AMSynths AM984 Four Channel Mixer (2025 Edition)
This is Moog's 1968 mixer rebuilt from the ground up in Eurorack form. It is not modeled and not emulated.
Overview
The AMSynths AM984 Four Channel Mixer (2025 Edition) is a 32HP Eurorack module. It is a faithful recreation of the Moog 984 Four Channel Mixer originally released in 1968, the kind of gear that shaped early modular synthesis before digital modeling existed. It doesn't simulate; it replicates. Every circuit trace, every transistor, every EQ curve is pulled straight from the original schematics.
The AM984 is built for people expanding their Behringer System 55 modular rigs toward a Moog Modular IIIp/c. Its niche is final-stage audio mixing. It's not a CV mixer - the decoupling capacitors in the signal path make that clear - so don't use it for modulating filters or panning LFOs. It is meant for bringing together your final VCA outputs, sending signals to effects, and shaping your stereo image, and it's reportedly superb at that. Owners note a warm, present sound, especially with the dual EQ per channel. Each of the four channels has independent Bass and Treble boost and cut, so you can fine-tune individual voices before summing.
The build is a transistor-only design, just like the original. No modern op-amp reinterpretation here. It uses low noise transistors and PPS SMD capacitors in the EQ sections, chosen for accuracy and performance, not convenience. The result is a mixer that behaves like a Moog, with the subtle coloration and interaction that implies. The front panel is black anodised aluminium, with 28 potentiometers covering levels, EQ, and routing.
The module is built to integrate. The four 3.5 mm jack sockets for audio inputs and outputs are standard Eurorack. On the rear there are four Thonkiconn jacks - two normalized to Inputs 3 and 4, two connected to Outputs 3 and 4. That suits semi-permanent patching, so you can hardwire returns from effects or feed downstream processors without using up front panel space. It ships with a 10-pin power cable and M3 black mounting screws and washers.
Key Features
Transistor-Only Design, True to Original
The AM984 uses the exact schematics from the 1968 Moog 984 and keeps the transistor-only architecture. There are no op-amps and no ICs. Discrete transistors handle the gain and mixing, as they did over half a century ago. That choice affects everything from transient response to harmonic behavior, and gives the module a slightly organic, "alive" quality that modern mixers sometimes lack. The low noise transistors keep unwanted hiss out of your chain, and the PPS SMD capacitors in the EQ sections handle the tone shaping.
Four-Channel Matrix with Full EQ Per Channel
Each of the four channels has independent Bass and Treble controls, boost and cut, followed by a final level fader. That's 28 potentiometers total. Per-channel EQ is rare in Eurorack mixers. Most modern designs skip EQ entirely or offer only basic tone controls. The AM984 brings back the full Moog treatment, so you can correct or color individual voices before they hit the mix. It's useful when combining VCOs, noise sources, or external synths that don't sit well together by default.
Rear Thonkiconns for Flexible Integration
The four rear-mounted Thonkiconn jacks are a practical touch. Two are normalized to Inputs 3 and 4, so you can patch into them from the back while still using the front jacks normally. That works well for semi-permanent effect returns. The other two connect directly to Outputs 3 and 4, for sending signals to external processors or feeding a secondary mixer without cluttering the front panel.
Designed for the Behringer System 55 Expansion
The AM984 works in any Eurorack system, but it was explicitly designed to complement the Behringer System 55 Modular System. For users building a Moog Modular IIIp/c-style rig from Behringer's affordable recreations, it fills the gap of a proper final mixer. It's not only about form factor or voltage levels. It completes the signal chain with the same topology Moog used.
Historical Context
The AMSynths AM984 is a direct recreation of the Moog 984 Four Channel Mixer from 1968, a module that sat in Moog's large-format modular systems. Back then it was the last stop before tape or speakers, where engineers could balance, EQ, and route multiple synth voices. Over five decades later, AMSynths has brought it back in 32HP Eurorack format as a functional replica. Its purpose today is to let modern builders assemble an accurate Moog Modular IIIp/c by expanding affordable platforms like the Behringer System 55.
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