SPL IRON Mastering Compressor

The IRON Mastering compressor 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 is also perfect for the needs of modern mastering studios and 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 vactrol-opto-isolator. Thus, the output signal remains lively even with a high gain reduction. The compression is only noticeable with extreme settings.

The Tube Bias has three different settings. Together with the Input Gain of up to +/- 12dB and the Threshold control, it allows the compression behavior of the tubes to be perfectly adapted to any material.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).
The Sidechain EQ is yet another option to adjust the Iron to the signal being processed in an optimal way. It allows you to choose between an external EQ or one of the four internal EQ presets. The EQ presets have a complex frequency response and have been conceived with different program material in mind. Only the control signal is affected, not the actual audio signal. In the Off position, the Sidechain EQ is inactive.

After the compression stage, the signal can be boosted or attenuated up to +/- 12dB with the Output Gain, which makes the Iron easy to integrate into any signal chain.
All functions can be adjusted via switches or, in the case of the Threshold, with a detented potentiometer, making it easy to replicate exact settings.

The compressor has an additional passive 120V equalizer to give the output signal the finishing touches. You have two different EQ presets to choose from: AirBass and Tape Roll-Off. The AirBass mode gently boosts high and low frequencies approx. 2dB. For its part, the Tape Roll-Off mode is based on the frequency response of a tape machine and uses a high and a low-cut filter.

Both the left and right channels have separate illuminated activating switches. Further, in Auto Bypass mode you can use the Interval control to set a time frame during which the compressor automatically toggles back and forth between the processed and unprocessed signals. This makes AB comparisons between the original and compressed signals a breeze, besides making it easier to assess the settings in context.
The ergonomic design and clear arrangement of the control elements make working with the compressor more intuitive, while its shallow housing makes the Iron perfectly adaptable to tabletop rack stands.

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.

Features:

• 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