The basics of Ambisonics is that the Soundfield microphone
contains 4 separate capsules arranged in such a way that the
engineer can record the whole sound environment around the microphone;
above, below and behind as well as in front. The microphone
houses 4 separate coincident capsules arranged in a tetrahedron
which all contribute to what the Soundfield designers called
the B Format signal. This consists of 4 streams of sound information
around the microphone: The W stream is the omni information,
the X stream front and back information, The Y stream left and
right information and the Z stream up and down information.
What's important to realise is that all 4 capsules contribute
information to the separate streams and this 4 channel B Format
signal runs from the mic in a special multicore to the microphones
control unit. This unit enables the microphone to be remotely
configured in any possible mono or stereo microphone configuration,
the direct/ambient sound balance between front and rear can
be changed and the stereo width can be adjusted, all without
having to physically move the microphone...But there is much
more to it than that because if you record the B Format signal
to 4 separate tracks you can play these back through the unit
back in the studio and have complete control of the mic in post
production, spinning it through 360 degrees if you want or looking
straight up or down.
While the microphone isn’t used very often to record ambisonically
it remains one of the most versatile and beautiful sounding
stereo mics available today and in many ways it's the perfect
mic for mobile recording for a number of obvious reasons.
Firstly is the ease with which the engineer can get a great
working stereo picture of the band or choir from one microphone
position. If you want to use it as a stereo mic the controls
allow you to easily configure the mic into any pick up pattern,
alter the stereo spread from mono to 180 stereo and figure of
8 and also add in a controllable amount of the room ambience.
Positioning is vital and moving the mic just a few inches can
make a big difference but very often the Soundfield positioned
correctly in front of the performers is all that’s needed:
and of course if you record the mic onto 4 tracks in B Format
then all the stereo adjustment can be done in post production
back in the studio. No other microphone can do that.
Next up for the mobile is the ease with which the mic can be
suspended across large halls. I have a very simple home made
suspension rig that hangs the mic vertically from light mountaineering
shock cord which I tie off at each end with key clamps. The
mic automatically drops vertically and faces forward and the
whole setup is simplicity itself compared to hanging a stereo
pair of mics. All you need to do is press the invert button
on the control box and it configures the outputs automatically
and of course if the mic is pointin slightly off centre then
by recording the mic in B format you can adjust it's pick up
pattern in post production back in the studio.
Another great trick with the Soundfield is to record the four
outputs in B format onto 4 tracks and then back in the studio
run them back to create your ideal stereo picture of the choir
or band and record that onto a stereo track, Next wind the tape
back and run the whole thing again but this time with the mic
set to omni or just the back of the mic open to create another
stereo track highlighting the ambience. hey presto your own
phase perfect reverb that you can add to the original stereo.
Now that’s magic!
Finally another benefit of the Soundfield’s Mid/side stereo
output is that the stereo recording is mono compatible and this
is especially important for broadcast and film production applications.
All in all then a brilliant mic with a multitude of applications.
Superb for single point stereo recording but also a fantastic
tool in the studio. stick one infront of an acoustic guitar
and weep!........JR
When
we finally managed to get the Soundfield into the studio I though
it would be the answer to all our prayers- here was one of the
worlds most expensive and well thought of mics, so it must sound
good on anything. Interestingly I grew to love it and hate it
in about equal measure! Very early on I used it on a girl singer
called Vicky Clayton who was a fantastic singer with a great
voice, I put the mic up about 4 feet in front of her and it
was a stunning recording, even though I say it myself. I was
listening to it recently and the vocal sound, flat with a little
reverb was just beautiful. So I started using it on other singers
and it just scared the life out of me. On ordinary or poor singers
(we do get a few in Fairview) it was just too detailed and highlighted
all the inadequacies in their voices. With singers like that
you really need something a bit more forgiving. Also you have
to adopt a completely different strategy when using the Soundfield
because the idea of it is to capture the whole sound environment
and I found myself constantly putting the mic further away from
the singer, sometimes 4 or 5 foot away. Really I suppose that
Fairview is probably too small for the mic to get the best out
of and there is no doubt that when I've been out on the occasional
mobile and heard what its capable of it just has to be the best
one point stereo mic around......JS
