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Isn'tses FORT PROCESSOR - noise synth/effect/pcb-art circuit
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Isn'tses FORT PROCESSOR - noise synth/effect/pcb-art circuit
NEWS: workshop in London coming up on there 1st of June!
Event page:


This is something we've been working on for a while and was first released for Fort Process festival 2018, now we have a 2nd revision of the board and it's on sale at Thonk so about time we post about it here smile

The Fort Processor is an experimental noise synthesiser and audio effect circuit designed by UK harsh fun noise duo ISN’TSES (Tim Drage & Lisa McKendrick) for Fort Process sound art festival 2018. This event takes place in the tunnels and bunkers of Newhaven Fort on the Sussex coast, and the electronics and artwork of the synth are based on the layout of the site, with inspiration from the surrounding landscape and ocean.

Demo video:

The synth is controlled by light, touch pads, 3 knobs, and a trimmer. Audio is created and manipulated by four sections which have been combined using a circuit-bent approach:

1. The audio input, (3.5mm) used to connect devices such as a radio, walkman, phone, tablet, mp3, instrument etc. This signal is distorted using high gain then run through a frequency divider to add two noisy sub-octaves. When no input jack is connected, the circuit feeds back and self-oscillates.

2. Squarewave oscillators pitch-controlled by a Light Dependent Resistor located at the top right of the PCB. This LDR can be played by moving lights near it or by blocking the light. The resulting sound can be further modulated by the touch pads which are the metallic drawings across the middle of the circuit board. Touch two or more of these at once to alter the sound. This can be understood as a live circuit-bending effect.

3. A variable-speed chopper, controlled by the 2nd knob. This rapidly slices between the distorted input/feedback signal and the light-controlled squarewaves. Turning the knob changes the speed, creating various ring-modulation, tremolo and cut-up effects.

4. A bass oscillator/filter/beat/drone generator, mutated from the classic ‘Twin-T’ analog kick drum circuit. This is triggered and influenced by the audio input and is controlled by the 1st and 3rd knob in conjunction with the trimmer pot. Knob 1 controls the decay envelope; turned anticlockwise this produces more percussive sounds, while turning it clockwise makes bass drones. When turned fully-clockwise it gets quiet to allow the other noises to cut through. The 3rd knob and the trimmer pot interact with each other to control the pitch of this section. The trimmer can be gently turned with a small screwdriver and can be viewed as a tuner to achieve either a resonant drum-like sound, or a more continuous bass tone. The trimmer should be tweaked before playing according to each users personal preferences. Expect random and unpredictable results from this section according to how the rest of the sections are influencing it.

The Fort Processor is powered from a 9v DC, centre-negative power supply, ie a BOSS-style guitar pedal PSU. Other polarities or voltages will almost certainly damage/destroy the circuit, requiring at least the ICs to be replaced, so be careful! It is possible to wire up a 9v battery too, contact us for info on this.

The fort processor is available as a full DIY kit, as a bare PCB which you can build using your own components or display as an art object, and occasionally as a complete built synth:

Option 1
Fort Processor full kit
Order from Thonk​

The black version is now available as a kit from synth DIY shop Thonk - order now at

Option 2
Fort Processor PCB
£35 + £1.50 postage

There are now two versions of the PCB, the original green one and a slightly revised black one. The building of the synth requires intermediate/advanced ability in soldering and knowledge of electronics, and this is the PCB only - you will need to source your own components. Please be aware that if you are building your own that we are not responsible for any errors made during the build process. The black version is slightly easier to build, the green version is slightly more open for experimentation/modification. See the build instruction documents on this page for details and BOM:

Option 3 (SOLD OUT)
Fort Processor fully built

Completed version of the circuit. Not currently available, we may make more in future.

Ordering the PCB-only option:
Please include a message with your payment detailing which option you are ordering, your name and address. You will receive an email from us which confirms receipt of payment. If you wish to order more than 1 PCB we can combine postage, let us know first. Please send payment to: - Alternatively you may purchase via our merch section on Bandcamp:

We will also consider possible trades of a PCB for other interesting diy synth/eurorack/noise stuff, let me know any offers.

There's more info about the process of designing this circuit at:

Let me know any questions smile More demos etc soon.
We will be demoing the Fort Processor at the next CV Freqs - - and bringing some PCBs with us, if anyone wants to get hold of one.
Anyone in or near Brighton (easy day trip from London) can come and build one of these at our workshop at Thonk on the 23rd: -23rd-2019/
the bad producer
Love the design! Might have to get one as I played at pin 4 of the 4040 last year hihi
Thanks smile

Yeah was extremely surreal designing this thing then going to the Fort for the first time and wandering around inside our own circuit grin
We are doing another workshop, this time in London at IKLECTIC (right near Waterloo station) on the 1st June. The workshop runs from 11am for about 3 hours, and is suitable for complete beginners to soldering as well as more experienced synth builders/circuitbenders.

Event page:
Tickets £65 from (same price as buying the kit on it's own plus you get our help to build it! so it's a bargain smile )
Promo video for the workshop:

All tools and materials will be provided but if you feel like bringing your own and/or any bits for modifications then feel free, and/or bring something to play thru the circuit (eg walkman, radio, other small synths). There will be a short jam afterward where everyone can try out their Fort Processor smile
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