IGS Audio S-Type 500 VU

The S-Type 500 VU is a stereo VCA compressor occupying two API 500 slots, built by IGS Audio on the topology of the SSL SL 4000 G Series mix bus compressor – one of the most widely used dynamics processors in the history of mixing. The gain control element is a THAT VCA chip, replacing the now unavailable DBX VCA of the original. The signal path is balanced throughout using four fast op-amps on inputs and outputs. The two stereo channels are summed in the side-chain detection circuit to control both VCA stages simultaneously, delivering the same stereo link behaviour as the original G Series design. A moving-coil needle VU meter replaced the LED bar of the previous S-Type 500 version and serves as the gain reduction indicator. SNR: –102 dBA. THD+N: 0.012% at 0 dBu. Frequency response: 8 Hz – 20 kHz ±0.1 dB. Power consumption: 4.5 W.

Sidechain HPF, external side-chain input and New York mode

The S-Type 500 VU adds three functions to the original SSL G Series topology. The sidechain highpass filter with six steps (Ext, Off, 60, 90, 120, 180, 240 Hz) excludes low-frequency content from the detection circuit – bass and kick drum energy does not trigger compression, the mix breathes more freely without pumping. The external side-chain input (EXSC) routes a separate signal into the detection path, enabling ducking applications such as music compression triggered by a voice-over channel, or dynamic side-chain effects. New York mode routes only the left detection channel to control both VCA stages simultaneously – effectively a mono side-chain over a stereo signal path, useful where programme material requires detection from a single independent source rather than the summed stereo bus.

Mix knob and gain staging – parallel compression without external routing

The Mix control implements parallel compression directly in the module: from 100% dry (compressor transparent, full bypass of character) to 100% wet (full compression). The 20–80% wet range is the standard starting point for drums and group buses – aggressive compression on the wet path adds punch and density while the dry signal preserves dynamics and transients. Threshold is detented from –20 to 0 dB. Output provides up to +20 dB makeup gain with detents. Attack: 0.1 / 0.3 / 1 / 3 / 10 / 30 ms (six steps). Release: 0.1 / 0.3 / 0.6 / 1.2 s / Auto / 2.0 s (six steps). Ratio: 2:1 / 4:1 / 10:1. Maximum gain reduction: 20 dB.

KEY FEATURES

• Stereo VCA compressor (SSL G Series-style), dual-slot API 500
• THAT VCA chip replacing the unavailable DBX
• Four fast op-amps on inputs and outputs
• Moving-coil needle VU meter – gain reduction display
• Ratio: 2:1 / 4:1 / 10:1
• Attack: 0.1 / 0.3 / 1 / 3 / 10 / 30 ms
• Release: 0.1 / 0.3 / 0.6 / 1.2 s / Auto / 2.0 s
• Sidechain HPF: Ext / Off / 60 / 90 / 120 / 180 / 240 Hz
• External side-chain input (EXSC)
• New York mode (mono side-chain controls both VCA stages)
• Mix knob – parallel compression with no external routing
• SNR: –102 dBA

TECHNICAL SPECIFICATIONS

• Type: stereo VCA compressor (SSL G Series-style), dual-slot API 500
• Gain control element: THAT VCA
• Ratio: 2:1 / 4:1 / 10:1
• Attack: 0.1 / 0.3 / 1 / 3 / 10 / 30 ms
• Release: 0.1 / 0.3 / 0.6 / 1.2 s / Auto / 2.0 s
• Threshold: –20 to 0 dB
• Sidechain HPF: Ext / Off / 60 / 90 / 120 / 180 / 240 Hz
• Maximum gain: 20 dB
• Maximum gain reduction: 20 dB
• Input impedance: 10 kΩ (balanced)
• Output impedance: 600 Ω (balanced)
• Operating level: +4 dBu
• Maximum input level: +20 dBu
• Maximum output level: +21 dBu
• SNR: –102 dBA
• THD+N: 0.012% (0 dBu)
• Frequency response: 8 Hz – 20 kHz ±0.1 dB
• Power consumption: 4.5 W
• Shipping weight: 1 kg