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PreSonus AudioBox 22VSLUSB Interface

Issue #23

Still looking for the perfect audio interface? Andi Picker checks out one of the market leaders.

As most music is recorded these days, parts are overdubbed against pre-recorded backing tracks. This means that the performer needs to hear a cue mix at the same time that they hear their own performance and for singers this usually means singing whilst monitoring both the cue and live performance through headphones. Those headphones need to isolate well so that the backing tracks don’t leak into the microphone - and singing when you can hear yourself only through headphones can be very unnatural and disorientating. This obviously isn’t ideal when we want to hear emotion and conviction in a performance and most singers find that they are far more comfortable if they can hear a little reverb and compression on their voices. So let’s give it to them.

The standard PreSonus Audiobox 22USB fits neatly into the 2 in/2 out USB audio interface class. It is well made and sounds good. With this (and similar units) you would typically set up that “wet” mix for the singer by routing the mic input to your DAW, recording the dry signal (so that you can decide on final processing later), and at the same time adding the monitoring effects that you want and routing it back to the cue mix. This is very easy to do and works well, except for latency. Latency is the delay added by various parts of the digital processing round-trip and it quickly adds up to the point where the singer is hearing their voice played as a slap-back echo of what they are singing. Not good!

Mixing desks and larger scale interfaces often offer routing that allows an external processor or onboard DSP (Digital Signal Processing) to deliver a zero (or near-zero) latency cue whilst still recording dry. On-board DSP is a great solution, except that it adds complexity (and cost) to the interface. 

Enter PreSonus VSL. VSL stands for Virtual Studio Live and it’s a clever alternative to onboard DSP. In the box, along with the hardware and a copy of the rather good Studio One Artist DAW, you get a VSL software disk. Load this-up and you have a virtual 2-channel input plus 2-channel return (& master) mixing desk (based on PreSonus’ own StudioLive 16.0.2 digital mixer), complete with drag and drop FAT channel pre-sets and effects channels. When you switch this on and turn the mix knob on the hardware unit fully clockwise, you can add filtering, EQ, gating, compression and reverb/delay to the input channels, and/or the returns and master. When I first tried this and got near-zero latency I presumed that the box had DSP on board. Wrong. The VSL software runs on the host computer, after the USB Bus Clock buffer but before the ASIO or Core Audio buffer! Wow! Really? What? There’s a link here if you want it; if you don’t then don’t worry - it translates to really, really low latency without paying for extra DSP.  Oh - and I’d better mention in passing that it sounds very good too!

The Audiobox itself? Its metal casing appears well made and feels solid. The pre-amps are nice Class A, discrete (no op amps) high voltage models that sound clear, clean, quiet and open, with a wide marked gain range of -15dB to +65dB, and converters support the pretty-well standard 24 bit/96kHz.

The front panel inputs are on combi connectors, XLR for the mics and ¼” jacks for the instruments. This is actually the single question-mark I’d hover over the unit - you get 2 x instrument inputs but no line inputs - you need the next model up (4 inputs, including 2 instrument and 2 line) for that. Line ins are needed for drum machines, many external processors, CD/MP3 players, synths etc. so be sure about your needs before you buy. Some online forum posts have suggested that you can use the instrument inputs for line level - PreSonus support says “no”. 

Monitors and headphone outputs have simple independent volume controls, inputs have individual gain knobs and simple clip LEDs (the metering in VSL reflects levels in the virtual mixer, not at the converter, so you could actually overload the hardware whilst being clear in the software, you’ll need to keep an eye on these clip LEDs for that), one button activates phantom power on both mic inputs and the Mixer knob selects a balance of live inputs and DAW returns, or selects the VSL mixer when fully clockwise. Monitor and headphone sockets along with USB and MID in/out are on the back panel, and that’s the lot. Power is USB only, no external PSU is needed nor supported, main outputs for monitors or amplifier are balanced and the headphone out drives my various cans with no problems at all.

I used the 22VSL with both my standard Cubase 7.5 rig and with the included PreSonus Studio One Artist and it worked absolutely fine with both (I could run lower latency without audio drops and pops with Studio One than with Cubase ?!?). Studio One Artist is a fine entry level DAW; it has some restrictions but crucially allows you to run as many tracks as your computer will support - and I think we need to take a look at this in more detail at a later point. I did get a couple of head-scratch moments with the VSL software where no signal showed on the meters and I had to restart the interface to get it to come back to life - this only happened twice and when I tried to trouble-shoot it all worked perfectly so I really don’t know what happened there.

This is just my opinion, but I think that PreSonus is on a bit of a roll at the moment. Their attention to detail is very nice and their software reflects thoughtful and intelligent design rather than simply re-treading what others have already done.

This interface is a good one, as are many others of the type, and I absolutely couldn’t say that any one of the major contenders beats the class, but VSL is clever and (tiny glitch aside) works really well, the metal case feels physically pleasing with nicely weighted and simple to use controls (and it’s got metal knobs!), and the inclusion of Studio One would put it high on my shortlist just so long as I didn’t need those line level inputs.

To sum up, I find the lack of line level inputs to be a slightly bizarre design choice, but so long as the IO suits your needs then this is a very good interface and the included software pushes it into the top few in-class for value and performance. 


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Issue #74

Jim Root

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