Most small project studios nowadays don’t need a hardware (analog) mixer—they can run signals directly into and out of their interface, monitoring through powered speakers and/or headphones. But sometimes a small mixer can come in handy, especially for slightly larger sessions. For example, if several musicians are being recorded all at once, or if multiple mics are being used on a particular instrument but recorded on a single track (stereo or mono) track, having a small external analog mixer can help with both the signal routing and the logistics of the session.
Project studio operators that want to incorporate a small analog mixer often choose a rackmount 16-channel unit (like the ubiquitous Mackie 1604VLZ or similar mixers from other manufacturers). This kind of design would be a good companion for an 8x8 (8-in 8-out) interface, providing additional routing and monitoring possibilities, and offer the convenience of a second physical workstation that could be manned by an assistant during the session, taking on some of the workload from the primary engineer.
A flexible setup might also incorporate a patchbay, to make it easier to re-route signal paths if/when needed. Various input signals could be plugged into the analog mixer, and its direct outs or subgroup outs patched into the line inputs of the interface. The main stereo output from the DAW would be sent into a spare stereo input on the analog mixer for monitoring. Any additional inputs could be used to set up more flexible monitor mixes for a group of performers, with the patchbay providing simple rerouting capabilities for different session requirements. There are several advantages provided by this kind of setup..
When musicians monitor themselves in headphones during a recording session, they’re usually hearing a blend of any already-recorded tracks along with their own live signal(s) in the phones. This is fine, but with a live signal going into the interface, through the DAW, and back out to the headphones, there’s always a certain amount of latency. Remember, latency is a delay caused by the signal passing through the interface’s AD/DA converters and the computer’s RAM buffers, and—depending on the computer specs, interface, and connection—this can sometimes be enough of a lag to throw the performer’s timing off just enough to compromise the performance a bit.
Many interfaces offer a feature that routes the live signal right back out again to the performer’s headphones before it passes through the computer, though there’s still a little converter latency involved—this is sometimes referred to as near-zero latency monitoring. Most performers are fine with this, but some—especially drummers and rhythm instrument players—might still be sensitive to even a small amount of latency. And if the performer is able to hear a bit of their own signal in the room (or in their head, as with singers), this can sometimes cause a subtle flanging/phasing effect against the delayed signal in the phones, even with a very small amount of latency. With an external analog mixer in the picture, any latency can be eliminated, for true zero latency monitoring.
While live signals (mics, instruments) plugged into an analog mixer are routed to the interface/DAW to be recorded, those signals can also be (split and) routed via the hardware mixer’s Sends to a bus/output feeding a headphone amp. The main stereo output of the DAW is also routed to the analog mixer, where it not only feeds the speakers, but also feeds that same headphone amp. That way, during recording the performer(s) are listening to both the recorded tracks, and their own signals before those signals pass through any latency-inducing computer signal path, eliminating any potential subconscious or subliminal distractions from even small amounts of latency.
There’s another monitoring-related advantage to using a small analog mixer. Performers always need a dedicated monitor (cue) mix in their headphones while recording. This is often a different balance of tracks than what the engineer/producer needs to hear while the recording is going down. If multiple musicians are all recording together, sometimes each one may need a slightly different monitor mix to be able to give their best performance.
Most DAWs’ virtual mixers provide plenty of pre-fader Aux Sends to create several cue mixes right within the box, and as long as the interface has enough extra outputs, a single engineer could dial up the various cue mixers him/herself. But a bunch of players frequently requesting adjustments to their individual cue mixes (more kick, less guitar, more me, etc) can be a distraction to a lone engineer who’s trying to focus on getting good clean levels, checking for multi-mic phase issues and subtle extraneous noises being picked up by the mics, and other potential technical issues with the tracks being recorded.
With an external mixer that has its own Sends (typically at least 4 or more separate pre-fader Sends per channel), an assistant engineer can dial up the monitor mix levels of the live signals (and some of the prerecorded tracks as well, if their DAW mixer Sends are routed to separate outs on the interface). With the assistant engineer keeping an eye (and ear) on the cue mixes, and responding to the sometimes frequent performers’ requests for adjustments as the recording session progresses, the lead engineer may be freed up to devote his attention to the other important technical aspects of the recording, as above. I’ve done many sessions this way, where an assistant engineer manning several cue mixes on a small Mackie provided a very welcome division of labor in a busy recording session.
Running input sources through a small mixer on their way to the interface can also allow for easy subgrouping, like when the engineer has more mics set up than individual inputs on the interface. A good example would be a drumkit that’s being multi-miked for sound quality, but due to interface i/o/ limitations is being recorded as a single stereo track. Using subgroups on the analog mixer, the drum mics can quickly and easily be routed to a pair of subgroup outs feeding a stereo recording channel in the DAW.
Even small mixers will usually have a decent EQ section and an insert per channel, so the drum sound can be shaped to some degree on the way in, just like it was done back in the early days of 3 and 4-track multitrack recorders (Motown, Abbey Road), when many decisions had to be made at the recording stage.
Finally, if the small analog mixer is a high-quality unit, it may provide a little of the subtle analog sound quality so sought after by so many recordists. Admittedly many of the more inexpensive small analog mixers don’t really offer much in the way of analog “character”, but there are a few higher-end small mixers (sidecars) whose mic preamps and EQ sections could provide a nice analog front-end, offering some of the analog character that still drives people to record and mix on large analog consoles, without the size and expense of a full-blown large-format board.
So while working in the box is certainly the SOP for most small/medium-size recording setups, a little analog help can sometimes be a welcome addition to the modern DAW studio.