DEMO Cremulator [A Mosfet Tone Bender]

This post contains an audio or video demo
Aleph Null

Aleph Null

Well-known member
Cremulator is an all-mosfet Tone Bender. Using mosfets has some advantages, foremost being that the biasing required makes the circuit much less sensitive to transistor beta—no need to test dozens of transistors, just slam some BS170s in and rock! It also cleans up better than the BJT version and gets just as wild. I added a versatile tone stack to complete the design.



The enclosure is an LMS limited run that I got for Christmas.



The layout was just for shits and giggles, but I do think it sounds cooler with all the components on the 45°.



The Fuzz is a volume with a treble bleed after the initial boost stage. I choose this approach because it keeps the control from crackling and it doesn't darken or get muddy as it is turned down the way a more traditional implementation would. The fuzz section looks like a Fuzz Face because it basically is. Unlike a BJT implementation, R5 is needed to get Q2 to bias properly. C5, C6, and C7 are all added to reduce noise and to keep the clipping from getting too fizzy. The Tilt control is a pretty standard BMP tone control. What makes it special is the Mids control. The high pass portion of the Tilt has a set knee frequency of 1.2kHz, but the Mids control allows the low pass portion to be shifted from 390Hz at the lowest to 4.8kHz at the highest. It scoops the mids that make things muddy, it boosts the mids that make things cut, or it leaves them flat.

I'm really pleased with this circuit. It does the thing I want from a Muff. It does the histrionic and bloated Fuzz Face or Tone Bender thing. Plus it chugs and grinds in a way that those other pedals can't.

Here's a demo:


As always, I have extra PCBs. If you're interested, DM me!
 

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jessenator said:
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Hit enter too soon man strikes again?

Sounds great!
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This is very, very cool. Lower noise floor than a BJT TB maybe?

It certainly doesn't need this (at all), but I take it adding a bias/starve to intentionally get some broken sounds wouldn't be too hard? I honestly haven't worked with MOSFETs a ton, curious how that kinda thing might work here.
 
Thanks for all the kind words, everyone!

Ginsly said:
This is very, very cool. Lower noise floor than a BJT TB maybe?

It certainly doesn't need this (at all), but I take it adding a bias/starve to intentionally get some broken sounds wouldn't be too hard? I honestly haven't worked with MOSFETs a ton, curious how that kinda thing might work here.
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The noise floor is comparable to the Fuzz Face and Muff pedals I have on hand. If it's quieter, it's still within 6dB. If I were going for that broken sound, I'd start with a potentiometer in place of R5 or maybe R7. That said, I have another circuit in the works that's designed with starved/mis-biased sounds in mind. ;)
 
Aleph Null said:
Thanks for all the kind words, everyone!


The noise floor is comparable to the Fuzz Face and Muff pedals I have on hand. If it's quieter, it's still within 6dB. If I were going for that broken sound, I'd start with a potentiometer in place of R5 or maybe R7. That said, I have another circuit in the works that's designed with starved/mis-biased sounds in mind. ;)
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Ah! I figured you'd say R6 or R8, very interesting! As is this upcoming mystery project... 🤔
 
Ginsly said:
Ah! I figured you'd say R6 or R8, very interesting! As is this upcoming mystery project... 🤔
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Those might work too. Generally, I would expect adding resistance at the drain to increase gain and mids a lot before any gating started to occur.
 
Very cool!

How would you compare the tone stack to a normal Muff-with-mid-control tone stack? As far as I understand the high pass is moving in that, but the low pass is in this, so it's similar, but can get the "scoop" to a lower frequency instead of a higher one.

Also makes me wonder if you could have a dual gang mid pot and could switch between moving the high or the low pass at will, although I don't know if it would actually be that useful. You might need to duplicate the tone stacks though, but it's not that many components 🤔 Not sure if dual gang pots with the right value are easy to find.
 
Fama said:
How would you compare the tone stack to a normal Muff-with-mid-control tone stack? As far as I understand the high pass is moving in that, but the low pass is in this, so it's similar, but can get the "scoop" to a lower frequency instead of a higher one.
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With Mids all the way down, it's close to a Ram's Head tone stack, but with a little less of the upper mids scooped. I've found that once you start cutting 1.5kHz to 2kHz, the guitar just disappears in a mix. The idea was to get that scooped feeling without sacrificing all midrange presence. The deepest part of the scoop is around 500 or 600 Hz, the boxy or muddy region. The biggest mid hump is near 2 or 3kHz, which is the presence and pick attack region. The more traditional approach has you scooping or boosting around 800Hz, which either makes you completely disappear or sounds like a bloated tube screamer...at least to me.

If I wanted even more flexibility in the mids, I'd probably start looking at using a gyrator like the Metal Zone does.
 
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