Behringer 1004 (Years Not Documented)

A 16 HP Eurorack oscillator with ARP 2500 DNA and dual-core flexibility, at a low price

Overview

The Behringer 1004 is 16 HP and built for Eurorack. Behringer markets it as the "Legendary 2500 Series Dual Core VCO Module," and it is a deliberate re-creation of the voltage-controlled oscillator from the ARP 2500, a modular giant of the 1970s. Owners report it sounds reminiscent of those original systems, with the raw, analog weight ARP was known for. It belongs to the broader Behringer 2500 series, a lineup aimed at making vintage modular synthesis accessible. That mission comes with baggage: aggressive pricing, outsourced manufacturing, and mixed reliability.

The module is built around a dual-core oscillator design, taken from the ARP original's architecture, which allowed complex interactions between waveforms and modulation paths. It covers both audio and sub-audio ranges. It switches between LFO duties (0.03 Hz - 32 Hz) and full audio bandwidth (15.5 Hz - 16 kHz). It also has modern patching conveniences, like CV-controllable pulse width modulation with adjustable length and depth, plus dual frequency modulation inputs for layered control. The output is a 3.5 mm TS jack, and waveforms can be routed either normal or inverted, which is a small but useful flexibility for patch design.

Some people dismiss it as a "knock-off," but collectors note its accuracy in waveform shape and pitch stability across five octaves. That is a critical benchmark for any VCO. There is no official calibration documentation, so users have developed and shared their own procedures. For those willing to dig in, the 1004 is a surprisingly capable entry point into dual-core synthesis.

Specifications

Manufacturer	Behringer
Model	1004
Type	Dual-Core VCO Module for Eurorack
HP Width	16 HP
Depth	46 mm deep
Dimensions	46 x 81 x 129 mm
Current Draw	60 mA (+12 V), 50 mA (-12 V)
Power Supply	Eurorack
Audio Range	15.5 Hz - 16 kHz
LFO Range	0.03 Hz - 32 Hz

Key Features

Dual-Core VCO Architecture

The 1004's dual-core design is its defining trait. It replicates the internal structure of the ARP 2500 oscillator. The architecture supports complex modulation routing and waveform blending that single-core designs can't match, allowing richer, more unstable, and harmonically dense tones. This core layout gives the module its "authentic" ARP character, particularly in detuned or modulated patches.

CV-Controlled Pulse Width Modulation

Pulse width modulation is a staple of analog synthesis, but the 1004 makes both the length and depth of PWM controllable via CV. External sources such as LFOs, envelopes and sequencers can shape the width of the pulse wave, and also how intensely that modulation is applied. That opens up evolving timbres that feel organic and unpredictable, especially combined with the dual-core design.

Normal and Inverted Waveform Outputs

The ability to output waveforms in both normal and inverted forms adds real patching versatility. Inverting a waveform can be used for phase cancellation effects, differential modulation, or creating complementary control voltages. It’s a feature often omitted in budget modules, so its inclusion here is a quiet win for advanced users building complex, interdependent patches.

Dual Frequency Modulation Inputs

The 1004 has two dedicated FM inputs. One input might take a steady pitch control voltage, while the second can be patched to a fast LFO or noise source for gritty, metallic textures. The dual-core design adds to this, since FM can be applied asymmetrically to each core, creating beating and phasing effects that evolve over time.

Historical Context

The Behringer 1004 is a direct descendant of the ARP 2500's oscillator section, explicitly designed as a replica ("Nachbau") of that system's core sound generator. It is part of Behringer's "Legendary 2500 Series," a product line aimed at recreating classic modular components at a fraction of the original cost. The ARP 2500 was a rare, expensive, hand-built instrument of the 1970s. The 1004 brings its architecture into the Eurorack format. No production years are documented, but its release aligns with Behringer's broader push into modular synthesis in the late 2010s.

Collectibility & Value

The Behringer 1004 was sold new at a retail price of $119. Used units appear on marketplaces like Modular Grid for as low as $81.90, and used listings start around $66. It's not a high-value collector's item, since it's too new, too common, and tied to Behringer's reputation for cost-cutting. It does have practical value as a functional, full-featured VCO in a crowded Eurorack market. Reliability is a known concern, and when units fail, repair can be a chore. A dedicated troubleshooting guide exists, so issues clearly do arise. Calibration is another pain point. No official procedure is published, so users have to reverse-engineer the process.