it "tube emulation" I am not a fan of this term despite the fact that many people out there use it.
The goal was to build a FET-based circuit with similar topology, same controls, with a frequency response close to the original pre-amp and with a relatively high-gain capabilities.
The parametric EQ (Bass/Treble) is exactly the same as in the original circuit and the Presence control was implemented in a similar way, originally in the triode's cathode, here on the FET's source. The F.A.C. (Frequency Attenuation Control) behaves in the exact same way while minor changes have been made to the capacitor selection in order to maintain its flexibility similar to the original.
A voltage doubler has been added in order to provide the FETs and the circuit with the necessary headroom and gain range.
The circuit has been tuned for gain oriented use and even with the gain knob at minimum position the sound doesn't clean up completely but it has a slight grit and goes up to high gain levels when turned to maximum.
dOTRsmoker is actually an all-around drive/distortion pedal with great range and flexibility. We designated it as "pre-amp" because its design was based on a pre-amp and of course it can be used as one since it provides more than enough output volume especially in high gain settings and can take other boost/drive pedals in front of it if you want to push it.
▹ True bypass
▹ Voltage Required: DC 9 Volt (voltage doubler inside)
▹ Current consumption: 8mA
[Do not exceed recommended voltage! It may damage the circuit.]
▹ Polarity: Negative tip ▹ Current consumption: 8mA
