Fuzz Face question Difference between the .1uf and the .01uf

[jimbob]

Im wondering what kind of difference having a 01.uf  versus a .1uf in the fuzz face there is. My understanding is that one leg goes to the 500k volume pot. What reasons would there be to have a .1uf there instead of the typical .01?


thanks

james

[jimbob]

From what I have read from GEO changing the input and output capacitors changes the bass response of the unit.

[tcobretti]

If you are talking about the output cap, then yes, smaller values allow less lows to pass thru.

The input cap has more of an effect on the fuzziness of the circuit.  Bigger input caps generate thicker sounding fuzz.

[newfish]

Definately!

Built one today, and ended up changing the 2.2Micro cap (input) for a 0.047 (having tried other values before jumping straight to the tiniest value...)

To my ears, all the treble disappeared with the FF switched 'in' - hence the changing to 0.047 - which to my ears gives much more treble.

[Gus]

google, ask etc
Plate to plate  and brit face

The link at the top of the page "links" has links to sites with good information
http://www.diystompboxes.com/wiki/index.php?title=Links

[Dragonfly]

Definately!

Built one today, and ended up changing the 2.2Micro cap (input) for a 0.047 (having tried other values before jumping straight to the tiniest value...)

To my ears, all the treble disappeared with the FF switched 'in' - hence the changing to 0.047 - which to my ears gives much more treble.

It will also reduce the amount of "fuzz" available.

Check Joe Gagans "Easy Face" for a blend pot....allows you to dial in any value you wish.

[joegagan]

i stumbled across an old ampage thread that documents my first experiment with the blend cap pot.
early 2001, osakr bruil, rg keen and myself discussing. oscar told me in an email at the time that he got the idea for the blend pot from an old post by jack orman.

so, as usual, rg and jack are at the ground floor of almost everything that happens in the diy effects world.

http://archive.ampage.org/threads/2/fxsb/086737/Capacitor_mini-circuits-1.html#086737

[Skreddy]

The blend pot is at work in my Screw Driver's "Sharpness" control, too.  I added a tiny bit of lowpass filtering to the big side (a .22uf in my case; and I use a .01uf for the small side), 'cause for some reason it seems to add more noise.

But the OP was about the output cap.  I use a .1uf output cap in my Screw Driver, and it's very full range.  I went down to a .01uf output cap on my Lunar Module, and it's still plenty bassy (was too bassy before, and I wanted it to have more "cut").  Just depends on other parameters how much bassiness you get from the output cap.

[John Lyons]

Skreddy
Are you saying that you had more hiss with the smaller cap that the larger?
I have a 10uf on one side of a 100K blend pot a la Easy face and towards the smaller side in it will hiss noticably.
Rotated to the large cap side  the hiss goes away somewhat like a switch.
Why is this? Maybe esr do to the large "slow"/sloppyness of the big cap at high freqs?
Or did I mis-understand you.

John

[Skreddy]

Skreddy
Are you saying that you had more hiss with the smaller cap that the larger?
I have a 10uf on one side of a 100K blend pot a la Easy face and towards the smaller side in it will hiss noticably.
Rotated to the large cap side  the hiss goes away somewhat like a switch.
Why is this? Maybe esr do to the large "slow"/sloppyness of the big cap at high freqs?
Or did I mis-understand you.

John

I get more hiss and hum (which is from the pickups, not internal to the circuit) with the bigger cap.  It's just because the bigger cap gives a generally louder signal all around than the smaller one, I reckon.  I'll put a small resistor inline with the bigger cap to try and equalize the volume, etc.

My blend in the Screw Driver goes after the mosfet input stage and before the modified Fuzz Face stage, and it looks like this:

It's almost a BMP tone stack at this point. 

[drewl]

I'm experiencing the same problems with a couple fuzz faces I built.
with the stock cap values it's just too bassy or thick, but changing to the lower values kind of limits the output level.
More experimentation is needed.

[Skreddy]

You can try other values such as .047uf, and you can tweak the output volume by adjusting the voltage divider between 9v and Q2's collector.
For example, you can try 3k instead of 330R and 5.6k instead of 8.2k for a really loud output.

But rarely have I ever built a good Fuzz Face with stock values.  To do it properly, you have to audition a whole lotta transistors (e.g., if you're repairing a vintage unit and don't want to change values).  If you're making a one-off for yourself, it's easier to adjust the parameters of the circuit than it is to find just the right transistors.

[John Lyons]

Thanks for the diagram mark, clever...
I do get a bit more hum on the large cap side which makes sense...more level/low end etc.
But I get the hiss when turned to the smaller cap for some reason. It's not really there panned hard over to the big 10uf cap.
I should try to put a small cap in parallel with the large cap to see if the large cap is blocking some high end for some reason. That's why I was thinking ESR in the post above. But that's usually not a night and day difference as I have here.

John

[newfish]

Tonight's task could well be putting the 'Hendrix' Mods in the Fuzz Face.

Simple Resistor changes around Q2 (as detailed on RG's excellent FF article) - and we'll see.

I'm not too worried about a volume drop, as I have the FF volume set at about 3 o'clock - so it doesn't take my head off when I switch it on...

It's a brilliant circuit though - so much you can do (and learn) from it!

...and it sounds ace too!

[Skreddy]

Thanks for the diagram mark, clever...
I do get a bit more hum on the large cap side which makes sense...more level/low end etc.
But I get the hiss when turned to the smaller cap for some reason. It's not really there panned hard over to the big 10uf cap.
I should try to put a small cap in parallel with the large cap to see if the large cap is blocking some high end for some reason. That's why I was thinking ESR in the post above. But that's usually not a night and day difference as I have here.

John

I'm using plastic caps on both sides; I can see why a 10uf electro would dampen the hiss compared to a plastic cap.  So you'd want a low-pass that stays in all the time or maybe just on the high side, yeah?  My Screw Driver does a lot of low-pass filtering in several places.  That mosfet input really pumps the treble into the fuzz section.  Try a Big Muff style neg-feedback treble cap in your Fuzz Face, for example, and/or one in parallel with the 100k neg feedback resistor. 

[Ronsonic]

All the old-school pedals, and the FF is a perfect example were voiced to compensate for tone-suck. When you'd put a FF in the signal path you'd have to adjust the tone controls on the amp to offset the tone suck. So the FF was voiced to sound good on an amp that had the treble turned up and the bass turned down.  Now, when you build a full bypass version, there is no tone-suck so the pedal is too boomy and bassy.

Expect that pretty much any non-bypass design is going to need tweaked when you convert it to true bypass.

I am astounded that this seems to have never been mentioned before, but it's pretty damn obvious.

Ron

[drewl]

Here's another stupid question:
What effect does changing the value of the 22uf cap on the 1k gain pot have?
as in if you increase the value does it change the gain or tone, and vice versa?
I'm sure some of you have tried it and it's easier to ask than swap different values in/out...well not really but I'm lazy.

[Skreddy]

Here's another stupid question:
What effect does changing the value of the 22uf cap on the 1k gain pot have?
as in if you increase the value does it change the gain or tone, and vice versa?
I'm sure some of you have tried it and it's easier to ask than swap different values in/out...well not really but I'm lazy.

It's already as big as it ever needs to be.  You can use a 100uf with no difference in tone.  However, if you make it smaller, you tighten up the bass of the circuit.  Try a .1uf for mid-heavy distortion instead of woolly fuzz.

[Skreddy]

All the old-school pedals, and the FF is a perfect example were voiced to compensate for tone-suck. When you'd put a FF in the signal path you'd have to adjust the tone controls on the amp to offset the tone suck. So the FF was voiced to sound good on an amp that had the treble turned up and the bass turned down.  Now, when you build a full bypass version, there is no tone-suck so the pedal is too boomy and bassy.

Expect that pretty much any non-bypass design is going to need tweaked when you convert it to true bypass.

I am astounded that this seems to have never been mentioned before, but it's pretty damn obvious.

Ron

I don't know if this post was a joke or you were just sleepy, but you do know that the Fuzz Face has always been a true-bypass design, right?  (i.e. no tone suck)

What astounds me is why they never put a tone control on the Fuzz Face.  It's not like there wasn't room on the enclosure. 

[Mark Hammer]

I was going to make this a new thread, but figured I stick it here.

How interchangeable are the outcomes of altering the input cap vs the emitter bypass cap.  If you make the emitter bypass cap to ground smaller, the gain is applied primarily at higher frequencies.  If you make the input cap smaller, a fixed gain is applied to low-frequency input signal that starts out at a lower amplitude because of the the highpass filtering effect of that cap.

So do these two cap-related consequences essentially equal the same thing in the final analysis, or do they have only somewhat related outcomes?