Full disclosure out of the gate – Sam Winston, who is Squarewave Industries, has been a good friend for many years. He brought the initial breadboard version of the Comptroller to my studio a few years ago to play around with component values as he was putting the initial circuit together. Sam has my total respect as an equipment designer/engineer, as well as a genuinely excellent human, so call me a little biased if you must. Many of his designs are for clean, mastering-style situations, but the Comptroller is a different beast; it is a stereo VCA compressor followed by a JFET limiter. This is not a generic “gently-control-dynamic-range-and-keep-things-sounding-pretty” dynamics processor. It can be gentle, but it’s much more fun as a spotty, snarling processor!
The front panel has seven switched controls for Input Gain, compressor controls, and limiter Threshold; there is also a variable Output at the end. The compressor section has the typical Attack/Release controls found on many compressors, but it also has a Contour control that works in conjunction with the Attack and Release to shape the envelope of the signal. There’s a Compression knob that behaves similarly to the ratio control on most compressors, plus the Threshold control. Whereas most compressor circuits place the Threshold control ahead of the Attack and Release, the Comptroller puts the threshold after those, and when combined with the Contour, it allows for some radical reshaping of the incoming transient signal as well as how it is presented to the threshold and where the onset of compression occurs. While most compressors begin to react when the incoming signal crosses the threshold, the Contour control, when set to higher values, effectively adds a delay to the transients and stores this energy until after they have crossed over; this energy is then released and contorts the response of the circuit before settling into normal compression. Sam has included some excellent diagrams in the Comptroller manual (downloadable from the Squarewave website) to visually help explain what is happening and why you should want it (think incredible mangling of drum sounds).
Following the compressor is the JFET peak limiter, which has three modes available on a toggle switch – Soft, Medium, and Hard. These increasing levels of peak reduction are based on where the limiter Threshold is set. The limiter is always in the circuit, but it can effectively be bypassed with Threshold at the highest value while set to Soft. The Hard mode at a middle range on Threshold will entirely prevent the output from clipping converters downstream of the Comptroller.
Following the limiter are the options for the compression Detector; this is normally fed directly from the output of the compressor circuit VCA, but switching on Post PK Lim moves the detector post-limiter. This is an additional way to manage the Contour and transient detection by smoothing out transients if they are more dynamic than you would prefer. Powerful stuff! The single input detector circuit derives the control voltage from a sum of the left and right channels; engaging the Mono button will take the right channel out of the detector so only the left channel defines the control signal. This allows you to have two mono signals coming into the Comptroller and have the left channel trigger the compression on the right. Or, if you are sending a single channel into the Comptroller (left is for mono only), Mono will ensure that the proper level of the left channel reaches the detector. Many compressors have a high-pass filter in the sidechain of the detector to prevent low frequencies from sources like kick drums and bass guitars or synths from triggering the compressor too quickly. Sam went against convention and put in a 12 dB per octave, 500 Hz low-pass filter instead to allow only those low frequencies to trigger the detector – another fun trick to help shape the Contour! The external sidechain is engaged by a switch and allows you to feed it an EQ to act as a de-esser. There is also a Key input option, which feeds the sidechain input through a separate VCA so you can trigger compression from a completely different source for creative pumping effects.
The previous paragraphs should give a good indication that this isn’t your average compressor. It is capable of some sonic tricks I’ve never heard another hardware or plug-in compressor do. It can make the drum bus of a kit mic’d in a small room sound anywhere from a little larger than life to positively explosive. Room mics can sound like they are in a warehouse, or you can use the Contour and limiter to shape them into little pips of sound. I love the Comptroller as an alternate mix bus compressor when not smashing it, as it can smoothly even out pokey transients while making the overall mix feel more glued together and wide. Sending two mono signals into each input while using the left channel to control the envelope of the right can lead to some very interesting and musical effects. It’s a bit of a box of magic!
There are balanced XLR inputs and outputs, as well as XLR I/O for the sidechain on the back panel. The built-in power supply can be switched from 115V to 240V just by changing out the fuse. Sam hand-builds each Comptroller with care and sources the PCBs, front panel, and enclosure from US companies. Given the care of construction and quality of components, you could imagine the Comptroller selling for a far more boutique price. I think it’s the finest specialized and workhorse stereo compressor you can buy. I guess I am still a little biased.