Recording Channel Strip

Preamps / Channel Strips

Published December 2025

With switchable input impedance, dual compression voicings and a semi‑parametric EQ on board, the Pro Channel III certainly offers tonal versatility. Could it be your next ‘front end’?

Founded in 1984, ART Pro Audio now seem to have been delivering competitively priced preamps, processors and other audio products for as long as I can remember, but it strikes me that in recent years a number of their rackmount products in particular have really grown into maturity. We looked at their Solo MPA & Solo VLA — the former a preamp, the latter a compressor — about a year ago (SOS November 2024) and my fellow reviewer Bob Thomas seemed pretty much blown away by the combination of sound and facilities for the price, noting as his only ‘con’ the lack of side‑chain filtering on the compressor. ART have now combined elements of both those devices with an EQ, to create a full channel strip called the Pro Channel III, which is currently available in North America (but not yet Europe or the UK), and is reviewed here.

Overview

The Pro Channel III comes in a black, 2U 19‑inch rackmount steel chassis, whose front panel is divided visually into four sections, and whose profusion of knobs all control detented pots. The construction quality seems decent to me, and the finish on the front panel is similarly pleasing, and certainly on the review unit the detents all seemed to line up nicely with the panel labels and other markings.

The left‑most section is the preamp, of course, and next come the EQ and compressor in that order, but their position in the signal path can be reversed Finally, a ‘master section’ comprises a large analogue moving‑coil VU meter with a recessed trim pot, and this can be switched to show the input or output level. Below this, a 10‑LED gain reduction bar meter for the compressor comprises one yellow and nine red LEDs. And to its right, a master output level control is labelled from silence minus infinity to +15dB. This doesn’t actually quite give you full attenuation, but there’s certainly a useful practical gain range on offer here. This knob serves both to set the main output level and as the makeup gain stage for the compressor. Doubling up in this way is an understandable decision when balancing costs and benefits, but note that since the Master knob remains active when the compressor is bypassed, it’s not as easy as with some units to compare the compressed and uncompressed signals.

The insert point means you can patch, say, a de‑esser or gate/expander in between the preamp and compressor/EQ stages, but the return point can also be pressed into service as a line input.

Around the back, you’ll find a balanced input XLR socket, and the balanced XLR output is paralleled on a TRS jack, and there’s a button to set the operating level to +4dBu or ‑10dBv. The maximum input levels are +22 dBu in the +4dBu setting, and +13 dBu for ‑10dBV, while the maximum output level is +26dBu. Unusually, for what’s a relatively affordable device, there are also two TS jacks providing separate (unbalanced) insert send and return points. Obviously, the insert point means you can patch, say, a de‑esser or gate/expander in between the preamp and compressor/EQ stages, but the return point can also be pressed into service as a line input. That cuold be useful, since while the preamp did seem happy to accommodate line‑level signals, some might prefer not to risk exposing line‑level devices to phantom power, or prefer to have the line input available separately from the mic one on a patchbay. You’re bypassing the mic/instrument preamp when you patch in to the insert return, so you have no input gain control and will need to manage that with the computer or device your routing to it, but it could be a handy option. Finally, there’s a standard IEC C13 power inlet (with integral fuse compartment) for the internal power supply, and this accepts 110‑240 V and 50/60Hz mains AC.

As well as the XLR mic input, there are balanced outputs on TRS jack and XLR, and there are separate TS jacks for the unbalanced insert send and return.

Stages

The FET microphone preamp stage has knobs for Gain (0‑40 dB) and a wide‑ranging sweepable high‑pass filter (10‑250 Hz). There’s also a +20dB gain boost switch, which is rather like having a Cloudlifter‑style clean‑gain booster preamp on board, and takes the total input gain range to 0‑60 dB — though that’s not counting the ±15dB in reserve at the Master output level control. What there isn’t is a pad of any sort, and thankfully that didn’t seem necessary — the Gain button doubles as a clip LED, and when hitting a snare drum hard with a sensitive mic placed close to the batter head, I never encountered a situation the preamp couldn’t cope with.

Further switches engage +48V phantom power and select the input impedance, the options being 600Ω (useful for some vintage mics, and potentially coaxing a different character from passive dynamic mics) and Max, which at a whopping 47kΩ should present a suitable load to almost any mic. There’s also an 800kΩ front‑panel instrument jack that takes precedence over the rear‑panel mic inputs. And while we’re on the subject of input impedance, the aforementioned insert return presents a 7.5kΩ load, and the unit’s output impedance is given as a suitably low 47Ω. The final control in this section is the master on‑off rocker switch — and it’s good to see this on the front rather than tucked around the rear.

While there’s no polarity inverter in the preamp section, you’ll find one in the adjacent compressor. Here, you also have knobs for the familiar compression controls, again all fully variable across their range: Threshold (‑30 to +20 dB), Ratio (a very gentle 1.25:1 up to a near‑limiting 20:1), Attack (0.25 to 50 milliseconds) and Release (0.15 to 3 seconds). As you can see, those ranges are all pretty generous, so allow you to configure the compressor for pretty much any application. Of course, that also makes the controls quite sensitive in operation, but there’s a pleasing physical resistance so it’s not that difficult to dial in your desired settings in practice. Beneath, alongside the polarity inverter, are three more switches: Voice, which switches between a FET compressor and a valve‑amplified optical compressor; Comp, which switches the compressor in/out of the signal path; and a button to toggle the order of the compressor and EQ in the signal path...

Which leads us neatly on to the stage — whose low and high shelves and two swept‑mid bands combine with the preamps high‑pass filter to give you five bands in total with which to shape the sound. Each of the EQ section’s four bands has a ±12dB gain knob. For the 12kHz high shelf, in fact, that’s all you get but it’s ample for brightening or taming the top end and of course its gentle curve reaches much further down into high mids than its nominal turnover frequency. The low shelf, on the other hand, has a switch to toggle the turnover frequency between 40 and 120Hz, while the two central bands have generously variable frequency knobs, ranging from 20Hz to 2kHz for the Lo‑Mid band, and 200Hz to 20kHz for the High‑Mid. So there’s plenty of overlap, and that last one can operate well beyond the mids, should you want more control over the high end than is offered by the HF shelf alone. Generally speaking, this emphasis on versatility is very welcome, as it means you really can deploy this strip on pretty much any source, but the flip side of this coin is that small movements of the controls can result in significant changes. There’s no control over the bandwidth, which seems to be a proportional‑Q type — in other words, the greater the boost/cut, the narrower it becomes. The final control for this section is an in/bypass switch for the EQ stage.

In Use

That concludes our tour of the facilities, so what’s this thing actually like in use — and how does it sound? I tried it with a range of mics, including moving‑coil dynamics, both a passive and active ribbons, and a couple of capacitor mics, to capture a number of sources that I felt should reveal any strengths and weaknesses of the Pro Channel III: vocals, acoustic and electric guitar, electric bass, a tambourine and a snare drum.

The preamp sounded decent to my ears. Not something that adds any obvious character to my ears, but coming across as clean and detailed, and I never had any difficulty finding the necessary gain — and, importantly, that includes the minimum gain, which allowed me to capture very hard snare drum hits close miked with a sensitive capacitor mic without problem. The switchable VU meter also made it really easy to dial in sensible amounts of gain, as well as setting the master output level. I did find it a little strange to have to look to the ‘compressor section’ for the polarity inverter, but it wasn’t what I’d call a problem. The passive pickups of my bass and a couple of guitars also seemed perfectly happy running into the instrument input, and as with the mic preamp I never struggled for level or noticed any obvious character being imposed.

The preamp’s clean character is, of course, complemented by the various other options on board. The single‑pole (6dB/oct) high pass filter’s smooth slope is designed, say ART, “to remove rumble, pops, and wind noise,” which it did successfully. But since it’s continuously variable up to 250Hz, I found it equally useful in correcting for proximity effect bass boost, and for working in tandem with the EQ section to shape the bottom end and low mids of various sources. So full marks for versatility there. Some might lament the fact that this HPF can’t be switched out of the channel path entirely, but while its lowest 10Hz setting does mean a very small phase shift, it’s as good as off for most real‑use cases.

I like to shape things with EQ and compression ‘on the way in’ — I know that it’s fashionable to record ‘clean’ and put processing off until later, but I’d much rather get close to the right sound down in the first place, and even if you err on the side of caution, it generally makes the job of mixing easier down the line. I wouldn’t say there’s huge character on offer in this EQ stage outside of the boosts and cuts you dial in — it’s pretty clean sounding in the style of a typical console EQ — but any EQ can have a big impact on the tone, and this one is really quick and intuitive in use; the layout is familiar, and with just six knobs and one switch to control four bands, you’re never overwhelmed. The detents and apparently accurate legend that lines up with them nicely mean it’s pretty easy to jot down and recall settings too. And that makes it a decent all‑rounder EQ in my book. Certainly, I was able to dial up the breathiness in a vocal, to brighten ribbon mic recordings and, for example, to push up the mids nicely for various miked guitar cabs.

But it’s when you bring the compressor into play that you can really start to coax something more out of the Pro Channel III than ‘workmanlike service’. Its two flavours definitely impose different characters onto proceedings. The valve‑amplified optical circuit generally sounds, as you’d expect, gentler, more rounded and more relaxed than the FET one, which can be made to act in a much grabbier, more assertive fashion. I could often simply switch from one to the other and discern which sort of action I preferred — it was easy to hear that I preferred the Tube/Opto variant on a bass guitar, for example — but note that the different actions mean you will then most likely need to tweak the threshold, attack and release too (if not always the ratio). Either way, it was pleasing to have both options to hand, because each proved to be preferable on different material. It was also great having the option to place the EQ pre or post the compressor too; as well as allowing you to attend to any ‘issues’ before compression, such as the proximity effect bass boost I mentioned above, it can sometimes be great fun to crank the EQ a bit harder going into a compressor!

There were just a couple of small limitations worth mentioning. First, there’s no dedicated compressor makeup gain control — to restore any level lost through compression, you must use the Master output level knob, and since this remains active when the compressor’s bypassed you can’t easily A/B compare the dry and compressed signals, which can sometimes be a useful sanity check. It seems a missed opportunity that neither the HPF or any EQ band can be switched into the compressor side‑chain to fine‑tune its response. And it would be nice to have proper accommodation for balanced line‑level signals. But given the price of this thing, that all feels rather like nit‑picking!

The bottom line is that not only is the Pro Channel II a very versatile recording channel, but it’s one whose combination of sound and features mean it punches above its price bracket. If you like to get hands on with your processing, it could make a great affordable front end for any DAW‑based setup.

Pros

Clean‑sounding preamp and EQ.
Genuinely useful compressor options.
Very versatile.
Separate insert send/return.
Good metering, with front‑panel trim.

Cons

Compressor lacks side‑chain filter and dedicated makeup gain control.
A dedicated balanced line input would be nice.

Summary

A decent‑sounding recording channel, the Pro Channel III is definitely a cut above the more budget options out there, and boasts some impressive features for the price, not least the choice of optical or FET‑based compression.