The Simble Predrive is a pedal from Mad Professor, announced in January 2015. The company describes it as more than a preamp: "Simble Predrive is not just a preamp, it is a preamp/booster/compressor/upper harmonic enhancer." In practice it lifts a guitar's signal, compresses it without a slow attack, and adds what the maker calls musical harmonic overtones1.
What it does
The circuit is built around a low noise transistor with a high input impedance, over 2 Mohm. Mad Professor says that is enough to boost even piezo pickups without tone loss, which opens the pedal up to acoustic guitars and other instruments that standard buffers can flatten1.
The amount of lift is deliberately moderate. The maker gives the maximum as about +10dB on lower level notes, and the average as about +6dB. Because the compression does not slow the attack, picked notes keep their edge while quieter ones come up to meet them1.
Where it fits on a board
The output impedance is 50 Kohm, and Mad Professor says the pedal "works even in front of fuzz pedals." That matters: many fuzz circuits misbehave when fed from a low output impedance, so a preamp that can sit ahead of them is a useful placement option1.
Mad Professor notes that if you remove the input jack when not playing, the pedal can run on a 9V battery for a few years1.
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Questions
Can the Simble Predrive work with piezo pickups?
Yes. Mad Professor says the circuit uses a low noise transistor with an input impedance over 2 Mohm, high enough to boost even piezo pickups without tone loss. That makes it a practical front end for acoustic or baritone instruments fitted with piezo saddles, as well as for standard magnetic pickups that need a clean lift.
How much boost does the Simble Predrive give?
According to Mad Professor's announcement, the maximum boost is about +10dB on lower level notes, with an average of about +6dB. Because the circuit compresses without a slow attack time, quieter notes get lifted more than louder ones, which evens out a performance while adding harmonic overtones.
Can it run on a battery?
Yes. Mad Professor says the pedal runs on a 9V battery, and that if you remove the input jack when not playing, the battery can last a few years. The input jack acts as the power switch, as on most pedals.
Sources (1)
- Mad Professor Launches New Guitar Gear 2023, Premier Guitar, 2015-01-30