Vendor: WMD


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OSD, aka OR SUM DIF, is 3 independent blocks of useful utility in 4HP. 

OSD is centered around combining voltage in useful ways. Audio, V/Oct, and control voltage are at home in this utility. OSD offers a fully DC coupled signal path with precision components to make this happen.  High quality, configurability, and compact size ensure OSD will always find it's way into your patch.

- Combine v/Oct sequences with precision summing, or enable the the precision OR circuit for completely different results. 

- Mix two envelopes or an envelope and lfo using sum to create large accented voltages or combine with OR to keep the output  in the original range.

- Crossfade between audio or control voltage using the potentiometer in block one. Setting DIF will invert the signal at the B jack.

What is OR, SUM, and DIF?

OR - Input voltages are compared and the higher of the two is passed to the output. 

For example if A = 4V and B = 8V, the output will be 8V.

SUM - Input voltages are added together to create the output voltage. 

For example if A= 3V and B=4V, the output will be 7V.  This clips at -10V and 10V.

DIF - B voltage source is subtracted from the A voltage, producing an output of the difference between the two.

For example if A= 3V and B = 5V, the output will be 2V.

Controls / Configuration

Block 1 - Sum, OR, or Difference of two inputs and effect the mix of the A input to the B input with the Knob.  The third input ORs with the result of the A/B inputs. Not a precision channel.

Block 2Sum, OR, or Difference of two inputs with high precision.  The third input ORs with the result of the A/B inputs.

Block 3 - 3 input OR with high precision.  Mix gates or CV from three sources for some wild results.


  • Analog Summing / Difference / Maximum
  • Ch1: Crossfader for dialing and performance
  • Ch 2,3: Extremely Precise = 1V/Oct capable
  • Size: 4hp
  • Depth: 40mm(with cables)
  • Power: 50mA +12V, 50mA -12V
  • All Inputs: >=100k ohm impedance .1% Resistors
  • All Outputs: 470 ohm impedance impedance compensated for precision.
  • 20Vpp range
Regulatory & Warranty

RoHS, CE, & WEEE Compliant

Manufactured with Lead Free Processes

WMD is committed to reducing excess and single use plastics in its products and packaging.

WMD warranties our products for 12 months from purchase date. Please contact us if you have issues.