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A-Designs Mix Factory

Analogue Summing Mixer
Published January 2017
By Bob Thomas

A-Designs Mix Factory

Can this California company’s first summing mixer reach the high standards set by their outboard processors?

California-based manufacturers A-Designs Audio have recently added a summing mixer to their already impressive range: the Mix Factory, named for the studio of Tony Shepperd, the recording engineer who conceived it. Described as “a totally new concept and approach to summing out of the box,” the Mix Factory is a manually controlled, 16-input unit that features transformer-balanced main outputs, a flexible architecture based on two summed stereo subgroups (inputs 1-8 and 9-16), plus switchable stereo inserts for those and the main stereo summing bus.

The Box

Designed by highly respected gear designer Paul Wolff, the Mix Factory is a handsome, 2U 19-inch rackmount unit whose black fascia is populated by 35 custom-designed aluminium knobs, 20 illuminated buttons that control 20 switching relays, and a stereo, discrete-LED meter ladder. On the rear you’ll find two Tascam-format D-sub connectors for analogue inputs 1-8 and 9-16, balanced XLR stereo I/O for the three inserts, transformer-balanced XLR stereo outputs for monitor (pre-master fader) and main (post-master fader), a stereo external input for linking to another Mix Factory (which comes in pre-main insert) and, finally, the five-pin XLR connector for the unit’s external switched-mode power supply.

Of the front panel knobs, 16 are centre-detented LR pan controls, one for each input channel, 16 are input-channel gain controls, and the final three cover the rotary stereo Master faders for the two subgroups (1-8 and 9-16) and the stereo Grand Master. Each input has an illuminated Cut (mute) push switch, which lights green as signal passes through (its brightness indicates the channel’s signal level) and lights red when muted.

Three green/red illuminated buttons, which sit underneath the Cut buttons for channels 13-15, switch the subgroup and main output inserts in and out of circuit, turning red when the insert is active. Personally, and it’s a minor point, I’d have preferred the colour switching on these three to have followed the same scheme as for the channels: red when inactive and green (with level indication) when active. The 35th and final button, beneath channel 16, allows you to bypass the twin custom-designed Cinemag output transformers, glowing blue when bypass is active and being dark when the transformers are in circuit. As with the insert switches, I’d have preferred green when the transformers were in circuit and a red when not, but again, that’s a minor point.

The inputs are summed passively to their respective subgroup’s stereo mix bus and the signal then passes via the subgroup’s stereo insert send and return (if active) to the stereo subgroup master. From there the signal routes to the main output via the main bus stereo insert send and return (if active), the output op amps (the only amplifiers in the Mix Factory), the balancing transformers (if active) and the Grand Master. The Grand Master controls only the main output level as the monitor output is taken off post-transformer, pre-Grand Master fader. Whilst it’s perfectly possible to mute the two stereo subgroups and the main output by switching in their insert loops with nothing connected, and even though the provision of Cut buttons on the subgroups and the main and monitor outputs is perhaps overkill, for my way of working I would have liked to have had them available — if only because muting a subgroup requires muting eight channels one by one. I could build mute groups in my DAW to accomplish this, of course, but sometimes it’s just easier to hit a button.

In Use

Hooking up the Mix Factory to your DAW is the work of moments, assuming you have the necessary D-sub cables. It’s then simply a matter of setting up stereo and/or mono mix stems routing these to one or other of the Mix Factory’s two summed subgroups, setting the input pans appropriately and building your mix.

A-Designs rightly recommend starting out with the channel gain controls, which are in fact passive attenuators, set at the three o’clock position, leaving approximately 13dB of gain available for adjustment if necessary, and with the three master faders set at maximum. Since the two eight-channel input blocks are summed passively in stereo and their insert send and return loops are also passive, any outboard equipment inserted in those loops will need to be carefully gain-matched to maintain sonic quality. However, since the insert return runs directly to the subgroup master there’s space for attenuation of any unavoidable level increase in the insert loop. The same applies to the insert loop on the main output bus where the Grand Master can handle any output level issues, although the monitor output is left to fend for itself.

The Mix Factory’s inputs can handle +27dBu. So unless you’ve got a rare set of converters that are capable of outputting in excess of that figure, you’re not going to have to worry about lack of headroom! Gain through the Mix Factory is unity, so again there are no headroom worries at the output, assuming that you haven’t gone crazy with the insert return levels from any outboard signal processors.

In use, the Mix Factory delivers an extremely clear and detailed soundfield and, with its output transformers bypassed, is completely transparent. A-Designs provide noise and frequency-response traces as part of the user manual and these show that the ‘transformerless’ output is, for all practical purposes, flat (+0/-1 dB) from around 15Hz to 30kHz, with a noise floor that’s well below -100dB.

With the output transformers in circuit, the frequency response trace shows a +1dB hump that peaks around 15Hz and then falls away so that the trace is flat (+0/-1 dB) from approximately 100Hz to over 30kHz. The noise floor is well below 100dB except around 15-20 Hz, where the transformer hump pushes it up to around -90dB.

With the transformers out of circuit, the Mix Factory is everything that you’d want a summing mixer to be. To me, however, its custom-designed Cinemag output transformers are what the Mix Factory is all about, not only adding the expected warmth in the low frequencies, but also producing an increased sense of clarity across the mid-range, smoothness and air in the upper frequencies and a subtle, but very noticeable, apparent widening of the stereo soundfield. Personally speaking, if I owned a Mix Factory I doubt that I’d ever switch the transformers out of circuit as, to my ears, the ‘transformerless’ sound, superb though it is in absolute performance terms, can tend to feel slightly flat by comparison.

Conclusion

The A-Designs Mix Factory is, by any measure, a superb analogue summing mixer. Its sonic performance — with or without the Cinemag transformers in circuit — is of the highest order. Its configuration of 16 inputs running into two eight-channel stereo subgroups (each with a stereo insert loop), and thence to the main mix bus (again, with stereo insert loop), gives you bags of flexibility. Not only can you deploy EQ or compression, or even preamps, on your mix but you can also bypass parts of the Mix Factory. For example, you could connect a subgroup loop out to a stereo, transformer-balanced, tube mic preamp and return it via the external inputs or the main insert returns. If I owned a Mix Factory, I could easily see myself with a pair of high-end M/S compressors sitting on its subgroups — my idea of mix heaven, and my bank manager’s idea of hell!

The Mix Factory is one of the finest-sounding analogue summing mixers that I have ever had the pleasure to use. Of course, high levels of analogue performance bring with them high price tags and the Mix Factory is no exception, despite the fact that its performance makes it comparatively good value for money in this market. If you value the subtle improvements that a high-end analogue summing mixer can bring to your mixes, the Mix Factory is a unit that you really must audition.

Alternatives

At its price point, the Mix Factory sits below the SSL Sigma, the Tube-Tech SSA 2B and the Dangerous Music 2-Box+, and right on top of the Neve 8816, Maselec STM-822 and SPL Mixdream XP. All of these are well worthy of your consideration, as are several more, including the Phoenix Audio Nicerizer products and, one of my personal favourites, the Funky Junk 3202.

Published January 2017

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