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.

True Tube Tone

The signal path of each channel on the IRON compressor features two twin-triode tubes each with intentionally differing response curves. According to SPL, this unique configuration leads the way for IRON’s high level or transparency and musicality, allowing music to avoid sounding lifeless even at higher levels.

Pick Your Rectifier

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.

120V Technology

A feature shared with many of SPL’s most revered products, 120V is a proprietary design trait allowing 120 volt operating voltage aimed at providing optimal headroom with a super-low noise floor. For processing well-mixed tracks in need of a volume boost at the mastering stage, IRON is the ultimate tool for increasing loudness white still maintaining dynamics.

Built-In Equaliser

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.

Main Features

  • Tube compressor/limiter for mastering
  • Switchable stereo and dual-mono modes
  • Detented knobs for ease of settings recall
  • 6 rectifier circuits for wide ranging tonal variation
  • 120V operating voltage for high headroom
  • On-board EQ presets for additional gentle track polishing


Frequency Range:
10 Hz - 40 kHz (40 kHz = -3 dB)
Common Mode Rejection:
› 80 dB @ 1 kHz / › 65 dB @ 10 kHz
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


-98 dBu (A-weighted)


0.24 Amp, 230V/50Hz, 44 Watt, 55 VA
1 Amp @ 230 V/50 Hz

Physical Properties

482 x 177 x 311.5mm (WxDxH)

Authorised Retail Partners

Funky Junk
KMR Audio
SX Pro

Authorised Retail Partners

Funky Junk

Authorised Retail Partners

Funky Junk
KMR Audio
SSP (inc VAT) £ 4,599.00
EAN 4260149321398