Thought I'd share this.
Over the past few months, I've done quite a lot of recording work with singer-songwriters, who usually sing and play guitar. There's something to be said for being able to capture the full live performance in one take. Many artists are more comfortable playing that way (rather than one channel at a time), so the performances tend to be better. There's also the natural-ness of the sound: rather than playing one instrument at a time and attempting to get the timings right, recording everything at once means you capture the synergy created by the artist. It feels more real.
So, how should you go about capturing that sound?
Ideally, we'd like stereo guitar sound, plus a vocal channel, each with a good degree of isolation from the other if possible.
My earlier efforts involved having three mics. Two as a stereo pair for the guitar (positioned at the height of the strings), and one for the vocals. I'd also record the DI feed.
The problem was this: bleed. Guitar was getting into the vocal mic, and vocals were getting into the guitar mic. Because of the time-of-flight differences between the two mic positions, there were cancellations which lead to poor sound. Since the bleed was going both ways, there was no way to fix the problem - delaying one mic or the other would always result in further problems.
So, I started to think: is it to make it so that bleed simply isn't a problem?
After some thought, I came up with the VXY mic technique. The idea is simple: set off with an XY pair for the guitar, and then add a vocal mic underneath, pointing upwards towards the singer's mouth - hence Vocals, X, Y as the three channels. The mics should be arranged so the capsules are all lined up, but facing in different directions. It's best to use 3x matched microphones for this. I use Beyerdynamic MC930s, but other mics are available.
Let me be the first to say - this isn't a perfect solution. There are disadvantages:
- There is a lot of bleed in the mics
- You're relying on the pickup pattern of the mic to provide isolation. With a cardioid mic, that's usually around 6dB.
- Since you've only got 6dB of isolation (for cardioid mics) between the guitar and vocals, the mics need to have a smooth off-axis response.
- Positioning becomes more important. Changing the balance of the mics during mixing can help, but see the points above.
It does have some advantages, though:
- The mics are all coincident, which means you can mix them however you like, without needing to worry about cancellations.
- You can capture a singer-with-instrument in one take, and have it sound excellent.
If you decide to try this technique, get in touch with your thoughts!