To illustrate this month's feature on recording singers who also play acoustic guitar, I teamed up with excellent singer-songwriter Greg McDonald to create the following audio examples. Greg sang the first verse and chorus of the folk song 'To The Begging I Will Go' with amazing consistency, while I moved the mics!
Here I've taken recordings of five performances recorded with different mic setups and mixed them as similarly as possible, so as to give an idea of some of the range of sounds that can be achieved. In the first three, and the last, Greg sings into a Neumann U77 condenser mic set to cardioid pattern; the odd one out, vocally, is the fourth example, where a Shure SM7B was used on the vocal. The five examples showcase different guitar mic options: respectively, a pair of Neumann KM84 small-diaphragm cardioid condensers, a single AKG C414EB large-diaphragm condenser in figure-8, a pair of Oktava ML51 ribbon mics, a pair of AKG D19 dynamic mics, and the undersaddle pickup in Greg's Martin guitar. In all cases I used no compression or EQ beyond a high-pass filter, but adjusted Greg's vocal level using automation. Some plate reverb was added to the vocal, with about 80ms pre-delay and a low-pass filter at about 5kHz, and a bright room reverb to the guitar.
In my experience, spill from the vocal onto the guitar mics is usually more of a problem than the converse. These two examples are the same performance, recorded with the Neumann on vocals in cardioid, and the AKG C414 on guitar in cardioid. In the first example, you can hear that vocal spill on the guitar part is causing unappealing comb-filtering in places (listen to the word 'best' at the end of the first line for instance). The second example is the same recording, except that I have shifted the vocal part a few samples later in my DAW so that the vocal part is aligned with the vocal spill on the guitar mic. You can hear that the vocal sound is noticeably fuller, and in fact slightly louder, as a result.
This series of six examples is intended to illustrate the amount of vocal rejection achieved by different guitar mic choices and placements. The first two examples, respectively, are a cardioid Neumann KM84 condenser and AKG D19 dynamic pointed downwards towards the neck joint. The third and fourth are an AKG C414 large-diaphragm condenser in cardioid and figure-8 modes. The fifth is an Oktava ML51 ribbon mic, while the sixth is the raw output from Greg's guitar pickup. As you can hear, the amount of vocal spill changes — and so does its character.
These four examples are arranged in order of increasing guitar rejection from the vocal mic. The first three are Greg singing into the Neumann U77 in omni, cardioid and figure-8 modes respectively, while the last is the Shure SM7B. Notice how the tone of the vocal changes with the U77 polar pattern.
You could take the purist approach of treating singer and guitarist as a single sound source, to be miked using a mono mic or stereo array, but we tried lots of different ways of doing it and didn't really like any of them! Here, in order, are three mono takes recorded just using the U77, and five stereo takes recorded using different well-known coincident and near-coincident arrays. Notice how in all of these examples the vocal balance against the guitar feels wrong in places.