--- In "John Lundsten"
<> wrote:
> 1) sorry the right hand side showing Frequency seems to have been
cut off. Top of display = 60Hz, the bright yellow band is centred on
50Hz and is the loudest frequency of the file and 20Hz is quite loud
on the "Rapid", the bottom kinda quiet band is 10Hz.
> 2) The 50Hz is clean & loud, IMO must be mains hum, This is hardly
environment.
> Could I suggest you do a test with the mics sealed (so picking-up no
sound but just system noise) having 1st adjusted the gains of the 2
mics on a broadband noise type acoustic signal
Hello John and the Group
Thanks for your additional comments.
First, I have to say that I'm a tyro so most of the analysis of the
spectrogram is a little beyond me. However I'm doing my background
resading (trying to choose between WaveLab 6 and Audition 2to improve
on Audacity) so can now understand a little better.
I have been racking my brain trying to think of a possible source of a
50Hz mains hum. I thought i'd switched ecverything off in the house
howerver I forgot about the wallwart transformer that powers my
panasonic hhouse prtable telephone system. This was left on, and
bearing in mind the long unshielded lead of the Panasonic Triplets
(and to a lesser extent the Rapids) could well be the cause of the
hum. I will test the mic's susceptability to mains hum from this
source at some quiet time.
I'm happy to try your suggestion re sealed tests but I'm not quite
sure what you mean by "sealed". Some kind of faraday cage? or actual
physical sealing? I guess an off tuned radio receiver would be
suitable as a constant broad band noise source?
Cheers
Tom Robinson
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