Fuzz Face and volume control question

[ljudsystem]

Hi guys

So, the Fuzz Face "cleans up well" when you turn the volume down on your guitar... this little "secret" has been shared about half a million times in different guitar mags and blogs over the years 

But why?

The general consensus among guitarists seems to be that this is some kind of magic germanium effect ("gemanium fuzzes clean up well and silicon doesn't") but that doesn't make any sense to me.

From what I can gather it has to do with the low input impedance of the Fuzz Face (around 5K according to Electro Smash) and the way it loads down the pickups.

Is that it? The lower the impedance the more interactive the volume control gets or is there more to it? How do you replicate this effect in another fuzz/overdrive/distortion?

[Electric Warrior]

The general consensus among guitarists seems to be that this is some kind of magic germanium effect ("gemanium fuzzes clean up well and silicon doesn't") but that doesn't make any sense to me.

Because it's not true. Silicon Fuzz Faces do clean up, but with high gain transistors they do it more gradually than with low gainers. With hfes around 200, they can still have sparkly bright clean up and the volume control is pretty much like an on/off switch

[ljudsystem]

Ok, thanks. I have some BC108/109 transistors. I Think they have a higher hfe... like 300-400 mabye?

[Electric Warrior]

These can be all over the place if you don't buy them pre-sorted for gain buckets (i.e. BC108A, B or C)
If you don't have an hfe meter, measuring Q1C in a stock circuit will give us a rough estimate. With high gain transitors it willl probably be between 1.2 and 1.3V, with lower gain ones it should be closer to 1.4V.

[ljudsystem]

Yeah, I have a Peak component tester.

So, that's the secret? low gain transistors and low input impedance?

[antonis]

So, that's the secret? low gain transistors and low input impedance?

Without "and"...

Low gain transistors provide low input impedance (h_FE + 1 times intrinsic emitter resistor for a grounded emitter configuration - ignoring input impedance due to feedback..) so any other high input impedance involved is dominated by that low impedance..

[ljudsystem]

ok, thanks. I didn't know that.