Scotch Bonnet: another stab at an Escobedo classic, the 'Bronx Cheer'.

[garcho]

As it has for so many of us, Tim Escobedo's brilliant and generous "circuit snippets" page has provided me with endless inspiration for breadboarding, tinkering, noodling, etc. Here's my take on the 'Bronx Cheer', an Escobedo snippet named after a fart.

The Scotch Bonnet
A spicy version of the Bronx Cheer. 4 controls: output, tone, resonance, frequency. Filtered fuzz. Sounds like harmonically-rich velcro; at its heart it's a fuzz pedal, don't expect any 4-pole sculpting, but it can go from blooming distortion to funky synth fuzz to dark metal drone to mosquito dentist drill to acid rock.
The 'highpass/lowpass' is a dual-ganged pot controlling both the 'high' and 'low' controls of a James network filter (passive Baxandall). As the 'high' goes up, the 'low' goes down, or vice-versa, with one turn of one knob. While breadboarding, I noticed that the dual-gang wiring ended up achieving what I was often doing manually, anyway, with nice extremes and a useful mid section to the turn. The values were determined by ear. Also, I generally feel that for guitar pedals (as opposed to say, rack processors) the less knobs, the better. Dan Armstrong wasn't dumb.

I made the board on EagleCAD through OSH Park. My design is crappy: the eyelets for the pots are too small, I let EagleCAD do most of the routing, stand-off holes prevent it from fitting into a smaller enclosure, etc. but at least the PCB works and was cheap and I didn't spend 1000 hours on it. The circuit itself is most likely rife with redundancy and missed opportunities but I got it sounding good to my ear after many hours of futzing on the breadboard. Hopefully, I'll make a few revisions and make better boards in the future but for now, here it is:

Please excuse the demo, I'm shamefully inadequate at making these.

I hope somebody here gets something out of it. Any suggestions are very welcome!

[Morocotopo]

Nice pedal Gary.

Never heard the Bronx Cheer, but this sounds like a fuzz mated with a broken synth and gave birth to some mutant child! In a good way of course.

[deadastronaut]

cool, i like it...

[italianguy63]

It is way cool.   

[nick d]

               Sounds awesome/crazy , and I must try it ! One query regarding the schematic - the 10k pot marked
               " TUNE " does not seem to be connected to anything . Can you clarify ?

[smurfedelic smurfberry]

Nice work!

I built a stock Bronx Cheer a while back and while I really like it, it felt a little bit limited, and you seem to have adressed just that really well!

What kind of markers did you use?   Molotow and Posca tends to crackle up after a while when you clear coat it, which is a bit discouraging.

I would love to buy a pcb of that!

[garcho]

Thanks for the kind words gentlemen!
If a few people want a PCB, I'll fix up the boards and get a batch of 10 or something. Should end up being pretty cheap.

I used Sharpie oil markers and DecoColor 'opaque paint' markers. The DecoColor are really nice with cool shades but smell awful. Ventilate!

Thanks for pointing out the error in the schematic! Yes indeed, the 'tune' pot should be connected to +V rail, as a variable resistor. Also, R6 (5k6) should go between +V and the 'tune' pot. That's something I'll definitely fix for the new batch of boards. I'm on the phone now, I'll post the correct schematic later today.

[noisette]

I also experimented with this circuit, it´s a waver folder , that responds to amplitude(diodes) as well as frequency (caps). It works really nice with synthesizer-leads and bass (with a little modified circuit).
Nice, someone finally polishes Escobedo´s little sleeper sketch into something flexible. Tone control is really powerful imho, I had fun with it being switchable pre/post transistor stage.

[Strategy]

Hi Garcho, I'd definitely be in for a PCB,
THANKS!
STRATEGY

[garcho]

Here's the updated schematic:

I would love to buy a pcb of that!
I'd definitely be in for a PCB

I just started revising the board, I'll let y'all know when to expect the batch. It was $26.85 for 3 boards, so the price will be right around $10, including US shipping. If 10 or more people want boards the price will be around $6. I'll solder one up as soon as I get the new boards - before sending them out - to make sure changes to the layout are kosher. So maybe in a month or so? It depends on OSH Park's order volume (and my schedule). Cheers!

[smurfedelic smurfberry]

Nice!  I'd probably want 2 boards if it helps.

[smurfedelic smurfberry]

Any progress on this?

[garcho]

Thanks for asking! I just moved to Richmond, VA a couple weeks ago, so things have been mega crazy, broke ass, can't find anything, etc. I'm in the process of building a workbench in my basement right now and then it's the first thing I'm diving in to, been itchy!! Man, I miss my breadboard!

[iampoor]

Could you explain how the resonance and tune controls work? Im confused by how they work, but they sure do sound great!

Also, have you tried a gain stage/attenuator in front of it? Curious if that would change the envelope response.

[garcho]

Could you explain how the resonance and tune controls work?

ha, i wish!     i believe that somehow, the tune is controlling the diodes' 'conduction knee' (?), which allows the diodes to act as a very janky voltage-controlled-resistor style filter, along with C5 and the "res" control. I might be completely wrong. I don't think it's a "real" resonance control, it just altered the sound somewhat similarly to the way a res knob on a VCF would, so that's what i ended up calling it.

Also, have you tried a gain stage/attenuator in front of it? Curious if that would change the envelope response.

if i recall, there was somewhat of a sweet-spot for my guitar, where there's a bit of shape to the signal, but not too much fizz. it takes to the guitar volume knob well, i found i could roll back just a little to dial it in without having to bend over. then crank it up when need be. it can sound kinda cool with quieter signal but it's definitely lo-fi. i am going to breadboard this again soon and tweak it some more. it has a few glitches, i mean unique features, that i want to understand better.

a few people have independently mentioned drum machines and samplers sounding good through it. maybe the next one will also have line inputs. i gave the few i made away and never got around to populating my last board and since then i've moved a few times, so it's in limbo. i don't play with the band that i gigged with it now so i haven't felt the urge when so many other things are on the list...

i'll make new boards eventually, PM me if anyone is interested, i believe they end up being about 10 or 12 bucks including shipping. i'm hopefully buying a house and moving soon, so it might not be until spring.

[blackieNYC]

I love the escobedos. But I skipped this one because it seemed a little silly. But you'v e got some really cool sounds!
I must ask - did you play around with single pot tone circuits? BMP or SWTC? Were they poor in comparison, or did you just have your heart set on using a dual 100k?

[garcho]

while i was trying to optimize the range of filtery fuzz tone, i noticed that with the tone and res controls all the way "down", it sounded like a nice overdrive, good for power chord parts or something like that. i liked the sound but the high-end needed to be carved out a little, the 'exciter' range, like what you don't hear when you have a bad cold. maybe 6-10k. that's why there's the dual control wired the way it is. when the fuzz is most fizzy, you can really tame it, when it's overwhelmed and muddy, you can carve something intelligible out of it, and you don't have to waste time adjusting two controls. i really like the sweep, and find it useful.

now that you mention it, i probably was thinking inside the box, ba-zink! maybe i could have solved the tone issue another way and simplified the manual controls, but at least you can wire it the way the you want, including hard-wiring a control (say the HPF if you don't care about that function and just want the fizzy filter fuzz). it would be easy to bypass the whole tone stack if you wanted anyway, although you're gonna wanna tame the high end somehow. i'd love to see someone who understands what's going on with the transistor filter figure out the nitty-gritty. might be able to ditch the res knob too and have a 2-knob pedal.

speaking of a lack of volume/gain control, i need to optimize this so it stays around unity, or gently above. i was doing a lot by ear and got tired of noodling so i had the boards made just to be done with it and play guitar. i think it sits below unity as is. adjusting feedback resistor values can fix that. plenty of room for improvement all around!

[iampoor]

Could you explain how the resonance and tune controls work?

ha, i wish!     i believe that somehow, the tune is controlling the diodes' 'conduction knee' (?), which allows the diodes to act as a very janky voltage-controlled-resistor style filter, along with C5 and the "res" control. I might be completely wrong. I don't think it's a "real" resonance control, it just altered the sound somewhat similarly to the way a res knob on a VCF would, so that's what i ended up calling it.

Also, have you tried a gain stage/attenuator in front of it? Curious if that would change the envelope response.

if i recall, there was somewhat of a sweet-spot for my guitar, where there's a bit of shape to the signal, but not too much fizz. it takes to the guitar volume knob well, i found i could roll back just a little to dial it in without having to bend over. then crank it up when need be. it can sound kinda cool with quieter signal but it's definitely lo-fi. i am going to breadboard this again soon and tweak it some more. it has a few glitches, i mean unique features, that i want to understand better.

a few people have independently mentioned drum machines and samplers sounding good through it. maybe the next one will also have line inputs. i gave the few i made away and never got around to populating my last board and since then i've moved a few times, so it's in limbo. i don't play with the band that i gigged with it now so i haven't felt the urge when so many other things are on the list...

i'll make new boards eventually, PM me if anyone is interested, i believe they end up being about 10 or 12 bucks including shipping. i'm hopefully buying a house and moving soon, so it might not be until spring.

How did you come across the "resonance" control? Trial and error? I am trying to wrap my brain around it and I just end up having a headache. 
The "Tune" control is just a low pass filter but it supplies the bias to Q1/Q2?
Which, speaking of that, any idea what they do?

Line inputs would be cool. Running some snares through this thing might be pretty cool.

while i was trying to optimize the range of filtery fuzz tone, i noticed that with the tone and res controls all the way "down", it sounded like a nice overdrive, good for power chord parts or something like that. i liked the sound but the high-end needed to be carved out a little, the 'exciter' range, like what you don't hear when you have a bad cold. maybe 6-10k. that's why there's the dual control wired the way it is. when the fuzz is most fizzy, you can really tame it, when it's overwhelmed and muddy, you can carve something intelligible out of it, and you don't have to waste time adjusting two controls. i really like the sweep, and find it useful.

Im not usually a fan of 1 knob tone controls, but from the demo video it seems to be about as good of a compromise as you will find!

[duck_arse]

just an observation on your "06 27 2014" schem [is it that long ago?] - you have C3 and C4, both 100nF, doing the same job. if my theory is correct, either could be omitted and linked out, and the remaining replaced with a 47nF, and make no difference to the circuit operation.

[Danich_ivanov]

Haven't built this one, but Push me Pull you was my first build, and i love it. I used wrong caps by accident, 1uf instead of siggested .1uf, and i haven't actually heard it with original caps, but this thing is mega inspiring, definitely in my top 3. If i was to attempt a desert island challenge, PmPy would be on the list.