Placing microphones very near the hammers will give your piano recording a very close and tight sound, because there they will pick up some extra ‘attack’ from the sound of the hammers hitting the strings. The stereo image is usually very well defined and spreads the notes from low to high across whole width of the image. The trade off is that you lose some of the mellow tone from the body and soundboard of the piano, and getting too close will mean the mics pick up a lot of noise from the piano’s action (see this article). This technique can easily be combined with others such as close omni mics or miking the soundboard to get the full sound the instrument.
How far away the mics are from the strings will determine a few things. The first is the tone, which will be very bright and possibly harsh when up close. Moving further away will pick up more of the naturally blended sound of the whole piano. The second is the amount of noise from the piano’s action that is picked up. This sound is not musical and can be very distracting if your mics are too close.
The third is the range of notes that your mics will pick up. Obviously having a mic a couple of inches from one string means that notes even six or seven strings away will be much quieter, so your whole piano sound will be extremely uneven across the whole range of notes. If the mics are too far away, they will all pick up the whole range of strings and the stereo image won’t be as strong. Somewhere between the two is where you should be aiming.
Balancing those three elements against each other is the key to getting your mics at the right height. Around 8 – 10 inches from the strings is probably a good place to start from, but as we always say – listen, move the mics and listen again, even if you think they might be perfect first time you can always put them back!
How far apart your mics are from each other will depend a lot on how high they are above the strings. You need to aim to cover the whole range of the notes on the piano, between how ever many mics you rig. Even if your pianist doesn’t play the very high or low notes the strings still vibrate in sympathy with the ones that are played, so don’t neglect them completely.
So long as your mics aren’t very low and close to the strings, you can probably position two mics to cover enough of the piano. Assuming they are about 10 inches above the strings, start with your mics about 2 feet apart and move them further apart if you lose the far ends of piano, or closer together if it sounds like there is a gap between them.
Clearly, if your mics are very low and close to the strings you won’t be able to cover the whole range of the piano with just two mics,so using three or four across the width of the piano will stop you having gaps in the range.
While you are tweaking the distance between the mics, you can also try changing the direction they are facing to alter the width of the stereo image they create. This is particularly helpful if your mics are quite close together and you want to spread out the range of notes they pick up, without the risk of creating a hole in the middle of them. Altering the direction of a mic is helpful if you are 90% happy with the stereo image, but want to bring out a bit more of one area of the piano (like the top end for example) then you can angle a mic more towards that area.
Having the mics close together and aimed away from each other is quite a common approach if you want to keep the lid of the piano on, as it reduces the chances of reflections from the lid reaching the mics at different times and causing phase problems.
Placing microphones near the hammers of a piano is a technique which requires a lot of playing around and experimenting to get the tone balanced just how you want it, so make the most of the opportunity and keep trying different positions until it works for you.
[image via akim_hobo]