#multi miking

When I record, I prefer to get my microphones to do the heavy lifting, rather than relying on masses of outboard processing to get the timbres I'm looking for -- it's more fun spending time in the live room with the musicians (rather than in the control room twiddling knobs), the results always seem to sound better with less effort, and it's usually cheaper into the bargain! In particular, I love using multi-miking to craft tones, which is why I never seem to have enough tracks available when recording bands!

My recent session for Brushes Held Like Hammers was a case in point, because I wanted to run up 20 mics out in the room with the band, but only had 16 inputs on the recorder. However, on this occasion I happened to have access to a pair of ASP008 units, which helped provide a rather elegant solution to this problem. Let me explain...

Too Many Mics, Not Enough Tracks!

The band use the classic rock line-up of two guitars, bass, and drums, and I'd allocated my 16 tracks as follows: kick, snare, hi-hat, ride, two toms, stereo overheads, stereo room mics, bass DI, bass amp, two guitar DIs, and two guitar amps. I had deliberately given the drums plenty of close mics, as well as factoring in instrument DIs, as a safety measure, because it was my first time working with the band and I figured I might need a good deal of mixing flexibility to cater for their eclectic collage of different styles. That did mean, however, that I didn't have spare tracks for multi-miking four instruments I really wanted to: the kick, the snare, and the two guitars.

There are lots of great things you can do with multi-miking. Firstly, you can blend contrasting mic tones to create a 'best of all worlds' combination. Secondly, you can pick up more of the overall character of an instrument by miking different bits of it and then adding those different perspectives together. And, thirdly, you can get creative with comb-filtering effects between the mics. The last of these is one my favourite 'secret weapons' in the studio -- just adjusting the distance between the same two mics only a few inches can change the sound dramatically, and you can also immediately access a second (and often quite different) sound for any given spacing by flipping the polarity of one of the mics.

I initially considered bringing a Mackie mixer along with me to preamplify additional mics for each of these four instruments and submix them to the four available tracks, but I really wasn't that happy about the idea of running through all that extra circuitry, which included each channel's (unbypassable) EQ -- I normally prefer to go straight into the recorder from the mic preamp if I can. In addition, I'd also have lost out on half the creative possibilities of the multi-miking, because of the lack of any polarity inversion switches.

An Elegant Solution: Two ASP008s

I was therefore delighted to be able to lay hands on a couple of Audient ASP008's, one of which I was able to combine with my own SSL X-Desk eight-channel line mixer to create a much more attractive system: a short, uncluttered, high-quality signal path from the mics to the recorder, complete with the necessary submixing from the X-Desk and the ASP008's per-channel polarity-inversion facilities.

However, there was another big reason I was so pleased to get hold of the ASP008 for this session, because of the specific way I'd decided to record the whole band (bar vocals) simultaneously. I wanted to let the band play exactly the way they do in rehearsal, set up close to each other without any headphones or monitors impinging on their sound or slowing down communications. Now I'm a big fan of spill -- I see it as the glue that holds a band recording together -- but in this instance I was nonetheless keen to keep the sound reasonably tight, and one of several tactics I used to achieve this was using directional mics and bringing them in close to their sources. As we all know, the proximity effect tends to make directional mics serious emphasise the lows under such circumstances, and while that's sometimes part of the appeal, it's just as often unwelcome.

Now there are lots of ways to deal with proximity effect. You can use a mic with a natural low-cut in its frequency response, such as a Shure SM57, but that restricts your mic choices somewhat. Alternatively, you might switch in a high-pass filter on the microphone, but this can often be a bit of 'sledgehammer to crack a nut' situation, because the filter always seems either not effective enough, or else it cuts way too much body out of the tone. The typical fixed-frequency filter switches you get on most mixers and preamps also suffer the same inflexibility, but this is an area where the ASP008 really scores for me, because it gives you a switchable and fully variable high-pass filter. If you want it out of circuit, you can bypass it. If you want it to protect a vocal compressor from rumble, it can stay really low. But, more importantly in this scenario, if you want it to counteract just the right about of proximity effect for each mic, you can dial it in to taste.

Enough of the theory, though. How did it all work out in practice?


Multi-miking Kick & Snare

The kick mics I put up were an ADK S7 and a BLUE Kickball, a good all-purpose condenser+dynamic pairing that delivered what I was looking for without too much fuss. I had a bit more leeway with the positioning here because I'd built a little blanket-covered tunnel out from the front of the drum to control spill, so I was able have both mics about a foot away from the drum. The S7 had started out three feet away, and already provided plenty of LF woof there, but I'd moved it inwards twice in search of more focus. The Kickball had started out in the hole of the drum's resonant head, but having heard the weight of the S7, I decided to move it back a bit, as well as reduce its low-frequency emphasis switch to the minimum setting, so that the signal provided a more complementary dose of attack and midrange tone.

Here already, the ASP008's high-pass filter helped me out by tightening up the S7's sub-bass, which felt like it was giving my speaker cones a bit too much of a work-out -- that mic goes way down low, and although I liked the rest of the sound, the subs felt too much for this particular production. A typical fixed high-pass filter would have been no use at all here, though, because it'd have turned over way too high, whereas I was able to set the ASP008's to 20Hz, allowing all the drum's 50-100Hz meat to survive intact while I toned down the extreme lows. Given that the mics were destined to be mixed together onto a single track, I wanted to make sure I had the best polarity combination, so flexed the polarity switches too, although it turned out that their default polarity relationship happened to give the most solid low end in this instance. Combining them with the rest of the drumkit mics, however, necessitated a polarity inversion on both mics to get the best blend.

The snare close mics were quite critical to this recording, because the drummer's rather dominant hi-hat meant I couldn't really draw the snare's character from the overheads as I often like to. So I paired two Shure mics for that: an SM57 and a KSM137, gaffered together on a single stand because space was tight around the kit. These did the trick straight away, once the tuning of the snare itself had been lowered to give it more weight, the close proximity of the mic capsules obviating any need for polarity inversion. Not that I didn't check, though -- the resulting super-thin combination provided ample confirmation that the mics were already well phase-matched.

Sculpting Guitar Tones

With the two drums is was more a case of just blending the mic characters, whereas with the guitar tones the mics had a little more distance between them, collecting different aspects of the cab sound and providing more opportunity for subjective phase-tinkering. I had given each of the guitars a Groove Tubes GT55: a large-diaphragm cardioid condenser mic. I was looking to these mics for body and warmth, placing them towards the edge of a speaker cone in each case to keep the sound fairly soft-edged. As I'd suspected, however, one of them became a little boomy from the close placement, so I switched in the ASP008's high-pass filter on that channel, sweeping it up to around 80Hz, allowing the natural frequency-recessing above the filter's cutoff point to pull the guitar's 100-200Hz zone subtly back into line.

To complement the GT55s I originally put up an Electrovoice RE20 and a Shure SM7 for the two amps respectively, but neither made the final cut, being replaced by a vintage Sennheiser MD421 and a Shure SM57 respectively before I was able to achieve the midrange solidity and cut-though I was hoping for. Again, though, the proximity effect was slightly clouding the SM57's low end, so I punched in another high-pass filter there at 50Hz to rein that in a touch. The polarity buttons got a big work-out here as well while we worked our way through different combinations of mics and mic positions -- some combinations seemed utterly hopeless until I'd flipped one of the signals, while others (including, by chance, both the final setups) turned out better without polarity adjustments.

Yes, But What Did It Sound Like?

Enough of the words, though: what did it actually sound like? In anticipation of this question I asked the band at the end of the session if they'd mind playing the same short section of one of their songs a few times for me, so that I could reroute all the multi-mics to separate tracks for demonstration purposes -- and they kindly agreed! So here are files for all the mics I've mentioned, which show what each of the individual mics sounded like, what the filtered mics would have sounded like without their filtering, and also how each pair of mics mixed together (both with the default polarity I preferred, and also with one of the mic signals inverted):

Kick:

Kick -- Mic 1: ADK S7 with 20Hz high-pass filter (MP3 - WAV)

Kick -- Mic 1: ADK S7 without 20Hz high-pass filter (separate take) (MP3 - WAV)

Kick -- Mic 2: BLUE Kickball (MP3 - WAV) Kick -- Mic 1 + Mic 2 mix (MP3 - WAV)

Kick -- Mic 1 + Mic 2 mix, Mic 2 inverted polarity (MP3 - WAV)

Snare:

Snare -- Mic 1: Shure KSM137 (MP3 - WAV)

Snare -- Mic 2: Shure SM57 (MP3 - WAV)

Snare -- Mic 1 + Mic 2 mix (MP3 - WAV)

Snare -- Mic 1 + Mic 2 mix, Mic 2 inverted polarity (MP3 - WAV)

Guitar 1:

Guitar 1 -- Mic 1: Groove Tubes GT55 (MP3 - WAV)

Guitar 1 -- Mic 2: vintage Sennheiser MD421 (MP3 - WAV)

Guitar 1 -- Mic 1 + Mic 2 mix (MP3 - WAV)

Guitar 1 -- Mic 1 + Mic 2 mix, Mic 2 inverted polarity (MP3 - WAV)

Guitar 2:

Guitar 2 -- Mic 1: Groove Tubes GT55 with 80Hz high-pass filter (MP3 - WAV)

Guitar 2 -- Mic 1: Groove Tubes GT55 without 80Hz high-pass filter (separate take) (MP3 - WAV)

Guitar 2 -- Mic 2: Shure SM57 with 50Hz high-pass filter (MP3 - WAV)

Guitar 2 -- Mic 2: Shure SM57 without 50Hz high-pass filter (separate take) (MP3 - WAV)

Guitar 2 -- Mic 1 + Mic 2 mix (MP3 - WAV)

Guitar 2 -- Mic 1 + Mic 2 mix, Mic 2 inverted polarity (MP3 - WAV)

(Click here if you'd like to download all the WAV files as a single 70MB ZIP archive.)

Of course, what I haven't yet mentioned is that I also took the opportunity to generate a whole series of examples of the ASP008's input-impedance switching while I was at it, but we'll leave that story for another post...

About The Author: Mike Senior is an award-winning audio engineer who's worked with artists such as The Charlatans, Reef, Therapy, Nigel Kennedy, and Wet Wet Wet. For six years he was Reviews Editor for Sound On Sound, the world's best-selling music recording magazine, and writes regularly for their popular Mix Rescue, Session Notes, and The Mix Review columns. He is also the author of the best-selling Focal Press book 'Mixing Secrets For The Small Studio', a complete mixing method based on the techniques of the world's most famous producers.

All photos taken by: Blake Lewis

Thanks for reading.

Audient