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PreSonus Quantum 2626

Thunderbolt 3 Audio Interface By Chris Korff
Published September 2020

PreSonus Quantum 2626

The newest addition to the Quantum range offers a plethora of I/O and excellent latency performance for a very reasonable price.

When it comes to audio interfaces, PreSonus have a long history of adopting new protocols. They were among the first few companies to make a Firewire interface (the 2003 FireStation, which was also the first to make use of Yamaha's mLAN protocol), and more recently they've been keen early proponents of both USB 3.0 and Thunderbolt. Their first interface to use the latter was the PreSonus Quantum, which took full advantage of Thunderbolt's data transfer speed to provide remarkably low latency. You can read our glowing review of it in the September 2017 issue. The Quantum is still available, but is now part of a range of Quanta that includes the Quantum 4848 (a no-frills but high-I/O-count device designed to work with analogue consoles) and the subject of this review, the Quantum 2626.

Quantum Mechanics

One thing that sets the Quanta apart in a very crowded market is that they all dispense with DSP. PreSonus reasoned that if they can get latency low enough, there's no need to include a DSP mixer in the interface itself, since the DAWs we all use have far more powerful mixers of their own. It's an attractive prospect: rather than plugging into the interface, routing the physical input to a DSP mixer channel, piping that into your DAW while also sending it back to a DSP foldback bus, and routing your DAW back into the DSP mixer, via the foldback bus and thence to a physical output — all so you can hear yourself and your backing tracks while you record — you just patch the Quantum straight into your DAW channels and do all your routing and monitor mixing in there. No more Alt+tabbing to tweak your monitor mix, or loading up DSP mixer scenes that may or may not work with your current DAW project. Routing, headphone mixes, monitor outputs and levels: all are recalled perfectly the moment you open a DAW project.

The remarkable latency performance of the original Quantum made the above a practical reality but, at its £1000$1000-plus price tag, it was competing with manufacturers who'd turned DSP into an artform. Universal Audio, in particular, have spent years considerably sweetening the DSP deal with some outstanding plug‑ins, and their powerful low-latency Console DSP mixer exemplifies the opposite approach.

Announced earlier this year, the Quantum 2626 promised all of the blissful simplicity of the original Quantum but at just over half the price. What's the catch?

Ins & Outs

Despite not having any internal routing or signal processing, the original Quantum still boasted some neat digital extras, many of which have been lost on the 2626. So the digital control of preamp gains and assignable monitor controller are gone, the latter meaning you can't perform surround-sound monitor control without getting a separate monitor controller. Also absent are the talkback section, the eight-segment LED metering, the individual phantom power switching, and the separate D‑A converters for the headphone amps — the two on the 2626 always follow the main outputs. The all-important I/O, however, remains intact: the Quantum 2626 features eight of PreSonus' XMAX preamps, all of which are accessed via combi inputs on the front panel. The first two can accept high-impedance instrument signals, and also have balanced, pre-conversion insert points on the rear. Also round the back are eight line outs, with outputs 1+2 mirrored on dedicated monitor outputs and controlled by the front-panel attenuator. In terms of digital connectivity, you've got stereo S/PDIF I/O, two pairs of ADAT ports, word clock I/O, a pair of proper five-pin MIDI sockets (In and Out), and one Thunderbolt 3 port (see box). The ADAT ports can either provide eight I/O at higher sample rates (ie. in S/MUX mode), or be used in independent pairs to add 16 extra I/O at base sample rates.

For a 'cut-down' interface the Quantum 2626 enjoys a generous provision of I/O.For a 'cut-down' interface the Quantum 2626 enjoys a generous provision of I/O.

Given the desire to bring the cost down, I think the omissions have been very well chosen. I rarely need a talkback mic or surround monitoring, and I'd venture that's the case for most home/project-studio owners. I have a nice big screen in front of me that can tell me more about my recording levels than an LED meter ever could, and the 2626's two banks of phantom power switching, rather than the Quantum's individual phantom switches, are fine by me. I also don't mind the lack of digital control over the preamp gains: the analogue knobs on the front panel are sturdy, and work smoothly and predictably. I had no trouble matching gains for stereo miking, for example. If digital gain control is important to you, though, I should mention that the 2626 can be paired with a PreSonus DigiMax DP88 ADAT expander (or two), which does have software-controlled preamps.

Firing Up

Setting up the Quantum 2626 was a painless affair. You need to register it with PreSonus, after which you can log in to the PreSonus website and download Universal Control, which is a simple app that takes charge of such exciting things as firmware updates, sample rate and sync options (internal, ADAT, S/PDIF or word clock). This is also where you can control your DigiMax DP88s, if you have any (if you're a Studio One user, you can even control them from your DAW). You hook up the external PSU (which has a twist-locking connector), plug into a spare Thunderbolt port (via any necessary adaptors), and the light on the front panel changes from red to blue to show that sync has been achieved. In my case, UC then told me that the Quantum 2626 was due a firmware update, which was again a simple process, taking all of about 20 seconds.

The absence of a routing matrix, DSP mixer, built-in effects and so on make using the Quantum 2626 refreshingly simple. You select your sample rate, open your DAW of choice, set your buffer size (I used the lowest option of 32 samples), and you're set. Everything behaved exactly as expected, with the one exception being that the headphone outs never quite went fully off; even at 'zero' there was still a very low-level signal. In terms of sound quality, though, there was nothing to fault. Indeed, the noise and distortion specs appear completely unchanged across the board compared with the original Quantum, and they are certainly more than good enough to not impose themselves. All types of signal I tried it with — mic, line and instrument — were handled perfectly well. I tend to really dig in when I'm playing bass, for example, and can easily overload lesser instrument inputs and DI boxes, but that wasn't the case here. I even had to turn the gain up a bit on the 2626, which made a nice change from having to turn my bass down or find a device with a pad to put between me and the input.

Since using the 2626, I've actually come to enjoy using my DAW more.

As important as the sound, however — and especially with an interface bereft of any internal routing — is latency. Guitarists, bassists and keyboardists can generally live with a bit of latency quite happily because they're used to being a few feet away from their amps (each foot adding a millisecond or so of delay), and for virtual instruments the round-trip latency is pretty much halved because there's no input latency to deal with. Vocals, on the other hand, are more of a challenge. We're so used to hearing our voices through our own skulls that even a handful of milliseconds can be remarkably distracting when you're trying to sing. So for my first test of the 2626's latency I got a small analogue mixer, plugged a mic into it, sent it to the Quantum 2626, and routed the direct analogue signal to one bus and the interface return to the other. I sang into the mic, alternately PFL'ing the direct signal and the DAW return buses. And once I'd matched the levels, I was hard-pressed to tell the difference. I make no claims to be a good singer, but if I ever felt compelled to commit my crooning to WAV, I'd have no qualms at all about monitoring from my DAW. And the enormous convenience of not having to set up a separate foldback mix would be the icing on the cake.

Next, I repeated the latency test that Sam Inglis did in his review of the original Quantum, and came up with identical results: 0.9ms input latency and 1.0ms output latency at a 32-sample buffer size, according to both Reaper and a loop-back test. Which goes to show that, in the 2626, PreSonus really have left all the important parts of the Quantum intact.

Get DSP Hence

Ever since I've had a home studio, I've flip-flopped between deciding that I do and don't need a mixer more times than I care to count. I've had a number of analogue and digital consoles, and I've had some enormously complicated DSP soundcards (I'm looking at you, Creamware), and they have all come with their own joys and frustrations. But other than the 'niceness' of having real faders and knobs to tweak, the main reason I've kept going back to mixers is the lack of latency. About half a year ago, I decided that mixers were good again, and rejigged and rewired my ever-changing lab to accommodate one. Since using the 2626, however, I've actually come to enjoy using my DAW more: having only one place to record, to monitor, to add effects and to noodle around has made me more focused and, I think, more productive. For one thing, opening projects has become more of a pleasure than a chore, now that I no longer have to remember how my mixer was set up whenever I saved 'piano & bass sketch v43'. And with studio time in ever scarcer supply, that has real value.

In terms of workflow, the Quantum 2626 has been perhaps the least imposing bit of equipment to ever grace my rack, and certainly the simplest multichannel interface I've used. It could well be the interface that makes me flip-flop for the final time.

Thunderbolt 2 vs 3

The original Quantum was a Thunderbolt 2 device, and sported two mini-DisplayPort sockets, allowing you to daisy-chain other Thunderbolt devices (including additional Quanta) off it. The 2626 uses Thunderbolt 3 via the newer reversible USB‑C-type socket, but it has only one port. You can use it as part of a multi-Quanta setup, but it must be at the end of the chain.

The 2015 iMac I used for this review only has Thunderbolt 2 mini-DP ports, but the 2626 manual says you can use it on TB2, provided you use the official Apple Thunderbolt 3 (USB‑C) to Thunderbolt 2 adaptor. That adaptor is bidirectional, so while Apple chiefly describe it as allowing you to plug older devices into TB3 ports, it also does the job of letting you use the 2626 on TB2-equipped Macs. I researched all of this quite carefully before buying the official Apple adaptor because it costs nearly £50$50. And given that PreSonus, in common with other Thunderbolt interface manufacturers, don't provide a Thunderbolt cable with the 2626, I was down 80-odd quiddollars by the time I'd also bought an official Apple Thunderbolt USB‑C-type cable.

What the manual doesn't make clear is whether there's any performance or latency penalty incurred by using the TB2 adaptor, so I asked PreSonus. Happily, they told me that performance is identical whether you're using TB2 or TB3, because their bus speeds are the same. (Thunderbolt 3 has higher data throughput, but audio isn't particularly demanding data-wise so TB2's bandwidth is perfectly adequate). Apparently there is a small increase in latency when using the 2626 via Thunderbolt 1, but I didn't have a TB1-equipped computer on hand to test that.

Bundled Software

The Quantum 2626 ships with a licence for PreSonus' Studio One Artist DAW, as well as the 2020 Studio Magic bundle, which includes Lite versions of Ableton Live and Arturia Analog Lab, plus a good selection of plug‑ins from Brainworx, iZotope, Cherry Audio, Lexicon, Mäag, Native Instruments, SPL and more.

DC Universe

All Quantum-series interfaces have DC-coupled outputs, meaning that, with the right software plug‑ins, you can send control voltage signals to analogue and modular synths. I didn't get a chance to try this out myself, but there's an excellent feature about it elsewhere in this issue [see 'Modular Interfacing'].

Pros

  • Excellent latency performance.
  • Well built.
  • Plentiful I/O.
  • DC-coupled outputs.
  • Insert points for channels 1 and 2.
  • Great price for what's on offer.

Cons

  • Headphone output doesn't quite go fully off.
  • No Thunderbolt cable included.

Summary

The PreSonus Quantum 2626 offers excellent latency performance and a generous amount of I/O for a very reasonable price.

information

€599 including VAT.

www.presonus.com

$599.95

PreSonus +1 225 216 7887

www.presonus.com

Published September 2020