This is going to be a stretch, but I plan to create an X/Y microphone that pairs with an analogue compressor specifically tailored to being used as overhead drum microphones in a for a small drum kit in a live-to-tape or large venue situation. There has always been a lack of microphones that are well designed for the battering that occurs when being an overhead microphone. There are some that have become industry standards for live sound and recorded sound (yes they are different standards, but an experienced engineer can make do with either in either space) but neither standard is really developed for micing drums. Engineers for decades have been having to play the dance of compression especially with the overhead microphones, but first let’s talk about what compression is.
Compression is when an input is brought to a different linear scale depending on the dB level the microphone is communicating to the compressor. I know that sounded like garbled mumbo jumbo, but I promise it made sense. Look at this graph:
As it stands, this graph is showing that at -22dB (the digital form of measuring sound level assumes that the loudest sound before clipping is 0dB, so everything else is negative) the input to output changes for 1:1 to 6:1. What this means is that for the output of the compressor to output -21 dB (the next full dB up from -22) the input must register -16dB (6 more dB). This is very important for a multitude of reasons, but the simplest is to think that this allows for the engineers to tamp down the wicked loud bits, while still giving them some dynamics to work with, while not ruining the quiet bits, giving them a seemingly larger dynamic range.
This is the idea of a compressor, obviously there are a lot more knobs, buttons, switches, and controllers to a really good compressor, but for the purposes of this explanation, that is what a compressor does.
In the world of drums there are 4 primary types of microphones—kick, drum, cymbal, overhead. These four mics live in harmony with one another on a good day. But the problem occurs when any type of drumming happens. Yes I know that sounds like it is all the time, and that is part of the problem. The kick drum often has one of the strongest and most aggressive compressors of the lot, but we only have one primary sound coming from it, so we can tune the dynamic range accordingly. The kick drum has its own group because of just how wide of a frequency range the kick drum produces (about 40Hz all the way up to 17,000 Hz) so those microphones have to be particularly designed for such a task. The drum mics tend to have a relatively low compressor on them, still high when compared to other instruments, but they also have pretty consistent dynamic ranges and are not all too difficult to control. The cymbal mics, generally only 2-3 in a full set-up, tend to have the second harshest compression on them. They have a fairly large dynamic range, but because generally they are positioned very close to the source (hi-hat microphones tend to be positioned within 1-2 cm of the underside of the hi-hat) they are not too difficult to engineer, though certainly the next step up. These three sets of microphones are happy to work together more or less.
As an aside my mentor started training me by allowing me to mix together the snare, kick and hi-hat, then he did everything else. Then we moved on to allowing me to mix the full drums and hi-hat. Then the full drums, ride, and hi-hat. It was not until about 3 months into training me he allowed me to touch the overhead microphones, and the reason soon became clear when he did. They are impossibleto work with!
Overhead microphones are difficult because the task they are being asked to do is a difficult one. They are being asked to listen to every piece of the kit (snare, kick, hi-hat, toms, crash cymbals, ride, floor toms, even the extraneous pieces of auxiliary percussion that get dragged out once a decade and no one is even sure of the name for) and are also asked to send them through to the mixer clearly and without bias. This is an impossible task. There is no way to design a compressor, microphone, eq, or any combination therein that can completely reproduce a kit. So that is not what I am going to try to do. I am going to try to create a pair or overhead mic and analogue compression unit that can very well fill the voids of the kit.
No matter how the kit is miced up, there are going to be voids in the sound field. I don’t mean “we are missing the snare!” I mean “700-800 Hz is not very well filled in. That is the idea of this microphone. It will change fill in the voids. It will complete the sound field that the individual microphones are missing. It will be attacking music, and the difficulty of music, the science.
This is taking the music, and the beauty (though sometimes harsh beauty) of the drum kit and knowing that it is difficult, nay impossible, to get that beauty through to the audience. Sometime this is an audience that can hear the drums, and it is strictly to enhance the auditory experience (500 people in a small venue, perhaps). Sometimes that audience is larger and might only be able to hear the cymbals and the higher end frequencies that travel farther and are more pronounced farther away, so we need to transport to them the rest of the frequencies (maybe 5,000 people in a concert hall). Sometimes that audience is live, but simply cannot hear the drums so we need to transport the entirety of the sound field to these people (think about 20,000 people on the side of a mountain). Sometimes the people are never going to be able to hear the drums no matter how close they get but the drums themselves are still “live” even if recorded later (on the internet or a TV show perhaps). Sometimes they are never going to see the drums at all, and they are in a nice well treated room (perhaps a record). I want to look at the middle ones. I know that if I try to design something for every single part it will be just a sub-par version of something that already exists. There is no getting around that. So I want to focus on the television, or the large concerts where people can see the drums, but cannot hear the drums themselves.
The reason that I want to design for this is because, frankly, it is the one that I am most comfortable with. I already have microphones that I know and love for smaller venues. I have microphones that I know and love when recording drums in a well-treated room. These are not the times when I want a microphone that doesn’t exist. Generally, in these instances we tend to use two microphones that are in a pair. Rode does an excellent job pair their microphones together to have similar frequency response patters (how well the microphone picks up different frequencies) and gives to those specific to the microphones. This is a really good way of ensuring people know and understand their microphones but comes out of a need for better quality control. Shure has excellent quality control and produces microphones that are so close to each other on such a regular basis that the need to pair them is almost non-existent (not that every engineer worth their salt won’t determine which mic is better for snare side vs tom side). Which brings us to my idea (good or bad it is my idea) to create an X/Y microphone. An X/Y microphone is a single microphone that is essentially two microphones in a pair. Often using a 5-pin XLR instead of a 3-pin XLR, it has a stereo output of two overlapping cardioid microphone patterns. A cardioid patter looks roughly like a heart, this is a great picture from Samson, a semi-reputable microphone company:
The reason this is more desirable than two pair microphones is that it is easier. I want to create a one-stop-shop microphone and compressor that works well for a simple drum kit: kick, snare, 1-2 rack toms, one floor tom, 1 hi-hat, 1 ride, 2-3 crashes and that’s it. This is not going to be something that can work for every kit on the planet, we need the variability of multiple microphones if we want to do that. This is not going to be for a massive kit, or a tiny kit. This is for the basic drum kit that a younger band would bring with them. This way we can just place that microphone above the head of the drummer and start mixing.
In this area, live-to-tape or a large venue, the Shure SM-81 pair of small condenser microphones is an industry standard. There are other microphones out there that are used as well, the telefunken M60s being another popular choice, in my opinion the SM-81s give the best price to performance and are something I use regularly. I believe that they are better with smaller venues than in this area, but they are not bad at all. If I can create a microphone and compressor pair that are on the same level as the SM81s with inbuilt compression on an Allen and Heath SQ-5, then I will consider this project to be a massive success. That is the standard I am going to hold myself to.
I intend to record my findings. Literally. I will be recording them through a Behringer UMC 1820, a decent audio interface, into reaper with no post processing on it at all, though I may need to boost it in post to get them roughly the same level. I will be writing a brief write-up about every step of the process to document the process throughout, and I will be writing a summary of my findings at the end, probably noting how I failed and what could be better with more time, money, engineering, and time (yes, I know I put that twice).
In order to complete this project, I obviously need a few resources. I have access to all the microphones needed. I have access to a drummer and a drum kit. I have access to a soldering station and supplies. I have access to all the other audio needs. I do not have access, currently, to the specific microphone supplies. I need to purchase the capacitors, resistors, capsules, etc. for the microphone and the compressor in order to build them. I also need access to a better CAD program than the one I have. I will be able to, in theory, get access to AutoCAD from Autodesk through the University, which will be a huge help, and I can learn online how to do the basic things needed for this project (I have experience with other CAD software, so it ought to translate fairly easily). I do need to somehow get funding for this project in order to purchase the parts for the microphone and compressor. I do not know how to do that yet, but I will certainly be able to work on it. I may be able to cover some, if not most, of the cost, but I may also need some external funding. Where to find that I do not know.
- I want to have a CAD drawn up for both the Microphone and the Compressor
- I want to have parts chosen and shipping for the microphone
- I want to have a plan for who, where, and when I will be testing the microphone itself.
- Have possession of the parts
- Put parts together for the microphone
round of testing the microphone
- Without the compressor
baseline Microphone test off the SM81s
- Both with and without it being compressed
- Order parts for Compressor
- Have parts for Compressor
- Put the compressor together
round of testing for Microphone
- With the compressor
- This week is to fix problems
- Perhaps put together a different compressor
- Perhaps retesting
- Be able to write a temporary summary synthesis of all work up to this moment
- Put together final (hopefully 3rd and 4th) round of testing the microphone
- Develop a model showing how the SM81 and the Pyke-Mic compare
- Finish the Summary Synthesis