Teac MU-20

Name: Teac MU-20
Brand: Teac

Four VU meters and a row of peak LEDs - the add-on that turned a Tascam System 20 pile of modules into something you could actually read at a glance.

Overview

The MU-20 is the least glamorous box in Tascam's System 20 modular mixing concept, and the one owners ended up relying on most. It is a meter unit: four VU meters fitted with peak-overload LEDs, built as an add-on module for the System 20 range rather than a standalone instrument. The System 20 was designed around patch cords instead of switches, and the MU-20 is where the signal finally becomes visible.

The System 20 was unveiled at the February NAMM Show in Los Angeles, and the MU-20 was announced as the fourth of four basic building blocks. The other three were the MM-20 Master Module, with six inputs (a pair of transformer-isolated mic and four line-level inputs), four main outputs, a stereo auxiliary send, and separate monitor and headphone feeds; the EX-20 input expander, adding four more transformer-isolated microphone inputs and a stereo auxiliary send; and the PE-20, four identical channels of parametric equalisation with three bands and up to 12dB of cut or boost at each centre frequency. The low band swept continuously from 60Hz to 1.5kHz, the mid from 1.5 to 8kHz, and the high section was fixed at 10kHz. The MU-20 was the metering layer on top of that stack.

Tascam's design idea was that the System 20 should behave like an electronic patch bay. The user gets access to signal outputs at every relevant point along the mixer's path and wires up the format they need. Tascam's US marketing manager Dave Oren, quoted in a period write-up of the launch, put it bluntly: the system's uniqueness lay in its absence of switches, and the original intent was a mixing system for the artist/engineer working alone, before the company realised the patching flexibility suited multichannel work generally. That is why the MU-20 is a separate purchasable unit at all. In a switched console, meters are built in. Here, you bought them when you wanted them.

In practice the MU-20 was the module that made the rest legible. A row of phono sockets on the rear of the MM-20 lets its outputs be routed to a multitrack. Connecting those same outputs to the MU-20 meter bridge allows foldback and recording levels passing to tape to be accurately monitored at the mixing position. Without it, you are setting levels on a modular desk with no visual confirmation of what is actually hitting tape.

The family resemblance to the Model 144 Portastudio is not accidental. The System 20 modules share roughly the same overall dimensions and weight, and similar style switches, knobs and faders. Modern Recording (January 1983, p.68) framed the MM-20 as the heart of a professional-quality four-track system for under $400, and pointed buyers toward patching in the MU-20 Meter Bridge with its four VU-type meters when they wanted more from the system. The meter unit was sold as the natural next step, not an afterthought. HiFI-Stereo (June 1981, p.18) described the System 20's patching approach in similar terms, noting that the operator has access to all signals at all important points along the signal path and that connections are made with patch cords.

The MU-20 was the cheapest module in the System 20. When the four units reached the UK market, recommended prices were £195 for the MM-20, £125 for the EX-20, £119 for the PE-20, and £85 for the MU-20. It was the one module that did nothing to the audio. A US classified listing from the period shows a full working System 20 rig - a Teac 40-4 package with two DX-8s, an 80-8, MM-20, two EX-20s, a PE-20, an MU-20, and a 64-point patchbay with harnesses - offered as a complete wired system, which is how most of these actually sold: as a bundle, not as individual boxes.

That is also the collector's problem. Buyers chasing a System 20 today are usually chasing a whole rack, and the meter unit is the piece that gets separated from the herd and orphaned.

That is fine if you are buying the rack and a nuisance if you only want the meters. The MU-20's own documentation is thin. The surviving period material treats it almost entirely as a component of the larger system, described in a line or two alongside the modules that do the actual work.