Page 2: Steinberg AXR4

A Touch Of Silk

The line inputs offer a choice of three different calibration settings, which is very useful, while the mic inputs have numerous additional controls available. All of these are, again, accessible using the front-panel buttons if you prefer, and include preamp gain, individually switched phantom power and pad, polarity, a high-pass filter and the optional high-impedance mode for the first pair. The turnover frequency of the high-pass filter is a freely variable global setting. Preamp gain is variable from +15 to +68 dB in 1dB steps, with the pad extending the lower range of this by 20dB.

Preamp gain is also affected slightly by the introduction of the Silk emulation, which operates in the digital domain courtesy of Yamaha's circuit-modelling technology. An apparently undocumented consequence of this is that it adds a short delay when engaged: this amounts to only nine samples, so not a significant problem in the scheme of things, but enough to be an issue if you're recording the same source through two inputs and Silk is engaged on one.

Silk can be either Red or Blue, and can be applied in varying amounts using a dial scaled from zero to 10. Red mode introduces a high-frequency lift extending from 10kHz or so upwards, while Blue mode does the same at the other end of the spectrum, rounding out and boosting the bass. There is also a non-linear aspect to the silkiness, with a certain amount of saturation and limiting taking place as things are cranked up.

I'll confess that I don't quite see the point in having digital signal conditioning at the front end of the recording chain, though I suppose conceptually it's not so different from UA's Unison technology. Given that it doesn't do anything you couldn't recreate later with plug-ins, my feeling is that you might as well record flat and keep your options open. The same goes for the high-pass filter, which presumably also operates in the digital domain.

Having used the AXR4 pretty extensively, I do absolutely feel confident in its sound quality, its stability and, above all, that it won't make the engineer look silly in the middle of an important session!

That apart, I generally liked dspMixFx, and although it's not a glamorous piece of software, it does boast a number of thoughtful design touches that make it easy to get along with. One that I particularly liked is the show/hide window, which allows you to quickly and easily specify exactly which channels you want to see. You never need to have the window cluttered up with endless digital channels you're not using! Quality-wise, the reverb is more than adequate for cue-mixing purposes, and more importantly, it's easy to introduce at the click of a mouse when needed. The 'vintage-style' EQ and compressor plug-ins likewise seem simple and effective, and any criticisms I can muster are pretty insignificant in the scheme of things — it would be nice if scrolling using a touchpad was supported, and for some reason the sub-window that displays the output channels can't be resized, so it's always four channels wide regardless of how many you enable in the show/hide dialogue.

Perhaps more restrictive to some will be the limitations of the AXR4's internal mixing and routing capabilities that are exposed in dspMixFx. The most obvious of these concern monitor control. The unit's assignable front-panel rotary controller defaults to acting as a volume control, but all this amounts to is that it can move one of the mixer's output faders up and down. Volume control is thus happening prior to the D-A converters, with attendant potential for loss of sound quality if you drag the fader way down, but also the potential for clipping, since these faders have headroom above unity gain. These issues are perhaps more theoretical than practical, but what's disappointing is that Steinberg haven't taken the opportunity to embrace the potential advantages of digital volume control. It's not possible to gang together multiple output faders for surround volume control, and neither in dspMixFx nor on the front panel will you find mono or dim buttons, talkback, alternate monitor switching and so forth. Consequently, I think that many AXR4 users will need to budget for an external monitor controller, or carry out monitor control in software.

Headphone routing is also a little unusual. The headphones don't have dedicated output busses that can be addressed directly from your DAW. Instead, each analogue output pair has two headphone symbols, allowing that pair to be selected as the source for Headphones 1 and/or 2. As long as you're not using all the outputs for other purposes, this is perfectly fine and, in effect, allows you to dedicate spare outputs to the headphones. However, if you want the headphones to mirror the main output, as is often the case, it means their level will be affected by that of the output fader and main volume control, as well as the headphone volume control; and that if you mute the main output in order to do a control-room overdub, you'll also mute the headphones.

Xtra Special

As you'd hope given its price, the AXR4 boasts technical specs that are impressive, and in some respects state-of-the-art. THD+noise is particularly good, at just 0.0004 percent on inputs 1-4 and 0.0006 percent on the other inputs and outputs. The mic and line inputs boast a dynamic range of 119dB; unusually, the line outs perform marginally less well, at a quoted 117dB. No EIN figures are quoted for the mic preamps, but there's no doubt that they sound clean and clear throughout their very wide gain range, unless you intentionally introduce coloration with the Silk emulation. Subjectively, I thought it a very good-sounding interface, and easily on a par with the rival units mentioned at the start of this review.

Thunderbolt interfaces generally offer excellent low-latency performance, and again, the AXR4 is no exception. It doesn't quite match up to PreSonus's Quantum range, but at a 32-sample buffer size, the reported round-trip latency was 4ms at 44.1kHz. A loopback test confirmed that the true figure was actually a few samples less than this. However, as with all interfaces that offer multiple I/O types, it should be noted that latency will vary slightly across these; and, as noted earlier, the Silk emulation introduces an extra nine samples' worth of delay into the input path.

When you're trying to evaluate the strengths and weaknesses of a review product, there's no substitute for using it on a real session, and the AXR4 found its way onto a particularly complicated live tracking date. The excellent Tape Runs Out are a seven-piece band who combine conventional rock instrumentation with hammered dulcimer and violin. With 20 or so inputs in action, there was quite some potential for confusion, and the floor of the live room looked like a disaster in a cable warehouse. However, I never once found myself looking at the AXR4 and scratching my head in puzzlement, and it coped admirably with everything from close-miked snare to delicate folk instruments. The dspMixFx utility made it easy to configure the monitoring setups I needed on the fly, and to apply 'comfort reverb' for vocal overdubs at the click of a mouse.

Not having used a Steinberg interface for many years, I wasn't quite sure what to expect from the AXR4, especially as it is such a departure for the company. It turns out to be an excellent product and, perhaps most reassuringly, one that feels surprisingly mature and polished. Personally, I'd rather all those front-panel buttons were used to implement talkback and decent monitor control than to replicate functionality that's more easily accessible in the dspMixFx software, and others might be disappointed that its versatile selection of I/O doesn't include any Ethernet audio protocols, but ultimately, the most important quality of an audio interface is that it inspires confidence. Having used the AXR4 pretty extensively, I do absolutely feel confident in its sound quality, its stability and, above all, that it won't make the engineer look silly in the middle of an important session! If you're looking for a high-quality, multi-purpose audio interface in this price bracket, the AXR4 should definitely be on your list to try out.