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Edirol UA101

USB 2 Audio Interface (PC) By Martin Walker
Published May 2005

Edirol UA101Photo: Mike Cameron

Edirol have pioneered USB 2.0 as a format for connecting audio interfaces, and their latest unit offers 10 inputs and 10 outputs, plus high resolution, at a price that compares well with Firewire alternatives.

In 2003, Edirol launched the world's first USB 2.0 audio interface, the UA1000 (reviewed in SOS November 2003). Since then, however, few USB 2-specific music products have been forthcoming — largely, I suspect, because USB 2 products can't as yet be used by Mac owners. Firewire audio interfaces, on the other hand, can be used by both PC and Mac owners, so when Edirol subsequently launched their Firewire-based FA101, many people assumed that the UA1000 was a one-off experiment.

The UA101 proves them wrong. As its name suggests, it's similar in many ways to the FA101 (reviewed in SOS September 2004), except that it connects via USB 2.0 rather than Firewire. It's presented in the same half-rack format, and at a similar £399 price. Both devices offer 10 inputs and 10 outputs: of the eight analogue inputs, six operate at line level only, whilst two also boast mic preamps, and one of these can serve as a high-impedance instrument input. There are also eight analogue output channels with a versatile analogue monitoring system, plus S/PDIF optical in/out and MIDI In and Out. Like the FA101, the UA101 supports audio formats up to 24-bit/192kHz, albeit with a reduced number of channels at the highest sample rates.

You'd be forgiven for assuming that the FA101 and UA101 were otherwise identical, barring a different colour scheme and the replacement of the pair of rear-panel Firewire sockets by a single USB 2.0 port. However, closer inspection shows that there are plenty of other differences between the two, the most intriguing being a front-panel button labelled Limiter.

In The Blue Corner

The two front-panel Neutrik inputs of the UA101 are fed to a pair of 'professional grade' mic preamps identical to those of the FA101, with up to 40dB gain controlled via rotary sensitivity knobs, and optional +48 Volt phantom power. As with the FA101, the button to switch this is on the rear panel — fine for mobile and desktop use, but not very handy if you've bolted the unit into a rack. There's the same optional high-impedance button for input 2 allowing you to use the inner TRS jack socket to plug in an electric guitar.

There are also six line-level inputs on the rear panel with balanced/unbalanced connections on quarter-inch jack sockets, but whereas the FA101 offered adjustable sensitivity between -10dBV and +4dBu only on inputs 7/8, here, each pair of line inputs can be switched between -10dBV and +4dBu operation via tiny rear-panel DIP switches. This is not a job you'd want to do very often in the dark, but is certainly a more versatile approach in the absence of software-switched options. A further DIP switch lets you switch between USB 1.1 and USB 2.0 formats, so you can connect the UA101 to almost any USB-equipped computer, although of course you won't be able to use the full quotient of I/O over USB 1.

Each pair of the UA101's inputs can be switched between -10 and +4 sensitivity settings using a DIP switch on the rear panel.Each pair of the UA101's inputs can be switched between -10 and +4 sensitivity settings using a DIP switch on the rear panel.Photo: Mike Cameron

The rest of the rear panel is straightforward, with 10 TRS-wired output sockets instead of the FA101's eight (the extra two are dedicated stereo Monitor Outs, hard-wired to the monitor mixer outputs along with the headphone output), plus MIDI input and output sockets, a USB connector, and the input for the supplied DC power supply.

The left-hand end of the front panel is completed by the aforementioned Limiter switch, which places a limiter with a -4dBFS threshold in the signal path on inputs 1 and 2, plus the Toslink optical input and output sockets. The five-LED meter is another improvement on the four LEDs of the FA101, and can display the peak levels of any input or output. The five LEDs come on at -42, -30, -18, -12 and -6 dBFS, so they provide a useful graph from signal present through to imminent clipping.

The black area at the right-hand end of the panel is devoted to digital and monitoring options, looking almost identical to the same area of the FA101, and comprises sample-rate selection, Digital In and associated Sync LED for internal/external clock selection, two buttons and one rotary control for monitoring, which I'll come to in a minute, the rotary level control for the dedicated monitor and phones outputs, the phones socket itself, and power and 'USB active' indicators.

Edirol UA101 Brief Specifications

  • Sample rates: 44.1, 48, 88.2, 96 and 192 kHz from internal clock.
  • Analogue inputs 1/2: Neutrik with outer balanced mic socket, optional global +48V phantom power and analogue limiting, inner TRS quarter-inch jack, high-impedance guitar input option on input 2, plus preamp with 40dB gain range.
  • Analogue inputs 3 to 8: +4/-10 switched line-level sensitivity on quarter-inch TRS balanced/unbalanced jack sockets.
  • Analogue outputs: 10 balanced/unbalanced TRS quarter-inch jack at fixed +4dBu level (two of which carry the dedicated stereo Monitor Mixer outputs), plus stereo headphone output with dedicated level control.
  • Digital I/O: S/PDIF in and out on Toslink optical, two MIDI Ins and Outs.
  • Dynamic range: not stated.
  • Frequency response: 20Hz to 40kHz, +0/-2dB at 96kHz.


I received the final version of the hardware and Windows XP drivers, but a preliminary Control Panel utility and no printed or PDF manual, so this was an ideal opportunity to see just how easy the UA101 was to use. The driver CD-ROM contained a Setup.exe file, so in keeping with most other USB and Firewire audio interfaces, I ran this before I plugged in the interface, and was pleased to find it provided on-screen instructions on the installation procedure, including when to plug in and power up the UA101 — not everyone reads the manual after all, even when it's supplied!

The UA101 can't be powered from the USB buss, so you need to plug in the bundled 9 Volt DC line-lump PSU and switch on the UA101 via the switch associated with the Phones/Monitor output rotary level control before it's detected by Windows. For those interested in mobile recording who have both USB 2.0 and Firewire ports available, this gives the FA101 an advantage over the UA101, since it can be powered from the Firewire buss if your computer is capable of doing so.

Like its USB 2.0 stablemate the UA1000, the UA101's drivers only currently support Windows XP, but this is after all what most PC musicians are now using, and I was up and running within a couple of minutes. I was pleased to see that Edirol are bucking the trend by offering multiple stereo WDM drivers in addition to a single multi-channel one, which is very handy for those whose applications only support stereo pairs. The UA101 offers five stereo pairs of driver playback options (1/2, 3/4, 5/6, 7/8 and 9/10 digital) in addition to the multi-channnel one, while the recording options add to this list the Monitor output from the UA101's 40-bit internal mixer. However, I was disappointed that Edirol still seem to be ignoring Gigastudio owners, and there's no GSIF driver support at all.

Control Panel

I experienced a strong dose of déjà vu when I located the Edirol UA101 software utility among my Windows Control Panel options and launched it: it was identical to the one I last saw when reviewing the UA1000, even down to still having 'Edirol UA1000 Control Panel' displayed in its title bar. The UA101 will ship with a control panel that looks rather more elegant, but its patchbay and monitor mixer functions remain fairly similar, so let's remind ourselves briefly of what's on offer.

The review unit was supplied with a preliminary Control Panel utility: the finished version will look like this.The review unit was supplied with a preliminary Control Panel utility: the finished version will look like this.Photo: Mike Cameron

In essence, you get a patchbay that lets you decide which signals get sent to the five pairs of WAV inputs that appear as recording options in your audio application, chosen from the five pairs of physical input signals, the five pairs of WAV playback signals coming from your audio application, or the combined output of the control panel's monitor mixer. The five pairs of physical outputs have similar options: the five pairs of WAV playback signals, the five input pairs, or the monitor mixer output. In addition, a second set of output routings is available, and can be selected using the front-panel Soft Ctrl button, so you can set up two different monitoring presets.

The main control panel display is devoted to the monitor mixer, with on/off, solo, pan, fader and link controls for each of the Wave Outs and physical inputs, plus a signal 'blinky' for each of these channels and a pair of monitor master level controls. Across the bottom there's a status display of various parameters including current sample rate, internal/external clock, and the direct-monitor Mono and Soft Ctrl buttons. The hardware front panel has the same unusual Mix control as the FA101, with a centre detent marking the default mix, and clockwise movements favouring the Input monitor mix, and anti-clockwise moves the Output monitor mix. There's also a front-panel Mono button that affects the input monitor mix. Overall, the monitoring facilities are comprehensive once you get your head round them.

Testing Testing

My double-blind listening tests against Emu's 1820M and Echo's Mia proved interesting. Once again I picked out the Emu for its superior imaging and ability to present greater front-to-back positioning during reverb tails, but I couldn't decide which I preferred of the other two. The Mia was warmer and 'cosier', whereas the UA101 gave a slightly more intimate sound, possibly because as I found later it exhibits a slightly boosted playback response above 6kHz, rising to a tiny peak of +0.3dB at 20kHz with a 44.1kHz sample rate. However, these are very subtle differences, and given its similarities with the FA101, I'd agree with the judgements Mike Bryant made in his review of that unit: it has a clean, open sound and good stereo imaging.

While recording, the limiter option on inputs 1/2 proved extremely useful in avoiding clipping, and let me achieve significantly higher input levels in a transparent way without worrying about compromising audio quality — only by applying input levels high enough to clip the analogue stages preceding the limiters did I start to experience any distortion.

Rightmark's Audio Analyser proved that the UA101 must have almost identical analogue circuitry to the FA101, returning exactly the same dynamic range of 104dBA at 24-bit/44.1kHz. Unusually, this stayed almost the same at both 96kHz and 192kHz, even though its frequency response was not capped at the higher rates (the most common reason for this). The -0.3dB points were at an impressive 8Hz and 21kHz with a 44.1kHz sample rate, extending to about 44kHz with a sample rate of 96kHz, and 57kHz at 192kHz.

Like both the UA1000 and FA101, the UA101's sample rate can only be changed from the front-panel switch, and the unit must be rebooted before this takes effect. However, whereas the on/off switch for the FA101 is on the rear panel, making it inaccessible if the unit is bolted into a rack, both UA units have the practical advantage of front-panel on/off switches. The control panel utility provides a handy readout of the unit's current sample rate, but it's up to users to make sure that this is the same as the one set in their audio application — I received no error messages when attempting to play back or record files through the UA101 at one rate when it was set to another, but my RMAA results displayed peculiar frequency responses when I did so.

A helpful routing diagram is printed on the UA101's top panel.A helpful routing diagram is printed on the UA101's top panel.Photo: Mike Cameron

As with the FA101, switching to 24-bit/192kHz reduces the I/O count from 10 channels to six, which is sufficient to play back DVD-Audio discs in 5.1 surround, while anyone who needs to plug into a low-bandwidth USB 1.1 port instead of a Hi-Speed USB 2.0 one will find themselves reduced to using analogue inputs and outputs 1/2 at 44.1 or 48 kHz only.

The slider to adjust the buffer size of the ASIO drivers is simply labelled from Min to Max, rather than stating number of samples or latency in milliseconds, but the default setting equates to an unusual value of 432 samples, resulting in 10ms latency at 44.1kHz. I experienced no glitching with Cubase SX at this setting, and was eventually able to drop the value down to the lowest setting on my system with no problems, giving a 3.3ms latency. The WDM drivers managed an even better 2.0ms with Sonar 4, and the Direct Sound and MME drivers proved to be as good as any I've tried under Windows XP, achieving 30ms and 45ms Play Ahead settings respectively with NI's Pro 53 soft synth.

Final Thoughts

Edirol have placed the UA101 into an already congested part of the market, and at a price of around £400 you can also buy various Firewire audio interfaces such as M-Audio's Firewire 1814 and Guillemot's Hercules 1612FW. The Firewire 1814 provides the most potential I/O with its eight-in/four-out analogue plus eight-channel ADAT support, and the highest dynamic range at a measured 109dBA. It can be buss-powered, but its analogue inputs aren't balanced, and its outputs don't offer the higher +4dBu levels compatible with more professional gear.

For those with more demanding recording requirements, the Hercules 1612FW is another strong contender with its 12-in/eight-out analogue plus co-axial and optical S/PDIF, word clock, and two MIDI Ins and Outs. It has very similar audio performance to the FA/UA101 boxes, but it doesn't support 192kHz at all. Both the 1814 and 1612FW also provide GSIF drivers, though, unlike the Edirol range.

However, the UA101's closest competitor is probably its own stablemate, the FA101. If you don't have a Firewire port then you can buy one on a card fairly cheaply, but nearly all modern PCs are already equipped with USB 2.0 ports, so which is the best option? Well, a USB 2 interface might have the advantage where high track counts are required from a Firewire hard drive, since it won't be sharing the same bandwidth. On the other hand, some armchair experts say USB 2 is unsuitable for professional audio, but I've now reviewed both the UA1000 and the UA101, the only available multi-channel USB 2 interfaces, and have had no practical problems with either. Since its launch, moreover, the UA1000 has gone on to win an enviable reputation for its reliability.

The strengths of both the UA101 and FA101 are their robust and compact half-rack cases, which make them the smallest of all these units, while their almost identical eight-in/eight-out analogue audio quality is on a par with the Hercules and only slightly behind the Firewire 1814. In its favour, the FA101 can be buss-powered, which is handy for mobile recording sessions, but the UA101 provides an additional stereo monitoring output, more flexible -10/+4 input options, and slightly better metering. Its most significant advantage, however, is the stereo limiter — the only other interface I can recall with this feature was the ill-fated Lexicon Core 2, but it remains a powerful incentive for anyone wanting to record anything cleanly when faced with unpredictable levels. For small live sessions, this is a big advantage, and should push the UA101 a long way up your shortlist.


  • Good audio quality in a compact and rugged package.
  • Versatile monitor mixing options.
  • Stereo and multi-channel WDM drivers provided.
  • Built-in analogue limiter.


  • No GSIF driver support.
  • Rear-panel DIP switches for phantom power and +4/10 input switching are fiddly to operate.


The UA101 finally provides a cheaper alternative to the UA1000 for anyone who would prefer their audio interface to plug into a USB 2.0 rather than a Firewire port, and its analogue limiter may sway those who don't mind either way.


£399 including VAT.

Edirol Europe +44 (0)20 8747 5949.

+44 (0)20 8747 5948.