Behringer 904A Quick Start Guide

Quick Start Guide

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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 re ferred to as “cuto

freque ncy”, this knob manually d etermines the f requency
above whic h frequencies ar e attenuated. The r esulting
freque ncy will depend on th is knob’s setting as wel l as
voltage re ceived from the cont rol inputs.

(2) FREQUENCY RANG E – Select one of 3 fr equency bands

in which the  xed control vol tage operates. Posi tion 1 is
1 Hz to 5 kHz, pos ition 2 is 4 Hz to 20 kHz, and p osition 3 is
16 Hz to 80 kHz.

(3) REGENERATION – This knob var ies the amount of

internal f eedback, crea ting a resonant pea k at the cuto
frequ ency. At higher set tings this bec omes self-os cillation.

(4) SIGNAL INPUT – Connect t he incoming signal via 3. 5 mm

TS cable.

(5) SIGNAL OUTPUT – Send the pro cessed signal to an other

module via 3. 5 mm TS cable.

(6) CONTROL INPUTS – Connect co ntrol voltage signal s from

other mod ules to a ec t the cuto f requency. The sum of
the voltag e received doubles t he frequency c uto point
for each 1 V in crease.

Power Connection

The 904A c omes with the requi red power cable for co nnecting
to a standar d Eurorack power suppl y system. Follow the se
steps to con nect power to the mod ule. It is easier to make
these con nections bef ore the module has be en mounted into
a rack cas e.

1. Turn the power supp ly or rack case power o and
disconne ct the power cable.

2. Insert t he 16-pin connect or on the power cable int o the
socket on t he power supply or rack c ase. The connec tor has
a tab that wi ll align with the gap in t he socket, so it can not
be inser ted incorrect ly. If the power supply does n ot have
a keyed socke t, be sure to orient pin 1 (-12 V) with the re d
stripe o n the cable.

3. Inser t the 10-pin connec tor into the socke t on the back of
the modul e. The connector ha s a tab that will align wi th the
socket fo r correct ori entation.

4. After bot h ends of the power cable h ave been securely
attac hed, you may mount the mo dule in a case and tur n on
the power supp ly.

Installation

The neces sary screws ar e included with th e module for mount ing
in a Eurorack c ase. Connect the po wer cable before mou nting.

Dependin g on the rack case, the re may be a series of  xed holes
spaced 2 HP ap art along the leng th of the case, or a tr ack that
allows individual threaded plates to slide alon g the length
of the cas e. The free-movi ng threaded plate s allow precise
positio ning of the module, bu t each plate should be p ositioned in
the approx imate relation to the mo unting holes in your m odule
before a ttaching the sc rews.

Hold the mo dule against the Euro rack rails so that eac h of the
mounting h oles are aligned wi th a threaded rail o r threaded
plate. Att ach the screws par t way to start , which will allow
small adjus tments to the pos itioning while you g et them all
aligned. Af ter the  nal p osition has been es tablished, tight en the
screws d own.

Speci cations

Controls

Fixed control voltage +/-6 V, summed with

Frequency range selector

Regeneration O to full feedback

Signal Input

Type 3.5 mm jack, DC coupled

Impedance 10 kΩ, unbalanced

Maximum input level +10 dBu

Signal Output

Type 3.5 mm jack, AC coupled

Impedance 1 kΩ, unbalanced

Maximum output level +10 dBu

Output noise <-78 dBu, 22 Hz - 22 kHz

Control Inputs

Type 3 x 3.5 mm jacks, summed

Impedance 100 kΩ, unbalanced

CV range 1 V / octave,

Power

Power supply Eurorack

Current draw 65 mA (+12 V),

Physical

Dimensions 40 x 129 x 38 mm

Rack units 8 HP

Weight 0.10 kg (0.22 lbs)

CV inputs

1 = 1 Hz to 5 kHz,
24 dB per octave

2 = 4 Hz to 20 kHz,
24 dB per octave

3 = 16 Hz to 80 kHz,
24 dB per octave

12-octave range

50 mA (-12 V)

(1.6 x 5.1 x 1.5")

LEGAL DISCLAIMER

Music Tribe accepts no liability for any loss which may be su ered by any
person who relies either wholly or in part upon any description, photograph,
or statement contained herein. Technical speci cations, appearances and
other information are subject to change without notice. All trademarks are the
property of their respective owners. Midas, Klark Teknik, Lab Gruppen, Lake,
Tannoy, Turbosound, TC Electronic, TC Helicon, Behringer, Bugera, Auratone
and Coolaudio are trademarks or registered trademarks of Music Tribe
Global Brands Ltd. © Music Tribe Global Brands Ltd. 2019 All rights reserved.

LIMITED WARRANTY

For the applicable warranty terms and conditions and additional information
regarding Music Tribe’s Limited Warranty, please see complete details online
at musictribe.com/warranty.

Zhongs han Eurotec Ele ctronic s Limited

No. 10 Wanmei Road, South China Modern Chinese Medicine Park,
Nanlang Town, 528451, Zhongshan City, Guangdong Province, China