Iridium

Iridium takes its name from “Iris,” the Greek goddess of the rainbow, a fitting reference for an EQ designed to offer a broad and refined tonal palette.

Built around inductor-based circuitry, Iridium delivers a distinctive EQ character with smooth, musical response and precise frequency shaping. Inductor EQ designs are highly regarded in audio, and were famously used in classic designs such as the Pultec equaliser introduced in the late 1950s. Thanks to their unique electro-mechanical properties, inductors contribute a sonic character that many engineers value for its depth and personality.

Iridium uses 16 inductors across its four bands, including custom-wound Carnhill inductors in the low and low-mid bands. This design provides precise control while bringing the inductor character to every band.

The unit features a Class-A discrete design, with carefully selected and matched components throughout. The result is a highly musical sound with a strong sonic identity. While inspired by the strengths of classic inductor EQ topology, Iridium is a thoroughly modern circuit that uses updated design techniques and components not available 60 years ago. It is not a clone or copy, but an original Interphase Audio design.

Because of its inductor-based architecture, Iridium offers a peaking, or bell-shaped, response for focused control over the selected frequencies.

Each band provides a switchable choice of six carefully selected frequencies, spaced at musically useful intervals. Every band also offers fine adjustment of up to 15 dB of cut or boost.

Specifications

• Input impedance: 30kohm
• Common mode rejection: 80dB
• Distortion: 0.001% (+4dBu output, 1kHz)
• Frequency response: 7Hz to 70kHz (-3dB)
• Boost / Cut range: +/-15dB (continuously variable)
• HF Frequency: 8, 9, 10, 12, 14, 16 kHz (stepped)
• HMF Frequency: 1.5, 3, 5 6, 7, 8 kHz (stepped)
• LMF Frequency: 125, 250, 500, 1k, 2k, 4 kHz (stepped)
• LF Frequency: 50, 80, 100, 150, 300, 600 Hz (stepped)
• Filter Q: 1.2 (just over 1 octave)
• Maximum input level (500 module): +28dBu
• Maximum input level (51x module): +32dBu
• Maximum output level (500 module): +28dBu (10k load)
• Maximum output level (51x module): +32dBu (10k load)
• Nominal input and output level: +4dBu (electronically balanced)
• Output impedance: 100 ohm
• Noise floor (typical, unweighted, EQ on): -80dBu
• Noise floor (unweighted, EQ off): -100dBu
• I/O connections (Rack XLRs): pin 2 +, pin 3 -, pin 1 ground
• Current requirement: 81mA (maximum) per rail
• Size and weight: Standard 500 Series, 0.4 kilos