Styled in red, the SPL IRON Compressor is a two-channel, variable-bias compressor and limiter intended for use in the mastering process. It is inspired by the classic designs found in Fairchild and Gates compressors, which utilize remote cut-off tube biasing to achieve a musical type of dynamic restriction. However, the IRON updates this design for a new modern era with several interesting features.
First, the compressor offers an ancillary sharp cut-off tube path in parallel; this topology can lead to much more transparent compression. Also, an independent feed-forward resitive opto-isolator has been placed in the control path of the tube circuit. This limits peaking, and allows for a small amount of THD when compared to other compressors of a similar ilk. The sonic byproduct of this desgin is a smoothier, silkier sound.
You'll also note a complex rectifier circuit, which changes the attack and release times, curves, and all around behaviors; this rectifier circuit makes the compressor truly versatile, and able to accommodate all sorts of program material. The compressor offers tube biasing, for more minute control.
For connections, SPL supplies the IRON with balanced XLR terminations on the inputs and outputs, and 1/4" jacks on the sidechain inputs. You'll also find a built-in sidechain EQ for filtering the sidechain signal, ensuring no stray kick drum accidentally triggers the compressor. However, note that this sidechain filter goes beyond the usual HPF found on many a compressor; complex filtering shapes are provided, so you can better tune the compressor's behavior to respond to individual elements within a mix, such as vocals or guitars. A power cord is included.