HKA Design Digitizer

We love this pedal. Many moons ago Tony tried one and immediately fell for it: simple to use, surprisingly versatile and beautifully-designed.

After a run of just over 100 designer/builder Harry Axten stopped producing them, but as of November 2022 they are back in production in limited numbers. It’s not a “V2” because why change it if it’s already great? There are a couple of minor component changes (due to the ever-present supply issues that every builder faces), however nothing that alters the sound or functioning.

From HKA Design:

None of the other bitcrusher pedals around were quite what I was looking for – I wanted it to be able to get very lo-fi and distorted, but I also wanted it to be able to be very subtle and musical. The stock bitcrusher plugin in Logic Pro was a big source of inspiration to me as a particularly good implementation of this effect.

Controls:

POWER
Uses standard Boss-type power supply. Requires 9V DC @ 100mA, on a centre-negative 2.1mm plug.

AUDIO IN
Unbalanced instrument or line level input. (There is a trimmer inside the pedal that sets the pre-amp gain if adjustment is required)

AUDIO OUT
Unbalanced output.

MIX
Controls the ratio of wet to dry signal sent to the output.

RATE
Sets how often the audio input is sampled. Range is approximately 100Hz to 30kHz.

FILTER
Rolls off the treble on the wet signal. Useful for smoothing out any harsh harmonics created by the sample rate reduction.

BITS
Sets the resolution of the analogue to digital conversion.

SAMPLED DATA LEDs
Displays the upper 6 bits of the current sampled byte. Updated 200x slower than the audio sample rate. Also serves as the bypass indicator.

BYPASS
Engages or bypasses the effect. Uses relay-driven “true bypass”. To set bypass action to latching, power on pedal with BITS toggle in the up position while holding the BYPASS button. To set bypass action to momentary, power on pedal with BITS toggle in the down position while holding the BYPASS button.

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How It Works

All of the processing is done with a 8-bit AVR microcontroller. It samples the incoming signal from the preamplifier as fast and as frequently as possible, and then sends it straight back out again to the DAC, at an adjustable interval determined by the position of the RATE knob to drop the sample rate. The sampled data is 8-bit, although this can be reduced down to 6 or 4 with the BITS switch. The LEDs are updated 200x slower than the audio sampling rate. This gives them more of a blinking appearance, as at audio rate they just appear solidly lit.

The microcontroller also manages the bypass switching. As mentioned previously, the bypass switch can work either latching or momentarily. The setting is remembered and recalled at power-on.