Tascam EX-20
A four-in, four-out microphone expander that existed only as one module of a modular console system — and that's the whole story.
Overview
The EX-20 is the microphone expander module from Tascam's System 20, a modular manual mixer concept that Tascam advertised as "a flexible new tool for the creative individual." The pitch was unusual for the era: instead of fixed-logic switches, the System 20 put patch points along the entire signal path so the user made every routing decision by hand. Tascam's own advertising billed it as a mixer where "nobody but you determines the routes your signals travel" — and the EX-20 was the piece you reached for when you needed more microphone inputs than the system's core module provided.
The module itself is a 4x4 design: four transformer-isolated microphone inputs with twelve patch points. That patch-point count is the tell — the EX-20 was never meant to be a standalone preamp. It was meant to be wired into a System 20, where its transformer-isolated inputs could be routed wherever the session demanded. The transformer isolation is the part that matters to anyone who has worked with this era of Tascam gear: it's the same design philosophy behind the System 20's master module, which carried two XLR transformer-isolated mic inputs of its own.
System 20 was built around the MM-20 Master Module, which carried four line inputs, two XLR transformer-isolated microphone inputs, and six output busses. Tascam's advertising in Modern Recording (October 1981, p.59) framed the whole system as a low-cost recording mixer with versatile add-on features, and the EX-20 was one of those add-ons — alongside the PE-20 four-channel parametric equalizer and the MU-20 meter bridge. The PE-20's sweep ranges are worth noting as context for how seriously Tascam took the System 20's sound-shaping: low frequency continuously variable from 60 Hz to 1.5 kHz, midrange sweep from 1.5 kHz to 8 kHz, high frequency fixed at 10 kHz, with ±12 dB boost and cut on all three bands. The MU-20 added four VU-type averaging meters with peak LEDs, patchable anywhere in the system. This was not a toy console.
The modular logic extended to expansion. Tascam's own materials noted that when a user was ready for 8-track, they added another Master Module rather than buying an expensive new mixer — the System 20 grew with the studio. The EX-20 fit that same philosophy: buy the mic inputs when you need them, patch them where you need them, and skip the circuits you don't. Tascam's copy made a point of the sonic benefit of that bypassing — fewer unnecessary circuits in the path meant cleaner signals.
What the EX-20 is not, and this is the honest part, is a documented product in its own right. The available material on the EX-20 comes almost entirely from System 20 advertising and dealer-facing literature, and it describes the module only as a component of the larger system. There is no independent bench test of the EX-20 alone, no published frequency response or noise figure for the module, no confirmed production window, and no original price specific to the EX-20. Anyone claiming otherwise is extrapolating from the System 20 as a whole. The system-level literature is consistent and specific about the EX-20's input count and patch points; everything beyond that is unknown.
Collectors chasing System 20 pieces should understand what they're getting into. The EX-20 is only useful inside a System 20 — its twelve patch points are the entire point, and without the MM-20 and the rest of the modules there's nothing to patch into. Complete System 20 setups are the collectible unit; a lone EX-20 is a spare part looking for its system. That's not a knock on the design. It's the nature of modular gear from this era, and Tascam built the System 20 to be expanded module by module. The EX-20 is the proof of that promise — a mic expander that made the console bigger when the session got bigger.
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