You are here

Session Notes: Impossible Colours

Multiple Mics For Guitar Amp Tone Sculpting
Published August 2013
By Mike Senior

David, the guitarist of the band Impossible Colours. Behind him you can see the drum-miking setup that we cannibalised to create the elaborate multi-mic rig we used for all his subsequent overdubs.David, the guitarist of the band Impossible Colours. Behind him you can see the drum-miking setup that we cannibalised to create the elaborate multi-mic rig we used for all his subsequent overdubs.

In this month's Session Notes column, we focus on a recent overdubbing session, which demonstrated the benefits of the multi-miking approach particularly well.

These days, I rarely put up just one mic for recording electric guitar. Partly, that's because I find it easier to get a well-balanced picture of an amplifier from typical close-miking distances if I blend different elements of its frequency dispersion. However, multi-miking also has powerful tone-sculpting potential, and tracking guitars seldom seems to be just a question of preserving for posterity exactly what's coming out of the amp.

Session NotesFor a start, the sound that the player is hearing in the room may not be exactly what they're looking for, given that most players working on a budget don't have an unlimited selection of guitars and amps to choose from. And even if it is, that tone may not suit the required function of a particular part in the arrangement. This is especially the case where you're laying something extra over an existing track recorded using the same guitar/amp, because layered textures typically sound more solid when the constituent timbres are contrasted.

Multi-miking For Guitar Overdubs

In this month's Session Notes column, I'm going to focus on a recent overdubbing session, which demonstrated the benefits of the multi-miking approach particularly well. The band in question is the psychedelic rock outfit Impossible Colours (www.impossiblecolours.com), which regular readers may remember from SOS April 2013 (/sos/apr13/articles/session-notes-0413.htm). The guitar session was scheduled to follow on directly from the full-band takes, which is just the way I like it. Not only does it keep the momentum of the session going psychologically, piggybacking on the excitement generated between the band during their ensemble performances, but it also has several practical advantages.

Firstly, you can repurpose a whole bunch of mics already in the studio, so putting even half a dozen different mics on the amp is just a question of repositioning stands. In this instance, I grabbed the Shure SM7B dynamic mic I'd had on the snare; a Shure SM57 dynamic from the rack tom; my phantom-powered Blue Kickball dynamic mic, which had been outside the bass drum; and a stereo pair of KSM141 small-diaphragm condenser mics that had been on overheads. However, even if you change the mics completely, you've still already set up the stands, sorted out your signal routing, and tested the lines, so it's still much quicker to get started. Indeed, I repurposed the other two tom-tom channels on this session to add an Electrovoice RE20 and AKG C414B XLS into the line-up.

In this picture, you can see how the five close mics were arranged for the overdubbing session. Closest to the amp were a Blue Kickball and a Shure SM57; a Shure SM7B and an Electrovoice RE20 were set up a little further back; and an AKG C414B XLS was bringing up the rear.In this picture, you can see how the five close mics were arranged for the overdubbing session. Closest to the amp were a Blue Kickball and a Shure SM57; a Shure SM7B and an Electrovoice RE20 were set up a little further back; and an AKG C414B XLS was bringing up the rear.

If you're not relying on a single mic, the exact positioning of the mics is also less critical, which saves time. In fact, as you can see from the pictures, I deliberately like to set up the mics in a fairly loose pattern, in order to introduce tonal and phase differences between them, because that not only gives me a wider palette of colours to work with, but also allows me to make creative use of inter-mic comb-filtering effects. My main concern when setting up the close mics for this amp was to avoid placing any of them right up against the grille, because I'm not a huge fan of the way extreme close miking spotlights only a very small proportion of the overall cone/cabinet sound. It always seems like hard work making a grille-hugging mic sound natural at mixdown, so if spill isn't a consideration I'd rather save time by getting something more satisfying straight out of the mics.

In heavily overdubbed productions I rarely bother with room miking, but here I knew that the band's guitar sound would frequently be coming from just one or two guitar parts, so I figured that a little bit of stereo spread from the room might be a nice way to fill in the overall panorama, and the room's character might also help bind the guitar parts in with the drums, to a small degree. However, I didn't want to imply too large a space, so although I had the mics roughly 3m away from the amp, I made sure to aim them directly at the cab, rather than emphasising the reverb decay by angling them away. I also repurposed a couple of live-side/dead-side gobos which we'd been using to dampen the drums ambience for the full-band session, reversing them to fire a few more early reflections into the room mics.

How To Blend The Mics

All of this enabled me to prime five close mics and a stereo room array in less time that it took the guitarist (David) to finish setting up his amp and pedalboard! He was keen to stand right next to his amp while recording, so that he could work the feedback from the amp, but as there were already headphones set up from the full-band session, this didn't slow us up either, and I could immediately start putting together some sounds while Michael jammed over that backing track.

I switched the AKG C414B CLS dual-diaphragm condenser mic to its hypercardioid polar response in order to reject more of the room ambience, so that the signal would remain well-focused despite the mic's more distant positioning.I switched the AKG C414B CLS dual-diaphragm condenser mic to its hypercardioid polar response in order to reject more of the room ambience, so that the signal would remain well-focused despite the mic's more distant positioning.

Quickly auditioning each of the close mics confirmed that I already had the two most important things: first, a couple of close mics that immediately seemed in the right kind of ballpark sonically (not really a tall order, given five mics to choose from and a bit of experience/luck thrown in!); and second, a good contrast between the sounds coming from each mic, which is vital if you want lots of control over the sonics. Had I decided I couldn't tick one of these boxes, I'd have hot-footed it into the live room and shuffled the mics around, but it simply wasn't necessary.

Faced with so many mics, here's what I typically do to home in on a suitable sound. First, I'll find the mic that seems to provide the most promising starting point. In this case, that was the C414, which was actually the most distant of the close mics (positioned about three feet away), but with its hypercardioid mode purposely engaged to minimise the room pickup and remain fairly focused on the cabinet itself. Then I'll start fading up other mics against the primary one to see if they contribute anything worthwhile. On this session, pulling up the SM57 not only added a nice throaty 'growl', but also cancelled out some of the condenser mic's low end into the bargain, tightening the sound of the mix as a whole (the bass guitar was already injecting plenty of low end on its own).

It's important to fight the loudness bias, because adding a mic may well make the composite sound louder — and juggling the faders to combat this will help you make better-informed decisions. So as you fade up a secondary mic, keep your hand on the primary mic's fader, to keep the total subjective volume as constant as you can.

The room mics were a pair of Shure KSM141s in cardioid mode, and spaced to provide an extra-wide stereo image. The panel to the rear has been placed to direct a few more early reflections at these microphones. (A second panel is just out of shot to the left of the combo.)The room mics were a pair of Shure KSM141s in cardioid mode, and spaced to provide an extra-wide stereo image. The panel to the rear has been placed to direct a few more early reflections at these microphones. (A second panel is just out of shot to the left of the combo.)

Polarity Disorders

In some cases, you'll find that a certain mic will utterly destroy the sound you're looking for, emphasising frequencies you don't like, or hollowing out your favourite bits of the timbre and causing the instrument to apparently recede from you as you push up the fader. Don't immediately write off that mic as a disaster, however, because it may do something much more useful if you invert its polarity — in fact, the worse it sounds to start with, the more likely it'll actually sound great with opposite polarity! This was exactly what happened with my SM57 here: it made the guitar sound awful to start with (flat, fizzy, annoying...), but flipping the polarity immediately moved the tone in a much more desirable direction.

If you're looking to add some specific characteristic to the combined sound, it can be useful to quickly solo your way through the available mics to locate that more quickly. By the time I'd added enough mid-range attitude to the C414 from my SM57, for instance, I felt that the comb-filtering interaction between the mics had sucked out too much of the low-mid range, so I hunted around for a mic that might be able to reinstate some of that warmth. The RE20's off-axis positioning had captured an unattractively woolly sound when auditioned independently, but sneaking just a little of it into the mix proved to be just the ticket (once that channel's polarity switch had been punched in).

By this point, I had a close-miked sound that seemed to work, so all that remained was to ride up the KSM141 pair to enhance the stereo image. I'd gone with a fairly wide-spaced configuration for these mics, to over-emphasise the stereo spread, which meant that they widened the close-miked sound appreciably, even at a very low level, and affected the mono sound of the guitar very little, on account of their stereo signal's weak Middle component. As such, adding them into the mix was pretty straightforward, although I still checked their polarity against the other mics, just to make sure they weren't going to undermine any of the work I'd already done. I also panned the SM57 and RE20 close mics a little to the left and right, respectively, to widen the close-miked image slightly — although not enough to significantly damage the overall mono compatibility.

More Mics, More Speed

In print, all this might seem rather long-winded, but in reality it's the exact opposite. Indeed, one of the things I like about multi-miking is how fast it allows you to work. Checking the suitability of the five close mics took me less than a minute, and although trying different mic combinations unavoidably involves an element of 'suck it and see', the sheer variety of different sounds you can conjure from your faders and phase switches means that the odds of finding a great, mixable sound in a matter of seconds are overwhelmingly in your favour.

The Roland multitracker's mixer Scenes allowed me to store and recall different mixes of the seven microphones, such that it was easy to return to any sound later on if required.The Roland multitracker's mixer Scenes allowed me to store and recall different mixes of the seven microphones, such that it was easy to return to any sound later on if required.

And this working method speeds up workflow in other ways, too. Firstly, you can completely reinvent the timbre you're recording without needing to move a single mic, and this makes adapting to the needs of different overdubbed lines a breeze. It's also very easy to store any mic blend for later use, by either saving the fader/polarity settings in a mixer Scene (as I did in the Roland VS2480 I was using on this job), snapping a picture of the mixer's front panel on your phone, or just jotting down the relevant stats on paper — there's no serious processing involved, so it's an extremely simple recall even on all-analogue setups.

Another thing you're extremely well equipped to handle is a situation in which the guitarist disapproves of one of your initial sound choices. With Impossible Colours, I first encountered this during overdubs for the second song, where David wasn't happy with how we'd captured a particular heavily overdriven part. We could easily have spent half an hour moving mics around and doing test recordings, but it was far easier just to bring David and his guitar into the control room (with a long lead stretched back to the amp) and then choose a more fitting sonic personality under his direction, while he played. I didn't have to second-guess what he was listening for, or work out how to position a mic to get closer to that nebulous goal — I could just try different combinations of faders and ask him to tell me whether I was getting hotter or colder! In two minutes, we were back on track, ready to hit Record once more.

Many Mics Make Light Work

Although plugging in loads of mics for a single guitar amp might seem like overkill, it's pretty simple to do if you're able to re-use an existing multi-mic drum-recording setup, and the payback in terms of better sounds and faster workflow can be enormous. Just don't let all those mics lull you into deferring your production decisions — you'll thank yourself later if you just grit your teeth and print what you hear!  

Committed Relationships

If you're using a multi-mic setup, it's tempting to just record all the mics to separate tracks and leave the final tonal decisions for mixdown. However, my firm opinion is that most SOS readers will be ill-served by this approach, and would do better to cement the complex relationship between the microphones while recording. Certainly all the multi-miked sounds I recorded on the Impossible Colours session were submixed to stereo for recording, regardless of the number of mics I was using. From a pragmatic standpoint, this simplifies any later editing and mix processing, as well as reducing demands on storage space and CPU resources. But, more importantly, it also forces everyone involved in the production to take greater responsibility from the outset for how they want the final record to sound. Either the sound works, or it doesn't — there's no "we'll fix it in the mix”. Committing yourself in this way can save a massive amount of time when you're working on a shoestring, and has the added advantage that any mix engineer approaching your multitrack recordings 'cold' will immediately know what you were aiming for as soon as he or she raises the faders.

Mix The Mics For Yourself!

Accompanying this month's column is a dedicated resources page on the SOS web site. This includes a series of guitar phrases played by Impossible Colours' David and recorded through our seven-mic overdubbing setup. However, rather than mixing all the mics together as I did for the actual overdubs, I've separated them all out to individual tracks, so that you can hear the degree of variety I was working with, as well as experimenting with moulding the guitar sounds for yourself, exactly as I did during the heat of the session. In addition, I've created a set of examples that walk through how I built my first guitar sound on this session, using five of the mic signals.

/sos/aug13/articles/session-notes-media.htm

Published August 2013