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TL Audio M3 Tubetracker

Eight-channel Hybrid Valve Mixer By Paul White
Published January 2002

All‑valve mixers can really warm up sounds prior to digital recording, but they're usually too large and expensive for the project studio. However, TL Audio's hybrid M3 now brings valve mixing within the reach of the home musician.

TL Audio are well known for producing good‑sounding outboard equipment based around a marriage of valve and solid‑state technology, and their new M3 Tubetracker console is based very closely on their existing preamp and equaliser circuit designs. Conceptually, the M3 is an extremely simple eight‑into‑two mic/line mixer with no multitrack playback monitoring section, but with post‑fader direct outputs on every channel, switchable between ‑10dBv and +4dBu. This is not a console to be used on its own for most recording applications, as it cannot be used both to track signals and to monitor them at the same time. The fact that each channel has a direct output suggests that the most popular application may be tracking, though for situations where only one or two parts are being recorded at any one time, it could be used for mixing/monitoring with a separate voice channel or two used for the source signals.

TL AUDIO M3The M3 is physically larger than a typical solid‑state mixer, but it can still be mounted into a 19‑inch rack and it is just 10U high, though it weighs a hefty 18kg. As supplied, the mixer is fitted into a wood‑effect particle board case for desktop use, with sufficient rear clearance for the cables and to allow ventilation. All connections other than the headphone jack are on the rear panel and power comes from an external, 2U rackmount power supply via a locking multi‑pin connector. The PSU is fan cooled and runs reasonably quietly, but a system without a fan would have been far preferable. After all, if a Marshall 100W amp can work without a fan, why can't a hybrid mixer with only a handful of preamp valves to power?

Each channel's mic/line stage is electronically balanced and equipped with a phase reverse button and a 90Hz low‑cut filter which operates in both the mic and line signal paths. A Gain control affects both inputs and allows up to 60dB of mic gain, with a single button switching between the two input sources. Increasing the gain setting increases the drive to the triode valve stage, which is designed to distort in a subtle way at higher drive levels. A Drive LED close to the fader shows when the valve is being pushed into its nonlinear range, which occurs at levels of between +6dBu and +16dBu. This is the only valve stage in the channel strip, with a further triode stage placed in the left and right master output stages. This means that, in total, the console uses only five dual‑triode (ECC83 type) valves — hence my earlier comments about the fan‑cooled PSU.

After being passed through the triode gain stage, the output from the mic/line preamp is processed via a four‑band equaliser with two sweep mid‑range bands and shelving high and low sections. This appears to be identical to the EQ used in several of the TLA outboard designs, where the mid‑range bands are sweepable over the range 50Hz to 2kHz and 500Hz to 18kHz and the shelving filters are set at 80Hz and 12kHz. All the filters have a ±15dB gain range and there is a bypass button which switches them in and out of circuit together.

There are two auxiliary sends, one switchable pre/post‑fader and the other fixed post‑fader. In addition to the usual Pan control and channel fader (100mm), there are Mute and PFL buttons. Status LEDs close to the faders warn of peaks (5dB before clipping) and show the valve drive intensity. At its maximum setting, the channel fader provides an additional 10dB of gain.

The master section includes two small, circular analogue level meters, as well as a single bar‑graph level display that shows the digital output level when an optional DO1 analogue‑to‑digital converter card is fitted. Although this optional board wasn't yet available at the time of review, the meter will apparently read whichever of the two channels is highest in level and the converter will provide simultaneous AES‑EBU, S/PDIF and Toslink optical outs (stereo). Two front‑panel rotary switches set the digital output resolution to 16, 20 or 24 bits, and the sample rate to 44.1kHz, 48kHz, 88,2kHz or 96kHz. A Lock LED shows when the converter is locked to an external clock source.

TL AUDIO M3Phantom power is switchable globally and the only monitor switching is between the main stereo mix and a two‑track tape return. Gain and Balance controls are furnished for the two stereo aux returns, with master level controls fitted to the two aux sends. Both the sends and returns have PFL buttons which solo non‑destructively only into the monitoring, not to the main outputs. The phones output follows the mix or two‑track master selection unless a PFL button is active, in which case PFL takes priority. Further level controls relate to the Monitor Level and PFL Balance, and a headphone jack is fitted to the right of the stereo master fader. There are no master insert points.

Connections

The rear‑panel connections for each of the eight channels are identical, and comprise balanced mic and line inputs on XLR and jack respectively, plus an unbalanced insert point on a conventional TRS jack. The balanced direct output jack has a switch for +4dBu or ‑10dBV operation and there are calibration trimmers for these two level settings.

In the master section, the main outs are on balanced XLRs while everything else is on balanced jacks. The two aux outputs and the two stereo aux returns may be switched from +4dBu to ‑10dBV operation. Two further jacks provide the monitor output, while a pair of D‑Sub connectors allow multiple M3s to be connected together in such a way that their aux and PFL busses are linked, and such that only the master controls in the last mixer in the chain are operational. Further calibration trim pots are available for the meters and the stereo outputs. A blanking plate above the master section accommodates the optional A‑D converter.

Tubular Balls?

One of the things I like about TLA equipment is that the contribution of the valves is subtle yet significant. Part of the reason for this is that the valve stages are run at a full 200 Volts. Some designs make use of much lower voltages and, though they can sound good, they tend to sound rather different to classic high‑voltage valve circuitry which, to my ears, sounds a lot less 'spongy'. This way you get both warmth and clarity, which I feel is very important.

The frequency response of the console is quoted as 20Hz to 40kHz (+0/‑2dB at 40dB gain) and the resulting sound has the same clean and open character as the TLA outboard processors on which the circuitry is based. In fact any criticisms of the M3 can only be directed at its facilities, not at its sound. Although it has all the essential features to get the job done, I would have liked to have seen switchable Q settings on the sweep equalisers, and master insert points would not have gone amiss for those occasions where you want to process the final mix while handling the fade out using the console's master fader. If you put a compressor after the fader (by connecting it between the mixer and the recorder for example), you'd need to find some way to do the fade after the compressor.

All the outputs have a wide dynamic range and can handle signal levels up to +26dBu when used balanced, which means you should have no shortage of level when driving A‑D converters other than TLA's optional DO1. For example, feeding the direct outs (and the mix outs for submixing) into a Pro Tools 888 interface or similar would produce an excellent tracking setup.

Weighing It All Up

The M3 may not be cheap in the UK, but it is a cost‑effective way of buying eight mic/line preamps with good EQ sections, and the fact that this is a mixer means you have a way to record submixed sources in addition to the direct outs. Though the 'valviness' isn't always right in your face, the mixer does have a sweet, musically satisfying sound and it is possible to force a little more energy into a track by driving the channel valve stage harder. I'm not a fan of deliberately overdriving valves for normal applications, but when recording guitar, bass or bass synth parts, it can add to the depth and quality of the sound.

To get the gripes out of the way, the fan‑cooled PSU is an intrusion when used in one‑room studios, and I feel the EQ should have featured switchable wide‑narrow bandwidth. The paucity of aux sends could be a problem when mixing pop tracks and the round meters are a triumph of design over functionality, but if the main application is laying tracks rather than mixing, then these latter observations are less important.

To be honest, there's very little, if any, difference in sound between this console and the hybrid TLA equalisers from which it was derived, but the package is practical for tracking, as the channels may be used independently via their direct outs or together for recording mixes of instruments. Viewed as a tracking device, the M3 is actually very good and seems to be supportive to the sound without adding obvious coloration, though maybe it would have benefited from having instrument as well as mic and line inputs. As a mixer, it is somewhat less flexible due to the limited number of aux sends and the lack of multitrack tape monitoring, but, providing you don't need more from it, the sound quality is again extremely good and the digital output option makes mastering to DAT or a computer‑based system straightforward. In most respects, the M3 is a classy piece of equipment with a sound to match.

Pros

  • Has the same confident sound as the TLA stand‑alone hybrid processors.
  • Very easy to use.
  • Ideal for tracking multiple sources at the same time.

Cons

  • Insufficient facilities to be able to completely take over the role as recording mixer except in very simple setups (for example, there's no multitrack tape monitoring and only two aux sends).

Summary

The M3 Tubetracker is far better value as a tracking facility than as a mixer, but it sounds good in both applications and retains the inherent tonal character of other TL Audio hybrid tube/solid‑state equipment.

information

M3 £2643.75 including VAT. DO1 optional A‑D converter board, £tba.

TL Audio +44 (0)203 086 7330.

www.tlaudio.co.uk

Published January 2002