The Multi-Mode Ladder (MML) Filter is a twist on the classic transistor ladder low pass filter by Dr. Robert A. Moog. This filter updates the classic 4-pole ladder design to provide Band Pass and High Pass filter responses as well as the traditional Low Pass filter, this module also adds CV control over the resonance as well as two frequency CV inputs.
The circuit features a fully discreet transistor design with an op-amp buffered output, this allows soft saturation of the input signal to get the classic overdriven tones of the ladder filter. A bass compensation circuit has been included to retain the bass response in Low Pass mode when the resonance is increased. The bass compensation also helps to improve the response of the High Pass filter. The bass compensation can be removed if the user wishes to have a more classic response (see mods section in build doc).
This is a partial kit only, including:
- 1x Multimode Ladder Eurorack Aluminium Frontpanel (6HP)
- 1x Multimode Ladder PCB Set
- 1x 1K Akaneohm Tempco Resistor
- 1x 2N3904 Matched Pair Transistors
- 6 x BC550 Matched Pair Transistors
- 1 x PIC Programmed Firmware chip
- 1 x TL2201 Momentary Push switch with red cap
- 2 x 5mm Light Pipe Lens and Retainers
- 3 x 3mm Light Pipe Lens and Retainers
- Low Pass, Band Pass and High Pass modes.
- CV controlled resonance.
- Added low frequency compensation.
- Soft saturation of input.
- 2 x frequency CV inputs.
- Width: 6HP
- Depth: 51mm
- Power: +12V = 50mA, -12V = 39mA