Hi Marc,
Date: Mon, 20 Feb 2012 16:11:52 +0000
From: Marc Draco <midnight.diam...@ntlworld.com>
I'd like to build my own soundfield mic. but right now, I'm having
trouble sourcing an affordable (which is relative concept, I know)
recorder that converts to digital and doesn't add a hiss like a
viper's
nest. So far, I can't find a low-cost stereo deck - and that would
be a
start if someone knows of a suitable unit.
Umshankar on this list has modified a Zoom H2, and so have I. This
has four microphones and can record four tracks simultaneously.
The modification involves some minor surgery, but the case is plastic
so easy to work with. I did find a guide on the web, which is clear
and helps a lot. You take it apart and remove the mics. Then you have
to find a suitable connector for your soundfield mic.
I made mine with some four core cable with an overall screen which
terminates in a mini 5-pin XLR. The male chassis connector mounted
in the H2 is male, mostly because the female version is too bulky to
fit neatly, but also it is virtually unobtainable. This means that
the plug on the end of the mic cable is female, but hey we're not
worrying about compatibility with anything else.
I put my input connector on the top of the cage around where the
microphones used to be, as there's really nowhere else and it is
quite a good place. There's plenty of room for it, though you have to
carefully file a semicircle in each half of the case so that the
chassis connector fits correctly. There's nothing much to fix the
male connector to, so it has to be glued.
The original mics were powered by the H2, around 1.5V, enough to
power most electret mic capsules. Obviously you could build a higher
voltage power supply for the mics and block the DC between this and
the H2. You could even use a 48V phantompower supply for the mics,
which would mean yo could use high quality mics.
Also I found someone on the web who had made 4-way line input in his.
I made an external box as I thought I was most likely to use the mic.
The H2 is very good value, a bit plastic, but easy to work, takes
standard AA batteries and it sounds as good as machines costing more.
Mic amps are not noticeably noisy, and I know that most noise in some
machines comes from the mics not the mic amps.
The modification is a bit fiddly, and getting the switches on the
side working involves carefully noting how it all went together in
the first place, and lining up some small plastic actuators. Not bad
at all, specially if you're used to taking things apart or building
them.
The original mic and line inputs still work, so you can still use it
as a stereo recorder, with an external mic of course.
I see that there's a new model of the H2, which looks nice, but my
mods were done on the original and don't know whether they so easy on
the new one.
Ciao,
Dave
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