Moo-Tron Auto Filter

NOTE: There are a limited numbers of kits avaialble with the required vactrols - they're now obsolete so stocks will become very difficult to source.

All the funk in the universe, compressed into a 1590BB and unleashed on your signal. Dig out any of your 70's vinyl with whakka whoop wha filtering on it (Zappa, Bootsy, Wonder, Santana....) and you can bet your bellbottoms its coming from the original box this is based on. Bass, guitar, keyboards... they all love this pedal.

Lots of controls to play with in this modernised version, including a Gain control to get your input signal just right (as auto filters like the signal just so) and a master volume to balance your level once you've messed with the gain. Volume can be set with an internal trimmer instead of a pot, but you'll have a strange control layout unless you wire up your pots instead of using vertical-pin board-mounts.

We've tried our best - really - but we've not been able to find a roll-your--own vactrol that works well with this. Most of the LDR-LED combos we've tried will produce good results across some of the settings, but nothing works across the full range of the circuit's capabilities. You really need a pair of VTL5C3 vactrols to get the best from this box. Kit is offered with or without the vactrols in case you want to try to get hold of some cheaper. We won't lie - they're becoming harder to source, especially at reasonable prices, but the results are worth it. Thonk are your best bet in the UK.

The kit is supplied with vertical-mount pots which have round shafts, so you'll need set-screw fitting knobs. Pot spacing is 20mm, so you'll need knobs smaller than that.

If you want the PCB without parts there's a link for that at the bottom of the page.

Partial kit: PCB, all board-mounted components, 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.

Enclosure (pre-drilled) is available as an option with full kits, and will not take a battery. Knobs are not included.

Inspired by: Mu-Tron Mutron III

Difficulty: Medium

PCB size: 80 x 60mm

Knobs required: 4/5

Enclosure: 1590BB

Direct-Connect compatible (4- or 6-way)

Please do not attempt this build unless you're confident in your building and troubleshooting abilities. We cannot offer any support with this kit.

Download the INSTRUCTION PDF

Product Code: Moo

Brand: Pedal Parts

Product Condition: New

Include vactrols?* Kit type* Ribbon connector?*

£48.00 inc. tax

£40.00 ex. tax

? Tax based on United Kingdom.

Updating Order Details

Please do not refresh or navigate away from the page!

Customer Reviews

12 review(s) posted (write review)

Make sure the vactrols are in correctly and this machine has sounds that are our of this world.
"I built this pedal and at first had the same issue as the others who found it disappointing. It was a really weak, and uninteresting effect that had little to no sweep and sounded more like a cocked wah than an auto filter. After reexamining the circuit board, I realized the vactrols were in upside down; the anode was in the cathode spot and the cathode spot was in the anode spot. After I flipped them, the pedal came to life and I realized how amazing this circuit truly is. So many sounds in this box, and proper, dynamic, full range sweeping. This is definitely one of fuzz dogs best boards, and in my top 3 favorites along with the ocean engine, and recurring nightmare." Twilight Zone Electronics - 01 September 2023

Makes everything better in the world
"Hard to describe the amazing shapes that come from this pedal. Its a classic and this board is perfectly designed to make your build easy. Mine was 100% first time. Got vactrols from thonk and wow. Obviously no brainer for anything funky. But even getting shoegazy with big reverb this pedal adds that sweet envelope that can also bring out your notes from a huge wall of sound. Enjoy...you will" Shlaptop - 19 October 2021

Superb kit with amazing variety of tones
"This was a very straightforward build once I'd sourced some Vactrols (from Thonk) and clarified how to install them (thank you Fuzzdog). Never having tried an original I can't comment on whether this pedal is a good clone or not but the range of available tones and effects is huge. The controls are quite interactive so you can spend a lot of time experimenting with different sounds for some whacky effects and some great funky squelch" MrGuiro - 17 May 2021

Totally worth the vactrol hunt!
"Had to import my own vactrols (went for the xvive copies for now but have a search saved for some proper ones in case it makes a difference) but it was totally worth it- I much prefer this to my old Q-Tron Plus. Like all EF effects it takes a bit of fiddling to get the sound right every time you change instruments, but once dialed in it's totally worth it. Once again a very well put-together kit with just the right amount of help in the instructions- but not too much that you don't have to put your thinking cap on to get it all right and properly fitted into the enclosure, and also learn what all the controls do to the circuit in order to get the best sounds from it(possibly the pitfall of the two negative reviewers below..?). The amount I'm learning by working on these kits is incredible! Many thanks once again!" Steve - 13 March 2021

Got da funk!
"Typically brilliant Fuzzdog kit. Used a pair of Vactrols from Thonk as were out of stock with Fuzzdog at the time." Alan Seeley - 03 March 2018

Vactrol substitutes
"A company name Macron provides Vactrol replacements, I've just seen it at Banzai!" Iznogoud - 25 February 2018

5 stars- Eventually...
"Took 3 attempts at this before I bit the bullet and shelled out on genuine NOS Vactrols. Finally the sound I was looking for. There are Chinese vactrols available which are far cheaper but just don't work properly . Honestly, just buy the legit ones and save yourself hours of ball-ache." Tom - 15 February 2018

With regard to the review below....
"We have no facility to reply to reviews, so here's a workaround. We've sold over 50 of these kits and have heard of two people having problems. The circuit and components have been identical in all cases. Go figure. As for support, we make it very clear on the site that we cannot offer build support, and it's your choice to go ahead with a purchase with that knowledge." FuzzDog - 01 November 2017

Look elsewhere
"This is a good looking kit that is easy enough to put together. The charge pump means it only needs a regular 9v supply, which is a bonus. However, the circuit just doesn t perform as it should. It does the filter thing to a degree, but the effect is weak and just doesn t work at all across a range of settings. Fuzzdog offer no support on this pedal, so buy it at your peril. I paid (on top of the already significant cost of the kit itself) to have it fixed by a professional audio electronics engineer, only to be told it would be cheaper to start again - too many circuit changes were required to make it function as it should for it to be economical. To be clear - this is due to the kit design and not my building skills - I have built a lot of pedals! Buy a Q Tron instead." Michael - 30 October 2017

disappointing
"Bought it to build it and give it to my brother as a birthday present. cannot compare with my personnal Q tron.. or with any Mu tron or other filter. don't know if I did something wrong with it. it works for sure, but cannot give any interesting sound. without any sound example on the site or any help provided, it's money i have thrown out the window. next time i'll buy the real deal, and i'll be sure to get what i want." rodolphe - 03 February 2017

Let there be funk...
"Wow. My wife bought me this kit as a Christmas present, and I'm absolutely loving it! I've built a couple of FuzzDog kits before, so knew what to expect - build was pretty straightforward, and it worked first time. Still working out all the sounds I can get out of it, but it's pretty wild (in a good way!). Shame the band went on hiatus before Christmas - I can't wait to gig with this! I replaced the LED with a blue one (it seemed fitting, somehow!) in a more sturdy chrome bezel. Now just deliberating whether to leave the enclosure as bare metal or to decorate it somehow..." Jim - 12 January 2016

Funking awesome!!!...
"Bust out the glass platforms with the goldfish swimming in the soles!... Da funk is here... Great kit, easy to build not so easy to stop playing with it... Usual fuzz dog quality... Clear concise instructions, an hour with the soldering iron and you will be funking out in every way... Shame to only give it 5 stars, should be at least ten stars!... Buy one now!..." Poopot - 02 October 2015