IGS Audio V8 Compressor

The V8 is a dual-mono diode-bridge compressor built by IGS Audio using exclusively discrete components and six IGS Custom transformers (three per channel: input, interstage, and output). The compression element is a bridge of four pulse diodes matched by hand according to carefully developed procedures – a topology derived from the classic Neve/EMI 2254 circuit. There are no integrated circuits anywhere in the signal path. The name V8 comes from IGS Audio's internal project numbering: this is the eighth compressor designed by the company. All controls are ELMA switches throughout, providing full session recall and precise matching between the two channels. Three-year manufacturer warranty.

Diode bridge as the compression element – what distinguishes this topology

VCA compressors control gain through an integrated circuit VCA driven by a side-chain voltage. FET designs compress by varying the impedance of a field-effect transistor. A diode bridge introduces compression through four diodes in a bridge configuration: at low signal levels the diodes operate linearly; at higher levels their characteristic curve begins limiting amplitude. The compression results from the physics of the p-n junction at higher signal voltages. The dynamic character is similar to FET compression – fast and aggressive – with the harmonic colour of an all-discrete transformer path: warmer and more musical than clean VCA electronics. Hand-matching of the four diodes by IGS Audio's procedures minimises channel-to-channel deviation and ensures a coherent stereo image when running the two channels as a linked pair. Dynamic range: 101 dBA at +24 dBu.

Side-chain HPF, +10THR switch and stereo link

A seven-position side-chain highpass filter (OFF, 40, 80, 120, 180, 240, 320 Hz) excludes low-frequency content from the detection circuit: kick drum and bass pass through without triggering compression, the mix breathes without pumping. The +10THR switch lowers the compression threshold by an additional 10 dB – useful for compressing very low-level signals or achieving very deep gain reduction without pushing the Threshold control to extreme positions. Stereo link couples the side-chain circuits of both channels, running them as a stereo pair with one shared detection centre. Attack time: 0.1–30 ms. Release: 0.1–1.4 s plus Auto. Maximum gain reduction: 30 dB. Analog VU meters with IGS Custom scales.

KEY FEATURES

• Discrete diode-bridge compressor (Neve/EMI 2254-style), dual-mono, rackmount
• Exclusively discrete components – no integrated circuits in the signal path
• 6 IGS Custom transformers (3 per channel: input, interstage, output)
• 4 hand-matched pulse diodes – the compression element
• All controls: ELMA switches
• Side-chain HPF: OFF / 40 / 80 / 120 / 180 / 240 / 320 Hz
• +10THR switch (additional –10 dB threshold offset)
• Stereo link (side-chain coupling)
• Hard-wire bypass
• Analog VU meters with IGS Custom scales
• 3-year manufacturer warranty

TECHNICAL SPECIFICATIONS

• Type: discrete diode-bridge compressor, dual-mono, rackmount
• Compression element: bridge of 4 hand-matched pulse diodes
• Transformers: 3× IGS Custom per channel (input, interstage, output)
• Switches: ELMA (all controls)
• Attack time: 0.1–30 ms
• Release time: 0.1–1.4 s + Auto
• Sidechain HPF: OFF / 40 / 80 / 120 / 180 / 240 / 320 Hz
• Maximum gain: 22 dB
• Maximum gain reduction: 30 dB
• Input impedance: 10 kΩ (IGS Custom transformer)
• Output impedance: 600 Ω (IGS Custom transformer)
• Operating level: +4 dBu
• Maximum input level: above +22 dBu
• Maximum output level: above +26 dBu
• Dynamic range: 101 dBA (1 kHz, +24 dBu)
• THD+N: 0.056% (20 Hz – 20 kHz)
• IMD (SMPTE): 0.16% (20 Hz – 20 kHz)
• SNR: 87 dBA (20 Hz – 20 kHz)
• Crosstalk: 91 dB (20 Hz – 20 kHz)
• Frequency response: 10 Hz – 25 kHz (+0.2/–0.4 dB)
• Power supply: 115/230 V AC, 50–60 Hz, internal
• Power consumption: 24 W