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Foote Control Systems P3EX

Stereo Compressor By Bob Thomas
Published September 2016

Foote Control Systems P3EX

Foote’s latest design could be that rare thing: a mastering-grade compressor for the masses.

Roger Foote’s mastering compressors are very highly regarded, but their price has always been commensurate with their reputation. His latest product, the P3EX stereo compressor, is designed to deliver a similarly high level of performance, but it’s intended for recording and mix engineers, and is available for rather less money. The businesslike appearance of the P3EX reflects Foote’s singular focus on performance. Whereas most devices these days have a screen-printed front-panel, this compressor’s legends are engraved through the black paint into the thick steel beyond; there’s zero chance of them becoming illegible this side of the next millennium. The compression controls feature winged Elma Classic Collet knobs on Alpha rotary pots, and the combination has a tangible sense of quality.

In addition to attack, release, threshold, compression (ratio) and makeup-gain pots, the P3EX is also equipped with a switchable side-chain high-pass filter, with options of 50, 80, 120, 160 or 240 Hz. A simple, horizontal LED ladder, scaled from 0-20 dB, displays the amount of gain reduction being applied to both channels. There’s no input or output metering but given the unit’s ability to accept and output a maximum of +24dBu, that won’t be an issue in day-to-day operation.

Next to the meter sits a row of three buttons, the first of which switches the side-chain detectors from peak to RMS (Root Mean Square) operation. In RMS mode, a compressor responds in a similar fashion to a human ear, in that short-duration sounds aren’t perceived as being as loud as a more sustained sound at the same level. An RMS compressor will therefore tend to deliver more natural-sounding compression. The downside is that short, fast, high-level transients may well pass through almost unaffected. Because of this, a common approach is to follow an RMS compressor with a fast peak limiter, in order to keep the transients under control. In Peak mode, as the term implies, the side-chain responds more accurately to brief signal peaks than in RMS mode.

The second button switches the P3EX from its default ‘soft-knee’ compression curve to ‘hard-knee’ mode, producing a firmer, more assertive control of the signal level, and a final red button activates the hard-wired bypass function, taking the unit out of the signal path entirely.

On the back panel are transformer-balanced stereo XLR audio inputs and outputs, TRS jack inputs to the left and right channel side-chains, and a multiway connector for the external power supply. Simple, self-adhesive labels identify what’s what, and their presence emphasises the fact that each and every FCS product is hand-assembled, tested and calibrated personally by Roger Foote.

Inside The Box

With the top off, the high standards of workmanship and component quality are immediately evident. Chunky, steel-core Edcor transformers take care of input and output balancing, wiring looms are very neatly executed and all components on the PCB are discrete and full-sized, with no sign of anything surface mount anywhere. One of Roger Foote’s stated imperatives is that his compressors must be able to be calibrated in the field so, to this end, the P3EX is fitted with 19-turn precision trimmers, one for each detector for precise gain-response matching, one for each VCA to trim symmetry, and one for each of the Class-A output sections to trim the final gain.

There are two parts to a compressor: the audio path from the input, through the VCA and makeup gain to the output; and the side-chain, where attack and release timing, detection, detector-signal processing, control-current generation and so on takes place. Roger Foote has drawn on his experience in instrumentation control technologies to develop what he describes as a “different way of treating the VCA from anybody else”, by being in the fortunate position of being able to port control-circuitry practices from the biomedical, scientific and aerospace industries over to his audio products. Foote believes that it is the differences in the way in which the control signal is manipulated in his compressor designs that endows these units with the performance that has built their reputation in the mastering market.

The rear panel hosts the balanced analogue I/O and a connector for the external power supply.The rear panel hosts the balanced analogue I/O and a connector for the external power supply.

According to Foote, unlike earlier FCS compressors, the detector circuitry in the P3EX has been designed to make it respond faster, thus optimising its peak reduction performance. As a result, its RMS mode has been derived from its Peak mode rather than, as in FCS’s other units, being the other way around. The P3EX’s attack and release controls are active only in peak mode, and have timings of 0.15-15 ms and 1.5-15 ms, respectively. The available compression ratio is continuously variable between 1:1 and 20:1, and 30dB of makeup gain is available.

Finally, the audio specifications are impressive: the quoted frequency response of 20Hz to 20kHz (-0.34dB, +0.07dB), noise of -102.7dB, THD of 0.14dB and channel crosstalk of -100.3dB are amongst the best that I’ve encountered.

In Use

There’s a lot to like about the sound of the P3EX, provided that you enjoy, as I do, the coloration that transformers provide. At nominal levels, the transformers and Class-A output stage produce the sense of warmth, depth and harmonic enrichment you’d expect and, when driven harder, saturate to deliver sonically and musically attractive increases in distortion; I could easily be tempted to leave it in circuit across my mix bus just for the sound of its transformers alone.

In Peak mode, with hard-knee compression engaged, the P3EX can deliver all the aggressive pumping you’re ever likely to need. In its soft-knee setting, with attack, release and threshold set appropriately for the track being processed, it’s extremely effective at bringing peaks under control without there being excessive collateral damage. Twenty-five or so years ago, when analogue tape was the only recording medium available, I’d have killed for a compressor like the P3EX when tracking bass guitar and drums. Its abilities are no less relevant in this digital age. To my ears, the Class-A output stage does seem to be particularly capable at delivering a clearly delineated, solid-sounding bottom end and that, I think, is what makes the P3EX a such an effective bass-guitar and kick-drum compressor. That said, it’s no slouch on vocals and guitars either!

Sitting across a stereo subgroup or mix bus in soft-knee RMS mode, the P3EX turned in superb performances. It doesn’t only have that prized ability to gently ‘glue’ a mix together; it’s able to level tracks out more aggressively as threshold is reduced and compression is increased. The on-board high-pass filter in the side-chain was very effective in avoiding unwanted compression being triggered when working with material containing significant low-frequency content, and the five selectable frequencies made this easy to tune for different material. The P3EX also produced a very solid, detailed and stable stereo soundfield — that could well be down to the combination of the unit’s superb audio specification and Roger Foote’s unique take on VCA handling.

Another important aspect of the P3EX is just how easy it is to find the right level and kind of compression. Once I’d set the input level to produce my desired amount of transformer character, operation was almost intuitive, especially in RMS mode.

Since it is both effective and good-sounding, the P3EX also makes a superb parallel compressor. Unfortunately, there’s no wet/dry mix control, which would have made that configuration more convenient to set up, but that certainly wouldn’t stop me from buying one.

Foote Control Systems P3EX


The FCS P3EX Stereo Compressor is a very capable, versatile and impressive device that exhibits a distinctly transformer-influenced character and a level of control that never gave any indication that it was in any way struggling with the source being fed into it. Having switchable Peak and RMS modes adds to its versatility and the combination of these and its superb audio path enables it to deliver very high levels of performance.

Roger Foote has written that he put the finishing touches to the design phase of the P3EX with fast-tempo electronic music and heavy metal in mind, and I found nothing whatsoever to contradict that statement. That said, I don’t think Foote’s words should be regarded in any way as limiting the P3EXs undoubted abilities to those two fields alone; it’s far more versatile than that.

As with any transformer-equipped piece of gear, a lot will depend on whether or not this particular unit’s sonic signature appeals to you. I really liked its character and would be more than happy to own a P3EX, but it has to be said that I couldn’t envisage it being the only compressor in my collection.

One tiny fly in the ointment for those of us on this side of the Pond in the UK is that the P3EX is only available directly from Foote Control Systems in the USA. This is a bit of a shame, as the P3EX is superb; I don’t feel it would disappoint anyone looking for a high-quality, transformer-balanced VCA compressor. If that pairing is your thing, the P3EX will certainly deliver it for you. On the plus side, buying direct probably keeps the purchase price well below where it deserves to be for a unit of this quality!


By taking the direct-sales route FCS have priced the P3EX well below where it would otherwise sit in the market; I can’t think of a directly comparable product that isn’t considerably more expensive. However, at around the same approximate price, you’ll find capable units such as the IGS Audio S-Type Bus Compressor, a stereo pair of Warm Audio WA76 compressor/limiters, the Roll Music Super Stereo bus compressor and that worthy old perennial, the Aphex Compellor.

Three’s Company

Roger Foote’s involvement in electronics goes back his childhood when, inspired by his grandfather, he became a serious audio electronics enthusiast, and this eventually led to a 20-year-long career as a senior instrumentation technician in the design and manufacture of wireless data acquisition and control systems. During this time Foote continued his obsession with audio electronics, designing and building dozens of compressors, EQs, synthesizers and electronic organs in his spare time, and gained much of the expertise that enabled Foote Control Systems (FCS) to be founded in 2003, the idea being to make Roger Foote’s audio processor designs commercially available. Staffed by Roger, his wife Karen and their son Justin, FCS truly are a family company.


  • Superb audio pathway.
  • Has that ‘warm’ transformer sound.
  • Switchable peak/RMS and soft-/hard-knee modes.
  • Top-drawer compression performance.
  • Designed with tracking and mixing in mind.


  • Lacks a wet/dry mix control.


This is a very impressive compressor, boasting a superb audio pathway and Roger Foote’s signature compressor side-chain implementation, and it offers tremendous performance for the price.


$1450 plus shipping, duty and VAT (approximately £1350 at the time of going to press).