Man, I love the sound of a good fuzz face... there is nothing quite like it.  I love it's huge tone that rips through the mix and also it's elegant rhythm tone that shines through when you roll back the guitar's volume to clean up the distortion just right.

As soon as you hear Germanium transistors and the original circuit plugged into a good tube amp you know that what you are experiencing is perhaps the sweetest sounding distortion ever.

Even with all of that great tone that we've had with throughout the years there are many factors that can make a good fuzz face sound bad. There are also solutions for most of the common problems that come with the circuit. Some are real solutions and others are just ways to work around the issues.

The ultimate solution is of course to use a guitar with a low output (like a strat) into the fuzz face and plug the fuzz face into the amp and do all of this in a room that is cold from a good air conditioner. If you want to put other effects in the chain then be sure that they are all true bypass. That is the ultimate solution. The following tips are just ways that I know of for getting as close as to this as I can while still using multiple types of guitars and other effects in the chain.

Input Volume - One problem that you find with the original two knob circuit is that if the input signal is too hot you lose much of the control that the guitar volume gives you and the character of the fuzz becomes more harsh and brittle sounding. The solution is the input gain pot that you find on most boutique clones. Some guys put a trim pot on the inside of the box and others leave the control on the outside. I personally prefer having a control that I can adjust with out opening the box up even if I keep it turned all the way up almost all of the time. I play my same old strat at nearly every gig (don't tell the parker fly) so I don't turn down the input gain on my FF clones very often.

Heat Sensitivity - A characteristic of most Germanium transistors is that they are sensitive to temperature changes. The idea is that for the genuine fuzz face tone you want to have roughly -4.5V at the collector of the second transistor, but as temperature goes up or down this fluctuates. On a two knob fuzz face the only way to change the bias is to physically exchange the resistor that connects to the collector of Q2 to another value which brings the bias point back to -4.5 or so, which isn't a real solution because you never know how hot or cold the next stage you play on will be.

The common work around is to add a bias control to the circuit. You see this feature on many boutique fuzz face clones in some form or fashion. One way is to use a knob that controls how much voltage the entire circuit receives by adding resistance to the -9v source which can bring the voltage at Q2's collector back near -4.5 in most situations. Another approach can be found in the Analog Man sunface where the sun dial controls how much voltage the collector of the second transistor receives. Both ways work to some extent, and I'm sure there are other ways. I like the second approach because I feel like it has less effect on the overall tone of the circuit since it only adds resistance before Q2's collector which is how the bias is set in the first place. 

Some transistors in some situations just plain wont be biased to the -4.5V area... usually they start dropping down below -4 volts and you end up with a sputtery fuzz face for the rest of the night unless your clone has an internal trimmer to set the resistance at the collector of Q2.Then you can open it up and adjust the trimmer while using a multimeter to check the voltage... You may have seen me at the back of the bar with my fuzz faces open... this is what I'm doing. I suppose another option would be to stick the FF in a refrigerator for a little while.

I recently looked at a design that used an opamp to regulate the voltage to Q2. I have not tried this yet but it may be the end all be all fix. Of course I'll put up a page about it when I know more.

Signal Buffers Before The Fuzz - With a buffer before the fuzz face you will most likely end up with an input impedance that is too high and also the fuzz face will no longer be able to interact with the guitar pickups. If the FF doesn't load the pickups it loses it's response to your picking and volume control which causes an unnaturally harsh tone. The easiest work around for this one is to have real true bypass switching on everything. I built a bypass loop for my Boss TU-2 because of this.

Another way the problem with a buffer in your chain before the fuzz face can be solved is to use a box that has a passive guitar circuit with a transformer instead of a pickup... I've seen it called a pickup simulator and also an anti-buffer. This work around is great when you're just going for that searing lead tone, but when it comes to cleaning up the sound with the volume knob it's a no go because you have to adjust the volume knob on the pickup simulator instead of your guitar. I'm toying with the idea of building one of these in a volume pedal so that you could get that nice clean up with a foot rocker, but I haven't tried it yet.

With my wireless system the pickup simulator is definitely the only thing I've tried that made my fuzz face sound anything like it's supposed to.

Signal Buffers After The Fuzz - With most buffered effects and buffered bypass systems (like boss pedals) after the fuzz face you end up with an impedance mismatch or the buffer takes away the high end rolloff that gives the fuzz face it's sound so it end's up too bright and heavy in the high frequencies. As far as I know the only way around this is to either use all true bypass effects or to match the buffer's input impedance to the FF's output.

What Next?

Hopefully the voltage compensation circuit will fix the temperature issues and also, it is possible to buffer the output so that the FF will play nice with other effects.  Maybe some company will come out with a digital effect that truly gets the sound... this hasn't happened yet. 

All I know for sure is that I've never played through a distortion that even begins to compare to the beautiful tone of a properly biased fuzz face with Germanium transistors. I'm picky and *biased*!!

ps. FX Gurus, email me if you see anything that needs correction. I write about FX to the best of my knowledge but I'm always learning something new.

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