BSS Audio DPR-901 (c.1990–1998+)
Little is formally documented about the BSS Audio DPR-901. There are no manufacturer spec sheets or service manuals to go on, but period press coverage gives a solid picture of what it was and what it did. The DPR-901 was a four-band parametric equalizer with a twist: each band's cut/boost control was replaced by a variable-ratio compressor/expander. BSS called it a "dynamic equalizer," and Mix Magazine (June 1991, p.75) called it "quite a box" at a list price of $1,350. Its job was taming feedback in house and monitor sound systems.
The front panel has shelving switches on the outer two bands and defeat switches on the center two. It also has output level metering through signal-presence LEDs and a hard-wired bypass for quick A/B comparison. A later revision, the DPR-901 II, was still appearing in Mix as late as March 1998 (p.226), described the same way: a dynamic EQ whose bands spanned 40-320 Hz (low), 150-1.6 kHz (low-mid), 800-9 kHz (high-mid), and 1.6-18 kHz (high), with channel assignments for stereo or dual-mono use. The II kept the same basic architecture.
Beyond those details, the archive is thin. No factory documentation has surfaced in public databases, and even the exact years of production are inferred from the magazine coverage (1990 through at least 1998). What is clear is that the DPR-901 was outboard gear for engineers who needed EQ that reacted to signal level, not just frequency. That is dynamic processing per band.
Known Specs
- Type: 4-band dynamic equalizer (parametric EQ with per-band compressor/expander)
- Frequency bands: 40–320 Hz / 150–1.6 kHz / 800–9 kHz / 1.6–18 kHz
- Front-panel controls: shelving switches (outer bands), defeat switches (center bands), output level LEDs, hard-wired bypass
- Price (1991): $1,350
- Input/output: ¼-inch unbalanced jacks; MIDI in/out/thru; DIP switches for default settings (MIDI channel, etc.)
- Revision: DPR-901 II known from 1998 press
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