Hi!
I'm new here so please fell free to move the post if it's not in the right place!
I'm looking for bipolar (+12/-12 or +15/-15) overdrive and fuzz schematic, but i«m having an hard time finging it.
Anyone knows some good ones?
Thanks in advance!
Welcome.
Fuzz/distortion is over-load.
It is easier to overload a 9V circuit than a 24V-30V circuit.
Steal a 9V plan and drop your 12-15V to 9V.
Craig Anderson designed for bipolar... and Boscorelli s "stomp box cool book" uses 19v .
Wellcome..
Roughly speaking, any "conventional" 9V Fuzz/OD can be modified for +/-12 or +/-15 PS by replacing GND with negative supply and off-setting various bias points by their new analogous difference - also saving items in some cases..
(e.g. a point biased to +4.5V for 9V supply should be set at 0V for a +/-12V supply..)
Quote from: PRR on March 17, 2018, 05:05:32 PM
Welcome.
Fuzz/distortion is over-load.
It is easier to overload a 9V circuit than a 24V-30V circuit.
Steal a 9V plan and drop your 12-15V to 9V.
I don't agree. While it's true that it's easier to overload a 9V circuit than a 24/30V one, not many overdrive/distortion circuits rely on the power rails for clipping. Some do, sure, but many don't. So if you've got clipping diodes of some type (even if they're mosfets) in there, what voltage the supply is doesn't really matter. Better to take a 9V single supply circuit and convert it to bipolar - throw away the virtual earth bias, and take everything that used to go there to ground, all original ground connections to -V, and all +9 connections to +V.
To answer the original question, the only bipolar distortion unit I know is the Frequency Central Meth Amp, a Eurorack module based on the EH Big Muff Pi with voltage control. But Rick doesn't share the schematic for that one, sorry.
And as Paul said, Welcome!
Tom
Well said Tom but, IMHO, it might be a trouble if you try to throw a bi-polar supply pedal in a single supply chain of half the voltage magnitude..
Quote from: antonis on March 19, 2018, 08:57:18 AM
Well said Tom but, IMHO, it might be a trouble if you try to throw a bi-polar supply pedal in a single supply chain of half the voltage magnitude..
They didn't say that's what they were going to do. And anyway, as long as the circuits are reasonably well designed, the worse that can happen is the signal level will be too big for the next pedal and you'll get some crunchy clipping.
TBH, I assumed that if they were looking for bipolar supply effects circuits, this was for either a synth or a similar studio application, rather than a one-off bipolar supply pedal in a pedalboard full of other unipolar 9V pedals (why would you do that?).
T.
> not many overdrive/distortion circuits rely on the power rails for clipping
FuzzFace?
And several popular plans (including FF) rely on supply voltage in a range to get happy bias. They sure can be re-biased for another supply. But that needs "thought", aided by past study. You and I do it in our dreams/nightmares. Someone less-experienced/bruised, a 9V drop-rail (Zener+R, LM7809) is "cheaper than thinking".
Not disagreeing, just saying there's different paths.
ProCo RAT sounds worse as rail voltage increases in my opinion. While there are plenty of drives that don't get their clipping from the opamp, the RAT is my favorite dirt pedal and it relies heavily on the tone of a clipped LM308. I tried running mine at 12V once because someone (misinformed) told me everything sounds better at higher voltages and I wasn't pleased with the results.