Roland SDE-2000 (1981 or 1982)
Roland's first rack-mounted digital delay: 640 milliseconds of 12-bit PCM in a 1U box, built like a studio tool and priced like one.
Overview
The number is 640 milliseconds. In 1981 that was long enough for slapback, doubling, and the chorus and flange effects that used to mean a tape machine with a moving head and all the maintenance that came with it. Roland's answer was a 1U rack unit with a 19-inch front panel and a delay time selectable from 0 to 640 mS in 1 mS steps, set by two switches that step the time up or down. A ×2 switch doubles whatever delay is dialed in, up to the 640 mS ceiling, so the range runs from near-zero to the full memory.
Roland's own service literature documents the architecture: a 16k-byte RAM system fed by a 12-bit A/D converter, using pulse-code modulation rather than the tape, BBD, or CCD methods that dominated delay design at the time. The service manual describes it plainly. The RAM is the tape, the read and write addresses are the heads, and the delay time is the distance between them. The converter is 12-bit, not the 8-bit resolution common to budget digital gear of the period, and that is what separates the SDE-2000 from the toys.
Roland positioned it as a professional, studio-grade processor, and the spec sheet backs that up. Input level is switchable between +4 dBm (with +29 dBm maximum) and −20 dBm (with +5 dBm maximum), so the same box can sit in a studio chain at line level or take an instrument-level signal without a separate interface. Input impedance is 56 kΩ. Output level runs +4 dBm into a 600 Ω load or −20 dBm into 10 kΩ, with output impedance switching between 100 Ω and 650 Ω depending on the level position. Studios needed that kind of flexibility, and it's why these units ended up in professional racks rather than bedroom setups.
Frequency response is specified in two bands, and they show what the memory is doing: 10 Hz to 16 kHz for delay times up to 320 mS, and 10 Hz to 7.2 kHz for the full 0 to 640 mS range. That's not a flaw. It's the arithmetic of a fixed memory allocation. Halve the sampling rate and you double the delay time at the cost of bandwidth, and Roland made that trade explicit rather than hiding it. Signal-to-noise is quoted at 80 dB in delay mode and 90 dB direct, with harmonic distortion under 0.2% in delay and under 0.05% direct.
Key Features
0–640 mS Delay in 1 mS Steps with ×2 Doubling
Two front-panel switches raise or lower the delay time one millisecond at a time, and the value shows on the front panel. The ×2 switch is the shortcut: dial in any delay, hit ×2, and the unit doubles it up to the 640 mS maximum. The units became fairly common in London studios in the 1980s and were quick and simple to use. No menus, no scrolling, just a number and a switch.
Two Modulation Waveforms — Sine and Triangle
Most digital delays of the period offered a single modulation waveform. The SDE-2000 provides two. The sine wave is intended for doubling and flanging, and the triangle wave produces the chorus effect. A modulation section controls the delay time directly, and the manual describes the modulation as equivalent to varying the speed of the read head in a tape system, which is what it's doing to the RAM addresses. A modulation CV input accepts 0 to +10 V (with ±20 V allowable) at 90 kΩ impedance, so external control works alongside the front-panel LFO.
Feedback Section with Single Repeat Mode
The feedback section has its own send and return: send level +4 dBm (+16 dBm maximum) at 100 Ω, return level +4 dBm (+19 dBm maximum) at 78 kΩ. In flanger and chorus modes, feedback adds intensity to the sweep. In long delay settings it produces multiple decaying echoes. There's also a single-repeat mode for clean doubling without regeneration. The front panel provides mixed and direct signal outputs, so dry and wet can be routed separately.
Remote Jacks for Delay, Single Delay, Modulation, and Repeat Hold
Four remote switch jacks on the rear panel allow footswitch or external control of delay time, single delay, modulation, and repeat hold. For a studio rack unit, that's a useful concession to performance use.
Switchable Studio and Instrument Level Operation
The +4 dBm / −20 dBm input and output level switching made the SDE-2000 adaptable. A synthesizer at instrument level and a console at line level both connect without outboard gear. The output impedance changes with the level setting - 100 Ω at +4 dBm, 650 Ω at −20 dBm, and 550 Ω in mixed mode at −20 dBm - so the unit matches the destination as well as the source.
Historical Context
The SDE-2000 marked Roland's first entry into rack-mounted digital delay technology, and by several accounts it was the Japanese company's first effects unit of any kind. It was promoted in the American trade press as a professional processor. An advertisement in Recording-Engineer (October 1982, p.34) carried the full specification block, and a similar ad ran in Mix-Magazine (February 1983, p.61) under the tagline "Incomparable Specifications."
Roland's UK distributor priced it at a recommended retail of around £600 including tax. That was real money for an effects unit in that period. The same EMM coverage identifies the design's core: an 8049C single-chip 8-bit processor paired with 416 dynamic RAM. These units became fairly common in London studios through the 1980s, valued for being quick and simple to use.
Production years are not firmly established. Sources disagree on whether the unit was introduced in 1981 or 1982, and no end date has been confirmed. Related Roland rack delays - the SDE-3000, SDE-2500, SDE-1000, and DEP-5 - are cited together as a family sharing vacuum fluorescent displays, but the SDE-2000 is not included in that list, and no confirmed lineup placement for this model has surfaced. It appears to have been a lesser-known member of Roland's early digital outboard line, though the record is too thin to place it precisely.
Collectibility & Value
No exact Roland SDE-2000 listings were live on eBay at the time of the source research, so current market prices are not firmly established. Reported asking prices have ranged from around $136.80 at the low end to £250 (with VAT, £300) for a unit listed as sold, with one Reverb UK listing showing an original price of £69.80 at a 20% discount. These figures are scattered and don't make a reliable market, so treat them as anecdotal.
Owners describe the sound as smooth and very analogue for a digital unit, and the 12-bit converter and its low sample rate for long delays are part of why. It's not a transparent modern delay. User reviews on Audiofanzine - four of them - call it one of the first units of its kind and a classic piece of gear, and Equipboard lists thirteen professional artists as users, though the specific names aren't documented here.
Documentation is the practical problem. A Gearspace thread requesting an owner's manual notes that nothing could be found online. The service literature exists, but owner's manuals are hard to come by. No confirmed common failure modes or repair procedures have surfaced in the research, so buyers should inspect carefully rather than rely on known-issue checklists. A 1981 digital unit with 416 DRAM and an 8049C processor is repairable by someone who understands the era, but not by a generalist.
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