Session Notes: Thomas Rumbold 'Reds'

Portable absorbers and diffusers were used to create a suitable acoustic around and behind the guitarist.

Our recording engineer tackles the challenge of recording a singing guitarist, and weighs up the merits of several mic techniques.

Which is the best way to record acoustic guitar and vocals is a decision almost every recording engineer is faced with on a regular basis. There are a few different techniques and approaches, and which is appropriate — or 'best' — will depend very much on the style of song and desired aesthetic. If 'faithful and natural' is the name of the game, many singer-songwriter types prefer to play their guitar and sing at the same time, rather than perform overdubbed vocals, simply because this is what they always do, so it helps them to give a more natural performance. Provided you're not working to a click or some sort of backing, it also means they have the option of slipping off the headphones, which can help preserve the natural balance between the guitar and voice and, I've found, also helps some singers with their pitching too.

Yet, while this sounds great in theory, it doesn't necessarily give you the best result, so when determining the best approach you'll need to ask yourself some questions. For example, although the artist might be able to nail the vocal, are they technically good enough on the guitar to do the same while they sing? And if not, are you better off just accepting some of the rough edges, in order to capture a more natural take with the right 'vibe'? There are many stories of legendary recording sessions where people have spent ages chasing their tail, trying to recreate the vibe of a demo recording done on an acoustic, only to end up working on the original.

For a more polished, produced sound, I find that it often works better splitting things up, so that both the performer and I can focus on the sonics and performance of the individual elements — particularly if the material you're working on is for a band, or if the song has lots of internal dynamics. Of course, although this route can achieve the desired 'polish', it often involves a trade-off, as those small, natural variations in tempo, movement and feel are sacrificed. It can then take a fair bit of manipulation with effects and dynamics processors or automation to help prevent the vocal feeling too 'detached' from the guitar, so that they sit together volume wise, and this of course can take the material further away from its natural starting point.

These are a few general considerations but, as with most recording sessions, they're decisions that you must make according to the needs of the song and artist, and the circumstances of the particular session too. In this month's Session Notes feature, I'm going to focus on the 'natural' option, and describe three different two-mic techniques I auditioned in search of the best way of capturing the song 'Reds' by Thomas Rumbold.

General Setup

I have an area of my recording room that I like to record acoustic instruments in; I use mobile absorbing panels and diffusers to help create a dry, but not too dull-sounding acoustic. Being in a corner, it has a slight low-frequency boost, which I find useful on a lot of sources.

The artist, Thom, preferred sitting down while playing and singing. I'm sure many voice coaches would tut at this position, but it certainly makes an engineer's life a little easier; a few inches of movement can make a big difference to the sound of an acoustic instrument, and when someone is standing I find that they naturally tend to move about at least a little. When faced with this challenge, I'll often make marks on the floor with masking tape, just as a point to refer to if the position does change, but in this case I simply ensured Thom was in a comfortable position, and he then happily rehearsed the track a few times whilst I busied myself setting up mics and headphones around him. In addition to giving him the chance to warm up and make sure he was comfortable, this meant that I could familiarise myself with the song, and with the sound of his voice and guitar.

While keeping the artist happy, and aiming to get the best out of them like this, I'm always weighing up exactly what it is that I want out of this sort of recording. I think it's important to capture the vibe of a natural take, and for the recording to sound good straight out of the microphones, before applying any processing. I also want to give myself at least some options when it comes to mixdown, so I'll work hard to make the level of bleed realistically controllable. With this in mind — and remembering that this was a real recording session, and not an experiment — I narrowed my choices down to three options, which were based on broadly similar mic positions, but employed different mics and made use of different polar patterns.

Technique 1: In this picture you can clearly see how the side of the two figure-of-eight mics is directed at the source from which the greatest rejection is desired, to minimise problems with spill.

Mic Technique 1

The first setup I used employed two figure-of-eight mics, and is quite a common technique for tracking singing guitarists because pointing the figure-of-eight mics' side nulls towards the source you're trying to reduce bleed from can be surprisingly effective. The off-axis sound that remains is normally quite pleasant, and you don't seem to get too many unwanted phase-cancellation artifacts. However, as you can see from the photos, it does involve a little compromise: you don't end up with the ideal position for miking each single source, and the technique relies on the singer's head not moving about too much.

The figure-of-eight pattern is particularly susceptible to the proximity-effect bass boost, and further fine-tuning of mic positions can help to make this work in your favour. I used the AKG C414's onboard 75Hz high-pass filter to help reduce some of the unwanted low frequencies. As the mic captures sound from both front and back, your acoustic environment comes into play more than with a cardioid setting as well, so if the room doesn't add to your sound in a good way, you might want to consider placing additional absorption of some kind close behind the mic.

Mic Technique 2

Technique 2: I tried combining a Shure SM7 cardioid dynamic mic for the vocals with a cardioid small-diaphragm condenser for the guitar.Next, I tried combining a cardioid dynamic mic for the vocals with a cardioid small-diaphragm condenser for the guitar. The Shure SM7, a moving-coil dynamic mic, is a favourite choice of mine for close-miking a singing guitarist's vocal, as it's designed to be used very close to the source. With a slight tilt away from the guitar, this reduces bleed even more, although admittedly what off-axis sound remains is not as pleasant as in the previous technique. For the guitar on this session, I chose an AKG C451 small-diaphragm condenser mic, which I pointed slightly down and towards the beginning of the fretboard, which gave a much brighter guitar sound than when using the previous technique. Also, whilst there was a little more vocal bleed in the guitar mic, the little bit of extra brightness and top end extension seemed to work well in contrast to the less bright dynamic vocal mic.Technique 3: I deployed a cardioid large-diaphragm condenser mic on vocals, and a small-diaphragm condenser on guitar.

Mic Technique 3

Finally, I deployed a cardioid large-diaphragm condenser mic on vocals, and a small-diaphragm condenser on guitar. I tried this third setup initially as a reference point, as I wanted to see what my preferred vocal mic in its usual position and polar pattern for vocals sounded like against the other setups. I preferred the tone of the vocal like this, but there was a noticeable increase in the amount of acoustic guitar spill in the vocal mic, and closer inspection revealed that it was causing slight phase cancellation. I made some adjustments to the mic positions, so that I could be confident that the mics were working together. For the guitar, I adjusted the C451 so that, in relation to its position in Mic Technique 2 the mic aimed slightly more towards the soundhole, and this helped to both fill out the bottom end and reduce some of the low-frequency phase cancellation.

Options, Options

Thom is the type of artist who is seemingly able to sit and play all day, and he was more than happy to run off a take of the track with each of the three setups. We timed this part of the session in order to record the takes, then take a short lunch break, and return to listen to the options with fresher ears. This was a nice luxury for me, as not all artists are happy to work this way, but Thom was very interested in the difference between the setups, and it was good to be able to exchange opinions about the pros and cons of each approach.

After listening to the takes in their raw form I spent a few minutes doing a rough mix of the tracks applying some basic high-pass EQ, gentle compression and reverb — which I discovered Thom likes to hear a lot of! It was important to put the tracks in this context, and after initially preferring different setups we agreed on the best option for this particular track.

Thoughts On The Process

This whole auditioning process would take rather longer if you were miking a whole band, of course, but with a singing guitarist the process can be conducted pretty swiftly: in this case it took us only about 20 minutes. You do need to make sure your decision making doesn't get bogged down by this auditioning process. Also, involving the artist isn't always the best option when you need to make a decision, and they need to focus on the creative process; it's often better to subtly find a way conducting your comparisons in the background. But for this session it just felt right to both Thom and me for him to be so involved.

Auditioning different recording setups in this way is far from being a scientific process, largely because you're always going to get differences in performance between the takes, and these will inevitably colour your judgement. Indeed, if you listen to the accompanying audio files you might notice the take for setup 2 is missing half of the first verse!

Another option, of course, would be to try and manoeuvre the mics to have them all set up at the same time, mix and match options on a single take and have room to change your mind at mixdown. But can you realistically get all the mics in the right position — and do you want to leave these decisions until later? (Not to mention the fact that the presence of so many mics and cables might be off-putting for some performers!)

Horses for Courses

I would happily have used any of the three options for the track we were recording in this session, as the track's style lends itself very well to this way of recording. If you're working on a track with more performance dynamics, things can get more tricky and the differences between the options become more obvious. The main problem I've encountered in the past is that when the guitar starts getting louder and the vocal isn't naturally balanced, the spill becomes too much, and you can't balance the vocal without a hefty amount of processing at the mix stage. A little spill can be good in getting things to gel together and feel natural, but if you get more than the source it's directed at, it becomes a major problem! I've got workable results in the past by strategically placing bits of foam below the vocal mic to help reduce spill, so it's well worth experimenting when faced with a more challenging track or an artist who doesn't naturally balance themselves so well.

Which did I prefer? Well, for this track I ended up going with the figure-of-eight setup. Although it sounded a touch boomy compared to the others, I really liked the way it scrubbed up with a little EQ and compression. The other setups certainly had aspects I liked — the AKG C451 added a nice 'hi-fi' quality to the guitar and Thom's vocal sounded really nice with the SM7, thanks to the rounding off of his esses. However, if I listen to the other options with fresh ears I'm subtly aware of slight phase problems and the effect of the off-axis sound on the individual mics. There was nothing that couldn't be improved at the tracking stage or worked with at the mix, though, and if we were working on an EP or album, I'd probably consider alternating the setups on a song-by-song basis.

To Take Away

When recording acoustic instruments in general, it can be an absolute breeze or require huge amounts of patience and experimentation with mic placement. Adding the crucial element of vocals into this mix adds to this challenge even more and, unless you're fortunate to be working with the type of artist where everything just falls into place, you have no option but to roll up your sleeves and get busy finding the best way of working. Other considerations might include the amount of processing anticipated in the post-recording stage; like it or not, many artists these days are quite comfortable talking about issues such as pitch correction, and sometimes even expect you to be able to 'help' them a little with their vocals. It is possible to tune vocals when there's only a little guitar bleeding in, but you can get some pretty strange artifacts if the spill level is too great. Also, if you like to heavily compress things when mixing, you'll find that this can bring up the lower-level sounds, throwing the natural balance out the window in the process. The bottom line is that, when recording these two instruments together, you will inevitably get some bleed. Your job is to find good combinations of mics and positions, and make everything work in your favour.

Recording guitar and vocals at the same time might not suit some artists or some more 'contemporary' production styles, so don't assume this is the best way to record every track or artist. However, this method of recording does have many advantages — despite the requirement for a bit of hard graft at the recording stage, your pay off is that it that can make an artist feel truly at ease, and thus lead to wonderful recordings that almost mix themselves.