The red SPL Iron Mastering Compressor is a tube-based stereo compressor designed to add vintage quality warmth while mastering a mix. 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. The compressor's output signal remains lively even with a high gain reduction, and the compression is only noticeable with extreme settings.
The tube bias has three different settings. The attack and release parameters have six different settings ranging from slow to fast. 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.
After the compression stage, the signal can be boosted or attenuated up to ±12 dB with the output gain, which makes the Iron easy to integrate into any signal chain. The compressor has an additional passive 120V equalizer to give the output signal the finishing touches. The 120V rail technology helps reproduce the finest details and deliver a relaxed-sounding audio experience.
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. Both the left and right channels have separate illuminated activating switches. The ergonomic design and clear arrangement of the control elements make working with the compressor more intuitive, while its shallow housing makes the Iron adaptable to tabletop rack stands. In addition to mastering sound mixes, the Iron can also be used to process individual instruments, like vocals, bass, guitar, and strings.