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ART Tubefire 8

Firewire Audio Interface
Published August 2009
By Mike Senior

ART aim to prove that it's better by tube, packing eight valve preamps into a Firewire interface.

This new audio interface from ART is based around the manufacturer's signature feature: valves. The tubes in question drive eight preamps, the outputs of which are then converted to the digital domain and squirted down a Firewire cable to your computer. Eight balanced analogue outputs can be fed either directly from the preamps or via D‑A converters from your sequencer. A simple analogue cue monitoring system provides true zero‑latency headphone monitoring of your inputs against playback from the computer while overdubbing, and an unusual headphone level control allows you to choose between a mono and a stereo cue mix, depending on whether you rotate the knob to the left or right of its centre detent. It's worth pointing out that no digital I/O or MIDI interfacing is fitted.

Latency & Preamp Performance

Physically, the Tubefire 8 makes a big impression the moment you get it out of the box, on account of its 6kg weight and unusual depth (it extends around 36cm behind the rack ears). It's probably fair to say that this might not be the first choice for a portable recording system! ART have sensibly provided fixing points for extra support at the rear of the unit should you need them. Part of the weight is internal heat sinks for the circuitry, but there are no air vents in the case, so the unit does run quite warm.

The supplied software installer provides both WDM and ASIO drivers, as well as a small control‑panel utility for configuring sync, sample‑rate and latency settings. The ASIO driver worked fine with both Cubase and Reaper on my machine, declaring around 3.5ms latency in the control‑panel utility for the lowest buffer size I could manage without drop‑outs (154 samples). This figure is a little misleading, though, as it reports only the latency of one of the driver's buffers. Cubase, on the other hand, gave a much better real‑world estimate of 11ms for the total input/output latency, given that the total system monitoring latency (as measured by re‑recording the software monitoring signal) showed up as 13ms in practice.

Unsurprisingly, perhaps, the Tubefire 8's preamps reminded me a good deal of the one in the ART Voice Channel I reviewed in the July issue of SOS, which also has pretty low noise and enough clarity to cope with most home studio eventualities. A similar tonality is also apparent, with a forwardness in the mid-range that suits sounds which benefit from extra presence and hardness in this region. I can imagine electric guitars, drums, and some vocals benefiting here, but would probably seek out a different preamp for strings, brass, or piano myself. By juggling the two channel level controls (Gain and Output) you have some control over how hard you drive the 12AX7 valves in the circuitry, but even with fairly conservative settings you can't really say that this is a particularly neutral preamp.

A potential danger in allowing you to adjust the valve drive in this way is that it's possible to push a preamp into serious analogue distortion well before you clip its A‑D converter, but ART have neatly anticipated this problem with the design of the LED meter on each input channel. Not only do the four LEDs show the signal level as measured just before the A‑D converters (as you'd want in order to set recording headroom and avoid digital clipping), but the little red Clip LED also lights up independently if necessary, to alert you if you're approaching the analogue clipping point of the preamp.

Zero‑latency Monitoring

The rear panel is a simple affair, featuring just the eight combi jack/XLR inputs, the eight balanced outputs and BNC sockets for the word clock I/O.

The zero‑latency monitoring is a good thing in principle, especially for recording vocalists, but its implementation here isn't ideal. For a start, the two gain controls on each preamp channel affect not only the zero‑latency monitoring volume, but also the level fed to the A‑D converters for recording, so anything you want to monitor at a lower level will also effectively have to be recorded at lower level.

My second concern is that the headphone preamp seemed rather under-powered with a variety of headphones, including high‑impedance Sennheiser HD650s and low‑impedance Sony MDR7509s, so that I could only just push the levels outside my comfort zone even when driving one of the D-A output pairs with a loudness‑maximised mix peaking at 0dBFS. In typical vocal overdubbing situations, for example, a sensible mic gain setting for recording will give a zero‑latency monitoring signal that is almost inaudible against a backing track which fully modulates the D‑A output. In practice you thus have to reduce the playback levels in your sequencer by around 18dB to provide a suitable cue balance, at which point the level of the backing track in the headphones will probably feel a bit puny, depending on the headphones you're using. I'd certainly not be happy working with the Tubefire 8 like that, so you should probably budget for a separate external headphone amp if you're planning on using the zero‑latency monitoring feature. You might also want to get one with multiple outputs, in case you need headphones for more than one person, as the Tubefire only has one output.

The final monitoring issue is that if you use the right‑hand side of the Mix Level control so that you can hear a stereo cue mix via the D‑A outputs, the mic inputs are all treated as stereo pairs: odd‑numbered inputs will be heard on the left and even‑numbered inputs on the right. This configuration won't necessarily suit solo overdubs such as lead vocals, because the performer will only hear themselves on one side. ART suggest a workaround for this by patching the output of an odd‑numbered recording channel into the input of an even‑numbered channel just to even up the picture in the stereo monitoring, but that seems a bit of a faff for such a common recording situation.


In the final analysis, ART's essential 'valve sound for pocket money' philosophy has to be considered the central appeal of the Tubefire 8. The zero‑latency monitoring may also win over some users, although the low headphone levels are a bit of a shot in the foot on that score and the DSP‑driven monitor mixers of the competition have the advantage of multiple independent cue mixes if you're willing to tolerate their small amount of monitoring latency. So the £539$699 question is this: how much do you want valve preamps? On the plus side, ART's designs are fully endowed with high‑pass filter, pad, and polarity‑inversion switches, they are by no means short on valve character, and the dual‑control format provides some range to the sonic effects. On the minus side, though, is that the tonality of the circuits will make some recording tasks less straightforward if this is to be your sole audio interface, and that the valves come at the expense of some other audio‑interface features that computer studio owners have come to expect for this kind of outlay. If you have fairly strong views about valves, ART is simply the only name in the frame for this kind of cash; if not, however, the Tubefire 8 could struggle to justify its price in terms of the remainder of its feature set, given the currently well‑supplied market in audio interfaces.  


There are a number of areas where similarly priced or less expensive competitors steal a march on the Tubefire 8, most notably in providing digital audio and MIDI I/O and more extensive bundled software. If such features are important to you, the Focusrite Saffire Pro 40, Presonus Firestudio Project and M‑Audio Profire 2626 are all worth a look. What none of these offer, though, are the valves or the analogue zero‑latency monitoring, a combination that can't be matched by any other manufacturer at this price.

Vital Statistics

  • Firewire audio interface.
  • Analogue inputs: eight, on combi jack/XLRs; front‑panel instrument inputs for channels one and two, disabling the respective rear‑panel inputs when used.
  • Mic Preamps: up to 70dB gain in conjunction with Output level control; phantom power switchable in banks of four channels; switches for 80Hz, 6dB/octave high‑pass filter, 20dB pad, and polarity inversion.
  • Analogue outputs: eight, balanced, on TRS jacks with global +4dBu/‑10dBV switching; headphone output with analogue true zero‑latency cue mixer.
  • Other connections: BNC sockets for Word Clock I/O; dual Firewire sockets for daisy‑chaining up to four Tubefire 8 units.
  • A‑D Converter: 24‑bit resolution at 44.1, 48, 88.2 or 96kHz sample rates.
Published August 2009

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