Motivation
This is my adaption of the Elektor Formant RFM module as described in Elektor Formant book 2 pg28ff. This is a quad version as used in the Trautonium. The first input is normalled to the following for easier patching. Each filter has its own in- and output. The outputs are summed together to the sum output as well. Each is a state variable filter with variable volume, Q (resonance) and frequency. It is thought to emphasize a certain frequency range. This can be used to reproduce the resonances of acoustic instruments. With the given values the frequency range is 50..2300Hz, Q 0.8..23,4, vol. 0..1. You can adapt the frequency range to your needs. The description can be found in the original article.
Specs and features
- Quad band pass with variable center frequency and Q
- Normalled first input
- Summed and single output
- Runs on +/-12V and +/-15V
- Power consumption below 55mA each rail
Implementation
Schematic
Quad Bandpass, Parametric Equalizer schematic
Description:
This is basically a SVF. Please refer to the original article(Elektor Formant book2 pg 28ff) and other implementations on the web.
Calibration
- None
Building hints
- You can adapt the frequency range to your needs. The description can be found in the original article.
Special parts
- None
Download
Quad Bandpass, Parametric Equalizer, Resonating Filter control board documentation downloadQuad Bandpass, Parametric Equalizer, Resonating Filter control board Gerber files download
Quad Bandpass, Parametric Equalizer, Resonating Filter *.fpd file download
Quad Bandpass, Parametric Equalizer, Resonating Filter: Front view
Quad Bandpass, Parametric Equalizer, Resonating Filter: Populated PCB top
Quad Bandpass, Parametric Equalizer, Resonating Filter: Populated PCB back
Quad Bandpass, Parametric Equalizer, Resonating Filter: Back view
Quad Bandpass, Parametric Equalizer, Resonating Filter: Half front view
