This morning's outdoor test went well. I placed the recorder at the limit o=
f the cable, a whole 1.5m away, and I see no trace of the bands on the reco=
rding. They might still be there on the frequency analysis graph, but very =
much reduced to almost nothing.
I'm glad that's solved, and also pleased that I now have a good way to test=
my shielding, which I'll work on a bit.
Peter Shute
From: O=
n Behalf Of Peter Shute
Sent: Monday, 12 March 2012 6:09 AM
To:
Subject: RE: [Nature Recordists] Re: Initial SASS test shows bands of harmo=
nics
The clipped noise is from me handling the array as I wrap the towel over it=
.
I've just proven it's interference from the M10. With the recorder on top o=
f the array , the effect is reproduced. With the recorder upside down it's =
even stronger. With the recorder inside the array, pressed again the wiring=
between left and right under the top, it's very strong, and I can clearly =
hear the hum from it.
Interestingly, with it insdie, pressed against the cable but upside down, t=
he effect is nowhere near as strong. Thus, the interference is coming from =
underneath the M10.
Even 1m away, I can see the regular spikes on a frequency analysis, but it'=
s too weak to see on the spectrogram.
Just to be sure it's electrical interference, not acoustic, I held it in fr=
ont of the mics, 1cm away, and the effect is weak. Therefore it's electrica=
l interference from underneath the M10.
The effect is on both channels, but is far stronger in the right channel, I=
assume because I ran the wireing from the right over to the left before jo=
ining to the cable I plug into the recorder, and so there are a few more in=
ches of wiring on that channel.
But perhaps Raimund is right, that it's caused by the PIP struggling with 4=
capsules. Can anyone recommend a battery circuit I could try? I was going =
to look into this anyway. Is it safe to just put a voltmeter across a capsu=
le to check it?
Now to get out of this house, and try some more tests at sunrise.
Peter Shute
From: O=
n Behalf Of Raimund
Sent: Monday, 12 March 2012 4:46 AM
To:
Subject: [Nature Recordists] Re: Initial SASS test shows bands of harmonics
Because the noise obviously starts on the first occurence of the broad-band=
and clipped noise (which does not seem to be an acoustic signal), I would =
guess that it might have something to do with PIP power provided by the rec=
order. It could be that the PIP supply circuitry just does not work properl=
y due to the heavy load by the four capsules. So, you might try to power th=
e capsules by an external battery.
Raimund
--- In <naturerecordists%40yahoogrou=
ps.com>, Peter Shute <> wrote:
>
> The link to the sonogram image works now. The album wasn't set for public=
viewing, I assumed that setting was the default. Sorry about that.
>
> https://picasaweb.google.com/pshute2/March112012#5718478097647090786
------------------------------------
"While a picture is worth a thousand words, a
sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.
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