Q Filter

From the original Catalog

“The Variable Q VCF (VCFQ) is an excellent general-purpose VCF offering simultaneous Low-Pass, High-Pass, Band-Pass, and Notch (Band-reject) outputs. The resonance (Q) of this filter is dynamically variable by manual or voltage control. The VCFQ has two signal inputs. One incorperates an automatic gain control to prevent the filter from overloding at high Q settings. The second input has a level control so that the percussive effects of overloading the filter can be exploited. When a pulse is applied to the Trigger input, the filter will ring, producing a damped waveform similar to that produced by striking a resonant object. The nature of this ringing is controlled by the Q and the filter frequency. Percussive effects ranging from clicks to the sound of wood blocks and bell tones can be produced and controlled. This ringing effect can be used in conjuction with signals applied to either of the audio inputs to achieve highly controlled complex tonal qualities.
In addition to the three VCF's, the EXTENDED RANGE VCF (VCFX) which is identical to the VCFQ except it features a second sub-audio range. This low--frequency range allows use as a control voltage processor . A fast envelope or trigger applied to the filter in
the low range at high Q settings will cause low-frequency ringing, generating complex envelopes and damped vibrato effects . The VCFX can be patch programmed to oscillate by patching the band-pass output to the manual input . The outputs will be in quadrature relationships (90
degrees out of phase) . ”

LGE112 Main board pcb’s include a set of LGE108 Gain Cells that have all the SMD parts pre-assembled. You will still need to install 100K trim pot, and headers (and calibrate).
LGE108 Gain cells can be purchased on their own as well.

Build Info: (Coming Soon!)
LGE112 Main PCB Bill of Materials
LGE112 Main PCB Schematic
LGE112 Main PCB Designators
LGE112 MAIN PCB Bottom Values
LGE112C I/O PCB Bill of Materials

LGE112C I/O PCB Schematic (wiring diagram)
LGE112C I/O PCB Designators

LGE108 Gain Cell Schematic
LGE108 Gain Cell PCB Designators
LGE108 Gain Cell Testing/Calibration circuit
LGE108 Gain Cell Requires 100K Trim Pot to be installed prior to installing onto pcb.

Mechanical Parts BOM generally required for building Low-Gain Electronics Modules

** 4U Modular is a term used for the format most commonly known as “Serge Format” or “Loudest Warning Format”. Out of respect for the ever growing format, 4U Modular is the easiest way to refer to it. More Specifically it refers to the panel height and mounting hole style. 4U Modular will patch up just fine with other 4U "Serge" formats such as "Random Source", but it will not mount in RS boats or Buchla Boats (or power off Buchla power for that matter). An info page about this will be added to the website soon to make this a lot more easy to understand.

Assembled Modules are built to order, please be patient when ordering. Use the contact page if you have any questions or requirements!