I've been experimenting with a PCM-M10 and EM172 capsules in a binaural set=
up for about a year. I don't live where it is easy to get to man-quiet pla=
ces, so I have experimented with recording man-made sounds.=0D
=0D
My experiences have been very positive re: very loud sounds, including an A=
merican Signal C-125, 50 horsepower siren from a distance of about 100 mete=
rs... That siren is rated to produce 125dB sound pressure at 100 feet. Onc=
e I adjusted the volume, I ended up with a very faithful recording. No hin=
t of distortion.=0D
=0D
On another occasion I had set up the two capsules about 12 ft off the groun=
d to record sounds in a freight train switchyard near Martinez, CA. As the=
various Amtrak and Union Pacific locomotives rumbled through, I caught bea=
utiful sound profiles, with some indications of the10 hz subaudible engine =
rumble detectible on the waveform analysis. At one point there was some ki=
nd of impact ringing from a switch, a very high frequency, high-decibel cla=
ng that echoed very rapidly from left to right. In person it was deafening=
, but again I could detect no distortion in post-production. In between th=
e locomotives, I caught chickadees, pheasants, and red wing blackbirds, ver=
y distinct in the distance. These capsules, with the PCM-M10, are QUIET.=
=0D
=0D
About a year ago I had some correspondence with the applications engineer a=
t Primo-USA and he sent me a set of profiles that he'd personally tested, s=
upply voltage vs load resistance, that sort of thing. Optimum performance =
is at the nominal 5v, 6.8k ohm as the spec sheet states. The PCM-M10 (by m=
y own measurements) supplies 3v at about 3.3k ohms. His profile sheet indi=
cates that the EM172 capsules suffer only a 3 dB degradation in s/n ratio a=
t that voltage and load. To get a 77-78dB s/n is not bad at all, for direc=
tly driven PIP mics. It is certainly possible to build a battery interface=
, say, with two stacked lithium coin cells and a 6.8k resistor on each chan=
nel with a blocking cap... in fact I bought all the components to do so, bu=
t I have not yet decided I needed to go to the trouble since these capsules=
work so well on their own.=0D
=0D
As to physical construction, I've been experimenting with making binaural p=
airs like the set that Frogloggers used to sell. I am convinced that solde=
ring directly to the capsule, replacing the factory-supplied flying leads, =
is a bad idea. Any overheating of the capsule, at all, can depolarize the =
electrostatic media and deafen the microphone. I've been experimenting wit=
h Mogami lavalier microphone cable and Neutrik right-angle 3.5mm connectors=
, with good success. Recently I've worked out a way to cover the capsule wi=
th an open-weave PEP braid, and to strain-relieve capsule and microphone ca=
ble. I have not decided to spend any energy building a cylindrical microph=
one body, since the capsules are omnidirectional to begin with and I thnk t=
hat the freer they are from obstructions, the better they will work.=0D
=0D
In fact, I'd be willing to build a set as described for anyone who has an i=
nterest. Email me at =0D
=0D
A few of the tracks I've mentioned are here:=0D
https://soundcloud.com/grickerd/tracks https://soundcloud.com/grickerd/trac=
ks=0D
I'll try to post one or two of the switch-yard tracks in the next 24 hours.
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