December 23, 2013, by Bruce A. Miller
Often, a young engineer will start to position microphones based on what they see done by others or read in a magazine. Sometimes they experiment and move the mics to see if the sound improves, but usually once someone ends up with a mic setup they like they stop trying to improve it.
There are certain standard approaches that have been successful, but even these approaches should never be considered “etched in stone.” Always experiment, especially if it just means putting up a second mic to try a new position without moving the mic you are already happy with.
Once upon a time I had fallen into a typical routine of going with what I was told worked or what I watched the engineers I had assisted use.
I was recording piano with a pair of matching mics in an XY pattern around the hammers. I knew of many approaches (another mic at the far end of the piano and then pan that mic over to the bass side of the stereo spread, pair of PZMs taped to the piano lid, throwing mics under, over, and in the holes, etc).
Sometimes I would use a pair of mics just outside the lid but only when I could get away with more warmth and less percussive clarity.
One day I was working with the talented pianist Warren Wolfe. I was setting up my mics and he said, “You know, nobody ever wants to hear my advice to get the best piano sounds, they always just put mics in the same places.”
I stopped what I was doing, looked him right in the eye and said, “OK, tell me.”He then said, “All you have to do is to put your head in the piano and listen. Where it sounds good is where you put the microphones.”
So I moved the mic stands out of the way and listened while he played. Fortunately he played in a way that allowed me to hear how the different sounds from the piano at different ranges and volumes bounced around the piano box…the resonating chamber.
I then put mics where my right and left ears where (very different from the tight XY I usually used) and played with the angles until I felt they were closer to my actual ear positions. When I threw up the faders, I was blown away.
The sound was full, and had a more intimate sound than when I used outside mics (click here for an example). Now I always move my head around inside the piano while the musician played not only wide range material but the actual parts and ranges they would be playing that day.
Sometimes I went back to the XY over the hammers or pair just outside the box, but in general I always found places in the piano I liked.
I now find it especially helpful to listen to all instruments before placing the mic, often getting weird looks from the musician while I walked around them getting closer and farther and moving my head up and down searching for the sweet spots (you would be surprised there can be more than one, each slightly different).
Even guitar amps deserve listening to as each speaker sounds slightly different. Yes, you can accomplish the same thing by having someone moving mics around from an eye driven position while you listen in the control room until your mic hits the sweet spot, but doesn’t it make sense to go find the sweet spots first?
Sometimes you may need to find different spots that emphasize different parts of a sound, or even different parts of a sound that must be captured independently.
A good example of this is how I record Sanshin, which sounds sort of like a fretless banjo made of snake instead of paper played with rhythmic syncopated notes rather than arpeggios.
When I walked around and listened while the Rinken Band played, I noticed a spot where it sounded rich, and that within that spot I could easily hear both an attack and a throaty twang. To capture that I used a condenser for the highs and an old ribbon for the throaty twang, both in the sweet spot I prefered.
Rinken told me nobody had every captured the real sound of the Sanshin before. Had I not listened first and in doing so learned what was important to capture I would have ended up with something typical (thin) rather than strong.
In general, you are best off moving your head around the area of an instrument (including above and below, close and far), then placing the microphone where your ear hears the best sound.
Start with suggested positions, but put your head there and listen before you automatically put a mic there and assume it is the best starting placement.
The key to mic placement is understanding what you are tying to capture, choosing the right mic and finding the location and positioning to most strongly capture the sound source.
You may have to make sacrifices for the performance (moving the acoustic guitar mic because the musician is wildly throwing his picking arm around) or sacrifices due to available microphones (etc) but you will always capture the music if you mic with your ears instead of your eyes.
Bruce A. Miller is a veteran recording engineer who operates an independent recording studio and the BAM Audio School website.