Ge Rangemaster sound from opamp?

Started by Passaloutre, May 10, 2017, 12:58:21 AM

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Passaloutre

I love the sound of my Rangemaster. Love the boost, love the grit, love the subtle %^&*ed-wah tones. It's a bit noisy, which is certainly the nature of a treble-boosting circuit, but I'm wondering how much of it might be avoidable. Opamp circuits for example seem to be less prone to power supply noise, and more predictable, but can they get the same grit as a Ge transistor?

Anderton's frequency boost seems like a candidate, maybe with some LED clippers?

Kipper4

Maybe breadboard an op amp booster with a high pass filter and some clipping mods. I suspect it may not have the same feel though.
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bancika

Why complicate things...I'd try a discrete MOSFET or jfet stage first and play with biasing and source cap values until it gets into the ballpark.
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Passaloutre

#3
Not trying to complicate anything, I have a Ge Rangemaster that I love (it was my first pedal build). I'm just wondering if there is an opamp design that might give me a similar sound, because I've been getting into opamp builds lately. The opamp designs seem to have a few "modern" improvements like low noise, consistency, etc, flexibility.

I'm thinking I can take something like the Mr Black Boost tiger and change either the input cap, or add a cap to the feedback network to boost only the treble. Maybe with a few clipping diodes in series, I can maintain the high boost level while also adding some clipping.


anotherjim

Rangemaster is famously interactive with the guitar pickups/controls.
In principle, I for one think it ought to be possible to duplicate somewhat with the opamp.

Copy the RM input impedance and input capacitor. This sets the treble boost curve in the RM.

Use inverting op-amp circuit. A non-inverting will always have x1 flat signal whatever the feedback does.

Use the feedback R to set gain and have some low pass with a feedback cap to simulate Ge high end loss.

Asymmetric class-A BJT distortion might be met partly, but not exactly, with odd feedback clippers, say a LED against a diode. In inverting op-amp, the clipper network sometimes needs some resistance always in series so the gain drops to at least unity when a clipper conducts.

Not sure though if an RM by itself ever really clips much unless mis-biased or overdriven from something else.