Miking the sound hole...
I'm trying to reduce drum spill when I record my jazz trio (piano, bass and drums) at home. The drum overheads — Oktava MK12 cardioids — don't pick up too much of the surrounding sounds, but recording the baby grand is more problematic. The two Studio Projects C3s (switched to their cardioid pattern) pick up way too much spill, even though I've tried to reduce it. The piano opens opposite to the drums and is surrounded by absorbers, but even more separation would be desirable.
SOS Forum Post
Getting the mics as close as possible to the piano will minimise the amount of other sounds that the mics pick up. Miking the soundhole (top), or placing the mic on a soft cloth atop the soundboard will help with this, but you may encounter balancing problems, as the sound from the strings closest to the mics will seem louder.
SOS contributor Mike Senior replies:
This is one of the trickiest spill problems to deal with in the studio. At pro sessions, in multi-room studios, the piano or drums will often be recorded in a separate isolation room to resolve the issue. Given that you don't have the luxury of a separate booth, it's probably going to be easiest to try to isolate the piano.
Assuming that you're close-miking inside the piano with the lid fully up, then enclosing the whole piano-plus-mic setup by draping it in heavy blankets is a well-worn tactic, but you should extend the enclosure all the way to the ground for the best isolation. The piano's own dust cover can lend a hand here, especially if it's thickly lined.
Partly or fully closing the piano's lid is common in live environments, and can provide even better spill rejection. But the lower the lid, the closer the mic positions have to be, often making it difficult to record a balanced sound, as some strings will be much closer to the mics than others. A closed lid also introduces boxy resonances and complicates running leads to the mics. A tip here is to prop the lid open with an unread copy of Stephen Hawking's A Brief History Of Time (surely a plentiful resource), leaving just enough room for cables.
Within these constraints, your choice of close-miking techniques is still fairly wide. Boundary microphones would perhaps be a better alternative than large-diaphragm capacitor designs, given their more slimline design, which allows them to be gaffered unobtrusively to the underside of the piano lid. The excellent off-axis response and lack of proximity effect also recommend boundary microphones over large-diaphragm cardioid microphones, especially if you're asking them to capture a balanced picture of the strings from very close up.
Another alternative when the lid is closed is to mic up the soundboard through the soundholes in the piano's frame. Small table stands can be useful for this, but you can also try resting the mics on pieces of foam or cloth. For more piano-miking tips, surf to www.soundonsound.com/sos/jan08/articles/pianorecording_0108.htm.
If you are faced with extreme spill problems, but still need a clear recorded sound, then you have to start getting a bit more creative. If you're handy with the DIY, this idea from Elton John's producer, Gus Dudgeon, could provide some inspiration: "I found the thing to do was take the [piano's] lid off, and then get a carpenter to build the shell of another piano, upside-down. So, in other words, on top of the original frame of the piano we built another one about three times as deep, so physically the piano was now about ten feet tall, and it was padded inside. We had two holes at the side, and we just poked the mics in there, and then you could get the mics high above the strings."
However, having said all this, I think you might be looking for more separation than you actually need. Particularly for jazz, some spill between the instruments will do you a certain amount of good, binding everything together in a way that means you won't have to use much in the way of reverb. It's more important that the spill sounds good than that it is really low in level. If you have any leeway to experiment, try switching your piano C3s to omni and reposition mics, players and gobos to make the spill on each mic sound as pleasant as possible. If there's too much ambience, deal with that in the room using foam, duvets, or something similar. Check how the mics interact when mixed, and adjust mic positions or polarity inversion for the best sound. I think you'll get a more natural result with this approach, both because omni mics will pick up more of the large piano and bass instruments, and because omni patterns will pick up more neutral-sounding spill than cardioid patterns.
If you're going to be creative with your use of spill, take some advice from Alan Parsons (engineer of Pink Floyd's Dark Side Of The Moon) and try moving the piano as close as possible to the drums, counter-intuitive as this may seem. Although you pick up lots of spill, it doesn't make the room sound overly large and the spill is delayed very little when compared to the signal from the drum close mics. If you really have a problem with too much room ambience, you could try setting the piano mics to a figure-of-eight pattern. This will generally give better-sounding spill than the cardioid pattern when using budget large-diaphragm condensers.
Published May 2008
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