Lexicon EMT 244
A rack-space digital reverb that traded bandwidth for a price and, by most accounts, kept the natural decay intact.
Overview
Sort out the name first. The front panel says EMT, and this page says Lexicon. The unit is an EMT product, designed and built by EMT-Franz GmbH of Lahr, West Germany, and imported into the United States by Gotham Audio Corporation of New York. It appears in this archive under Lexicon because that is how the catalog groups it. No Lexicon engineering went into the 244. The branding confusion is a catalog artifact, not a manufacturing fact.
Per the manufacturer's own specification, the 244 is a rack-mountable pure digital reverberation unit, a simplified sibling of the EMT 250. It exists to deliver EMT's digital reverb approach in a box that takes up a fraction of the room.
The engineering story is a microprocessor story. By the time of the 244, microelectronics had advanced enough that multiplexed microprocessors could stand in for that custom hardware. That simplified the design and cut the cost. The tradeoff was bandwidth: the 250 reached 11kHz, while the 244 tops out at 8kHz. That is the single biggest compromise in the machine.
The 244 stores a reverb "programme" in read-only memory and holds the incoming audio in random-access memory, with the program operating on the stored audio in 13-bit digital form. The conversion is 13-bit on both the A/D and D/A sides. Reverb time at 500Hz is selectable in 16 steps from 0.4 seconds to 4.5 seconds. There are separate two-position switches for the low-frequency behavior (linear or boost) and the high-frequency behavior (linear or roll-off). The high-frequency roll-off switch is not a gimmick. Ford found that without cutting the treble reverb time, the results could sound a little hard, and with it engaged the unit produced a pleasing, spacious character in stereo.
The measured performance held up. Ford's testing showed a frequency response flat from 20Hz to 8kHz, where a sharp anti-aliasing filter cuts the response. Because of that filter's characteristics, he never saw any sign of beating effects at high frequencies. The response extended well into the low end, though the unit distinctly disliked inputs at 10Hz above -12dBm. Signal-to-noise at a 2-second reverb time is quoted at 65dB in the Mix product description, and the manufacturer's spec lists a 6dB overload margin above the adjusted nominal level, with a maximum of +21dB. The analog I/O is balanced. Inputs have an impedance greater than 5kΩ and a nominal +6dB level adjustable between -10dB and +15dB. The two balanced outputs have an impedance under 60Ω, nominally +6dB and adjustable across the same range. Ford measured the output impedance considerably lower still, on the order of 12Ω at 1kHz. He noted the output is always transformer-coupled and floating, so one end can be grounded for an unbalanced feed.
The 244 occupies 7 inches of rack space according to Mix, with dimensions of 20.1 x 8.4 x 19.1 inches (505 x 210 x 480mm) and a weight of approximately 44 pounds (20kg). Power consumption is 70VA. Ford's inspection of the interior found the power supplies completely screened from the main electronics along the left side, most of them on a large glass-fibre board set at a sloping angle. A second board plugs vertically into the main board, and a small interface board in the base connects by ribbon cables. He called the standard of construction excellent, with good quality components, an uncluttered layout, and easy access to everything. One caveat from that review: many of the maker's IC identifications had been removed, presumably to protect the design, and only a provisional instruction manual was available at the time, so serviceability could not be assessed.
The manufacturer's specification lists the price at £3,713. That is a serious figure, and it explains why the 244 ended up in professional rooms rather than home setups. The contemporary record bears that out. Studio Sound's 1990 equipment listings show the EMT 244 sitting in hire stock alongside a Lexicon 480L, Lexicon 224, Yamaha REV7 and Eventide H3000, and a 1984 Canadian studio directory lists an EMT 244 in the outboard rack next to a Lexicon 224.
Remote control is possible via a five-conductor electrical cable for DC control, and Mix noted that a simple modification allows unbalanced lines to be used. Ford's summary verdict: if you require really natural reverberation, digital is effectively mandatory, and the 244 gives excellent results, with measured and subjective performance on a par with the far more expensive, more fully featured EMT 250. The 8kHz ceiling and the missing pre-delay are real limitations.
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