Model 1411 Discrete Mixer

The Slightly Nasty Model 1411 Dual Discrete Mixer is a basic mixer module that provides two independent 3:1 mixers, with switchable soft-clipping overdrive distortion and both inverting and non-inverting inputs.

The circuitry in each half of the 1411 is based around a pair of discrete opamp-type circuits that operate as summing amplifiers – providing signal isolation between the inputs. Additionally, when in “Linear” mode, input C is inverted, allowing for more CV mixing and phase cancellation options.

Inputs A and B can also be fine-trimmed to have better unity gain when turned up to maximum – which is useful when mixing pitch CVs that require accurate scaling.

The “Distortion” mode engages a soft-clipping diode circuit with an asymmetric high-frequency response, to emulate the sort of distortions found in some early synthesiser mixers. This is useful for adding just a touch of saturation and overdrive to sounds like bass percussion that might otherwise struggle to be heard in a mix, as well as providing a nice aggression to detuned oscillators.

Because the Model 1411 is a true summing mixer (inputs are added together rather than averaged), the distortion may be overdriven further by bridging the inputs together, thus amplifying the input signal by a factor of three, Additionally, feeding the output back to one of the inputs creates a more aggressive disortion, going into self-oscillating feedback at higher levels. Experimenting with different modules in the feedback path opens up a whole world of interesting distortion timbres and feedback effects.

Current Documentation (Rev A for PCB v1.0) :

> Updated 30th July 2021 to add BC547 and BC557 as alternatives for now-discontinued BC550 and BC560

Model 1411 Construction Manual

Model 1411 Schematic

Model 1411 BOM