Quick Start Guide
904A VOLTAGE CONTROLLED LOW PASS FILTER
Legendary Analog Low Pass VCF Module for Eurorack
Controls
(1)
(2)
(3)
(4)
(5)
(6)
(1)FIXED CONTROL VOLTAGE – Also referred to as “cutoff frequency”, this knob manually determines the frequency above which frequencies are attenuated. The resulting frequency will depend on this knob’s setting as well as voltage received from the control inputs.
(2)FREQUENCY RANGE – Select one of 3 frequency bands in which the fi xed control voltage operates. Position 1 is 1 Hz to 5 kHz, position 2 is 4 Hz to 20 kHz, and position 3 is 16 Hz to 80 kHz.
(3)REGENERATION – This knob varies the amount of internal feedback, creating a resonant peak at the cutoff frequency. At higher settings this becomes self-oscillation.
(4)SIGNAL INPUT – Connect the incoming signal via 3.5 mm TS cable.
(5)SIGNAL OUTPUT – Send the processed signal to another module via 3.5 mm TS cable.
(6)CONTROL INPUTS – Connect control voltage signals from other modules to aff ect the cutoff frequency. The sum of the voltage received doubles the frequency cutoff point for each 1 V increase.
Power Connection
The 904A comes with the required power cable for connecting to a standard Eurorack power supply system. Follow these steps to connect power to the module. It is easier to make these connections before the module has been mounted into a rack case.
1.Turn the power supply or rack case power off and disconnect the power cable.
2.Insert the 16-pin connector on the power cable into the socket on the power supply or rack case. The connector has a tab that will align with the gap in the socket, so it cannot be inserted incorrectly. If the power supply does not have a keyed socket, be sure to orient pin 1 (-12 V) with the red stripe on the cable.
3.Insert the 10-pin connector into the socket on the back of the module. The connector has a tab that will align with the socket for correct orientation.
4.After both ends of the power cable have been securely attached, you may mount the module in a case and turn on the power supply.
Installation
The necessary screws are included with the module for mounting in a Eurorack case. Connect the power cable before mounting.
Depending on the rack case, there may be a series of fi xed holes spaced 2 HP apart along the length of the case, or a track that allows individual threaded plates to slide along the length
of the case. The free-moving threaded plates allow precise positioning of the module, but each plate should be positioned in the approximate relation to the mounting holes in your module before attaching the screws.
Hold the module against the Eurorack rails so that each of the mounting holes are aligned with a threaded rail or threaded plate. Attach the screws part way to start, which will allow small adjustments to the positioning while you get them all aligned. After the fi nal position has been established, tighten the screws down.
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