<john.lundsten IE Me wrote:
> I listened to both and noticed there is quite a lot of 50Hz hum,
which is very clean with few harmonics and IMO is a major contribution the
sound of the noise and by implicaton the weight of the bottom end. This is
quite
> visible using Spectral view in Adobe Audition (I used 16384 bands) See
>
http://f1.grp.yahoofs.com/v1/oBPKRYNKJkLTPYi3YMafOlS3QeC2AGVdExDt-we8MKX048CQEnCSQC6y_y5FGEYACkkfCE0Yj8yGSMOkITMQ6Oge3NuGg4BwWOnK/Spectral%20_ClockPanaPmp%2050Hz%20Filter%20.png
> Which is from the ticking clocks recording.
> I normalised both halves of the file separately so the tick sounds
are the
> same level - this is what appears in the pic - bar the last 5sec of the
> Panasonic rec & 1st 5sec of the Rapid's which I severally attenuated
the
> 50Hz region.
> Here is the file
>
http://f1.grp.yahoofs.com/v1/oBPKReit2obTPYi3R1XIGyNGyXGg3gxLmXwxroUATpUyrzW9x1H-Bm8NNOrQ-vcIqkIv3zVJa90koW_tqoyZZWK7cl7lHYelQ9gk/10secpanrapmp%2050Hz%20cut%20last%261st%205sec.mp3
>
> Re the
>
http://ad2004.hku.nl/naturesound/TomR/rapidVpanasonic/panrap60compmp3.mp3
> file, there is as well as the hum some other modulating LF activity.
> Probably (I guess) wind induced - it goes down to about 40Hz on Pana
& 20Hz
> on the Rapid
Thanks for the analyses John.
I think the hum/wind noise is the sound of neighbours' central
heating boiler flues.
Yes that makes perfect sense - so the Rapids have a better LF response but
unfortunatly a lot more midband noise
The triplets are very sensitive. I took the
precaution of switching things (boiler, frigges, freezers and
flourescent lights in my own house). However, the recordings were
made at 5:30am last Sunday morning when the outside temp was -1
centigrade, hence the boiler noise (at one time I believe I could hear
three of them).
Not sure if my ever so long links worked for you but re the Spectral display
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 surprising
to me as from the pictures I've seen of your Triples they appear to be
Unscreened, the signals are unbalanced and with a medium to high source
impedance. Oh and the gain was obviously quite high
It could also be 50Hz mains hum from somewhere.
Another possibility is noise from the Minidiscs' MC40ELK remotes (the
NH!s are ergonomic nightmares to operate without them).
I need to rerun the tests on the quieter (domestically) saltmarsh
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
Cheers
Tom Robinson
Best regards, john L
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