Transient Designer 4, DeEsser and SPL’s popular IRON mastering compressor have all received upgrades for 2023!

Following the dynamic stage, IRON also features two EQ curve presets for adding a final gentle polish to any mix. AirBass mode offers a 2dB boost to high and low frequencies adding a nice sense of sparkle, while the Tape Roll-Off mode engages high and low cuts. The latter shapes the track’s response in an almost tape-machine style way adding an extra layer of warmth.

IRON offers a range of mastering-optimised features allowing engineers to dial in pristine optical dynamics all the way to fat, warm and downright vintage compression tones and its sonic talents lend truly market leading flourish to any musical material.


Introduced in late 2022, SPL's improved v2 model features balanced side-chain inserts with send as well as return ports, new side-chain EQ filter presets and Wathen CryoTone tubes. The second incarnation of IRON features an identical faceplate but can be identified from its barcode sticker on the rear of the rack.

SPL IRON v2 Compressor

£0.00 £5,549.00 inc. VAT
£4,624.17 exc. VAT


SPL IRON v2 Dual Channel Mastering Compressor

Featuring six rectifies, on-board passive EQ and a fantastically robust build, IRON is a Mastering Compressor designed to offer unbeatable sonic flexibility and provide the exacting sound quality standards that all mastering industry engineers seek.

Under the hood IRON utilises no fewer than six different rectifier circuits, each based around different diodes and each featuring a different set of transient characteristics. Switching between settings such as germanium and silicon offers different flavours of tone as well as unique response curves.


Frequency Range 10 Hz - 40 kHz (40 kHz = -3 dB)
Common Mode Rejection › 80 dB @ 1 kHz / › 65 dB @ 10 kHz
THD 0.3% @ 100 Hz; 0.06% @ 1 kHz
Input Impedance 20 kOhm
Max Input Level +32.5 dBu
Max Output Level +32.5 dBu
Output Impedance ‹ 50 Ohm
Noise -98 dBu (A-weighted)
Dimensions 482 x 177 x 311.5mm (WxDxH), 11kg