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Kush Audio Clariphonic

Parallel High‑Frequency Equaliser
Published September 2011
By Eric James

Kush have established a reputation for unique‑sounding gear that features idiosyncratic controls, and their Clariphonic is no exception...

Kush Audio Clariphonic

Although Kush Audio's Clariphonic Parallel EQ falls into the general category of broad, tone‑shaping analogue EQ, it is unlike any other EQ that I know of. It has no bells or filters, just boost‑only high shelves, and it has a parallel signal‑path topology, about which I'll say more in a moment. It's not the only parallel EQ on the market, and it's not the only one that predominantly uses shelves for sonic enhancement... but as far as I know it's the only one that does both, and whose shelves have quite the shape and high reach that they do.


The Clariphonic doesn't look like any other EQ, either. It's a 1U rack design in the signature Kush Audio colours — a warm, muted brown with yellow highlights (Kush's full philosophy of 'general aesthetic eccentricities' can be found on their web site), and is small and neat, with just four chicken‑head control knobs, five small, silvered three‑way toggle switches for each channel, and three two‑way toggles in the centre. The rear panel has both balanced and unbalanced input and output connections, and a switch on each channel to choose between them.

Signals coming into the Clariphonic are split into six paths to allow for the parallel processing that lies at the heart of this design. Two, which form the FF path, go direct to a summing bus, and remain untouched. The other four go to the Focus and Clarity 'engines', where they're processed before being sent to the same output bus as the FF signal.

If that sounds confusing, the signal flow diagram overleaf should make this much clearer! In short, the design means that at the output the summed stereo signal is made up of one element which is entirely unprocessed, one that has passed only through the Focus engine, and another that has passed only through the Clarity engine.

The chicken‑head knobs provide gain control for each engine, and this determines the blend of the two that will be summed with the FF‑path signal. To hear just what those engines are doing to the signal, it is possible to kill the FF path. This is an interesting exercise in itself, but one which can be given some greater purpose by the possibility of splitting the signal in a DAW or mixing desk prior to feeding it to the Clariphonic, further manipulating the non‑FF blend (with compression, for example), and then mixing that back in with the original signal (although obviously this cannot be accomplished inside the Clariphonic itself).

So within each channel there are the two engines, but within each engine there are further choices. In the Focus engine, these are of two different shelf frequencies (Lift and Open), and two different shapes (Tight or Diffuse); and in the Clarity engine there's a choice of four shelves called Presence, Sheen, Shimmer and Silk. Although these qualitative labels seem cute and cuddly, I have to say that at first I found the lack of quantified information a tad irritating and potentially limiting — even though the manual provides approximate corner frequencies (respectively 800Hz and 3, 5, 9, 19 and 39 kHz), and an approximate description of the shapes (Diffuse is a normal shelving plateau, whereas Tight is "a gigantic Bell shape… gently falling off in the neighbourhood of 14kHz”).

In Use

The front panel of the Kush Audio Clariphonic equaliser.The front panel of the Kush Audio Clariphonic equaliser.

An invaluable skill for an audio engineer is knowing just how certain processing moves are going to affect the sound before you actually make them. Compression techniques for mastering and the mix bus, for example, are almost impossible to learn if you do not know what to listen out for (transient softening, bass reduction, pumping and so on) as you change the threshold or time constants. In this respect, equalisation is a bit easier, as you can EQ both positively and negatively using a sweeping technique, which highlights and identifies the frequencies you want to change. This works better for 'surgical' tasks than it does for euphonic improvements, though, and it's not the most time effective method when making a number of changes. So if your main professional role is as a mastering engineer, for example, where euphonic and surgical EQ is rather more than half the overall task, it's generally better to rely on identification skills that can be 'sort of' taught, but which grow quite naturally the more you listen to sounds and twiddle the knobs to see what happens.

When I have interns working with me, I introduce them to this topic by playing some music and asking: what will happen to the sound if I add, say, 1.5dB at 1.2kHz? What are the goodies to look out for (guitars generally), what are the nasties (can make the vocals irritating) and what can we ignore (sub‑bass, for a start)?

I'm a pretty well seasoned EQ‑er, and this anticipation of the effect is generally the way I like to work. Most times, of course, I have to adjust the first guess, but generally I have three or more EQ moves in my head before making any. This being so, my normal modus operandi was at first completely thrown overboard by the possibilities on offer from the Clariphonic! I had simply no idea what to expect if, for example, I dialled in a small handful of Diffuse Open‑ness, and what was worse for my professional pride was that because I didn't know quite what to listen out for (what can you expect when you add an unspecified amount of boost at 39KHz?), it seemed to be taking a long time to learn.

From the very beginning, however, some mix‑fixing things worked immediately and very well, without me knowing precisely why, and this was a pointer for the future. I had a troublesome mix to master that was both fizzy and muddy, and my repertoire of standard EQ approaches was just about coming to a frustrating and fruitless end when the Clariphonic arrived.

Reading through the manual (for a change!), I came across the first of many useful hints provided by the very helpful designer, Gregory Scott. 'Lift' (the lowest shelf), he tells us, is "absolutely amazing for breaking open the mids and top on sources that are too low‑mid heavy or boomy… it has the power to completely transform the energy and attitude of a recorded sound”. Fearing designer guff, I sceptically ran the unprocessed mix through the Clariphonic, chose the Tight profile — with just half of the available boost because of the warning that "Lift …can get very aggressive, very fast” — lit the blue touchpaper, and retired to a safe distance.

Scott is not exaggerating in the slightest when he uses words like 'amazing' and 'transformation' to describe the effects of his creation. The difference this one tweak made to this troublesome mix was so unbelievably good: it un‑muddied the low mids in a way that I simply hadn't anticipated from a high shelf, and which no amount of knob‑twiddling on a standard EQ had so far managed to achieve. I immediately printed the result and sent samples of the original and 'Clariphonicked' tracks to three other mastering engineers to get their reactions, which were uniformly enthusiastic.

The parallel signal flow in the Clariphonic.The parallel signal flow in the Clariphonic.

Then I wrote to Gregory and asked him how on earth he did it! I asked for a few more technical details, explaining that, like many engineers, I don't like flying blind. His reply, in essence, was "get used to it: it's good for you,” the main point being that he deliberately used descriptive rather than numerical tags for the parameters, because to do otherwise, he said, would encourage a certain set of expectations that would tend to become rigid and limit creative possibilities. Likewise, the heavy reliance on switches was intended to help break familiar patterns, and thus encourage new ways of using the EQ.

Some people might react unfavourably to this kind of approach, insisting that an engineer needs to know his tools, and that this advice to 'suck it and see' simply sucks. Indeed, this would probably have been my reaction if the Clariphonic hadn't already realised some of its potential on that muddy mess of a mix. But that persuaded me to start working with the unit, exploring a few settings, learning a few things.. and I soon began to feel a little more at home. I comforted myself with the thoughts that these engines were just shelves (long, low and slender shelves, but shelves nonetheless), and that those corner frequency figures must mean something to be going on with.

On one project, I had a drum stem that was a tad too sleepy for the song. The snare was 'correct' enough, but it wasn't really sufficiently present. I gave it a quick injection of 'Tight & Open' and it all came much more to life, as the top end of the toms came into focus and the snare drove things a little more. After my initial enthusiasm with that setting, I realized that the overheads had become just a touch too forward. I'd started that fix with the boost at about midway to maximum, and mindful of Greg's other piece of advice ("When in doubt, take what you think is a sensible amount of boost and cut it in half”), I reduced this to a quarter turn. The result was that the overhead problem disappeared, but all the fixed goodies remained.

Much the same kind of thing happened with vocals when using the Presence engine. Although at first the bigger handful seemed to do the trick of lifting the voice up without changing its character or throwing it out of balance, I found that far less than that avoided introducing sibilant splashes and was all that was required to do the work.

Clarity & Focus

In general, I found that although the Presence and Sheen from the Clarity engine had their place for raising slightly lifeless mixes, the Clarity engine was most useful for individual elements, and the Focus engine for entire mixes and stems.

What went missing from bypassing the Focus engine was often fairly obvious: instruments and voices would drop back into the mix — you would have to listen a little harder to hear them — and for some performances, the energy levels seemed to turn down a notch. The Focus engine is a great antidote to saggy mixes.

What was notable by its absence when the Clarity engine was bypassed could be almost as obvious, but is much harder to describe, as the linguistic resources we have to deal with these higher frequency ranges are simply not so well developed, and you can find yourself tempted to start wittering on about emotional responses rather than engineered reality. Avoiding all that, I can point out, for example, that the whisper element in female vocals could be brought out, with all the advantages in certain situations that whispering has over full vocal cords; that acoustic guitars could somehow be made to sound more expensive; and that cranking this range a little more for almost anything recorded with a ribbon microphone was generally very, very rewarding.

As these examples indicate, I found that although Presence and Sheen from the Clarity engine sometimes had a place in helping the Focus engine to further raise slightly lifeless mixes, in general the Clarity engine was most often used on individual elements, and the Focus engine for entire mixes and stems. It probably was not designed with this in mind but, as the Shimmer and Silk frequencies are simply too high to affect any of the naturally present harmonic information of most music (except maybe a dog‑whistle quartet!), for my own way of working, the Focus was the problem solver and the Clarity provided the euphonic additions.


Is there a down side to all this? Not in itself: what the Clariphonic is designed to do, it does beautifully. Of course, it might be that, having such a special nature, it needs to have a special place in an outboard rack. What I mean by this is that it is not designed to address the whole range of issues that most EQs are: it has no cut, only boost; it has no bells, and no filters. So it would have to be added to a setup that already had an EQ or two in place for the more workaday aspects of mixing and mastering. But if you already have those, this could be a welcome addition.  


There are no EQs I can think of with these particular features. The Dangerous Music Bax EQ has the shelves, but it is rather closer to being a standard EQ package.

Published September 2011