Allen & Heath ZED-14 Mixer

Allen & Heath ZED-14

Compact mixer

The ZED-14 is part of a new range of compact mixers from Allen & Heath. The design brief was, according to chief designer Mike Griffin, to build a "small pro mixer" and not a "small cheap mixer", with performance and quality uncompromised when compared to their more upmarket models. The ZED series will be expanded to include other models — four-group versions are already in production and larger versions of the ZED-14's stereo format are in the pipeline, along with onboard effects variants.

Mixer Overview

The Zed 14 has a look and feel that is similar to the larger-format GL series, the main visual difference being the positioning of all connectors on the top panel, rather than the more traditional rear-panel arrangement. Build quality is up to the usual Allen & Heath standards, with a strong steel casing, individual vertically mounted channel circuit boards, and every nut bolted directly to the top panel. The whole thing has a very solid feel about it, and the moulded side pieces make it easy to pick up and move about.
The ZED-14 is a fairly straightforward fourteen-into-two desk, with six mono channels, four stereo channels, and an additional four stereo inputs, which can be mixed to the stereo strips or sent direct to the main mix. What sets this mixer apart from the more traditional designs is the inclusion of a USB port, which allows two-way transfer of audio data and can connect directly to a Mac or PC.

Mono channels

There are three extra stereo inputs on the front panel, which are the stereo returns to the desk and can work either on their own or together with channels 7/8, 9/10 and 11/12.
Channels 1 through 6 are standard mono inputs, capable of accepting microphone-level signals via a balanced XLR socket or line levels through the balanced jack input.
Interestingly, there is no attenuator (pad) switch on these channels; the channel's Gain control trims the input preamp gain over a range of -6dB to +63dB for XLR signals, and -10dB to +26dB for signals on the line input jack. So, if a line source is too hot for the XLR input then the line input jack must be used. Plugging anything into the line input automatically disconnects the XLR input, and inserts the input signal after the first preamp stage. This arrangement has the additional advantage that any line-input sources cannot be affected by even low-level noise produced in the (higher gain) first stage. This combination of wide-ranging gain adjustment and a choice of input points should cater for virtually every possible audio source.

A high-pass filter can be switched in on each channel, and this attenuates frequencies below 100Hz at 12dB per octave. It is useful for reducing undesirable low-end noises, such as wind rumble, vocal popping and microphone handling noise. The 100Hz filter can also be a handy 'instant clean-up' button in a variety of live situations, and can prevent your amps and speakers wasting power trying to reproduce low tones you don't want anyway. I always have these filters switched in as a starting point, and remove them only where necessary, very often (but not always) for kick drum and bass.
Just after the 100Hz filter, the signal path is interrupted by an Insert jack. This is used as an unbalanced, nominal 0dBu send/return point for inserting outboard effects, such as compression, reverb and the like. Note that any signal sent from this jack will not be affected by the EQ controls, speaking of which

The looks

On the inside of the ZED-14, vertically mounted channel circuit boards are bolted to the top panel and surrounded by steel casing, giving the unit a strong and sturdy feel.
The EQ section on the mono channels is a three-band design with fixed-point shelving for high and low frequencies and a swept centre frequency for the mid control. The HF control provides cut or boost of more than 15dB and has a 'corner frequency' (3dB away from the maximum cut or boost) of 12kHz. The LF control does a similar job at 80Hz, and the MF knob allows the same generous degree of cut or boost based on a centre frequency between 120Hz and 4kHz, which can be set by adjusting the sweep control. The range of the frequency sweep gives a lot of control in the lower-mid region, often inhabited by those nasty 'boxy' microphone sounds, and the upper limit extends smoothly into the region managed by the HF circuit (have a look at the EQ curves in the user guide). The EQ is smooth in operation and gives more than enough control for live sound and recording applications. It's easy to set up, and the swept mid gives you the ability to home in on problem frequencies and deal with them with no messing about.

Aux sends

The four auxiliary sends are configured as Aux 1 and 2 Pre(-fade), Aux 3 and 4 Post(-fade). Sends 1 and 2 have their own master level control and would normally be used for foldback feeds or creating live recording mixes, as these outputs will not be affected by movement of the channel faders.
Aux sends 3 and 4 do not have an overall level control, and the channel fader affects the amount sent to the buses from each channel. These sends are useful for sending to group effects where the amount of signal sent to the effects should be related to the channel level at any time. There is an internal modification available, which will convert the Aux 3 sends to operate pre-fade — this involves changing soldered jumpers on the circuit boards and must be carried out by an authorised Allen & Heath repair agent.

The usual stuff

As expected, each mono channel has a Pan control that assigns the channel output anywhere between hard left and hard right, and a channel Mute switch that kills all output from the channel into the main left and right outputs and all four aux sends. The Mute switch has a nice bright red LED, which warns that the channel is isolated, and that no signal will be coming from that channel into mains, monitors or effects sends. Pressing the PFL button sends the channel signal directly to the headphones and output meters, so that individual channels can be monitored and their levels trimmed without anyone else hearing them. The PFL function can be used even when the channel is muted, which is a great benefit when setting up input levels for the first time, or in the early stages of soundchecking a band. A small red LED next to the PFL switch shows that PFL is selected for that channel, and also acts as a peak signal indicator — it lights brightly when the channel signal gets to within 5dB of clipping.
Last in the mono channel feature set is the channel fader itself, which, although very much taken for granted, is the thing that generally gets used the most, and with which the engineer will bond closely during the performance! I'm pleased that, on the ZED-14, Allen & Heath have provided their usual excellent-quality, full-travel 100mm faders, which have lovely smooth control and a nice, just-light-enough-but-not-flimsy feel to them. As is fairly standard practice these days, there's a unity gain (marked as 0) position near the top of the fader travel, but with an additional 10dB of gain above, which can be invaluable in the middle of a live gig where an extra bit of level is called for, and means you don't have to start messing with your other channel settings.

Stereo channels

Now, this is the place where you can usually say, "The stereo channels are a kind of cut-down version of the mono channels and, well, they're stereo," but on this desk, there's a lot more to tell. The basic channels are indeed stereo versions of their mono counterparts, and each is equipped with a pair of balanced line input jacks with the ability to operate in mono (ie. signal sent equally to left and right) if only the left jack is connected. Instead of three-band, swept-mid EQ, there's a fixed two-band circuit, and the Pan control becomes a Bal(ance) control, which alters the relative levels of left and right signal being mixed into the main output buses. Instead of an input gain control, there's a trim control labelled 'In', which gives a range of control from fully off to +10dB. The channel faders are stereo versions of the mono ones, and are only very slightly heavier in feel — another nice A&H touch, and certainly something I've come to appreciate when using my own GL2400 desk.

And there's more

Something else that the ZED-14 has in common with its larger relatives is the provision of additional mini-channels, which can operate in conjunction with or independently of the stereo channels. These extra inputs are in fact the three stereo returns to the desk, and they are paired up with channels 7/8, 9/10 and 11/12.

Above stereo channel 7/8 is a pair of unbalanced RCA phone sockets for the 'stereo return' input. This stereo return is not linked to any send, it's just another line input and can be mixed in to the main left/right outputs or mixed into its associated stereo channel (in this case 7/8). The stereo return channel has its own level control, which, like the stereo channels, gives control from off to +10dB, and it has an on/off switch, which is useful for cutting out potentially noisy unbalanced sources when they're not being used. A small under-panel switch (you need to operate it with a pencil point or something similar) lets you decide whether to assign the stereo return direct to the main left and right buses, or send it into channel 7/8 — in this 'mix' mode, it can be blended with the signal already on channel 7/8, or it can give access to the additional channel's controls within the channel strip. This arrangement is copied on channel 9/10 with the unbalanced stereo input, 2-track return, and again on channel 11/12, which accommodates the stereo input from the USB port. This all adds up to six additional inputs, so they could have called it a ZED-20

USB live

Here, we come to another clever feature of the ZED-14: the inclusion of a bi-directional USB port. The port can be used in a number of configurations. In terms of output, it can carry the main stereo output in either pre-fade or post-fade mode, or it can be used to send either Auxes 1-2 or 3-4. Used as an input, it can be mixed into stereo channel 11/12 or sent direct to the main mix.
Although an obvious use of the USB connector is with a computer-based recording setup (there's a free copy of Sonar LE bundled with the mixer!), it can also be used as an effects send/return for live sound work. This is a fabulous feature and gives access to all kinds of real-time software processing. You're no longer limited to the hardware in your effects rack, you can take along a laptop loaded with suitable software and simply connect a single (supplied) USB lead.
One notable factor is the quiet performance of the USB port. There is an issue with this type of interface, in that the communications part of the USB codec takes its power from the connected computer, which is, I think, to ensure that it doesn't operate when it's not in use and therefore doesn't contribute to overall noise or power drain. This can give rise to undesirable digital noise, especially when using a laptop plugged into a mains charger, but careful design of the grounding and isolation in this part of the circuit has addressed this.

Mission control

The master section of the ZED-14 is fairly straightforward, with the main left/right impedance-balanced outputs appearing on XLR sockets — a summed mono signal (post-fade) is available on a balanced jack socket. The auxiliary outputs are all impedance-balanced jack sockets, and Aux 1 and 2 each have rotary master level controls located just above the main output faders. There's also a useful pair of insert jacks for the main mix signal, giving the opportunity for any global outboard effects to be connected right at the end of the mix process. The insert point is just before the main faders, which feeds a more constant level to any connected equipment and should give better signal-to-noise performance than feeding the output from the desk into an external device, such as a feedback suppressor.

Flexi-monitoring

The ZED-14 monitor section allows various signal configurations to be sent to the headphone output and to the main meters. A series of push-button switches are used to select the monitor source, which can be main left/right, Aux 1, Aux 2, 2-Trk input or USB input. If Aux 1 and Aux 2 are selected at the same time, Aux 1 feeds monitor left and Aux 2 goes to the right — very handy if you're using these Auxes for a stereo recording feed. The headphone output is plenty loud enough for live sound monitoring and didn't distort when I cranked it up as loud as I could stand it. And there's even a stereo mini-jack socket in addition to the standard size connector.

Even more outputs!

There are two additional pairs of outputs available on unbalanced RCA phono sockets. The Rec Out signal is the same as the main left/right mix, but is tapped off before the faders so that level adjustments made during a performance do not affect your live recording. The Alt Out sockets are fed from their own little master section, which has a dedicated level control, and you can select the source as left/right mix (pre- or post-fade) or send whatever is currently feeding the monitor section. Talk about spoilt for choice!

Conclusion

With all this functionality, the ZED-14 should find employment almost anywhere! I used the review model as a live sub-mixer for drums, and as the front-of-house mixer for a small-scale conference. I also used it to prepare some audio-visual presentation material and found it just as easy to work with as my 'everyday' GL2400 mixer. The ZED-14 has exactly the same feel of quality about it as its larger and more expensive brethren, and I love its compact size, neat low-profile appearance and user-friendly flexibility. It's very good to see that, in producing a mixer at a lower price point, the sensible folk at Allen & Heath have not abandoned any of their quality principles with the ZED-14, and have packed so much functionality into it that the front panel is like an Aladdin's cave of mixer features. According to the A&H website, there are 99 controls on the panel, but I beg to differ — if you include the various switches as well as the knobs, I make it 153!

There are so many things you can do with this versatile little desk that, for me, its only limitation would be the number of input channels. If the ZED range now includes larger format four-group models (which I seriously hope to get my hands on very soon), and extended stereo versions (some with onboard processing) are on the way, then this is going to be the series to beat for portable live sound at a very reasonable price. However, for project studio work or smaller scale live events where loads of mics are not required, the ZED-14 is a little gem and has got to be on everyone's shopping list.