Apologies for the lack of new material but the mobile and the studio are so busy at the moment that weve just not had time to put any new stuff up. We have some great new sessions waiting to go up and a sneak preview of a fantastic new compresser but thats all to come!!!!! In the meantime have a read about the first in our series of great mics under £100
Boundary
mics or PZMs (pressure zone microphones) look very different to
a normal mic and work by exploiting a particular characteristic
of sound, in that when sound bounces off a hard surface, in the
small zone immediately next to the surface the sound pressure
is doubled meaning that any mic in that zone will have a higher
output. It sounds simple, and it is, but of course there are limitations.
I'm not going to get into the physics here but as always there
are some great sites on the net particularly The
Crown Microphone website. What this technology means for mic
design is that a very small mic capsule is fixed in a low profile
metal housing which you place directly onto a hard reflecting
surface such as a floor or wall and it's this surface (boundary)
that makes the mic work. Stick one on a stand or hold it in your
hand and you don’t get the effect. To prevent phase cancellation
the mic capsule has to be very small (less than ¼ inch)
and traditionally boundary mics had an omni capsule though today
there are a range of cardioid and hypercardioid versions.
Recording
The
physics states that the doubling effect of the pressure zone
will happen equally right across the frequency spectrum if the
“Boundary” is infinitely long and infinitely wide
but unfortunately, infinite surfaces are difficult come across
even in the most expensive studios and microphones exhibit different
frequency responses dependant on the size of the surface they
are placed. Most applications for boundary microphones are in
the conference or audio visual field for sound re-enforcement
where they make great lectern mics and table top mics for discussion
groups but studio engineers being what they are have tried using
them over the years on all kinds of instruments, sometimes to
great effect. Boundary mics can be taped to the lid of a grand
piano or placed on the floor in front of a drum kit and the
only application where they can't realistically be tried is
on vocals. One of the first studios I worked in had a pair of
cheap Tandy PZM mics Gaffer taped to the walls of the drum room
and with a bit of eq they made a pretty good job as drum overheads.
Today most companies make a boundary mic and prices range from
a few pounds to a few hundred depending on application and quality
but at the top end Crown produce a very high quality stereo
boundary mic, the SASS system based on a form of dummy head
and priced around $1000.
