Fuzz Buffering

A Technical Discussion

The thing that many people miss when they discuss buffering a fuzz is that there are actually three components to effectively (i.e. transparently) buffering the input of classic Fuzz pedals. The "Big Three", if you'll bear with me:

1.) Placement

2.) Impedance

3.) Dynamics

Placement is tied to the magnitude of your input impedance. Placement is typically an issue because of the output impedance of the device directly feeding the fuzz. Impedance is tied to what the device "sees" before it. Dynamics is tied to the specific high and low end content of the device directly before the Fuzz.

Now I imagine some of you are asking: "Why are 1.) and 2.) different?" Let's use the Fuzz Face as our example for simplicity...

The most elegant, simple solution to all three of these issues is running it first. As a person sort of leading with his buffer design, I can still marvel at how this solution works 75% of the time. Running a fuzz first accomplishes the following:

1.) It merges Placement and Impedance issues because Placement is solved by being first in line and the Impedance of your guitar pickups is high enough not to cause a mismatch with the 0.5-1k or so input impedance of something like the Fuzz Face.

2.) It maintains Dynamics by keeping the guitar/fuzz frequency rolloff trick when you turn down.

So what the hell happens when we try to buffer a Fuzz Face? First off, if we simply introduce a high impedance buffer and nothing else, we only solve Placement issues. We solve this issue because now the input impedance is high enough at the input of the Fuzz Face that the output impedance of anything driving it is now irrelevant.

Awesome, right?

In a way, yes. But now we have uncoupled the "direct in" connection, so we've lost the reasonably high guitar pickup impedance and the volume control dependent low end rolloff that gives us that wonderful clean tone. Enter something like a Wah Friendly Buffer, the FoxRox unit in particular. A wah friendly buffer takes things a step further than just high input impedance by also addressing the Output Impedance of the buffer. Now you've solved the first two of the "Big Three". The opamp's high input impedance solves Placement issues, while the specifically tailored series resistance of the Wah Friendly Buffer solves the Impedance issue.

The last one tends to be the one people ignore completely. Dynamics is partially maintained by tailoring your buffer output impedance to something that plays nice with the input of the Fuzz Face, but without the direct connection between guitar and Fuzz Face, you lose the volume control dependent low end rolloff that naturally happens with the Fuzz Face. This is the famous "cleanup". You have to artificially add frequency shaping post-buffer to do this. When you do, the pedal will "cleanup" just like it was first in line.

So now you have a device that can be put anywhere in the chain (Placement), that does not suffer from changes to the full up Fuzz tone (Impedance) and that has cleanup anywhere in the chain as well (Dynamics). Furthermore, the buffer solves a number of other issues as well, including tonal changes from running pre-dirt modulation, wah/fuzz squealing and impedance mismatches, the negative interaction between fuzz and wireless units and also the eradication of RF Interference.