Gimp FX Ultr-Fk Fuzz

A behemoth of bass fuzz. If you want to take down the walls at a molecular level, this is the fuzz for you.

A bass fuzz at heart, this will work just as well with guitar, throwing out massive, saturated doomy sludge with abandon.

Take control of the madness with controls for:

  • INPUT - input signal level - higher = more saturation
  • MORE FK - how much more gain and volume you want when you kick in the second footswitch
  • OUTPUT - master volume
  • SLOPE - essentially your tone control, adjusting the frequency balance
  • NOTCH - cut your mids or leave them in
  • SHIFT - moves the cut-off frequency of the notch

The last three controls are very interactive. The pedal this is based on had a three-way switch for the shift control. This version can be built with a three-way toggle switch or a pot that will give you much more control.

Board-mounted pots (and switch if you're using one) make this a quick, simple build considering the amount of controls. Coupled with the seperate daughterboard for the footswitches, connected to the main circuit by a 7-way ribbon cable), this is as neat as it gets. Only six off-board wired to connect.

Please choose your knobs to suit the pot shaft you select in the options. The vertical-mount pots have round shafts, so require knobs that fit with a grub/set screw.

Partial kit: PCBs, all board-mounted components (not footswitches), pots.

Full kit: As above, plus footswitch and appropriate daughterboard/components for your selected bypass type (see Downloads section for details of those), jack sockets, DC socket, battery snap, hook-up wire, LED.

1590BB Enclosure (pre-drilled) is only available with full kits, and will not take a battery. Knobs are not included.

Builds are only available with full kits including enclosures. Please choose appropriate knobs.

Difficulty: Medium

PCB size: 80 x 40mm / 80 x 20mm

Knobs required: 5 / 6

Enclosure: 1590BB



Pedal Parts


£43.20 inc. tax

£36.00 ex. tax
? Tax based on United Kingdom.

Customer Reviews

1 review(s) posted (write review)
Beautiful noise 5 product stars
"This is truly an evil, wicked, probably sinful fuzz, especially when applied to bass guitar you can take your instrument that basically goes 'boing' and give it almost-infinite sustain, shroud it in swathes of harmonic textures, and basically make a heinous amount of beautiful noise, forever. If you only want to put a bit of mild distortion on it you can do this too. But where's the fun in that? Also works a dream on guitars and synths. It's the sort of pedal where you don't even have to play anything, you can just twiddle the knobs and let the noise roll. I love it. This wasn't my first DIY pedal, but it was my first successful one. Previously I've bought PCBs, sourced the components individually,and put the circuits together by logic, instinct, and trial and error. Unfortunately there usually proved to be more error in play than anything else, plus buying components turns out to be not very much cheaper than buying a kit. Plus you end up with multiples of things you only need one of, because that's usually how they're sold. That's alright if you're already versed in electronics and collect components to enable advanced tinkering 'til the early hours, but for complete novices like myself it just makes so much more sense in terms of time, money and general aggro to buy a kit. I've build two Pedal Parts kits now and by god they're worth the money. Tip for novices like me: Do the spadework before even thinking about plugging in the soldering iron identify your capacitors and resistors, stick them on a piece of card and write the values and build numbers above them. Then you know what you're doing when you get down into close focus on the board. There are plenty of websites that'll enable you to work out what everything is, including the downloadable Electronics Assistant. This is the best bit you learn as you go along and it gives you a foot in the door of the Great Mystery of Electronics. On the other hand if you just want to build an affordable pedal for your rig with no intention of going further, then follow Pedal Parts' instructions and you can't go too far wrong. If you do go wrong (as I did by getting three resistors muddled up) the Pedal Parts after-sales support is truly excellent he'll point you in the right direction to figure out your error and get your pedal going. He was even kind enough to give me some tips modding another pedal when I got stuck. It's all good learning surely one of the duties of any musicians is to understand at least something of how his (or her) kit works and how to maintain it. If she (or he) can then learn to build his own equipment - so much the better." Francis Blackman - 13/02/2016

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Full kits DO NOT include enclosures unless you select them in the 'Kit Type' drop-down menu.

Don't forget to download the appropriate daughterboard build document for your kit:
Standard 3PDT