Steinberg is on an impressive roll with sexy hardware interfaces, collaborating with Yamaha and Rupert Neve to deliver products that lean into the strengths of all three. The AXR4 is clearly meant to be a flagship in their hardware line, and it’s absolutely something to be proud about. Boasting 28 inputs and 24 outputs over a Thunderbolt 2 connection, with sampling rates up to 384 kHz and capable of 32-bit conversion with SSPLL ultra-low jitter reduction (sub-sampling phase locked loop), they’ve really pulled out all the stops! To be fair, 16 of those inputs and outputs are over ADAT or AES/EBU, which I didn’t test, so I’m not going to focus on them. As purchased with no expansion, this is effectively a four mic pre input, eight line input, and eight line output interface – I really like that the eight line inputs are separate from the four mic inputs. I also really appreciate that there are two Thunderbolt jacks, so you can easily daisy chain gear, like multiple AXR4s (supports up to three units)! I put together a stellar racked mobile rig with the AXR4 and a 500 Series chassis that included eight channels of Classic Audio Products, Inc. VP28s [Tape Op #95]. This allowed me to record twelve separate mics to individual channels in my DAW for some mobile sessions (I’m starting to call late March the “Tiny Desk Submission Season,” as I get a lot of fun gigs for that annual contest). When you install the drivers, you get the dspMixFx AXR matrix mixer and control panel. Once I learned my way around the app I preferred this as a remote option to set mic pre levels, to insert the built in zero-latency DSP plug-ins, and to build my monitor mixes.
Three Yamaha DSP plug-ins run internally, and they all sound excellent. You get a barebones channel strip that includes a nice VCA-style compressor, a fun drive knob, and a three band EQ. The Comp276 seems clearly inspired by an 1176, which should be familiar to most engineers. I was impressed with the EQ-601, which is a six band EQ where all four mid bands are fully parametric – really sounds fantastic! You can run two inserts on each channel, which meant I found little reason to the use the three band EQ on the channel strip, since the EQ-601 just gave me so much more to work with.
Each channel also includes an AUX send to a single (global) instance of Yamaha’s (again) zero-latency REV-X reverb plug-in, which includes a Plate, Room, and Hall. This seems intended for monitor mixes, which is exactly how I used it. I found the controls for the different reverb settings really nice to work with, and the visuals make it clear what each parameter does. However, since there’s no easy way to access any of the on-board DSP effects from a Pro Tools session, I ended up switching back to something available in my DAW for final mix down.
The four built-in preamps offer a lot of range, both in terms of gain and timbre. You’ve got up to 68 dB of digitally-controlled gain, plus two types of a digitally-modeled version of Rupert Neve’s Silk circuit. It’s even got his signature on the face, right next to the button that engages the circuit. It’s been years since I briefly played with the analogue circuit that inspired these, but it sounded pretty close to what I remember. I prefer the Red flavor over the Blue, which adds some lo mid weight to the sound. A little goes a long way, and because I own so many flavors of harmonic saturation plug-ins, I chose to play it conservative when out on paying gigs.
When the AXR4 first arrived, I was excited to use it in 32-bit integer recording, which is supported by Cubase [Tape Op #131], Nuendo [#77], and WaveLab [#127]. Note that Cubase AI (a “lite” version of Cubase Pro, also 32-bit compatible) is bundled with the interface. I downloaded a demo of Cubase and tracked one of my mobile sessions at 32-bit. I really love everything about the AXR4, but at this stage in my work, the extra bits on each sample aren't enough of an improvement in my opinion to consider switching to a DAW that I'm not yet comfortable with.
If you are a Cubase user, however, other nice integrations allow you to control the preamps without having to switch back and forth between your DAW and the control panel app. I'd sure love to have that control in my DAW, but executing a simple keyboard shortcut in order to move between my DAW and the control panel app is worth the trouble for me in order to use the fine AXR4’s converters while working inside the software I'm most comfortable with. If you're in the market for a premium expandable multi-channel converter, you should absolutely place the AXR4 on your short list.