Electro-Harmonix Mainframe Bit Crusher Guitar Effects Pedal for 48kHz to 110Hz Sample Rate Reduction

Buzz, beep and bloop. Get high on the lo-fi sounds of ‘old-school’ games, toys and terminals. The Electro Harmonix Mainframe Bit Crusher Guitar Effects Pedal provides sample rate reduction ranging from 48 kHz to 110 Hz. A little background, the sample rate is the number of times per second that a sample or snapshot of an analog signal is taken. For example, CDs had a sample rate of 44.1 kHz which means that the original analog signal is sampled 44,100 times per second. The sample rate defines the frequency range that can be reproduced while maintaining good fidelity. When the sample rate is reduced the quality of the audio is degraded and aliasing occurs. Aliasing means audible artifacts created when higher frequencies are sampled at an inadequate rate and the result is distortion. The Mainframe’s sample rate range is wide enough to take you from sounds that are quite pristine to sounds that are unrecognizable when compared to the input signal. It also provides bit crushing ranging from 24-bit to 1-bit. Bit crushing is bit depth reduction. Back to the CD example, CDs used a 16-bit bit depth meaning that each of its samples was represented by 16-bits of information. Higher bit depths can accurately represent a greater dynamic range while bit crushing increases the number of sampling errors and creatively degrades the sound to bring us back to those nasty ‘old school’ sounds loved by all. The Mainframe’s selectable High or Low or Band-Pass filter lets the user shape the artifacts of the bit crushing and sample rate. Another very cool feature is its Sample Rate Tuning Mode where the pedal analyzes your input signal in real-time and sets the sample rate to match the pitch of your signal, or a set interval above your signal. This allows you to set the sample rate to match the key of a song, or it will continually adjust the sample rate based on what you play.

The VOL knob sets the master output level of the Mainframe while the BLEND knob blends between the dry guitar signal and the effect signal. As the knob is turned clockwise, the output ranges from completely dry guitar to a fully effected signal with the filter applied. The BIT DEPTH knob is turned clockwise, the bit depth of the signal is reduced, producing a distorted, noisy tone. When the SAMPLE RATE knob is turned clockwise, the sample rate of the signal is reduced, producing a ringing or glitchy tone. The FILTER HPF, BPF, LPF switch is a toggle switch that controls the direction of the Mainframe’s filter. The FILTER FREQ knob controls the frequency of the Mainframe’s filter. As the knob is turned up, the frequency increases. The frequencies cut or passed by the filter vary by the filter type. The FILTER PEAK knob controls the resonance of the Mainframe’s filter. Turning this knob clockwise increases the resonance, producing a sharper, more cutting tone. The EXP or PRESET Button and Green LED button turns expression mode or a saved preset on and off. When the Green LED is lit, expression control is enabled, or the preset is enabled. The INPUT Jack is an ¼-inch phone jack for audio input of the Mainframe. The OUTPUT Jack is a ¼-inch phone jack is the main audio output of the Mainframe. EXP Jack is for connecting an expression pedal or control voltage jack to allow for external control over every knob on the Mainframe.