Alesis MIDIverb II (1987)
16-bit rackmount reverb and multi-effects processor with 99 presets, MIDI control, and a distinctive 1987 digital character
Overview
The Alesis MIDIverb II is a 19-inch rackmount digital effects processor introduced in 1987 as a budget-friendly professional reverb unit. It features 99 preset effects including 29 natural reverbs, 10 gated and 10 reverse reverbs, 20 echoes, 10 flanges, 10 choruses, and 10 miscellaneous programs. Known for its "Bloom" effects (Programs 45 and 49), which Alesis claimed were unobtainable from other affordable processors, the unit delivers a characterful, slightly hissy sound often described as "glued and greasy" with an analog-like feel. It was praised for its near-perfect MIDI implementation, instant recall via MIDI or front panel, and ease of use. The MIDIverb II followed the original MIDIVERB and Microverb and was succeeded by the Midiverb 4, though later Alesis FX units did not replicate its sonic character.
Specifications
| Year | 1987 |
| Bit Depth | 16-bit linear PCM |
| Bandwidth | 15kHz |
| Channels | 2 |
| Analog Inputs | 2 |
| Analog Outputs | 2 |
| MIDI Inputs | 1 |
| MIDI Outputs | 1 |
| Preset Effects | 99 presets plus defeat |
| MIDI Patch Locations | 32 |
| Dynamic Range | 85dB |
| Distortion | 0.1% |
| Input Impedance | ~1 Mohm per channel (500k ohms in mono) |
| Input Signal Level Range | -10 to +20dBv |
| Power Requirement | 9V AC adaptor |
| Microprocessor | 8031 |
| Microprocessor Clock Speed | 8 MHz (early units), 12 MHz (later units/factory mod) |
| DSP Chip Clock Oscillator | 16 MHz |
| Internal Chip | Custom-built VLSI chip clocked at 8MHz |
| On-board NVRAM | Xicor X2444P with 32 bytes storage |
| NVRAM Data Retention | 100 years |
| Op-amp Chips | TL084 (early units used LF354) |
| Reset Circuit | 4.7uF capacitor, 10k resistor |
| Format | 19-inch rackmount |
| Electronics | Analog Digital Solid State |
Design
The MIDIverb II uses a 16-bit processor and features a simple front panel with three knobs (Input, Output, Mix) and 14 rubber pushbuttons, plus an LED display. The rear panel includes stereo ¼" input/output jacks, MIDI In/Thru, and a footswitch jack marked Defeat. Power is supplied via a 9V AC adaptor, with early units using a 3.5mm jack and later ones a DC barrel jack (still AC). Internally, it contains a DSP chip, A/D and D/A converters, small blue film decoupling capacitors, and a power supply board that can be recapped. The reset circuit uses a basic RC design (10k resistor, 4.7uF capacitor), known to be less reliable—later Midiverb III units improved this. The PCB in later versions has separate oscillators for the 8031 microprocessor and DSP chip. The unit is noted for reliable analog and digital circuits, though front-panel potentiometers, especially the Mix control, wear with use.
Context
The MIDIverb II followed the original MIDIVERB and Microverb and became a popular inexpensive reverb option in the 1990s, especially in home studios. It is associated with the sound of My Bloody Valentine's "Isn't Everything" era and 90s electronica. While later Alesis FX units lacked its character, the Midiverb 4 is considered its worthy successor. The unit's "Bloom" presets are often cited as a unique reason to own it, and it is favorably compared to a Lexicon PCM70 at a fraction of the cost. It pairs particularly well with gear like the Roland SH-101 and shares sonic similarities with the Yamaha REV100.
Market
The MIDIverb II has been found on the second-hand market for as low as $40 to $100, with one repair unit noted at £30 in 2020. Common issues include failing PSU capacitors that leak or lose capacitance, causing hiss or erratic behavior—replacing them often resolves these problems. Bad tantalum capacitors can overheat, discolor, and cause the overload LED to stay on, prevent effects from passing, or introduce hum. Small 0.1mfd blue or yellow capacitors are known to short and burn through copper traces, requiring repair by replacing the cap and bridging the trace. The reset circuit’s simplicity can lead to unreliability. Recapping the power supply is a common service, with care needed to avoid pulling vias or installing capacitors backwards. A hardware reset may be possible by holding buttons during power-on.
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