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Wes Audio Rhea

Stereo Vari-mu Compressor By Matt Houghton
Published November 2022

Wes Audio Rhea

This powerful 500‑series processor combines Wes Audio’s cutting‑edge digital control technology with the timeless sound of valve compression.

We’ve featured several Wes Audio ng500 modules in SOS and have found them all impressive, in terms not only of the digital remote control but also the analogue electronics and the build quality more generally. The Rhea, which joined the range late last year, is a stereo module which occupies two vertical slots in the 500‑series host chassis. It’s billed as a vari‑mu compressor, meaning that the valves are responsible for the gain reduction, not merely amplification. As with others in this range, it’s compatible with any VPR Alliance‑compliant 500‑series chassis, but to use the control plug‑in you must plug a USB cable (one is supplied) into the front‑panel port. A tidier option is to use Wes Audio’s Titan, a 10‑slot 500‑series rack which makes use of a small connector on the Rhea (above the standard 500‑series contacts) to cater for data transfer. All ng500 units installed in the Titan can communicate with the plug‑in over a single USB or (better for longer distances/multiple machines) Ethernet connection.

At the heart of the analogue side of things are two new‑old‑stock (NOS) Russian 6N3P dual‑triode valves. One is used in each signal path, with one half responsible for general amplification and the other gain reduction. Wes say they not only test and match both valves but do the same for the triodes in each one, to minimise ‘thumping’ and ensure consistent gain and gain reduction in both channels.

The valves, which take care of both amplification and gain reduction, are carefully matched NOS Russian 6N3P types.The valves, which take care of both amplification and gain reduction, are carefully matched NOS Russian 6N3P types.Unlike in vintage vari‑mus, while the gain reduction itself is performed by valves, the sidechain circuitry, which dictates when and how much gain reduction is applied, is entirely solid state. Some purists (snobs!) may scoff, but it’s an approach that’s necessary given the form factor — the Rhea already accommodates two valves and a pair of Carnhill interstage transformers, so there’s little space, and more tubes would make heat management nigh impossible. (The Rhea already runs pretty warm; you won’t want to cover the vents of the host rack!). The sidechain circuitry has, though, been designed to exhibit valve‑like behaviour.

LED‑ing By Example

The Rhea is a true stereo compressor, with a single set of controls governing both channels. Unlike with some other Wes processors, then, dual‑mono or Mid‑Sides operation isn’t possible, though you can use the Rhea to process one mono source (it sounds lovely on vocals and bass guitar!).

The front panel is styled like Wes’ other ng500 modules: clean‑looking, with minimal black labels on a painted white front panel and, for the most part, it’s easy to read. If viewed from above, as when the unit sits on a desktop or in a rack beneath, some labels are obscured by knobs, but you soon grow accustomed to what’s where — and there’s always the plug‑in remote control! A white backlit (perhaps a tad too bright) gain‑reduction meter dominates the upper third, and below are six knurled‑knob rotary encoders, each circled by tiny LEDs, along with a quintet of buttons and the mini USB socket. The LED indicators have been beautifully judged. The ‘background’ brightness is tastefully dulled but easy to see in pretty much any studio lighting conditions, and those for a specific control grow brighter as you make adjustments (whether via the hardware controls or the plug‑in).

While, technically speaking, the encoders all select switched settings, for some of them (Input, Threshold, Output and Mix) the steps are so tiny as to create the impression of a continuous pot. As these pseudo‑continuous controls are turned, their white LEDs change brightness, giving great, detailed visual feedback — there are 16 LEDs for these parameters, and several degrees of brightness for each. The more obviously switched Attack and Release encoders are distinguished visually with red LEDs, while individual green LEDs give feedback on the status of the five buttons. A couple more, adjacent to the USB port, indicate when connection with a computer is established and data being received.

The buttons engage some nifty functions. THD offers three degrees of harmonic distortion: off (or ultra‑low; there’s always some!); Medium; and High. SC Filter places a high‑pass filter (off, or 60, 90 and 150 Hz) in the sidechain, to reduce sensitivity to energetic low‑frequency signals. A Bypass button acts on the whole wet signal path including the Input gain and Output level. The two buttons either side, labelled A and B, are hardware memory slots. This makes possible instant comparison between two different control settings (or the ability to switch between two active projects — handy if working out of the box, though the plug‑in has the ability to store/recall many more presets). Pressing and holding the B button overwrites its stored settings. Given the bypass setup, I liked that I could use B, with threshold to max, to bypass the gain reduction while leaving the transformers and tubes in the signal path.

Soft Centre

Getting up and running with the hardware takes almost no time: plumb it into your 500‑series rack, switch on and it’s ready to use. As with any tube processor, though, it’s probably an idea to allow the valves to warm up. It’s not that it sounds ‘bad’ initially, but the sound seemed to stabilise after 10‑15 minutes, and that’s going to be important if you’re making decisions about the sound or recalling previous settings.

While you’ll always be able to use this as a standalone hardware device — whatever happens in the future world of operating systems and drivers! — I can’t imagine that anyone will be planning to use it without the plug‑in. To do that, you must install Wes’ driver and plug‑ins. Yes, plug‑ins plural: you can’t install the Rhea plug‑in without installing the rest of the ng‑series control plug‑ins, which is fine for DAWs which allow you to manage your plug‑in lists, but could be annoying if working with one which doesn’t! The latest versions work with Mac OS and Windows, and support AAX Native, AAX DSP, VST2, VST3 and AU plug‑in formats, and there’s no authorisation process. I should stress that there’s no A‑D/D‑A conversion in the Rhea — the plug‑in doesn’t handle audio but is purely for communication with the analogue hardware. So the Rhea needs to be connected to your DAW/audio interface (or mixer, patchbay...) in the usual way.

The DAW plug‑in for Mac and Windows caters for two‑way communication with the hardware, and allows storage of many more presets than on the hardware alone.The DAW plug‑in for Mac and Windows caters for two‑way communication with the hardware, and allows storage of many more presets than on the hardware alone.To establish a data connection you click a drop‑down at the bottom of the plug‑in GUI. Any connected devices compatible with the plug‑in are detected and you simply click on the one you wish to control. You could, in theory (though I had no way to test it), have multiple Rheas connected to different plug‑in instances. When connection is first established, the plug‑in reads and updates to reflect the current settings on the hardware unit. Communication is then two‑way: adjust a hardware control and the plug‑in GUI will update accordingly; adjust a virtual control and the hardware’s data light will blink and the settings and LEDs will track the moves you make on the plug‑in. Save and close your DAW project, and the next time you load the project the hardware will automatically recall the settings in the plug‑in loaded in that project. That arrangement is usually very convenient, but you can also suspend communication using a logo in the bottom left‑hand corner of the GUI — handy to prevent settings for an outside‑the‑box mix from being overwritten when opening a DAW session.

The plug‑in has a similar comparison facility to the hardware, though here the A and B are joined by a C and, if you scroll along in banks, all the way to X. This is great for quick comparison of multiple settings, but there’s also an undo/redo facility and more conventional save/recall of presets. The tiniest gripe here is that you can’t simply type in a name and hit save, but have to enter a category and author name too. You can use your DAW’s own preset facility if you find that tedious, but if you create a lot of presets it does help you to keep things organised!

The two‑way communication isn’t just about saving and recalling static settings: you can use your DAW’s plug‑in automation to capture any real‑time moves you make, whether on the hardware or software, and to play those moves back again. I realise that you’re pretty unlikely to want to do crazy things in real‑time with a vari‑mu compressor; typically a bus compressor will be left on the same setting throughout a project or even for every project. And in any case, if you go too wild with the switching you’ll hear some low‑level clicks (an inevitable side‑effect of the switched approach, and Wes have done well to minimise it). But it does open up the possibility of, for example, using different thresholds or drive settings in quiet verses and big choruses.

The GUI is scalable up to 200%. 100% is already a decent size on my 1080p screen, and 150% pretty much fills it vertically, while 200% should be handy for high‑DPI screens. I also found 200% useful with my 1080p touchscreen; while it’s slightly larger than the screen can accommodate, all the knobs fit onscreen and become really easy to turn in finer increments (eg. the finest 0.25dB steps for the Input gain).

In Use

Whether you prefer to use the plug‑in, the hardware controls or both, operation is really intuitive. The behaviour in terms of gain reduction is in classic vari‑mu territory, though with the fastest attack times there’s perhaps a touch more of the ‘modern’ and ‘solid’ about the sound than you might expect. Yes, it always remains flattering and expansive, there’s a certainly flair and sparkle, it exhibits that ‘easiness’ that feedback compressors always do, and yes it’s well suited to use on a stereo mix bus or in a mastering setup. But used in this way, it also tends towards a rather ‘tighter’ and more ‘focused’ sound than vintage‑style vari‑mus are typically capable of, and I found that really handy on the drum bus generally, and especially for parallel compression on a rock mix’s drum‑plus‑bass bus.

Setting aside the compression for a moment (which you can do simply by setting the threshold to max, fully clockwise), it’s possible to use the Input and Output level controls to use the tubes‑plus‑transformers circuitry as a distortion/saturation processor. There’s a significant and very audible difference in the level of harmonics across the Input control’s range, with second and third harmonics becoming increasingly audible as you start to turn it away from the fully anticlockwise position, and higher harmonics making a greater contribution as you get towards the extremes. As you then start to bring down the threshold and gain reduction is increasingly applied, the contribution those harmonics make to the sound increases. As you’d expect of tubes and transformers, it’s generally a pleasing character; a combination of thickness at the low end and low mids, and a sort of ‘flair’ higher up.

You can use your DAW’s plug‑in automation to capture any moves you make, whether on the hardware or software.

Between the Input, Threshold and Output knobs, then, you already have a huge amount of creative tonal control. But there’s also the dedicated THD facility, whose contribution in other Wes devices I’ve explored before and whose appeal is probably greatest on the drum bus or perhaps basses (whether guitar or synth). I’m sure plenty of people will enjoy it on other instruments but this is where it seems to work best for me! Do bear in mind when assessing the contribution of the THD settings that each step up adds about 1.5dB to the overall signal level. While I’m on the subject of levels, the review unit’s two channels were always closely matched, regardless of the settings.


In short, then, this is yet another very appealing processor by Wes Audio. Sonically, it’s firmly in vari‑mu territory, and while it does have its own sound there’s nothing really ‘quirky’ about it; I like it very much. And with the wet/dry mix for parallel compression, a pretty snappy fastest attack for a valve compressor, the THD feature and the ability to drive the circuitry harder to really put the signal in its sonic sweet spot before fine‑tuning the gain reduction, there’s so much control available. Then there’s the price... There are very few stereo vari‑mus available for this sort of money, and this one boasts huge USPs: precise digital control and recall on the hardware, and slick DAW plug‑in remote control. As I’ve opined before, I reckon Wes have really nailed that side of things.

If you’re into your analogue hardware, fancy a vari‑mu and like the idea of instant recall, you owe it to yourself to check out the Rhea. I wonder if Wes might think about a rackmount version like their ngBusComp. Hmm...


  • It’s a vari‑mu, and it sounds great!
  • Option for pretty fast attack times.
  • Versatile feature set.
  • Full digital recall of analogue settings.
  • Plug‑in remote control and works with DAW automation.
  • Keenly priced for a stereo vari‑mu.


  • Runs a tad warm.
  • Labelling not always easy to see.


Wes remain at the top of their game: this is a stunningly good processor that blends high‑quality analogue electronics with digital control and seamless integration with your DAW.


£1199 including VAT.

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