Vacuum Tube Fuzz?

[ManuVel]

So I'm in the process of building a tube amp. Still in the very early stages (haven't really started designing it yet).
Anyways I thought it would be a really cool idea to have a built in fuzz in it.

I tried googling but I couldn't really find any examples, has anyone here built any tube fuzzes? How did it work out? If not, know any one out there who has?

[vigilante397]

#beginOpinion;

I've done tube overdrive and tube distortion, but never tube fuzz. I played with tweaking the gain on the distortion and got what could be described as fuzz, but it wasn't as pleasant sounding as any of the Germanium fuzzes I've played. So if you wanted fuzz built into an amp you would probably get a better sound out of a Germanium fuzz section.

#endOpinion;

[digi2t]

Kustom amps had a great sounding fuzz in them. Jimi isolated it into a pedal called the Suzy Q.

[merlinb]

A couple of antiparallel tube diodes (e.g. 6AL5, EB91...), in series with a pot, connected between signal and ground, can work quite well.

[teemuk]

There's one in Laney Klipp -series amps. It's a differential gain stage, which when overdriven clips more softly than a generic triode gain stage. The "magic" to get the thing to "fuzz" is in driving that overdriven stage with wide bandwidth signal.

...But, IMO, it doesn't sound like anything a $1 transistor circuit couldn't do better.

[Bill Mountain]

Tube fuzzes never sound as awesome as one would hope.  I would suggest switchable clipping diodes after one of the gain stages to get some fuzz.  LED's work great for this.

Here was my attempt:

http://www.diystompboxes.com/smfforum/index.php?topic=821.0;prev_next=next

[petemoore]

  There is a seriesed tube stage distortion effect I 'would buy that incorporates stepped B+'s [working toward the input the supply voltage drops allow the early stages less headroom/more chance to clip than the latter ones]. The dual rectifier of course does have the output stage as part of the design, which contributes a good lot to the overall distortion/sound, but only when speakers [transducers produce and also influence tone] caused to load it. If I knew that would be able to consistantly produce the must have distortion, I'd buy it.
  A BSIAB or other Runoff Groove Jfet analog to a tube distorter [preamp] will probably get closer than an extensive and fierce effort with preamp tubes, all at greatly reduced risk.
  It's most likely less expensive to buy and in turn is sellable to simply buy and try out a DR distortion first, especially when considering cloning a very difficult tube amp build.
  Anything less seems to result in the belief that diodes and small signal clipping devices can be greatly satisfying except when something like a DR causes intractable cravings that only something like a DR can satisfy.
  Unless it is known exactly what reasons that tubes must be used, and exactly how to implement them to perform those specific tasks etc. it is worth  considering to have SS clipping as your friend, tube distortions builds can present a risk of great injury, large squeals and expensive frustrations.

[liquids]

It should be quite doable, but take a fair amount of tweaking.

Lots of "fuzz" sounds are purely tube based.  Some of Neil youngs tones and Bjddy guys tones on "Sweet Tea" come to mind.  Cranked tubes with blocking distortion, walloping low end and assymetrical,clipping, etc.  Even Brian mays AC30 sounds a LITTLE bit fuzzy, to me....

Try 3 or 4 stages, use big caps on the cathodes so the bass is farty, misbias a stage or two (have to know how to center bias first so as to misbias but not entirely enter cutoff),  big caps across the plate resistors or from plate to grid, maybe some large negative feedback resistors from plate to grid....

Id just as soon use low voltage components, including op amps (i like the op amp big muff myself), but hey, if you want to try it, lots can be done with just two 12ax7s. 

Since your going for fuzz, lower in the B+ voltage range will generally be less high fi and the clipping will be fuzzier as it is.  If you have a high preamp B+, just use some serious filtering with a big resistor and cap to lower the tube fuzz triodes effective B+ voltage, etc. 

Or build a fender champ with a tweed or no tone stack, misbias the 6V6, make the OT see a 4 ohm resistor load with sufficient wattage, and a big volume pot in parallel to use the amps sound as a preamp. Those things are fuzzy...see the herzog for precisely that idea, only they probably werent thinking fuzz...just keep the bass up and the treble down and you got tube preamp,and power amp fuzz, and it doubles as a space heater...