From the Sound On Sound article on Mix Compression (May 2008 -
https://www.soundonsound.com/sos/may08/ ... ession.htm)
"FET compressors use a particular type of transistor to control the amount of gain reduction, similarly to the way a triode tube works, and are not as widely used for mix bus applications as optical or VCA models, thanks to a distinctive bright and focused sound quality, which can become less pleasing with the amount of gain reduction that is applied. The attack times achievable are generally much faster in FET models than any of the other three analogue compressor types. For this reason FET models are generally used and thought of as limiters. There are, however, classic and modern units available that can produce great results when used on the mix bus..."
That paragraph alone should be pretty eye-opening, if you thought the Softube FET compressor works anything like a standard compressor.
The best source of information regarding the Softube FET compressor RE can be found in their plugins PDF manual, on page 47:
http://download.softube.com/manuals/Sof ... Manual.pdf
Here are some excerpts from the manual that illustrate some of the differences between a standard compressor and the Softube FET compressor:
"The original hardware has some quite quirky circuits, and a lot of its sound comes from far from ideal components and design."
"The Input knob on this compressor works both as a gain control and a threshold control. If you increase the Input volume you will also increase the gain reduction, which makes it work sort of like a combination of a gain knob and a reversed threshold knob. You can drive the INPUT VU far into the reds without any unwanted digital clipping. Just make sure that the OUTPUT PEAK meter doesn’t indicate any clipping. (If it does, just lower the Output volume a bit.)"
"Ratio: The ALL mode ('All Buttons In') is a peculiarity found on this type of compressor. Originally the different ratios were selected with push buttons, which made some mix engineers try out what happens if you press all buttons at once. From a technical perspective, pushing
all buttons at the same time makes all bias levels go berserk. From a sound perspective, this means that you will get a very pumping compression with lots of distortion. This mode is often called the “British mode”. By setting the Ratio somewhere between 20:1 and ALL you’ll get a sound that’s definitely unique for this product."
"If the Ratio knob is set at ALL, the Gain Reduction meter won’t show the same results as the original hardware. Instead it will display the actual gain reduction (which the original unit doesn’t). You will also notice that the Gain Reduction sometimes display positive values when the Ratio is set at ALL, which is correct. The ALL mode does indeed have negative gain reduction (=positive gain) for some settings."
"The attack time on this unit is very fast, ranging from about 20 μs at the fastest setting to about 800 μs (that’s micro-seconds!) on its slowest setting. Other kinds of compressors often have much slower attack times. In comparison to the attack time the release times are much slower – ranging between 50 ms and 1.1 s. Please note that these numbers only give a general idea of the attack and release times. In practice (and just like in the modeled hardware), the attack and release times will be program dependent, ie. depend on the characteristics of the input signal."
Once you wrap your head around the device and get comfortable with the controls, you will likely find that for some types of program material the FET works wonders on the signal, whereas for other types of program material you are better off using a more conventional compressor.