SPL IRON V2 Dual-Tube Mastering Compressor

Operating Principles of a Compressor

The basic operating principles of a compressor/limiter can be easily explained. The level of an audio signal is reduced according to the specified Attack time and Ratio whenever it exceeds a given threshold. This reduction ceases when the Release time elapses, while the compressed signal is amplified with the Make-Up Gain. Compressors basically differ from each other in the technology used. This technology tubes, opto, FET, or VCA - is what gives a compressor its particular character. Some units sound soft and silky, some sound pounding, while some others make sound fatter, and there are those that make sound clearer, harder or more percussive. The trick resides in how the unit is technically designed, in the signature of the maker. Different compressors with the exact same settings might work and sound completely different. They provide different sounds for different applications and music styles. Nowadays, the compressor has become a key element when it comes to provide dynamics and punch to any production. The number of compressors available is huge and it‘s easy to succumb to the promises made by software emulations and analog recreations of vintage gear as the perfect solution. Unfortunately, many of these emulations and recreations differ quite a bit form their original counterparts. You must simply accept that the components used today, like the transformers, tubes and all other passive elements, are different to the ones originally used and that they can‘t be digitally emulated. No software (DSP-emulated compressors) or hardware replica will ever be able to sound like the original. An authentic sound can only be achieved with the original unit.

IRON Mastering Compressor

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 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. 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.