This module has now been discontinued.
The standard VC-mixer module in a 2U wide panel.
This module can be built to a variety of options. The standard version, allows four audio or CV inputs to be mixed to give one combined output. The level for each input channel is set either by a front panel pot or a control voltage applied to the relevant CV input. When an external CV input is used, the front panel pot then acts as an attenuator to control the depth of modulation to that channel.
Since the mixer will probably used to control audio more than anything, the input CVs will affect the level in a exponential fashion. 5V will produce 0dB of gain, ie. unattenuated. 0V will effectivelly silence the channel. The sensitivity is -60mV/dB. Each channel is controlled by a dedicated VCA chip, and offers exceptional audio performance.
A peak overload LED is included, which is set to light when the mixer output levels exceed +/-10V. Also, provided is a circuit that drives another LED, or moving coil meter, which can be used to give an indication of signal magnitude.
The module is also available in a 3U 'deluxe' version. This allows access to the four internal VCAs independantly and gives you utlimate control of each channel. A separate reversible attenuator is provided for each CV input, as well as a pot to set initial gain of that channel. Inserting a jack into any one of the channel outputs removes that signal from the main mix output. Therefore, for example, you can use this module as three way VC mixer, and a high quality exponential VCA at the same time.
To make wiring easier for the 3U version,the Oakley 'Four pot' board can be used. This board houses the four CV attenuator pots, and provides four reversible attenuators for each CV input. This additional board is not required for the 2U panel option.
The 3U wide panel for the 'Quad Exponential VCA with Mixer' module.
Project Downloads
2U version User Guide
3U version User Guide
Use 'save as...' button to download and view the file. IE users need to right hand mouse click and then choose 'save as'. Links to schematics are available to purchasers of the PCB or module and will be sent via e-mail when the board(s) are shipped.
Front Panel database
A Schaeffer front panel can be made for a MOTM compatible 2U wide VC-Mixer or 3U wide Quad VCA/Mixer. The database for the each module can be found at either 2U panel or 3U panel. To read this file you will need a copy of 'Frontplatten designer' which is freely downloadable from Schaeffer-Apparatebau. The program will run in English or German, and the company representatives speak good English too.
This is the prototype VC-Mixer in the standard 2U Panel. Two of the VCA chips are yet to be socketed.
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