Model 25

Multi-tasking Audio Processor

The M25 is one of two Swiss Army Knife processors that, along with it's counterpart, the Model 26 Control Signal Processor, provides a bank of essential audio synthesis functions within a single module: a Manual Attenuator, a Waveshaper, a White/Pink analog Noise Source, a Dual-VC Linear VCA and a DC coupled Ring Modulator and Fuzz Distortion -- all under a single 10HP faceplate.

The functionality of the M25 is broken down into three sections:

1) Wave Attenuator / Waveshaper / Noise Generator

With it's Mode switch set to the right, the top section of the Model 25 provides an often overlooked audio synthesis function - Manual Attenuation of both audio and control signals. It's range travels from full attenuation (no signal), through unity gain to +6dB, so that signals can be amplified from their input level by a factor of 2.

With the Mode switch thrown to the left, the M25's diode-based Waveshaper is put into the signal path. The level pot at that point effects both the signal amplitude and the amount of folding. Along with the manual pot, the Waveshaper has a dedicated voltage control input.

WIth no input present in the Attenuator/Waveshaper, the output of the returns a manually-adjustable analog White Noise source. When the Mode switch is thrown to left , the White Noise is shaded Pink. There is also a dedicated unity gain noise output. .

2) Linear VCA

The center section of the M25 hosts a standard linear VCA. Unlike the M13, no filtering is applied to the signal path and both AC and DC sources may be gated. There are two control voltage inputs provided - the first will take the output from full attenuation to unity gain. The second VC input is preescaled for the velocity output of a midi to CV converter.

3) Ring Modulator

The bottom section of the M25 is a 1496-based balanced dual sideband four quadrant multiplier - a Ring Modulator. Boasting over 65dB of carrier suppression, it features a unique corss-modulation Feedback switch not found in other Ring Modulators that introduces harmonic content with minimal sidebanding.

Fuzz Distortion

By running the same signal through both the X and Y inputs of the M25 Ring Modulator and engaging the Feedback Switch, the output is fuzzed (in a very big way). Have a listen to sound sample 3 below.