Monday, February 05, 2007
Drum Miking Part 2 - Them drums!
Before we look at the 'how' we need to understand a little more about drums, cymbals and percussion and dynamics. How they make sound, affects how we capture and process it.
A huge topic which we have to condense. I'll talk about more 'ethnic' drums in the percussion section. Here I'm looking at more conventional kit drums; kick drum, snare and toms. Each drum will have a shell made from wood, metal or possibly plastic with heads made from Mylar (plastic) held on with hoops made from metal or wood. The sound of the drum is affected by the shell material, head material, size, condition and tuning.
There are lots of extras I could mention, such as dampening built in to heads, power dots, moon gel (I kid you not), o-rings and on and on. These things are the drummers responsibility and as it's usually their kit, they will deal with all of this. All you need to know is that they affect the frequency content of the sound. The more dampening you apply to a drum, the more you will reduce ring and the high frequency response.
It's the result we need to be aware of. Do we have a high pitched snare or is it low and 'fat'? Is the kick drum open and clear or dead and muddy? Are the toms all thud and 'blat' or ring and cut? Are there parts of the sound we don't want or like? such as 'ring'.
Drums can produce frequencies from around 20Hz to over 20KHz. Mainly centered on the Mid and Lower Mid range. Way beyond our hearing and probably beyond your Sound Reinforcement System.
As a point to note, the sound a drummer is listening to affects how they play. They will want it set for them. This is the hardest lesson I had to learn as a drummer; the sound of my kit needs to sound right for the setting, not me. I used to put huge amounts of dampening on my drums to try and create the 'recorded' sound I was after. Now, I don't use any except a foam pad in my kick drum. My kit is miked and by making use of the more open sound, I get a great sound back through my monitors and my sound engineers get a good sound to work with. It's a win:win situation, but it's a hard lesson.
Basically a piece of metal shaped, formed machined and finished to create a sound. The way they are pressed, rolled, lathed and hammered affects the response, speed and tone of the cymbal. There are 5 main types: Crash, Ride, Hi-hat, Splash and China. The crash and splash and china are fast cymbals for emphasis (depending on how you play them) and the hi-hat and ride are generally used in a more rhythmical way. You can find hundreds of variations including air-ports and rivets. There are also cymbals such as the Zil-bell or gongs that have unique sounds. Cymbals can create frequencies from around 400Hz to over 20KHz. Mainly in the High and Mid High frequency range. Most cymbals can create frequencies below 400Hz, but the way they are played usually precludes this.
Covers a huge range of instruments. It's difficult to write much here because it includes shakers, tambourines hand drums,djembes and any other hand drum (which is a massive section in itself!) and then goes one to cover so many that there isn't space. So, instead I go back to that 'Why?' question. What does this percussion instrument do in the mix? If it's and mark-tree or bar-chime, then it's probably and effect that is used only a few times in a son. If it's a djembe it may well be there to drive the rhythm of the song. In each case, the sort of end result required will vary. What you need to do is to listen to the sound of the instrument and decide then how to treat it. Often you only need to reinforce whats there so flat miking is what you need.
This is a very important aspect of drum miking. Percussion sounds are shaped differently to most other sound sources that you will be dealing with. This affects how you compress them, how you gate them and how you mix them. Most of the sound comes very quickly and decay is usually very quick. This short decay is the opposite of a vocal, for example. So you want your compressors set to let a little of the initial attack through and then compress and to release quickly too. This allows you to control the sound without flattening them so much that they lose their purpose. Similarly, gates set at their fastest with a low-ish threshold will keep the 'dynamics' of the sound as natural as possible. That is assuming that you are using this sort of processing.
The Ancient Art of Chew-ning
This really is an area for the drummer themselves, but a basic understanding of chew-ning (or Tuning) can help a lot when it comes to getting a good drum sound through a PA. As I mentioned earlier, the dampening and overall construction of the drum affects the sound of the drum, but what really matter is the tuning of the heads. Kick drum tuning has less effect than most drum tuning, as the frequencies you want are so low. Try to keep the heads loose for a low sound (less dampening will make the sound more open.) Snare drums vary greatly, but you have three factors to balance: batter head, snare head (underside) and the tension of the snare wires themselves. The snare head needs to be very tight to transfer the snare vibrations easily. The batter head affects the tone of the drum; the higher the tension, the higher the note and vice versa. The snare wires affects the response and decay of the drum; a lower tension can create a slower and 'fatter' sound, a higher tension gives a faster and brighter sound. The sound you achieve will be a combination of all three. Toms can either be single headed (batter only) or more commonly now, double headed (batter and resonant.) Single headed drums are just about the tension of the one head, with the usual rule of the higher the tension, the higher the note. Double headed drums get more interesting...Simply, there are three possibilities:
1) Both heads are of equal tension.
2) The batter head is tuned higher that the resonant
3) The resonant is tuned higher than the batter
This gives the following results:
1) A loud, resonant, slowly decaying note
2) A note that bends up at the end
3) A note that bends down at the end.
These tunings refer to the relative pitch between the two heads and can be transferred up and down the tension range to give the desired tone or note.
So, that's a good entry in to how drums make their sound and what affects that sound. It's time to look at how what microphones we need, in Part 3.