Paul White explains how you can do serious multitrack work with a far simpler mixing console than you may have been led to believe.

We, as members of that creative elite, the recording fraternity, tend to think of ourselves as free-thinking spirits, but underneath it all, we're just as likely to be swept along with the marketing tide as the next man. Take mixing consoles; you'd never dream of trying to make a serious multitrack recording using a mixer designed for PA use would you? It simply hasn't got the facilities. Or (as they say on Tomorrow's World) has it? We're so used to being told that we need fancy monitoring sections and multiple-buss routing that most of us actually believe it, but when you take a step backwards and think about what you actually need from a mixer, does all this complexity make sense?

The idea for this article came after talking to several recording engineers about the way they actually use their mixing consoles, rather than the way the manufacturers expect them to be used. As you know, the studio mixer serves a double function; during recording it allows signals from microphones and instruments to be routed to specific tracks on a multitrack recorder. Along the way, it allows you to set the recording levels, EQ and so on. Once you have recorded your first batch of tracks, these can be heard via the monitor channels, enabling you to play along with what you've already recorded. Being able to hear what you've already recorded is vital in enabling you to build up a composition in layers — the very essence of multitrack recording.

When all the tape tracks have been recorded, the multitrack's outputs are fed back through the console's main input channels and mixed down to stereo. This is the conventional way of working and indeed, it is the method you'll more often than not find explained in the manual that came with your mixer. It can be a frustrating way of working though, because all the time you're recording, you're fine-tuning the monitor mix to get a good balance, you're adding effects and tweaking the EQ — but when the time comes to do the real mix, all this work has to be scrapped. You have to build your mix from scratch using the mixer's input channels. No wonder, then, that on so many sessions, the cassette taken from the rough monitor mix sounded better than the final version!

Because of the above limitations, many engineers (myself included) have adopted a different way of working which flies in the face of accepted wisdom. For us, the monitor inputs are a useful source of additional line inputs if we run out of main input channels at the mixing stage, but as a rule, they remain unused. When you think about it, a monitor input (whether split or in-line) is just a second-class input channel routed directly to the stereo mix buss; it has no mic amp and usually has less in the way of EQ and aux sends than the main inputs — so why not use an input channel instead?

The All-Input Approach

Let's start with a hypothetical setup comprising a 24-channel, 8-group mixer linked to a 16-track recorder. The first thing we do is permanently wire all the tape machine outputs to mixer inputs 1-16 and route all these channels to the Left/Right stereo mix. In other words, these channels are set up just as they would be for a normal mixdown session. That leaves us with eight spare input channels (17-24) which we can use to handle the mic and line inputs we wish to record. In this example, we can only record signals from up to eight mixer channels in one go, because we only have channels 17-24 left to work with; but when you're working with 16-track, how often do you want to record more than eight instruments in one take? And if you do, a 32-channel mixer should cover all eventualities.

There's no mention of monitor channels because we are, in effect, monitoring the output of the multitrack tape machine at all times via channels 1-16. And, because we're using these same channels to do our final mix, there's no need to dismantle a perfectly good monitor mix in the process. Figure 1 shows how this setup works. My own studio is based around a 16-track recorder coupled to a 32-channel console, and it's very rare that I need to consider using the monitor channels, even when running my MIDI sequencer and several stereo effects units live into the mix. Apart from being able to work on the mix as the tracks are being recorded, it means I can go straight from track laying to mixing with no repatching at all. And if, during the mix, somebody decides they want to re-record something (as they so often do), there's no need to reset the whole console to make it possible.

Group Requirements

On the face of it, a 16-track tape machine needs a mixer with 16 output groups, otherwise you can't record on all 16 tracks at once with complete flexibility. Certainly, 16 output groups make life easy if you do want to record all your tracks at the same time, but apart from live recording, it's very rare that you'll want to record more than half the available tracks in one take. For that reason, many budget consoles cut down on the number of output groups, offering eight groups for use with 16-track recorders, 12 groups for use with 24-track machines, and so on. Such consoles are cheaper to build, and with the demand for low-cost recording systems ever on the increase, the compromise is a sensible one.

But if you think hard about your actual requirements, you might find that you could happily halve the number of groups yet again. Most mixing consoles have channel insert points and direct channel outputs, either of which can be used to take a signal direct from an input channe to the input of a multitrack tape machine without involving the console's routing buttons or mix busses at all. If all you want to do is to record a single signal, such as a solo mic, onto one track of tape, this is an ideal way to work. It may involve a little patching, but it saves using up your mix busses and, more importantly, it gets your signal to tape without it having to pass through any unnecessary circuitry.

Even the best mixer circuits cause some degradation of the input signal, so if you can avoid the channel pan circuit, the routing switches, the mix busses and the group output amplifiers, then so much the better.

Reasons To Be Different

The only real difference between a PA-type mixing console and a studio console is the routing and monitoring. PA desks have no monitoring, they usually have more basic routing — and they tend to be a lot cheaper! Many basic PA consoles have some provision for playing a two-track recorder back through the desk, though even this can be accomplished by patching if the facility is absent. A very basic 'something into two' live mixer is of no real use for multitrack, but a number of live or general-purpose consoles are available which have routing to four group busses, plus the main Left/Right stereo mix. Providing these consoles have direct channel outputs or, at the very least, insert points, it is possible to use them as outlined above for multitrack work, not only with eight-track tape machines but with 16- or even 24-track models.

Should you feel that this would leave you short of inputs when you come to run a MIDI sequencer into the mix, consider using a separate keyboard mixer for the MIDI stuff and feed this back into either two channels of your main mixer or into a pair of aux returns, as shown in Figure 2. Because you're not paying for facilities you don't need (such as mic amps, for example), what you do get tends to be of good quality and sensibly priced, not to mention compact. A rack-mount keyboard mixer can take up just a few units of rack space, yet may offer 16 input channels with basic EQ and two or more aux sends.

One limitation to keep in mind when adding a separate mixer is that the effects send systems are also separate, which makes it difficult to share the same effects units between the two mixers. If you are using a reverb or multi-effects unit with stereo inputs, then you can feed, for example, the Aux 1 sends from each of your desks into the two inputs. It is possible to use an effect with a mono input, but with the method described here, you lose one channel of your main mixer for every send you wish to connect. For example, if your keyboard mixer has two aux sends, you could feed these aux outs into two channels of your main desk. The main mixer channel receiving the Aux 1 signal would have its Aux 1 send turned up to near maximum and the channel output would be turned on but unrouted. If the channel send is a post-fade send, then the channel fader will also need to be turned up. Likewise, the other channel would receive the Aux 2 output from the keyboard mixer and it would have its Aux 2 send turned up. The result is that that the aux outputs from the keyboard mixer are mixed into the aux busses on the main mixer enabling the same two effects units (connected conventionally to the main mixer) to run on both mixers.

In most cases, this added complication will be unnecessary, as the majority of studios have several pieces of outboard equipment, much of it with stereo inputs, and, in any event, a great many modern MIDI instruments come with some form of effects system built in.

Noise Notes

Even the best mixers in the world generate some noise — it's a matter of basic physics and can't be avoided. The more channels you mix together, the more noise you get, so a sensible first step is not to mix more channels than you need. For example, say you have a 32-input desk and you're mixing 16 tracks from tape and two stereo effect returns, making a total of 20 inputs — that still leaves 12 channels doing nothing. If you mute these unused channels and pull the faders down to zero, you may be surprised to learn that they're still adding some noise into the mix, just by virtue of being routed to the mix buss. The only way of removing them from the system altogether is to make sure the L/R routing buttons are in their off position for all unused channels. You can check this out for yourself by turning all your channel faders down, turning all the mutes on, and then turning up the studio monitor level until you can hear the hiss. You'll be amazed at the difference in hiss level between all the channels being routed to L/R and all the channels being unrouted. Of course this applies to the group busses too, so unroute anything that's not needed.

Less obvious is the fact that this noise build-up problem also affects your aux sends, and there's usually no way of turning these off on a budget desk. Many an innocent effects unit has been blamed for adding noise to the mix when the real culprit has been the aux send buss. On some desks, you can route the aux sends to different busses, often in pairs, and this can help. For example, aux 1,2 may be switchable to aux busses 1,2 or 3,4. If your effects are connected to sends 1,2 you could route any unused channel aux sends to 3,4, thus reducing the noise on busses 1,2. This is fine so long as you don't need sends 3,4 for anything, but if you need all your sends or have no routing options like the ones described, you can still gain some benefit by setting the channel aux send levels as high as possible. This will enable you to use a lower setting on the aux send master control which, in turn, will reduce the amount of noise fed into the effects unit.

More For Less

A properly designed multitrack console offers the most flexibility, but its very complexity makes it costly. As we've already seen, a lot of engineers prefer not to use their monitor sections at all, unless they are forced into it by a lack of inputs — so why pay for monitor inputs when you can use the same money to buy more input channels instead? After all, the majority of low and mid-priced consoles either have restricted EQ on the monitors or they force you to share one EQ section between the main and monitor signal paths, so even these are a compromise. To be quite fair, a well-designed in-line console does give you the option of mixing without repatching, but you still have a lot of buttons to press. By spending your money on a simpler console with more channels, you get full facilities on all channels and a simpler way of working.

If you are prepared to accept fewer output groups and resign yourself to the odd bit of patching between direct channel outputs and your multitrack inputs, you can pick up something like a 32:4:2 for less than half the cost of an equivalent multitrack desk. Adding a separate rack-mount line mixer to handle MIDI instruments and aux returns can also be very cost effective, saving not only money but valuable studio space.

I'm not suggesting in this article that we should all buy more simple desks, but in a situation where finances are tight, it pays to sit down and consider what you actually want to achieve. Looking at all the glossy ads makes it easy to see what you want, but less easy to see what you need!