When I first took a look at the WMD Geiger Counter pedal I thought for sure that the WMD stood for Weapons of Mass Destruction and thought , “OK, these guys are no joke”. Come to find that WMD actually stands for William Mathewson Devices and that he is actually… definitely no joke! The company started with pedals like the Geiger Counter Digital Destruction and the Super FatMan Envelope Filter but has since moved into the world of Eurorack Modular Synth modules. Seems to be a common progression for many an eclectic tinkerer.

What is the Geiger Counter, you say? From the website it’s described as a high gain modern preamp that drives an 8 bit computer, creating sounds which range from nice (tubey overdrive, lofi aliasing, hot gated leads) to total madness (impossible amounts of gain, multiple octave foldover, harsh digital data errors, and piercing sculpted noise). The company makes it a point to stress that this is no DSP modeling pedal.


With items on hand such as a High Gain Modern Preamp, Dramatic Tone Control with Disable, Sample Rate from 260Hz to 58kHz, 1 to 8 Bit Depth with Mask mode, 252 Wave Table Modulator, CV In for Expressive Control, Hand Wired True Bypass, and the highest quality components this pedal is a highly detailed piece of sound art. Let’s dig into to some of the controls.


Gain- Low settings provide clean tones with no distortion at all, while high settings will brickwall your signal for great sustain. Use the Gain control as a coarse setting for getting the desired tone from the selected wave table.

Tone- The Geiger Counter’s tone control blends muffled low-mids with chimey and clear upper mids and highs providing a very large range of sounds in junction with the Gain. All the way down and the sound is muffled and grungy with little upper harmonic content. The middle range is smooth and full bodied. The top range cuts the lows completely for only upper harmonic content. Use the Tone to fine tune the sound of the wave table.

Tone Enable/Disable- This switch removes the tone control from the preamp circuit. The tone control sucks some volume from the gain, and this allows the pure ultra hot signal to go directly into the Wave Table. If a very clean tone is desired, set to Disable and adjust the gain to get the right amount of breakup. For most wave tables, disabling the Tone will produce completely different sounds by brickwalling to the extremes of the tables faster.

Sample Rate- Controls the length of the samples your signal is converted into. Full up and the Geiger Counter samples faster than a CD. Dial it down a little and you’ll lower the fidelity and frequency response, adding overtones and difference frequencies. Down a little produces some very nice chimey clean tones. Down more and higher notes disappear into difference frequencies, all the way down to 280Hz. The sample rate is sort of like a flange whammy.

The LED by the Sample Rate knob shows the key input and coarse/fine modes. When green, the Key input is active. When red, the sample rate is changed in smaller increments (fine mode), allowing for smoother adjustment for the high range of sample rates. The LED is yellow if the key input and fine mode are both active. Push the Wave Table knob to change the modes of the Bit Depth and Sample Rate LEDs.

Bit Depth-This controls the finer details of the signal. All up and your signal is represented by the full 8 bits. Each step down cuts the resolution in half, adding quantization error distortion, all the way down to 1 bit making a nasty square wave from a once clean tone. This produces a lo-fi gated distortion sound.

The LED by the Bit Depth knob shows the key input and post/pre wave table modes. When green, the key input is active. The Bit Depth function is available before (LED red) or after (LED off) the wave table algorythms for different sounds. Use the bit depth before wave table mode to change the response of the wave table. The LED is yellow if the key input and pre wave table modes are both active.

Bits/Mas- This switch controls how the Bit Depth knob works. In Bits mode, the Bit Depth knob reduces the resolution of the signal. In Mask mode, the signal is filtered through a number (0 to 255). This mode can be used to reduce noise and add gain. In pre wave table mode, it can turn off small ranges of the wave table, creating altered harmonic content from the tables. Adjust the knob to taste when in Mask mode.

Wave Table- This knob and display select the wave table to run your signal through. The wave table stage takes your signal and destroys it with math. This produces some incredible sounds. The wave tables are organized so that a more extreme version is typically found one up from the current one. There are 252 wave tables in all, each with different harmonic content.

The display is in HEX, displaying the numbers 0-9 and the letters A-F. Don’t be alarmed, it actually makes remembering your desired wave table easier! The wave table is remembered when the pedal is turned off.

Key/CV Input- The Key Input is a CV (control voltage) control over the Sample Rate, Bit Depth or both simultaniously. A slow LFO creates some incredible sweeping difference frequencies when modulating the sample rate, a faster LFO creates some cool tremolo sounds when modulating the bit depth. Use an expression pedal for direct control. The CV input has a 5.6 volt output on the ring of the CV jack, 0 volts on the sleeve and the CV input on the tip. Use any standard expression pedal or any 0-5 volt CV source for modulation. The 5.6 volt output will be shorted and will degrade battery life if a mono cable is used, but it will not damage the Geiger Counter.

Sample Rate Key In- In normal mode (LED not green) the knob controls the sample rate directly. Turn it green and the key input controls the Sample Rate. Turn the knob all the way up and the key input has direct control. Dial it down to introduce variations and interesting patterns in the sample rate.

Bit Depth Key In- In normal mode (LED not green) the knob controls the bit depth directly. If green, the key input controls the bit depth. With the knob all the way up, the key in will have smooth control. Dial it down to introduce graininess and patterns from the key input. Key input works with both bits and mask modes.

This pedal is extremely deep and I would recommend the company’s Geiger Counter Civilian Issue, which is a scaled down version of the Geiger Counter but with the same meat and potatoes, if you are a little intimidated by the vast feature set.

All in all I found this pedal to be unique and extremely interesting. I’m into modular synths so I found the depth of control and inclusion of Control Voltage modulation to be lovely. I am a huge fan of Bit Crushing as an effect but previously only found it to be available in software. WMD has found the prefect way to introduce it to the analog loving guitar community. I would like to see William put out more innovative pedal designs in the future. – Gus Green

Video from Pro Guitar Shop: