Trident A-Range Mic Pre/EQ is a two-channel, fully discrete microphone preamplifier and four-band equalizer in a 2U rack format — a direct replica of the channel strip from the original A-Range console built in 1972 by Barry Porter and Malcolm Toft for Trident Studios. Integrated circuits had not yet entered professional audio at the time; the entire signal path relies on discrete transistors, and the two mid-band EQ sections use inductor-based LC circuits. Only 13 A-Range consoles were ever built. The rack unit reproduces the original circuitry exactly, the result of three years of circuit analysis by PMI Audio Group before production began.
Inductor-Based EQ — Tone Character Derived from Circuit Physics
The four EQ bands follow the topology of the original: Low and High bands are shelving filters at 6 dB/octave, while Low-Mid and High-Mid are LC-based peaking bells with a fixed Q of approximately 1 — roughly 1.3 to 1.4 octaves wide. That fixed bandwidth is not adjustable, and produces measurable interaction between bands when center frequencies are placed close to each other; this is a property of the inductor topology, not a limitation to work around. Gain control on all four bands is handled by 70 mm Bourns linear faders with a center detent at zero — carried over directly from the console modules, allowing gain staging across all bands to be read at a glance without touching a knob. Each band has four fixed switchable frequencies and ±15 dB of boost or cut. The three HP and three LP filters are additive: engaging multiple LP filters simultaneously increases attenuation above the lowest selected frequency beyond what any single filter would achieve alone.
Signal Path and Integration
Each of the two channels has independent mic XLR input (with +48V phantom power) and line XLR/TRS jack input, separate input gain and output level controls, and a phase reverse switch operating across both inputs simultaneously. A pre/post EQ insert with bypass accommodates external dynamics processors or other outboard at either point in the chain without disrupting the signal path. Three LED peak indicators per channel sit at the output of the preamp, after the EQ section, and after the output amplifier — providing gain staging visibility at every stage independently. All inputs and outputs are balanced. Power is supplied by an integrated linear transformer with regulated +48V and +24V DC rails.
KEY FEATURES
- 2 independent channels: discrete Class A mic/line preamp + 4-band EQ
- Fully discrete signal path — no ICs; identical circuitry to the 1972 original
- EQ: Low-Mid and High-Mid bands use LC inductors (peaking, Q≈1); Low and High are shelving at 6 dB/oct
- EQ gain control via 70 mm Bourns linear faders with center detent at zero
- 4 fixed selectable frequencies per band, ±15 dB
- 3 additive HP filters and 3 additive LP filters with independent pushbuttons
- Pre/post EQ insert with bypass per channel
- Phase reverse on both inputs simultaneously
- +48V phantom power, independently switchable per channel
- 3 LED peak indicators per channel (post-preamp, post-EQ, post-output)
- All I/O balanced: XLR + 6.35 mm TRS jack
- Internal linear power supply with mains transformer
TECHNICAL SPECIFICATIONS
- Channels: 2, independent
- Form factor: 19", 2U rack
- Preamplifier: discrete Class A, mic and line inputs
- Phantom power: +48V, independent per channel
- EQ — Low Shelf: 50 / 80 / 100 / 150 Hz, shelving
- EQ — Low-Mid Bell (inductor): 250 / 500 / 1k / 2k Hz, peaking, Q≈1
- EQ — High-Mid Bell (inductor): 3k / 5k / 7k / 9k Hz, peaking, Q≈1
- EQ — High Shelf: 8k / 10k / 12k / 15k Hz, shelving
- EQ gain: ±15 dB per band
- HP filters (additive): 3 selectable frequencies
- LP filters (additive): 9k / 12k / 15k Hz, 12 dB/oct
- Inputs: XLR (mic), XLR + TRS jack (line)
- Outputs: XLR + TRS jack (balanced)
- Insert: 6.35 mm unbalanced send/return (switchable pre or post EQ)
- Power: mains-powered, internal linear transformer (+48V, +24V DC)
