This is a bare unassembled circuit board and THAT ICs for a "Wet Dry Mix Add" Parallel Processor based on the design published in the Pro Audio Design Forum.

The KA-Electronics "Wet Dry Mix Add" board provides the active circuitry needed for parallel processing with Wet and Dry stereo inputs that sum into a final Mix output.

Two Parallel Modes

An on-board relay switches the "WDMA" to either Mix or Add mode.

Mix uses a four section stepped switch or potentiometer to provide crossfading between Wet and Dry.

Add forwards the Dry inputs to the Mix output without level adjustment allowing Wet to be mixed in at varying levels. If using only the Add mode, a two section stepped switch or potentiometer may be used.

Level Control Buffers

To prevent loading, the four Wet and Dry stepped switch commutators (or potentiometer wipers) are buffered by voltage followers prior to summation.

Gain Trim

The Mix amplifier has an optional external +/- 5.5 dB gain trim to adjust the parallel-processed output. For gain trim a two section stepped switch or potentiometer is required. An on-board jumper sets the Mix gain to unity if the external trim is not used. An external fixed resistor may be used for other gain or attenuation settings.

Two Bypass Modes

An on-board bypass relay is provided. A jumper determines which input, Wet or Dry, is used for bypass. When linked to the Dry input the bypass relay can be used for processed/unprocessed comparison. When the jumper is linked to Wet, the external device is switched from parallel to conventional in-line "serial" processing.

Balanced Inputs and Outputs

The Wet and Dry inputs are fully-balanced using THAT 1246 line receivers. THAT 1646 OutSmarts® ICs drive the Mix outputs.

Additional Applications

The Wet Dry Mix Add board has additional applications in addition to Parallel Processing:

Monitor Attenuator Buffer

Two Input Stereo Mixer

Crossfader

Buffered Potentiometer

Power Supply Requirements and Dimensions

The board requires +/-15V at approximately 100 mA including external LEDs. No relay supply is required.

The board dimensions are: 3.7" x 2.75".

Mounting holes: #4/M3 0.125" dia on a 3.4" x 2.4" grid.

The construction thread for the Wet Dry Mix Add is featured in the Pro Audio Design Forum.

The Wet Dry Mix Add is sold as either a bare PC board, a "kit" including THAT1246, NE5532 and THAT1646 ICs, or an assembled and fully-tested module.

A Mouser Electronics Project Manager bill-of-materials is available for DIY builds of the Wet Dry Mix Add.