Issue 59



July 15, 2013


This fiery contender is no heavyweight, but its combinations are sure to leave more than a few heads spinning.

Text: Andrew Bencina

It’s becoming almost as reliable as the Roman calendar: another month, another mobile bus-powered audio interface. Don’t get me wrong, I’m not complaining. As more alternatives emerge we’re blessed with increased performance at greatly reduced prices. TC Electronic’s latest contribution to this ever-expanding class is the Impact Twin.


Marketed as a ‘go anywhere’ device, the Impact Twin audio interface is only a little wider than a standard half-rack unit. It’ll slip easily into your bag when you’re on the go and its matte black appearance merges unassumingly into the studio surrounds.
Similar to a standard DVD drive, the inner workings of the Impact Twin are themselves sealed within a seemingly impenetrable metal case. The whole unit is then sandwiched between a solid outer shell of rugged plastic, making it a genuine no-go zone for the amateur repairer. The front panel of this outer casing is recessed to partially protect the controls from physical damage, while the case itself tilts upwards to maintain visibility. In most lighting conditions this design works well but in my dimly lit control room at least, I did find the otherwise clearly labelled controls somewhat obscured by the shadows the design throws across them.
Compared to other interface options in this size and price range, the Impact Twin has a substantial selection of onboard I/O solutions (14 channels at 48k). The rear panel boasts four channels of analogue input and output via balanced TRS connectors, alongside coaxial S/PDIF I/O (both these formats being capable of sample rates up to 192k) and an ADAT bridge supporting an additional eights channels of digital I/O at 48k (or four channels at 96k). This optical channel can also be configured via a software switch to receive a standard Toslink stereo signal. MIDI I/O, two Firewire 400 ports (an adapter is provided for connection to Firewire 800 systems) and a 12VDC power input and switch round out the rear panel.


In recent years the sound quality of audio converters under $1000 has undoubtedly improved, although the clarity and depth of the imaging has still, by and large, remained inferior to the more expensive options. The Impact Twin, however, seems to buck this trend, sounding so good in fact that it’s caused me to detect a fault in one of my own more expensive converters. Paired with JetPLL jitter reduction (originally designed by sister company, TC Applied Technologies, and licensed to M-Audio and PreSonus, amongst others), this improvement in sound quality is significant in such an affordable device.


The Impact Twin also boasts a pair of mic pre/D.I. channels, accessed on the front panel by Neutrik combo connectors. These can be used as alternatives to the first two channels of line-level input, found on the rear. Unfortunately, this selection can only be made as a pair. Phantom power is also selectable only for both channels at once, so take care with any passive ribbons. A 20dB pad is provided on each of the XLR inputs, while this same switch activates the guitar-optimised instrument D.I. when using a standard mono jack. As with the converters, the Impact III preamps also go their own way, eschewing the modern tendency to maximise sparkle and air, instead focusing on a solid and defined midrange. Their tonal balance during my first test run on vocals was impressive to say the least. On 12-string acoustic guitar, however, this focus away from a truly open top-end made for a somewhat less remarkable outcome, highlighting once again the importance of matching your source sound to the microphone and preamp combination. Perhaps not surprisingly, the D.I. channels share the same pleasing musical midrange as the mic pres. Recordings of bass, electric piano and a hollow-body electric all matched or exceeded my tried and true options.
Both mic/D.I. channels of the Impact Twin also feature low-latency DSP effects, including a four-band parametric EQ, compressor and de-esser. Settings for each of these can be configured and saved as presets from the driver software control panel. An ‘all effects’ bypass for each channel and the one-parameter compressor can even be controlled from a multi-function rotary encoder on the front panel if necessary, and while these easy-to-use channel tools may lack nuance and advanced controls, they’re definitely worthwhile. The predefined compressor source presets, in particular, sound well matched and I’d certainly envision using them in stand-alone mode. Full MIDI control of the software mixer would have greatly improved such an application even further, of course, but alas…


The final front-panel controls on the hardware unit relate to the primary stereo output channels. Here a single button selects between three output modes: Stereo, Mono, and Side – the last of these highlighted by TC Electronic as being part of its ‘iCheck’ (Integrity Check) system. When listening to MP3s and other forms of data compression, for instance, the iCheck mode can help reveal the reduction artefacts and damage to the stereo image these may cause. Here at AT, however, we’d like to encourage you to forget data compression altogether and instead use the Side mode as it has been by engineers for decades: to detect and minimise the effects of excessive audio compression.
Finally, a master volume pot controls both the line-level outputs (of channels 1&2 only) and those of the two front-panel headphone outputs, one of which automatically mutes the rear channels (I found myself using outputs three and four with a passive volume control in-line for my monitors, freeing up the master volume knob to control the headphones). Curiously, the Impact Twin seems to deliver about 6dB more level than the accepted +4 standard. With limited output calibration in the software mixer and no preset for use with –10 consumer devices, it’s almost certain that some systems will be inexcusably overloaded by this increased output voltage. What purpose this serves I’m not entirely certain… all I can imagine is that the extra gain helps provide more power to the headphones, which are tied to the same output.


For those travelling internationally, the Impact Twin conveniently employs a standard IEC lead to connect between transformer and power outlet, ensuring a simple and inexpensive conversion between mains formats. Alternatively, if your computer provides a Firewire port with an incorporated power source you will generally find this to be sufficient. TC Electronic does however warn against using the Impact Twin at the same time as other Firewire devices, and for good reason. While the interface worked flawlessly on my quad-core studio PC, I did experience some audio drop-outs when using the externally-powered Impact Twin with a USB hard drive and mouse on a three year old Dell laptop. As with any laptop operation I’d always recommend in-store testing of your rig before purchasing. Occasional conflicts – particularly with legacy devices – are sometimes difficult to avoid.
As with almost every interface these days, the Impact Twin also comes packaged with a signature version of Ableton Live Lite 8. Meanwhile, 64-bit drivers are currently available for the Impact Twin in a pre-release package but I’m assured by TC Electronic that a full release will have become available by the time AT goes to press.


There’s simply no doubt that, for its price tag, the Impact Twin is an excellent interface. It does what you’d expect it to do with little fuss and throws in plenty of original surprises to boot (including a guitar tuner!). For a change though, the increased affordability of the device has not coincided with a significant reduction in hardware quality. Instead, it’s the software component of the interface that’s been left seemingly incomplete. I would have happily traded in the provided plug-ins (ResFilter, Assimilator and M40 Reverb) for a more realised software mixer with an improved patchbay, monitor mixer, MIDI control and complete output calibration settings, but hopefully these can still be added to future driver and firmware updates. Personally, I’ll be waiting with interest to see if it can deliver the knockout blow.


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Issue 59