Sunday, October 18, 2015

SPL's IRON Mastering Compressor

 I can't wait to audition SPL's IRON Mastering Compressor. I'm quite sure it sounds as impressive as it looks. Despite its "mastering" designation It will definitely be put to use in many recording studios and mixing suites. It comes in 2 colors but featurewise they're exactly the same.

From the manual: 

"The IRON mastering compressor is not a copy of a classic unit, but rather an original concept in itself. Our goal was to conceive a compressor that provided a pleasant, melodic-sounding, transparent compression, inspired on the vintage compressors of the radio era. And we wanted it 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. Thanks to the especially conceived Mu-Metal iron transformers, the signal of each channel is split across two different twin-triode tubes. The combination of the different response curves of both tubes results in a transparent and musically pleasant compression. Additionally, peak signals of the control voltage are limited by a feed-forward resistive opto-isolator. Thus, the output signal remains lively even with a high gain reduction. The compression is only noticeable with extreme settings.
But mastering is not the only domain where the IRON sets new standards. It can also be used to process individual instruments, like vocals, bass, guitar, strings, etc. The IRON is also an excellent option for subgroups."

SPL's teaser video on the IRON Mastering Compressor:

and a video by Sound On Sound Magazine at Musikmesse 2015:


  • Variable bias tube compressor
  • Parallel dual tube circuit
  • Tube selection and pairing with Weigl Roe Test
  • Specially conceived Mu-Metal iron transformers
  • Feed-forward resistive vactrol-opto-isolator
  • Six different Rectifier settings available
  • Sidechain that allows you to choose between Off, four sidechain-filter presets or an external sidechain signal.
  • All functions can be adjusted via switches or, in the case of the Threshold, with a detented potentiometer
  • In Link mode, the Threshold, Tube Bias, Attack, Release, and Rectifier parameters, as well as the Sidechain EQs, are controlled with the right side (channel 2) of the unit.
  • Additional passive 120V equalizer with two presets
  • High Dynamic 120V operating voltage
  • Auto Bypass mode
  • Made in Germany


  • Frequency Range: 10Hz - 40kH
  • CMRR (@ 0dBu) 1kHz: › 80dB / 10kHz: › 65dB
  • THD&N (@ 0dBu) › 82dB
  • Noise (A-weighted) - 98dBu
  • Total Harmonic Distortion 0.06 % @ 1kHz/-10 dBu; 
  • 0.01 % @ 1kHz/0 dB; 0.002% @ 1kHz/+10 dBu
  • Input Impedance 20 kOhm
  • Max. Input Level + 32.5dBu
  • Output Impedance ‹ 50 Ohm
  • Max. Output Level + 32.5dBu
  • Power Consumption: max 45W
  • Fuses 230 V/50 Hz: 1 Amp, 115 V/60 Hz: 2 Amp
  • Dimensions 482 x 177 x 311.5 mm, (19“ x 7“ x 12.25“)
  • Weight 11 kg / 24.25lb

MSRP: 4,158.82 €€/4,719.82 USD