It would probably help if I included the link :)
http://i.imgur.com/so7CG.jpg
--- In "doctorobotnik" <>=
wrote:
>
> Hi Peter,
>
> This is how your test file looks in Audition's spectral view. I don't see=
the harmonics you noted in the right channel. Perhaps it's a quirk in Auda=
city. Do you have access to another spectrum renderer to try the file on?
>
> Ben
>
> --- In Peter Shute <pshute@> wrote:
> >
> > Yesterday morning I made a 20 minute recording at the local wetlands wi=
th my new SASS array (4 x EM172's in a Rob Danielson style wooden structure=
, half finished - no nose baffle or internal baffling). I also made a recor=
ding using the Sony PCM M10's internal mics for comparison.
> >
> > When I loaded into Audacity and displayed the spectrogram, I see lots o=
f bands on the right channel, about 400Hz apart, to 20kHz and beyond. I ca=
n't see any sign of them in the left channel, and I can't believe this thin=
g has such good separation that it could be environmental. I can't hear any=
thing odd, but with my hearing, that doesn't mean much.
> >
> > I also see no sign of it in the recording using the internal mics.
> >
> > So it must be generated in the mic circuitry? I just made another test =
recording with it on the table here beside me, and I see no sign of the ban=
ds on that recording either.
> >
> > So maybe it picked up some interference with it's unshielded wiring? Ma=
ybe, but would that look like this? And I was at least a kilometre from the=
nearest powerlines. The site is an old saltworks, so there may have been s=
ome pumps running a bit closer than that. The lead to the M10 is only metr=
e long, and shielded, but there are a few inches of unshielded wiring in th=
e array.
> >
> > More intriguingly, the first 20 seconds of the recording don't show the=
bands. This includes the sounds of me wrapping the array in a towel for wi=
nd protection. The last part, where I unwrap it again, also doesn't show th=
e bands. That I don't understand at all. Unless perhaps my close presence s=
omehow damped some interference?
> >
> > I've uploaded one minute of it in wav format if anyone wants to have a =
look at it: http://soundcloud.com/petershute/sass-test-harmonics. The first=
20 seconds is very noisy and clipped, but I've had to include it to show t=
he band free section.
> >
> > Peter Shute
> >
>
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