Roland DJ-70 Sampling Workstation

A 37-key sampler with a motorized scratch dial, aimed squarely at the DJ booth.

Overview

Roland built the DJ-70 as a sampling workstation pitched directly at deejays. The centerpiece is a dedicated scratch encoder assembly - the parts list calls it out as a "Scratch Encoder Assy" with an optical encoder and a scratch wheel - that lets a performer scratch CD-quality samples forward or backward, with or without pitch change. That's an unusual pitch for a keyboard sampler.

The sampling engine is 16-bit linear with a DI method, running at either 44.1 kHz or 22.05 kHz. The A/D side is 16-bit while the D/A is 20-bit. Signal processing runs through a TVF with lowpass, bandpass, highpass and ring filter modes plus a TVA, both operating at 24-bit. Polyphony is 24 voices, and the frequency response is quoted at 20 Hz to 20 kHz (+0/-3 dB). Dynamic range is listed at more than 87 dB with one voice at rated output, and total harmonic distortion - measured across the A/D and D/A stages together - comes in under 0.01%. Those are respectable numbers for a 1992-era sampler. The 24-voice ceiling is generous for a machine whose main job is playing back loops and one-shots.

Standard sound memory is 2 Mbyte, expandable to a fully expanded 32 Mbyte using 8 or 16 Mbyte 72-pin SIMMs. The official Roland expansion path is the OMS-770, and the service notes are blunt about the rules: two SIMMs of 1 Mbyte each must be installed, because a single module won't be recognised. Install them and the LCD should report 4 Mbytes of operative memory after boot. Roland explicitly disclaims responsibility for third-party modules, though the manual does list compatible alternatives - an 8 Mbyte 72-pin, 2 Mword x 32-bit D-RAM module with 80 ns or better access time, and a 16 Mbyte 72-pin, 4 Mword x 32-bit module with the same access-time requirement. The DJ-70MKII takes different memory entirely. OMS-770, OMS-750, SIM-8 and SIM-2 modules won't work in it, and neither will 16 Mbyte SIMMs built from 32 4-Mbit D-RAMs.

The keyboard is 37 keys with velocity. Input impedance is 10K ohm with an input level range of +4 dB to -50 dBm continuous variance, and output impedance is 200 ohm on the stereo out and the individual R and L jacks. Residual noise is specified as more than -80 dBm with volume at maximum and the input shorted, measured IHF-A weighted. A SCSI connector handles the interface side, and a floppy disk drive - the FDD FZ-357 338F1DR - handles storage. EQ Magazine (April 1993, p.49) described the DJ-70 as the first instrument designed specifically for deejays, noting the 16-bit CD-quality stereo sampling, the two megabytes of memory expandable to four, tempo auto-looping of sampled beats, and the scratch dial's ability to work with or without pitch change.

The DJ-70 and DJ-70MKII are not the same machine under the hood. The MKII differs from the DJ-70 in its digital boards, top and bottom cabinet, and other details. The service documentation for the MKII only lists the differences, so you need the DJ-70 Service Notes (RJA code 17059654) for the full picture of the original. The parts list uses a "#" symbol to flag parts unique to the MKII. If you're sourcing spares or a replacement board, know which one you're working on.

Maintenance on a machine this age is mostly mechanical. The scratch encoder assembly, the scratch wheel, and the optical encoder are the parts most likely to need attention, and they're listed as discrete service items. Roland's own service notes also carry an erratum: on the digital board, IC27 - originally a J5179102 TIC PAL 22V102-25CNT - was superseded by a 7695235000 I.C.ROL GAL.002. The two are noted as compatible, which helps if you're chasing a replacement chip. The DJ-70 also has a full test mode, entered by holding a front-panel button while powering on, with sub-tests for program DRAM, boot ROM, EEPROM, keyboard, floppy disk, and the analog board. That includes a D/A converter check that expects 4.5 to 5.5 Vpp at maximum level on the output and 13.5 to 15.5 Vpp on the phones jack at level 12.

Collectors and working DJs still seek the DJ-70 out for the scratch dial. The 24-voice engine and 16-bit sampling are unremarkable on their own, but the tactile scratch interface is not. The catch is that it's a 1992 machine with a floppy drive, SCSI, and proprietary memory rules, so buyers should expect to deal with drive belts, encoder wear, and the two-SIMM requirement if they want expanded memory. Parts are findable but not plentiful, and the MKII/original split means you have to be specific about which model you're buying parts for.

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Roland DJ-70 Sampling Workstation

Overview

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