Quad VC Resonant Equalizer


4-band voltage controlled parametric equalizer.

The device has four identical bands with BP filters. Also first band is switchable to LP mode and fourth band to HP to make low and high shelves. Also each band is switchable to boost or cut modes.

Every parameter has voltage control, also master CV ins for all bands.

Individual INs and OUTs for each band. Out of previous band is normalled to IN of next band via jack's switchd pin.

Controls are:

FREQUENCY is peak frequency of a band. Range is 10 octaves. V/oct responce and initial frequency are trimmable with trimpots. CV range is 0...10V.

BANDWIDTH range is from 0.8 semitone to 2 octaves at 3dB point. CV range is -5....5V.

LEVEL range is bipolar -+16dB. CV range is -5...5V. Positive voslage boosts, negative cuts.

LM4040 precise voltage source for frequency offset voltages.

Temperature compensation.

Resonance switches turned the device in selfoscillation. It is for v/oct trimming. And possible quad sine VCO.

Filters are based on hi-end quality THAT2180 chips. VCA for resonance gain (level control) is discrete.

Chips used:

8 x THAT2180
2 x THAT300 (BCM847BS possible)
3 x TL074 (for CV)
12 x dual opamps for audio. I will use OPA2604 but TL072 possible.


  • 193 mA +12V
  • 193 mA -12V
  • 0 mA 5V
  • 33 mm deep
  • Ø 5.00 (3 Votes) Average Rating

Available as an assembled Module and as a DIY project.

This Module is currently available.

$680 Price in € submitted Jul 17th 2015, 06:16 by Endorfinity | last Change Oct 20th 2016, 11:40 by L-1

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