This unassuming processor reminds us how much fun can be had playing with distortion and filters!
Analogue saturation and distortion is something I don't believe software can yet mimic perfectly, and certainly not without hogging computing power. Even if you disagree, I find that it's often an effect that benefits from hands‑on control in any case, so it's always worth checking out analogue hardware which has been designed specifically to create this sort of effect. LA‑based Overstayer have been around for a while now, having started out with a FET compressor in the 1176 vein and then branched out a little, but they remain a small‑ish 'boutique' manufacturer, who still do custom‑build work. I recently got my hands on their Saturator NT 02A, after it came highly recommended to me by someone whose ears and opinions I trust.
Being a solid‑state device with an external PSU, the Saturator is surprisingly lightweight for a 19‑inch rackmount device. Despite this, it feels professional rather than flimsy. A quick tour of the array of knobs and blue‑backlit lit buttons on the front panel tells you most of what you need to know, but there's more functionality than you might expect to find on a 'saturator'. First, on the left of each identical channel, there's a 12dB per octave low‑cut filter, with both a frequency (30Hz to 4.7kHz) and a resonance control (marked with a scale of 1‑9). The signal is then routed via a switchable clean‑boost circuit to the next stage that you've engaged. The saturation circuit that gives the unit its name is followed by a switchable fixed‑frequency high‑cut filter (6dB/octave at 6kHz), and both stages have their own in/bypass buttons. Next is a make‑up gain stage, based around a discrete op-amp. There are no details as to the amount of gain on offer (the legend runs simply from 1‑10), but in practice, it's ample: you can push things all the way to clipping should you wish. The basic signal path is completed by wet/dry blend and output level controls. There is, however, no way to link the two sets of controls for stereo operation.
The eagle‑eyed may have noticed another control, the intriguingly named 'Shape 3' button, which lies in between the gain and blend stages on the front panel. This engages a pre‑ and post‑emphasis filter, which affects the response of the whole unit, and a third‑harmonic generator (hence, presumably the '3'). The idea is to mimic the sortof saturation one might achieve with an analogue tape recorder. I should stress that this is separate from the main saturation circuit, so the two may be used together or independently. The single remaining control, on the far right, governs whether both channels are engaged or both bypassed. Around the back, there's very little to write home about: there are balanced XLR inputs and outputs for each channel, and an inlet for the supplied line‑wart power supply.
We're talking about spending well over a grand of your hard‑earned here, and even on a cost‑per-channel basis, that puts it up there with some very impressive preamps and processors. So what does this thing do to justify the cost? To answer that question, I ran various sources through it, played with the different settings, and compared it with similar processors that I own. In case you consider uniqueness sufficient to justify high prices, then let me say up front that the Saturator is going to be worth it, because I can't think of another device which combines all of the Saturator's functions in one, nor one which sounds quite like it. Add to that the fact that some of the stages can interact to create less predictable sounds, and you have something truly unique.
First up, I tried it on drums, both individual electronic and acoustic kit pieces and full‑kit stereo loops, and on electric bass guitar. On low‑frequency sources such as kick and bass, the main saturation sound is really pleasant, and very easy to control. You can achieve anything from tape‑like saturation to something much dirtier. That tunable resonant second‑order low‑cut filter is great — for kick-drum abuse in particular (I got some seriously dubby and huge‑sounding kicks), but more generally for sound‑mangling of synth bass parts, such as the ones I fed to it from a Roland Juno 6.
With more mid‑rangey sounds, courtesy of synth and electric guitar, the NT 02A's filter opens up a world of creativity. It sounds great, with a very pleasant character that suits guitar in particular, and in conjunction with the two filter stages, there's a vast tonal palette available. Routing the outputs of the Overstayer into a stereo delay unit such as my Eventide TimeFactor really demonstrated the beauty of the HP filter stage: I just didn't get tired of juggling filter and resonance controls. I lost the best part of an afternoon, wearing a big grin on my face and tweaking the controls, marvelling at the textures emerging from the delay with the filter hovering around the point of self‑oscillation!
At the same time, this box is capable of much more familiar and more subtle effects. The filters can be used to achieve a dirty‑telephone sort of effect, for example. Also, although the tape‑like saturation is a little thick for some applications, by backing off the wet/dry mix a little I was able to create some very usable settings for not‑too‑intrusive vocal processing. I wish more processors had a blend control like this, as it increases the possible use applications enormously without the need for a mixing desk.
So, it sounds great on a range of sources, it's fun and easy to use, and it's unique — so is there anything not to like? Were the price lower, I'd say not. But on a cost‑per‑channel basis this unit isn't cheap, and there's much more sophisticated control on devices by the likes of Looptrotter and Moog which do at least some of the same job.
On the review model, the two channels were not particularly well matched. This was most apparent when playing with the high‑pass filter: the point of self-oscillation on one resonance control was much nearer the full turn of the knob than on the other (which made me wonder what how consistent things are across different units). To be fair, most sources I'd want this sort of effect on are usually going to be mono — kicks, snares, bass, guitar, vocal effects. But then, there's no mono version (yet — see later), so why do I have to pay for two channels?
I thought I'd better give Overstayer a chance to address these points, and I'm glad I did. Having already jumped through the stereo linking/matching hoop with their FET compressor, they seemed well aware of those issues, and were happy to discuss potential improvements. Apparently, another product, which will offer users more in this respect — as well as a few more bells and whistles — will join the NT 02A on the shelves fairly soon. That may be a more expensive product, but if cost is a worry, I wouldn't be at all surprised to see a more affordable mono version in some format or other before too long, either.
In the meantime, if you're worried that the stereo functionality might be an issue for you, I'd say that it's still well worth trying out for the sound alone. It isn't really the sort of effect where you usually need precise recall, and I found that I soon got the hang of matching channel settings by eye/ear.
It's easy to see why there's a (nicely controlled!) buzz about this product, and unless stereo linking or stereo matching of the filters is a huge issue for you, I can heartily recommend the Overstayer Saturator NT 02A — because I haven't worn a smile this big on my face when testing a processor for years!
There are several analogue saturation devices which do some of what the Saturator does, but they all sound very different — and the Overstayer is one of the best-sounding to my ears. You might also want to check out devices such as the Sound Skulptor STS analogue tape simulator, the Looptrotter Sat2Rate, the Chandler Little Devil 500-series preamp and Moog's Moogerfooger and Minifooger processors — not to mention a whole host of boutique guitar pedals and synth modules.