SPL Ships IRON Mastering Compressor

Units Available in Black and Red
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The goal of the company was to conceive a compressor that provided a pleasant, melodic-sounding, transparent compression, inspired on the vintage compressors of the radio era. And it had to be versatile enough to adapt perfectly to the needs of modern mastering studios. Thus, the IRON combines not only the sonic virtues of legendary vintage tube compressors with the advantages of the High Dynamic 120V operating voltage in a single unit. It also sets a new benchmark in terms of tube compressor technology, with the innovative implementation of a parallel dual-tube circuit

SPL's IRON mastering compressor is available in black (Model 1520) and red (Model 1524)

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Apart from the color, both models share the exact same technical specs:

  • Variable-bias tube compressor
  • Parallel dual-tube circuit
  • Tubes are selected and matched using a PC measuring system especially developed for the IRON
  • Custom-made Mu-Metal iron transformers
  • Feed-forward resistive opto-isolator in the control path of the variable-bias tube circuit
  • Six different rectifier settings
  • Sidechain with bypass, four EQ presets for the internal or an external sidechain signal
  • All functions can be adjusted via buttons or detented potentiometers
  • Stereo Link mode to control the Threshold, Tube Bias, Attack, Release, Rectifier, and Sidechain EQs with the right side (channel 2) of the unit
  • Passive 120V equalizer with two presets for the output signal
  • High-dynamic 120V operating voltage
  • Made in Germany

For more information about the SPL IRON visit http://iron.spl.info.

IRON in numbers:

Dimensions & Weight

  • Width x Height x Depth: 1.98" x 6.97" x 12.26" (482 x 177 x 311.5mm) (19", 4U)
  • Weight: 24.25 lbs (11 kg)

Power Supply

  • Voltage: 230 V AC, 50 Hz / 115 V AC, 60 Hz
  • Power Consumption: 4 W max.
  • Fuse: 100-120 V AC: T 2 A / 220-240 V AC: T 1 A


  • Input impedance: 20 kOhm
  • Max. input level: 32.5 dBu


  • Output Impedance: ‹ 50 Ohm
  • Max. output level: 32.5 dBu

Frequency Range (40 kHz = -3 dB): 10 Hz- 40 kHz

Common Mode Rejection (CMR) at 0dBu): 1 kHz: > 80 dB / 10 kHz: > 65 dB

THD & N (at 0dBu): > 82 dB

Noise (A-weighted): -98dBu

MSRP (including 19% German VAT): 4949 euros

About SPL
SPL has been developing and manufacturing analog and digital audio gear for the music, film, multimedia, and broadcasting industries since 1984. SPL products are respected worldwide for their innovative approach and user-friendliness, but most of all for their outstanding performance.

Among SPL's most celebrated developments are the patented Vitalizer® sound-optimization processing, the first-ever level-independent dynamic processor known as the Transient Designer, the 5.1 microphone system Atmos, as well as compact monitor controllers and channel strips.

The development of the SUPRA op amps by SPL allowed analog signal processing to outperform the best digital processing in terms of quality. These op amps, which make use of the unsurpassed 120-volt technology, were first used on the MMC mastering console. Ever since, the 120-volt technology has become a quality trademark of SPL products, including the Phonitor headphone amplifiers. More recently, SPL stormed the USB and MADI audio-Interface market with the introduction of the Crimson and Madison interfaces.

Its collaboration with German company Brainworx resulted in the Analog Code® plug-Ins, which translate to the digital realm the same quality expected from all SPL products. This relationship has led SPL to become a member of the Plugin Alliance.

With the Car Vitalizer app, SPL entered the smartphone market and redefined the concept of audio enhancement inside a car ─ without the need of any additional hardware or expertise. This know-how has allowed SPL to license its technology to major players in the auto industry.

SPL — Musiktechnik Made in Germany

For more information, visit spl.info