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Why do fuzz pedals lose fuzz below 8 on the dial...

Discussion in 'The Stomp Box' started by bluesholyman, Jan 7, 2021.

  1. bluesholyman

    bluesholyman Friend of Leo's

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    I have had this happen with a number of fuzz pedals, but it seems to be especially with Fuzz Faces....you roll down the gain from 10 on the pedal and fuzz basically goes away below 8.

    Logically, one would expect the gain dial to work across the spectrum, but this is not the case.

    Can someone tell me why? Is it the pickups and how they load the input - seems to happen for both single and hummers for me, although hummers fair a shy bit better.

    Inquiring minds want to know...
     
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  2. dlew919

    dlew919 Doctor of Teleocity

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    Someone else will explain better or more accurately than me, but the taper is logarithmic, not linear. I believe you can fix it.
     
  3. Suproman

    Suproman Tele-Meister

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    You really need a C taper (reverse log) pot in a traditional Fuzz Face style circuit to get the best range on the fuzz pot.
     
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  4. 11 Gauge

    11 Gauge Doctor of Teleocity

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    Yep, and even then, it's probably still not going to give a nice sweep across the dial.
     
  5. W.L.Weller

    W.L.Weller Tele-Holic

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    Most fuzzes are square-wave generators, more or less. Hence it's a binary condition, fuzz or not fuzz.

    Look for a new fuzz with a clean blend.
     
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  6. DougM

    DougM Poster Extraordinaire

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    Fuzzes are not like overdrives with clipping diodes attached to an op-amp. They get the fuzz by overdriving transistors, so when you aren't driving them into gross distortion, then they act as a transistor normally does, as a clean amplifying device.
     
  7. TeleBrew

    TeleBrew Doctor of Teleocity

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    I don't have anything to contribute, I just wanted to say that I learned a lot from this thread.
     
  8. 11 Gauge

    11 Gauge Doctor of Teleocity

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    No, not really input loading. Yes, the fuzz control does affect the input impedance, but it's not causing what's happening.

    I'm trying to think of how to explain this in terms that wouldn't be technical or hard to understand...

    ...If you understand the basics of negative feedback, then that should give you an understanding of it. Basically, gain/fuzz is adjusted via changes in negative feedback. The more negative feedback you have, the more gain is reduced.

    Particularly in the FF, it uses 'shunt-series feedback'. It takes output current from the second transistor's emitter and feeds it back to the first transistor's base.

    With the fuzz pot set to minimum, it diverts the maximum amount of current from Q2's emitter back to Q1's base. With the fuzz pot set to max, the negative feedback gets shunted to ground from Q2's emitter. So 'max fuzz = min neg. feedback'.

    The fuzz pot in a FF is a mere 1K, so min fuzz is with 1K resistance, and max fuzz is with no resistance. As you've experienced, it's anything but a linear relationship (e.g. with the fuzz knob set to 12:00, it isn't '1/2 the max fuzz').

    Look at the graph for different log tapers, below:

    [​IMG]

    ...The green line represents what's happening with a Fuzz Face's fuzz pot (with a stock unit being linear taper). Only for the sake of discussion, let's just say that it's at 150 degrees of rotation where it's the limit of a FF sounding 'good and fuzzy'. That equates to about 630 ohms.

    Now look at the purple/pink line, which is for a reverse-log taper pot. 630 ohms happens at roughly 70 degrees rotation - a much lower setting of the knob on the pot.

    So you're basically expanding on the increase/decrease of ohms for more of what is the 'sweet spot' of how the current gets either fed back from Q2's emitter to Q1's base, vs. what gets shunted to ground. No real tricks beyond that.

    The Fuzz Face circuit is crude. How gain is adjusted is equally as crude. The best we can do is use the most appropriate taper pot to try and optimize things within a useful range. The reverse-log pot is best suited for this. Just imagine how bad a (regular) log pot would be, given how much useless range a linear taper pot already has - you don't get 630 ohms until you reach about 200 degrees (almost max) rotation!

    Edited to add - this is just a hypothetical, simplified explanation. It isn't meant to really equate to what you're actually experiencing with where you set the fuzz knob on a FF!
     
    Last edited: Jan 7, 2021
  9. 4pickupguy

    4pickupguy Doctor of Teleocity

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    I have Fuzz Face based pedal by Moollon and it’s sweet spot is at about 50%. 100% is destructor beast. But half way up it’s a throttle for your volume knob. But it is sounds SO cool. Very Gilmoreish on neck pickup with the volume knob slightly rolled off. Can’t wait to hear it up windy loud!!
    12BAA7DD-83E5-4DBA-AD81-CFF6AB839D13.jpeg
     
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  10. Seasicksailor

    Seasicksailor Friend of Leo's

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    I love how this is framed as an issue to be 'fixed', when the cleaning with the guitar volume reduction is considered one of the most appealing characteristic of fuzz faces in particular. Goes to show there's no accounting for taste. :)
     
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  11. D_Malone

    D_Malone Tele-Holic

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    Seems to me the OP is merely curious as to why (most) fuzz pedals behave the way they do, nothing more.
     
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  12. beninma

    beninma Friend of Leo's

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    If you don't like this behavior than you need to go get a Big Muff or Big Muff derived pedal instead of what is likely a 2-transistor classic Fuzz (Fuzz Face, Tone Bender, etc.. and their million derivatives)

    Big Muff circuits don't behave like this at all. They have no Fuzz at 0, then they have a hard edged Fuzz at 1, and the Fuzz changes character to be smoother and smoother as you turn the Sustain knob up.

    The flipside is the big muff doesn't clean up much at all when you roll the guitar volume down.

    But if you want your fuzz to be FUZZ, that's why people like the Big Muff. (It's circuit being so different people argue it isn't even a Fuzz and is a Distortion.)

    Maybe the OP would like the RAT or one of it's descendants too.. I don't have personal experience with those.
     
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  13. Seasicksailor

    Seasicksailor Friend of Leo's

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    I'll admit it's subtle but it was the 'better' in the OP that prompted my thought ("seems to happen for both single and hummers for me, although hummers fair a shy bit better.")

    I might have read too much into the phrasing. :)
     
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  14. bluesholyman

    bluesholyman Friend of Leo's

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    Thanks for posting. I am down off the ledge now...was coming up there to push you off :lol::lol::lol::lol:

    You actually may have read the unwritten correctly. It was, intentional or not, from an internal perspective of "dirt boxes work like this, why don't fuzzes." It is something about a FF that bugs me (like a gnat around my ear,) but obviously that doesn't mean it's wrong.

    I could go into all sorts of details about how my mind thinks about this (I will spare everyone that pain,) but the question itself was more about understanding why and not necessarily that it was a problem to be fixed.

    I totally get how the view could have been taken that way in how I framed the question.
     
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  15. hotrodkid

    hotrodkid Tele-Afflicted

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    I have a few fuzz pedals that have a fuller gain frequency all the way down to 11 O’clock on the dial. My BAE Royaltone tonebender comes to mind. However most fuzz pedals I’ve played sound best fuzz maxed and working the guitar’s volume anyway so I don’t really sweat it. For the guys who try to make their fuzzes go into overdrive territory, it can be an issue. Btw, for the guys who want to get OD type sounds from their fuzz, the Carcosa by DOD is really good at that.
     
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