Overview

In 2015 SPL released the IRON mastering compressor based on an original concept.

Their goal was to conceive a compressor that provided a pleasant, melodic-sounding, transparent compression, inspired by the vintage compressors of the radio era. But they 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 120 V 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.

Iron is a variable-bias tube compressor, often called a “Vari-Mu” design. Unlike most standard variable-bias designs, which use the bias of a single tube for compression, Iron uses a dual circuit topology. This means, the incoming signal is split between two tubes via a specially designed Mu-Metal iron transformer, running in parallel and then recombined. One tube is a 12AX7/ECC83 and the other a 12AU7/ECC82. Each tube yields a slightly different compression curve and feel.

The Attack and Release parameters have six different settings ranging from Slow to Fast. The times are not constant, they vary according to the Rectifier circuit selected: There are six different Rectifier settings available with different diodes (Germanium, Silicon, LED, mixed).

Mastering is not the only domain where the IRON sets new standards. It can also be used to process subgroups or individual signals, like vocals, bass, guitar, strings, etc.

Features

  • Variable Bias Tube Compressor
  • Parallel Dual Tube Circuit
  • Custom 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
  • 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
  • Master out features an additional, Passive Equalizer with two fixed sounds
  • Brainworx plugin only features such as TMT, M/S Processing, Mono-Maker and Stereo Width, Parallel Mix and Headroom

Audio Examples

Industry Reviews

  • Gentry Studer

    Gentry Studer

    I downloaded the plug in, I've had to shoot it out against the real thing on every project, just to see how it stacks up. You guys did an amazing job with the plug in. Everything from the color it… Read More

  • Michael Romanowski

    Michael Romanowski

    Coast Mastering, GRAMMY nominated Mastering Engineer (Soundgarden, Pink, Evanescence, Seal, Lady Gaga)

    I use the hardware SPL Iron for my mastering everyday. What I love about it is the tonal and dynamic flexibility is has for every style of music. And it’s always smooth and musical. Brainworx… Read More

  • Brendan Duffey

    Brendan Duffey

    When I need a tool that gives me a plethora of gain, tone and shape controls the Iron Mastering Compressor is the first thing I turn to. The Iron Plugin has all the controls features of the… Read More

Customer Reviews

  • SPL IRON Compressor

    ★★★★☆
    by Excellence
    I've been searching for a long time for a quality Mastering Buss Compressor. I am satisfied my search is over. The SPL IRON looks and most of all sounds Excellent. Tightens and glues everything… Read More
  • Must Have Vari-Mu

    ★★★★★
    by Station
    Was not expecting that much out of this, but definitely became my favorite plug on my stereo bus. Just dropping it on at the end is enough a lot of the time to give the last bit of punch and glue.
  • WOW

    ★★★★★
    by oberholz_music_berlin
    Invisible-compression chameleon. Love it.
  • Iron

    ★★★★★
    by Chuck Baker
    This one stands out.......Nice iron quality to the sound, not brittle but smooth. Distinctive distortion when pushing. This company is reaching deeper into what I like to hear with this sound. Thank… Read More
  • Great sounding compressor, but...

    ★★★★☆
    by deadscenerecords.com
    I really like the sound of this compressor, especially with Germanium 1mF; however, I strongly dislike the incremental input and output at steps of 2dB. I understand this is a reflection of hardware,… Read More

Specification

Supported Plugin Formats
AAX DSP, AAX Native, AU, AAX AudioSuite, VST2, VST3

Supported Operating Systems
MacOS 10.9 through 10.14
Windows 7 through 10

Mac
Intel CPU only (minimum 2 GHz recommended)

PC
Intel-compatible CPU with SSE2 instruction set (Pentium 4 compatible or higher; minimum 2 GHz recommended)

System Requirements
Display resolution: 1440 × 900px or 1280 × 960px or higher
Memory: 2 GB RAM

Downloads

With the Installation Manager, you can select, download and install just the Plugin Alliance products and formats you need for your system.

ChangeLog

IRON

SPL IRON - Changelog

Version 1.2.1 (Feb 04, 2020)
- General: Processing performance improvements for all formats and platforms

Version 1.2 (Nov 06, 2019)
- General: Qualified for use with macOS 10.15 Catalina
- General: Qualified for use with Windows 10 November 2019 Update
- General: Fixed plugin validation in Logic under macOS Catalina
- General: Fixed preset name restore in Logic when reopening a session
- General: Fixed opening authorization dialog triggering automation
- General: Improved instantiation times for plugins
- General: Improved license functionality and branding for subscription
- General: Removed 32-bit support on macOS and Windows
- Fixed automation highlighting for the lower area in the mono version

Version 1.1 (Jul 10, 2019)
- General: macOS 10.14.5 Update compatibility
- General: Windows 10 1903 Update compatibility
- General: Fixed activation issue in Windows hosts set to non-English language (e.g. Cakewalk)
- General: AU: Fixed issue with increased CPU and memory on reopening UI
- General: VST3: Fixed issue with adapting to host knob mode, and now prioritizing linear
- General: VST3: Fixed issue with VST3 preset permissions
- General: VST3: Improved synchronization between parameter states and some UI functions, e.g. toolbar reset
- Fixed artifact when switching between LR and MS modes
- Fixed GR meter not being shown in Pro Tools
- Fixed UI coloring not being saved with session

Version 1.0 (Jan 9, 2019)
- Initial Release