The Defects FX Dirty Filter is a very tweakable, limited edition resonant fuzz and filter pedal (in that order) hailing from Prague, where it is lovingly hand-built. It was made in a run of 10 pieces, combining a fuzz circuit with an active filter circuit that follows it, and both effects can be used independently1. If you are new to the effect type, see our page on filter pedals, and for the other half of this pedal, see fuzz pedals.
How the two circuits work together
The fuzz circuit sits before the active filter circuit in the signal path, so the filter shapes the fuzzed signal, but each effect has its own separate footswitch and each switches as true bypass. That means you can run the fuzz on its own, the filter on its own, or both stacked1.
Delicious Audio's Paolo De Gregorio described what the combination can do in the maker's own terms: "It allows you to set really unobvious fuzzes. Resurrection of naturaly decaying sound that you never heard before."1
Controls and external control
The pedal's filter section carries a Filter freq knob, and a resonance toggle switch gives you two resonance levels, Normal and High, for a more intensely synthy effect1.
| Control | What it does |
|---|---|
| Filter freq knob | Sets the filter's frequency; can be controlled externally via the EXP / CV input1 |
| Resonance toggle | Two levels, Normal and High, for a more intensely synthy effect1 |
| Fuzz footswitch | Activates the fuzz section; switches as true bypass1 |
| Filter footswitch | Separate footswitch for the filter effect; each switches as true bypass1 |
The EXP / CV input accepts CV control (0 to 3.0 V) or an expression pedal for external control of the Filter freq knob, which opens the pedal up to swells and sweeps you cannot manage with your foot on the box itself1. If you need a controller, see expression pedals.
Power, build and physical details
The Dirty Filter is powered by a standard center negative 9V DC adaptor only and draws 25 mA1.
The pedal runs on a 9V DC center negative adaptor only, so it will not run on a battery, and it needs a spot on a standard pedalboard supply.
The build is described as handwired and hand-drilled from standard boutique quality parts, with Alpha pots, a professionally printed faceplate and a professionally made PCB board1. It measures 12.0 x 14.5 x 5.6 cm and weighs 554 g1.
What reviewers said
Delicious Audio, which published the product page the details above come from, added the pedal to its article about the best filter pedals overall, with the verdict: "This looks and sounds like a cool creative pedal, we added it to our article about the best filter pedals."1
Videos
Pedal Experiments
Questions
Is the Defects FX Dirty Filter true bypass?
Yes. The Dirty Filter uses a true bypass switch, and each of its two effects has its own separate footswitch that also switches as true bypass. That means the fuzz section and the filter section each bypass independently, so you can run one, the other, or both without the pedal coloring your signal when it is off.
Can I use the fuzz and the filter separately?
Yes. The fuzz circuit sits before the active filter circuit in the signal path, but both effects can be used independently. Each has its own footswitch, so you can switch on the fuzz alone, the filter alone, or both together.
Can I control the Dirty Filter with an expression pedal?
Yes. The pedal has an EXP / CV input that lets you plug in an expression pedal or a CV control source running 0 to 3.0 volts for external control of the Filter freq knob.
What power supply does the Defects FX Dirty Filter need?
The Dirty Filter is powered by a standard center negative 9V DC adaptor only, and it draws 25 mA. There is no battery option mentioned, so plan your pedalboard power supply accordingly.
How many Defects FX Dirty Filter pedals were made?
The Dirty Filter was built as a limited edition of 10 pieces, hand-built in Prague.
Sources (1)
- Defects FX Dirty Filter, Delicious Audio, 2023-04-03