Is there a limit to how small a microphone can be? From an electro-acoustic
angle, yes there probably is. The smaller the diaphragm, the fewer air molecules
cause it to vibrate, and the greater will be the effect of random motion of
the molecules in comparison to the motion caused by the sound wave. (If you
remember your school physics you will be familiar with the term Brownian motion).
From the users’ point of view, there are some people for whom a microphone
can’t be small enough. TV directors are among those who can spot a bug
sized mic on a video monitor at twenty paces, if it hasn’t been adequately
camouflaged by the sound recordist or assistant. Theatre audiences too may spot
the odd wart on the forehead of leading actors and actresses and wonder whether
there is some sort of skin complaint common to the profession. From the sound
engineer’s perspective, as long as the mic isn’t too conspicuous,
and isn’t too noisy, all it has to do is sound great and be easy to handle.
There haven’t been too many options in the miniature microphone market,
and over the years favourites have included the Sony ECM50, Beyer MCE5 series
and the Sennheiser MKE2, the latter arguably being the front runner at the moment
(argue with me via e-mail please). AKG have had miniature mics in their catalogue
for some time, but they obviously now hope that their new C577 will make a sizeable
dent in Sennheiser’s sales figures.
To start with, this mic is definitely small, with a small ‘s’. I
doubt if anyone but those in the very front rows of the stalls will notice it,
and since they paid extra money to be able to see the show better I don’t
suppose they will mind. The TV cameraman too will have to put on his macro lens
to spot this mic, if it has been even moderately well concealed. In fact, I
needed a magnifying glass to find it in the excessively large plastic case in
which it is supplied. Secondly, the sound quality is pretty good, and I don’t
imagine anyone will be disappointed on that score. It’s an interesting
point that you would be entitled to expect better sound quality (apart from
signal to noise ratio) from a mic with a small diaphragm, and mics in B&K’s
instrumentation range will bear this out. Of course, the subjective interpretation
of sound quality doesn’t always correspond to objective facts so I’ll
leave it up to you to decide next time the AKG rep calls round.