PYE 4061S

Ted Fletcher breathes new life into this venerable old name.

Ted Fletcher has been involved in a number of audio companies over the years. He designed the original Alice consoles, for example, and was behind both the original JoeMeek and TFPro brands, whose gear earned plaudits. Today, Ted’s again designing for Alice, who recently acquired the PYE brand name, and he was invited to design and build a high‑end stereo compressor that would be worthy of the old name. One of his aims was to keep the operation as simple as possible, in line with the ethos of hardware used in the 1960s, but to improve on the noise performance of those vintage devices. The result of his endeavours is the PYE 4061S, and while it may have little in common with the original PYE compressor’s circuitry, it is nonetheless impressive.

Design & Operation

Described as a 21st Century analogue levelling amplifier, the PYE 4061S is a stereo feed‑forward compressor that’s designed to sound as transparent as possible, both when controlling peak levels and when used for longer‑term levelling. It’s billed as being suitable in the recording chain for tracking, for track processing during mixing, and for mastering. The circuit employ’s Ted’s previously proven ‘sum and difference’ mode to eliminate stereo image shift when processing stereo signals.

The ‘feed‑forward’ description relates to the way the gain‑control circuitry is configured. Most compressors work by sensing the output level from the compression stage and then feeding it back to the side‑chain and gain‑control stage, which might be typically a FET, VCA or opto‑electronic circuit. By contrast, a feed‑forward compressor monitors the input signal’s envelope and then sends this information on to the gain‑control element, which in this instance uses a transconductance amplifier in the feedback path of a high‑performance BA4580 op‑amp. Ted says this feed‑forward analogue limiter/compressor design adjusts its compression ratio in a way similar to the old Altec compressor, but without introducing low‑frequency bumps and without the overshoots of the slower valve circuitry. By the way, there’s no external side‑chain access, as the topography of this circuit doesn’t have what you’d recognise as a conventional side‑chain.

The 4061S is housed in a 2U rackmount case, with a reassuringly thick, white‑painted front panel. On the front, a pair of illuminated moving‑coil meters monitors the levels and gain reduction. Levels of up to +28dBu can be handled by the output stage, which employs circuitry built around UK‑built Stevens & Billington transformers. Two illuminated buttons bypass the compressor and switch the metering from showing either the left and right levels, or showing the mono level on the leftmost meter and gain reduction on the right.

The controls are set out clearly, with an input gain knob allowing for up to 20dB of gain, using balancing transformers configured in Ted’s favoured current mode, which improves the low‑frequency performance. It’s by adjusting this input gain control that you set the amount of compression — there’s no separate compression or threshold knob — and the output level is then adjusted to taste (or to suit the next device in the chain) using a gain make‑up control. As with typical soft‑knee compressors, the higher the input level the greater the compression ratio, and when pushed hard the compressor ratio gets very close to pure limiting.

In addition, there are controls for attack (an eight‑way switch that includes an Off option) and release. When attack is set to Off, the compressor no longer applies gain reduction but the signal does still pass through the transformer input and output stages, and both the input and output gain controls still function. The Stereo Width control is made possible because of Ted’s aforementioned sum‑and‑difference approach to compression, and is essentially a Mid‑Sides balance knob, enabling a stereo source to be ‘dialled back’ to mono or widened up to 150 percent of its initial spread. The left‑right channel balance can also be adjusted using a Balance control. All the pots have a reassuringly smooth action and everything is clearly labelled.

The transient response can be set very fast — the attack time can be set from 0.2ms to 25ms — while the release is variable from 100ms to four seconds. At the fastest attack, which is under a quarter of a millisecond, the brief overloads that can sneak through a compressor circuit should be too short to be audible. The wide range of release times makes this device well suited to a range of different stereo compression and limiting duties.

On the rear panel, the balanced inputs and outputs are presented both on XLRs and quarter‑inch TRS jacks, making connection to other gear convenient. Also on the rear, you’ll find the IEC mains AC power inlet, and most common international voltages can be accommodated. The total power draw is under 6W.

The XLR inputs and outputs are duplicated on TRS jacks, so you should have no trouble finding a suitable cable!

Easy As PYE?

Those more used to plug‑ins with fast faux‑LED metering will need to get used to the more restrained ballistics of moving‑coil meters, which is especially noticeable when processing things like drums with a fast release time — in that scenario, the gain reduction meter may barely have time to blip before the sound has passed, and in such situations you must rely on your ears rather than ‘going by the numbers’, the more so because of how fast this compressor can operate. Of course, the engineers of yesteryear all worked that way, because moving‑coil meters were the only game in town, and once you’d learned to work with them you came to appreciate how intuitive they actually are: for most sources, they relate pretty well to the dynamics of human hearing perception.

I get the impression that Ted designed the PYE 4061S to be used more as a polishing tool rather than adopting the ‘angle grinder’ philosophy of things like the Empirical Labs Distressor, and that’s consistent with his previous designs (which I’ve enjoyed). Obvious ‘character’ compression is not the main focus, and there may well be other compressors that are more appropriate if your aim is simply to add some attitude to a track or mix. Having said that, though, if you push it hard it will start to slam in a very audible way when processing something like a drum track.

The 4061S seems to be ‘kinder’ to the high frequencies, such as the cymbals in a drum track, than some other compressors I’ve tried.

Still, to me it seems best‑suited to dealing with level‑balancing situations without making its presence too obvious — even when it is being used quite assertively. Also, to my ears, the 4061S seems to be ‘kinder’ to the high frequencies, such as the cymbals in a drum track, than some other compressors I’ve tried, with the result sounding somehow pleasing and natural. It works very well for tightening up bass tracks, although as the attack and release times can be set very fast, there’s some skill involved in setting it up — it’s important not to set the release time to be too short if used in combination with a fast attack, as the compressor can then respond so quickly that it reacts to the individual cycles of a low‑frequency input, rather than to the overall envelope, and that manifests itself as distortion. This isn’t a fault — just a possibility with any very fast compressor, and something the user has to keep in mind when treating very low‑frequency sounds.

A common challenge in mixing that every engineer faces is that of a vocalist with an excessive dynamic range or imperfect mic technique. The usual solutions involve using both level automation and compression, and in this role, the PYE 4061S does an excellent job of mitigating excessive peaks without making vocal sounds appear obviously compressed. At longer release times, it acts well as a leveller, smoothing out sounds that fluctuate in level over a longer time period and, because the compression ratio adjusts automatically with the input level, high‑level peaks get pushed down harder while more well‑behaved sections are treated more lightly. Again, that’s helpful in maintaining a sense of transparency. Those longer release settings can also work well when processing complete mixes or submixes, as they can help ‘glue’ the parts together. But as every job is a little different, it all comes down to using your ears when deciding how much compression to add and what attack and release times work best.

With the attack control set to its Off position, the signal can be treated to a trip through the circuity and transformer stages without any compression being applied. While the overall aesthetic is clean and transparent, as with any well‑designed transformer there’s an audible effect that’s subtle but still somehow flattering, adding just a hint of warmth and depth.

Conclusion

In summary then, the PYE 4061S is a high‑quality compressor that keeps operation simple, and has proven itself very effective for tackling a wide range of limiting, levelling and general compression jobs, just as it was conceived to be. It’s one I’d recommend reaching for more where you want control while still preserving the original character of the source sound, rather than using a compressor to beat and bend sounds into a different shape. But it’s capable of very fast attack and release times, so it can still get very assertive if you want that. The Mid‑Sides widening is a very useful tool to have to hand when compressing stereo sources too.