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Foote Control Systems P4S ME

Mastering Compressor By Bob Thomas
Published October 2016

Foote Control Systems P4S ME

Mastering engineers looking for a compressor with a distinctly vintage flavour would do well to check out Roger Foote’s latest creation.

California-based family company Foote Control Systems, formed in 2003 by musician and electronics engineer Roger Foote, have established a strong reputation amongst mastering engineers, courtesy of their P3S ME Stereo Mastering Compressor. That device combines a pristine audio path, switchable input and output transformers and Roger Foote’s unique technical approach to compressor side-chain circuitry. It’s a high-performance stereo compressor that can add colour when required and, as an example of the P3S ME in action, Foote told me that it was used by mastering engineer Antoine Chabert on the final masters (all formats) of Daft Punk’s Random Access Memories, which, among many other plaudits, won the 2014 Grammy for ‘Best Engineered Album, Non-Classical’. Not being one to rest on his laurels, Foote set out to design another mastering compressor that would offer an alternative tonality — the fruit of that work is the “vintage-sounding” P4S ME.


The P4S ME is a 2U rackmount device, whose engraved, powder-coated (the review model was silver but other colours are available) front panel carries the main controls. These include attack (0.15 to 15 ms/dB), release (15 to 150 ms/dB), threshold (-8 to +15 dB), ratio (1:1 to 4:1) and make-up gain (0 to 11.5 dB), plus a five-position side-chain high-pass filter (with options of 50, 80, 120 and 240 Hz). Of the three illuminated latching buttons, one toggles between peak (in which the attack and release controls are active) and RMS detection, the second between feed-back and feed-forward operation, and the third puts the unit into hard-wired bypass. A single LED ladder displays up to 5dB of gain reduction in 0.25dB steps. The rear panel is populated by the channels’ transformer-balanced XLR inputs, outputs, and TRS side-chain inserts, together with the multiway connector for the external switch-mode power supply. Hand-applied self-adhesive identification labels serve to emphasise the fact that, like all FCS products, the P4S ME is hand-built by Roger Foote personally.

The inputs and outputs are balanced by Cinemag transformers, which form an integral part of the audio signal path — they’re always in circuit unless the unit is in bypass. All compression controls are 24-position, single-gang, precision resistor ladders, built on Elma switches, to offer accurate repeatability of settings. The P4S ME circuitry is based on that of Foote’s P4DMS (Dual Mono Stereo) bus compressor, which has been reconfigured with (amongst other changes) a new PCB layout to produce a ganged-stereo mastering unit. The audio signal paths are essentially uncomplicated — input transformer to THAT 2002X VCA pack, to FCS 2520-style discrete operational amplifier, to output transformer — and contain no monolithic components.

As with all FCS compressors, the complicated part lies in Roger Foote’s individual take on side-chain circuitry, and in particular on the management of the control signals, using the experience that he gained during his career in instrumentation electronics. In the P4S ME, as in other P4-series compressors, the side-chain detector circuitry is based around the now discontinued THAT 2252 high-speed RMS level detector, of which FCS were (fortunately) able to purchase sufficient numbers to be able build a total of another 700 P4-series compressors.

The rear panel hosts all the Carnhill transformer-balanced connections, as well as a connector for the external switch-mode power supply.The rear panel hosts all the Carnhill transformer-balanced connections, as well as a connector for the external switch-mode power supply.

In Use

Once in circuit, the P4S ME imparts a definite sense of character to the audio passing through it. For me, there’s the feeling of rich warmth that I’d expect from high-quality transformers, and this supports a detailed soundfield, with real depth and width. This detail, depth and width are maintained under compression, which probably reflects not only the quality of audio components and circuit design but also the stability (I can’t think of a better word) of control in the side-chain.

In addition, the low-frequency extension is superb with, for example, the transients and depth of the low B string of a bass guitar being cleanly delineated in a quite exceptional manner — not to mention a quite stunning delivery of the bass end of EDM tracks. The high end sounds clear and extended and, in reality, the limits on the audio performance of the P4S ME will be those of the source material and the engineer’s ears.

Conveniently, I’ve just had to retrieve the Sony F1 Beta format digital copy master of an LP that I co-produced back in the late 1980s, in order to supply a WAV file of the track for a compilation CD. The track in question is a highly dynamic finger-style acoustic guitar performance that accompanies a similarly wide-ranging overdubbed male vocal, both of which were recorded and mixed to analogue tape with minimal compression and a few fader rides.

Thanks to the sterling services of Martin Nichols of the White House Studios in Weston-super-Mare, who did the F1 transfer to the analogue domain, time-aligned the stereo tracks — the F1 format uses a single D-A converter running at 88.2kHz producing a 11.3 s (half-sample) delay between the two tracks at 44.1kHz — and digitised the result, I had a pristine WAV file to work with. Given the quality (or lack thereof) of the F1’s converters, the WAV sounded a bit harsh compared with my copy of the vinyl LP. I also felt that the voice and guitar were fighting each other a bit, especially in the mid-range and high frequencies, and that the guitar seemed to be a bit out of control around 100-200 Hz.

My first attempt at sorting this out was with the P4S ME in RMS mode, with feed-back compression, the side-chain HPF set to 160Hz, a ratio of 1.35:1 and the threshold adjusted to give me approximately 2dB of compression. With this setup, the track sounded much more ‘together’ but there was still this sense of conflict between voice and guitar that I felt needed to be brought under control. I tried lowering the threshold and upping the ratio, and while that didn’t achieve what I was looking for, it did prove that the P4S ME, set to RMS in feedback mode, could be extremely transparent — virtually undetectable in operation, in fact, provided I was sensible.

Having switched to peak mode and experimented with different attack and release times alongside threshold and ratio, it didn’t take me long to realise that the feed-back mode just wasn’t working for this track because, in order to get the track where I wanted it to be, the gain-reduction level had crept past the point that gave me what I wanted to hear. Going over to feed-forward compression was, for this track, the magic bullet; I was quickly able to get the warring parties into peaceful coexistence. The feed-forward settings that gave me what I wanted to achieve sonically resulted in about half the amount of gain reduction that was produced when I switched back to feed-back operation so, next time round, I think I’ll probably start with the feed-forward mode rather than feed-back!

Foote Control Systems P4S ME


Sonically and operationally there’s nothing to criticise in the P4S ME. Roger Foote set out to design a vintage-sounding stereo mastering compressor of the highest quality and he has more than succeeded in doing so. Yes, I could quibble about the lack of such modern innovations as a wet/dry mix control or a Mid-Sides compression option — but to do so would be somewhat churlish in the face of the unit’s superb overall performance.

High-end hardware stereo mastering compressors occupy an esoteric position in the recording equipment market and they carry price tags that are commensurate with their component quality, the smaller market and, related to that, low-volume production runs. In addition, the mastering engineers of my acquaintance have in-house equipment setups that reflect their individual tastes and workflow processes, and each produces results that are as individual as their personalities. Foote Control Systems’ P4S ME Stereo Mastering Compressor fits right into those two scenarios. By any measure, it is an exceptional piece of audio equipment, with its own somewhat vintage character, and it should be auditioned by every mastering studio and engineer who is looking either to purchase a new stereo mastering compressor or to upgrade an existing unit.

Although I won’t be able to justify the expenditure required to make this P4S ME mine, I’m very impressed — and having noticed that FCS produce several lower-priced P4-series compressors, a couple of those are now on my must-hear list. If you’re not a mastering engineer, you might want to check those others out instead.


There’s not overly many VCA-based mastering compressors around, but the Vertigo Sound VSC-2, SSL XLogic G-series and RND Portico II Master Buss Compressor each have mastering in their list of possible applications and, of course, there’s always FCS’s own P3S ME to bear in mind.

There are some other wonderful mastering compressors around that are not VCA-based, but they tend to come with price tags that are considerably higher than that of the P4S ME.


  • Switchable RMS and manual peak modes
  • Switchable between feed-back and feed-forward side-chain topologies.
  • Five-position side-chain high-pass filter.
  • Produces superb results.
  • High-quality components and construction.
  • Delivers outstanding performance at an attractive price in its intended market.


  • None, assuming you like a slightly vintage feel in your sound.


The P4S ME is a stereo compressor designed specifically for use in a mastering workflow. It performs flawlessly at the highest level, and gives a vintage, transformer-based sonic sheen to signals passing through it. A superb compressor that deserves to be taken into consideration by everyone working in audio mastering.


$4750 plus shipping, import duty and VAT.

$4750 plus shipping.