Behringer 904A Voltage Controlled Pass Quick Start Guide

Behringer 904A Voltage Controlled Pass manual cover

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Year 2021

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Behringer 904A Voltage Controlled Pass Specification

The Behringer 904A Voltage Controlled Low Pass Filter module is a versatile component designed for modular synthesis systems, particularly compatible with the Eurorack format. This module emulates the classic sound of the Moog modular systems, providing a rich, warm filter characteristic that is highly sought after by synthesists. It features a cutoff frequency range adjustable from 10 Hz to 10 kHz, allowing precise control over the frequency spectrum. The module includes a resonance control, which can be adjusted to emphasize the cutoff frequency, creating the potential for self-oscillation and adding harmonic content to the signal.

The 904A is equipped with multiple control voltage inputs, enabling modulation of the cutoff frequency from external sources such as LFOs, envelope generators, or sequencers. These inputs support a wide range of modulation depths, enhancing the expressive capabilities of the module. Additionally, the module offers both audio inputs and outputs, facilitating seamless integration with other modular components. The audio signal path is designed to maintain clarity and fidelity, ensuring the processed output retains its sonic integrity.

Housed in a sturdy, compact form factor, the Behringer 904A is built to withstand the rigors of continuous use in both studio and live performance settings. It requires a standard Eurorack power supply and occupies a modest amount of rack space, making it an ideal choice for both large and small modular setups. With its classic design and modern reliability, the Behringer 904A Voltage Controlled Low Pass Filter is a valuable tool for musicians and sound designers looking to explore the depths of subtractive synthesis.

Behringer 904A Voltage Controlled Pass F.A.Q.

How can I integrate the Behringer 904A into my existing modular synthesizer setup?

To integrate the Behringer 904A, connect its input to a sound source module and its output to an amplifier or another module in your signal chain. Make sure to adjust the frequency and resonance controls to shape the sound as desired.

What is the recommended power supply requirement for the Behringer 904A?

The Behringer 904A requires a standard Eurorack power supply with +/-12V. Ensure your power supply can deliver sufficient current, typically around 50mA for each voltage rail.

How do I troubleshoot if there is no sound coming from the 904A output?

First, check all cable connections to ensure they are secure. Verify that the input signal is present and not muted. Adjust the frequency and resonance knobs to ensure they are not set to extreme values that could attenuate the sound.

What maintenance is needed to keep the Behringer 904A in optimal condition?

Regularly clean the module with a dry cloth to remove dust. Periodically check power connections and patch cables for wear. Store in a dry environment to prevent moisture damage.

Can the Behringer 904A be used for both low-pass and high-pass filtering?

The Behringer 904A is primarily designed as a low-pass filter. It does not natively support high-pass filtering. Consider using additional modules if high-pass filtering is required.

How can I achieve self-oscillation with the 904A filter?

To achieve self-oscillation, increase the resonance to its maximum setting. The filter will begin to oscillate and can be used as a sound source. Adjust the frequency knob to change the pitch.

Is it possible to control the 904A filter frequency with an external CV source?

Yes, the Behringer 904A has a CV input for frequency modulation. Connect an external CV source to this input to control the filter frequency dynamically.

What should I do if the knobs on my 904A become stiff?

If knobs become stiff, avoid using lubricants as they can damage electronic components. Instead, gently turn the knobs regularly to maintain smooth operation. Consult a professional technician if the issue persists.

Can I use the 904A filter for stereo processing?

The 904A is a mono filter. For stereo processing, you will need two 904A modules, one for each channel. Ensure both modules are set to the same frequency and resonance for consistent stereo imaging.

How do I clean the Behringer 904A without damaging it?

Use a soft, dry cloth to wipe the surface of the module. Avoid using water or cleaning solutions. For thorough cleaning, gently remove the module from the rack and blow out dust using compressed air.