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2. Re: Initial SASS test shows bands of harmonics

Subject: 2. Re: Initial SASS test shows bands of harmonics
From: "Peter Shute" pshute2
Date: Sun Mar 11, 2012 4:46 pm ((PDT))
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





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