Another mod for a FuzzFace (timbre concerned)

[jrc4558]

Fuzz face...
I probably built a 100 of them. Selling 'em, fixing 'em, perfboarding, modifying, you name it. Still there's always a feeling that it could've sounded better. Why? Stock capacitor values provide the gain levels that FF is loved for, however especially with Ge transistors it is very heavy on the low end. Some people like it, some people don't (like me). What is a solution?
We can go different ways here, but the easiest one would be to turn the output cap&volume control into a more definite high-pass filter. It is a HP filter after all, a cap followed by a resistor to ground. Stock values are 0.1mF(generally accepted as stock) and 500k potentiometer.
What we do is we take a 0.047 cap and use a 10k pot. this forms an CR network with a corner frequency of 338.8Hz. Everything below this point will get an attenuation of 6dB per octave. Thus we have strong mids(read Punch), clear highs and tight lows.

Just an idea. I'm pretty sure most people here tried it already, but there may be some that yet didn't. Decided to share.
Happy builds to all.

[Kleber AG]

Hello,

I may had missed some, but have you tried that? :lol:
If so how does that sounded, cool?

What about cuting the lows at the input instead of the output? As Joe Gagan does with a 100K paraleling a 0.0047 cap with a 10uf cap in the pot arrangement?

I wonder how does your sugestion would sound, as I only had tried to cut lows at the input so far...

Regards
Kleber AG

[gez]

Another (perhaps simpler?) approach is to make Q2's emitter bypass cap smaller.  This would feedback some of the lows at high gain and clean up the bass.

[jrc4558]

The thing with hte bypass cap is that unfortunately it ALSO controls the gain of the cirquit. If you have a super hot FF, you can decrease that to 4.7mF. But you will notice the difference not only in the timbre but in the gains of distortion too. The same thing applies to the input cap. with small one there FF sounds like a mosquito attack. Not really like a fuzz.
all of the the above -> IMHO

Hence the HP attempt at the output.

[RedHouse]

Yes I've tried it, and it works great.

I use a 50k Pot and .047 for Ge FF (.068 for Si FF) and I've also changed my opinion on the 2.2uF input cap, I now use an .068 mylar.

Sounds much better (IMHO) less dark and flabby specially when  amplified through the Marshall which is another interesting note, the sound of these boxes seems different when played through low volume practice amps or high volume gig'ing amps. Just when you seem to work out the "right" tone combo at the workbench, then you try it out in a live band volume setting through a 50w or 100w amp and it sounds a bit different.

On the other hand, it's hard to beat the original 2.2uF/.1uF/500k combo for the old Black Sabbath "Paraniod" and "Iron Man" sound though if that's what you're after.

[Kleber AG]

pppppp

I use a 50k Pot and .047 for Ge FF (.068 for Si FF) and I've also changed my opinion on the 2.2uF input cap, I now use an .068 mylar.

:? Sorry, how is that configured? You mean, .047 for output cap and a 50K vol pot?
:roll:

Thanks
Kleber AG

[phillip]

I like to use Eric Johnson's approach and replace the 500KA volume pot with a 100KA, which passes more highs.

Phillip

[jrc4558]

to phillip.
still with 100k the corner freq is below the low E of a bass guitar. which is an octave lower of our low E.

[bwanasonic]

Stock values are 0.1mF(generally accepted as stock) and 500k potentiometer.

From what I have read, 0.01mf was stock on many a FF. Fuzz Central shows a 0.01mf in it's pictures of an original Ge FF. This has come up here before, and as a result I have a 0.01mf instead of a .1mf in my Ge FF. Not sure what the numbers for corner frequency with 500k work out to, but it fit my setup well.  

Kerry M

[phillip]

Yep, the 0.01uF was the most common output capacitor value in the Fuzz Face.  I've built one with a 0.1uF before (when I was just starting out years ago) and it was way too muddy sounding.  I've heard of some Fuzz Faces (and ToneBenders) coming with 0.047uF output caps, too, but I haven't seen any with a 0.1uF factory-installed.

There seems to be quite a bit of variation in the capacitor values in "original" Fuzz Faces and related circuits.  For example, I was told about one that had a 1.5uF capacitor as it's input capacitor, and another that had a 15uF capacitor as the bypass cap on the Fuzz control.  I guess whatever they could get that was cheapest and still close to the intended value, eh?

I personally like the 0.01uF

Phillip

[RedHouse]

Wow, having just read Philip's post it inspired me to dig out some old pictures I have of some actual '67 and '68 FuzzFace's innards, low-and-behold when I zoomed-in for a look they are indeed .01 film caps on the output.
(I never noticed that before)

Funny how I got complacent through the internet, sort of a "values by comittee" mentality I guess, as I'd seen so many schem's with .1 used so often I actually believed that was the correct value.
(stupid me, I didn't even check my pictures)

[brett]

Hi.  0.01uF output cap and a 500k output pot still has a super-low cutoff freq (32Hz). (ie 10 times lower than the 330Hz CN is proposing).

I've used a .01uF cap and 100k pot, which cut out bass undertones and cleaned up somewhat. (cutoff = 160 Hz or somewhere around the bottom E)

Sometimes, though, I really dig that loose bass of a fuzzface or a Miss Piggy.  Cheers