Teac MB-20
A rack-mounted meter bridge that turned a Teac 80-8 and a Model 5 mixer into a real console - and one that buyers once got thrown in for free.
Overview
The MB-20 is not a tape deck, a mixer, or an effect. It sat on top of the mixer and showed you what was actually going to tape. It meters up to four line-level signals and adds a built-in 4 x 2 monitor mixer with buss/tape selectors for each channel. That is the difference between guessing at your levels and knowing them. For anyone running a Teac 80-8 eight-track or an A-3440 four-track with a Model 2A or Model 5 mixer, the MB-20 was the missing piece that turned a stack of separate boxes into a system.
The period advertising is direct about what the MB-20 was for. Teac's own copy in High Fidelity (November 1978, p.53) grouped the MB-20 Meter Bridge with the GE-20 Equalizer as "sound processors" that "take your act way beyond the limits of 'live,'" and the same ad ran in Recording-Engineer (December 1978, p.48). There the MB-20 is described alongside the Model 2A Mixer as metering up to four line-level signals with a built-in 4 x 2 monitor mixer plus buss/tape selectors for each channel. So the MB-20 is the monitoring layer of a small-format multitrack studio, not a standalone gadget.
The A-3440 manual is even more explicit about the intended stack. It recommends teaming the A-3440 with the Model 2A six-in/four-out mixer and the MB-20 Meter Bridge. It describes the MB-20 as providing "accurate readout of buss and tape output levels," along with a built-in headphone monitor amp with independent volume control and a left, right, or center channel monitor switching matrix. Accurate buss and tape metering, a headphone amp with its own gain, and a three-position monitor matrix - that list is what made the A-3440/Model 2A combination feel like a console rather than three boxes stacked on a desk.
Then there is the promotional history. Through the first four months of 1980, Teac ran a Tascam Series promotion offering more than $750 worth of gear free with the purchase of an 80-8 and a Model 5B between January 1 and April 30, 1980. The MB-20 meter bridge was on that list, alongside the Model 1 monitor mixer, the PB-64 patch bay, and all the cable needed to hook everything together. A separate dealer promotion advertised $1,300 in free equipment with a "Professional 8-Track Studio" built around the 80-8 tape machine, the Model 5 mixer, and the DX-8 decode unit. The MB-20 appears there too, bundled with the PB-64 patch bay, the Model 1 mixer, a case of Ampex 456 or Scotch 250 tape, the RMK recorder maintenance kit, a talk-back module, an RC-70 remote control, patch cables, and a multi-track primer book.
Teac treated the MB-20 as an essential part of the system, not an accessory you might get around to buying. Teac gave it away to make sure it ended up on top of the mixer.
The MB-20 also shows up in the classifieds of the era doing the job it was built for. A 1981 listing in Studio-Sound (October 1981, p.16) stacks a Teac 3440, a Teac Model 2A, and a Teac MB-20 together in a dealer's lineup of leading pro equipment. Another period ad, from a studio selling off its old console, describes two heavily modified Tascam Model 5s with three Teac Model 1s and an MB-20 meter bridge mounted in a custom console. It was wired for additional echo sends and returns and interfaced for 16-, 8-, 4-, and 2-track tape decks.
For a buyer today, the MB-20 is a strange proposition. It does nothing on its own. Plug it into a Model 2A or Model 5 mixer and an 80-8 or A-3440, and it becomes the monitoring brain of a small-format Teac studio. Buy one to use with something else and you are likely to find the connectors and the buss wiring don't line up. It is a system component, and its value depends on whether you own the rest of the system. Collectors who have assembled a complete 80-8 or A-3440 stack tend to regard the MB-20 as the piece that finishes the rig. Teac itself treated the meter bridge as important enough to give away.
Based on the available documentation, the MB-20 is not a general-purpose meter or monitor unit. Every period reference places it inside a specific Teac/Tascam stack: the A-3440 manual pairs it with the Model 2A, the 1980 promotions pair it with the 80-8 and Model 5B, and the period classifieds show it mounted alongside Model 1 and Model 5 mixers. There is no evidence in the available sources of the MB-20 being used as a standalone product, and no evidence of it being sold separately from the system it was designed to complete.
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