It is common practice among sound and recording engineers to choose microphones according to the instrument to be amplified or recorded. Sometimes you will see published guidelines, especially in the catalogs of microphone manufacturers, but microphones are best chosen by experimentation and experience. Try it and see, in other words.
But there are some classic mics for very particular applications. One example is the AKG D112, which is known everywhere as a kick drum mic.
Now this is specialization on steroids - a mic that you would use for no other purpose than kick drum? Well, you can use it for all kinds of sound sources, but the kick drum is where this mic has made its name, and it does the job very well.
So why is this mic so suitable for kick drum recording and amplification?
Firstly its heritage. The AKG D112 is a development of the venerable D12, which was found by trial and error during its heyday to be a very good kick drum mic, probably by accident more than intention. The D112 brings the D12 up to date in terms of manufacturing quality and design, and retains the D12's characteristic sound.
Secondly, the AKG D112 is a microphone that can handle a high sound pressure level, which is exactly what you get from a kick drum. Levels as high as 160 dB SPL are handled with ease, according to AKG, and there is no specified upper maximum level - probably the level was outside of the range of AKG's test equipment, and since any human being would be deafened instantly at this level, I think 'adequate' is the appropriate word here.
The AKG D112 is a dynamic microphone, so there is no internal amplifier to overload, and of course it does not require powering. The odd shape is due to the large diaphragm. It is a fallacy that low frequency sounds are picked up better by a larger diaphragm. On the other hand, you wouldn't expect this mic to handle very high frequencies particularly well, but that is not its purpose.
One puzzle is how to tell the front of this mic. Since the AKG D112 is nominally cardioid in sensitivity, it is more sensitive in one direction than the other. To be honest, judging from the polar diagram, it isn't all that cardioid, which leads to an interesting point that I shall reveal shortly.
Conventionally, you can tell which is the front of a microphone (if in doubt) by the manufacturer's logo. The side with the logo is the front. However, this mic has 'AKG' on one side and 'D112' on the other. Actually, the mesh grille side is the front, so this microphone defies conventional practice.
During testing however, since I wasn't sure which was the front of the mic, I tried it both ways round, and you can hear the results.
I placed the microphone about 5 cm outside of a Pearl kick drum that had a large hole cut in the front head. There was a moderate amount of damping material inside.
Here is the sound of the D112 with the front (mesh grille side) pointing towards the drum: audio
As you can hear, it is a full-bodied sound with a good subjective 'quantity' of bass - the subjective quantity of bass doesn't always correlate with frequency and level. I don't find anything lacking in this sound; in the context of the rest of the kit and with a little EQ perhaps it will work fine.
I don't know whether it would make me buy the mic though. Here is a much less expensive Shure SM57 in comparison: audio
There's not a lot to choose here, so I guess I would go for the cheaper mic.
However, when I placed the AKG D112 pointing directly away from the drum (as I said, I wasn't sure which side was the front), I got something I didn't expect. The level was lower, but the sound quality was something else entirely: audio
Now this is what I call a kick drum sound - not only can you hear the bass, you can hear the impact of the beater, and almost feel the rush of air coming from the drum. This is an excellent kick drum sound with all the elements well in place - anything you don't want can be EQ'd out. Perhaps there is some element of reflection involved, but nevertheless this is excellent sonic material to work with.
To my mind, this sound possibility fully justifies the price of the AKG D112. Plainly, orientating the mic in the reverse direction is going to lead to some unwanted pickup, which might be significant for live use, but for recording I doubt whether you could find anything better.
So, I have placed my order for the AKG D112 and it's going to be a permanent feature in front of my kick drum. The AKG D112 kick drum microphone is highly recommended.
P.S. Just to be clear, the unexpectedly good sound quality with the mic placed the wrong way round was due to reflections in the room and would probably be unrepeatable in other circumstances. Possibly worth a try though?
By David Mellor, Course Director of Audio Masterclass
Friday April 29, 2005
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