HI David Yes all balanced into the Sound Devices 788T. Cable length is short, 5 Meters and connects directly to the microphone with 4 XLR on the end
Cheers, Garth On Aug 7, 2014, at 12:52 AM, David Worrall <worr...@avatar.com.au> wrote: > I never achieved satisfactory (electronically quiet) environmental recordings > with the portable Soundfield. Maybe the ones I used weren't properly > calibrated: they were certainly affected by humidity. > I have had much better luck with the TetraMic - as long as radio interference > can be kept under control. > Garth: what cable lengths are you using and are the inputs balanced? > > D. > > On 07/08/2014, at 1:03 AM, Eric Benjamin wrote: > >> Garth, >> >> I wonder why it is that your recordings are so afflicted by noise. The self >> noise spec for the SPS200 is 12 dBA, which is similar to that of other >> soundfield microphones from Soundfield. While 12 dBA isn't noise free, it >> should be pretty quiet. As a reference, the average threshold of >> detectability for microphone noise is about 6 dBA, assuming a natural >> recording scenario. That is, assuming that the sounds are replayed at the >> same level at which they occurred in the recording environment. >> >> Of course, it may be that the microphone doesn't meet specifications. >> >> I'm a bit confused by the recordings that you placed at >> http://listen.ame.asu.edu/sonic_events.php >> >> >> The first recording is labeled as "no audio". The second recording is >> labeled as "you can hear Garth open his canteen and move some things >> around." There's certainly a lot more noise in that second recording. >> About 46 dB more, unweighted. It would be interesting to try to perform >> some more controlled recordings to find out whether the noise is coming from >> the mic, or not, and whether it meets specifications. >> >> Do you ever get to the SF bay area? >> >> Eric Benjamin >> >> >> On Wednesday, August 6, 2014 3:12 PM, Sampo Syreeni <de...@iki.fi> wrote: >> >> >> >> On 2014-08-06, Joseph Anderson wrote: >> >>> I take the noise profile from each individual A-format channel... >> >> At the risk of sounding trite, what is noise? I'd argue that it isn't >> one thing, and that it's pretty difficult to define with mathematical >> precision. If you're talking about environmental background, then >> approaches like gating A-format or some other suitable directional >> representation of sound is a good idea. >> >> If you're talking about tape noise instead, that isn't directional at >> all, at least until you get into directional masking calculations over >> what you can throw away without getting caught. In that case you'd want >> to operationalise what you consider noise, then find out an optimal way >> of extending that idea to B-format, and do the kind of joint processing >> Eero suggests. >> >> The easiest way probably is to go with just W in the sidechain and equal >> gating for all the channels in the main one. The next step would be to >> do the same per frequency, and so on. However, in the ambisonic world, >> you'll then bump into a third source: the mic. Since the Soundfield >> works on differencing principles, W has a totally different noise >> profile from XYZ, and typically it only gets worse from there as the >> order goes up. (Or it doesn't; that depends wholly on the mic geometry.) >> >> The point is, I don't think there is a monolithic thing called "noise" >> which can be just blindly "reduced". There never was even in monophonic >> recordings, and the free degrees of freedom in your signal chain just >> multiply when you go through stereo to ambisonic. So, you need to be >> careful about which source(s) of unwanted hiss, distortion or bogus >> sources you're talking about, you'll have to develop computationally >> tractable models of both your utility signal and the noise, and only >> then can you really start to combine all of the machinery into something >> which actually works/sounds good. >> >> E.g. when you expand/limit A-format, implicitly your noise model is a >> hiss which is directional to first order and your model of the utility >> signal is something like a strong, wideband directional signal near it, >> which makes directional sine-to-noise masking statistics relevant. Break >> those conditions and bad things will most likely happen. >> >> So, try your approach on a two sine test signal, separated in frequency >> more than a critical band's worth. Pan one of the sines due front, and >> revolve the other one around at about 1Hz and say -6dB. Then add pink >> noise at about -10dB to each of the B-format channels independently. I'm >> rather sure that while your approach will work beautifully for the front >> signal alone when adjusted right, it'll lead to nasty, anisotropic noise >> pumping with the dynamic signal in place. >> >> (Oh, and by the way, which A-format? As long as you're dealing with a >> perfect mic and linear, time-invariant filtering operation, you don't >> have to think about that because you can go willy nilly between A and B. >> But once you start applying this kind of processing, every possible >> orientation of the mic gives rise to a separate A-format. Which one >> should it be? The above example presumes one of the capsules is facing >> towards the reference. It gets much worse if you place the source >> directly between three adjacent capsules, in angle space.) >> -- >> Sampo Syreeni, aka decoy - de...@iki.fi, http://decoy.iki.fi/front >> +358-40-3255353, 025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2 >> >> _______________________________________________ >> Sursound mailing list >> Sursound@music.vt.edu >> https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit >> account or options, view archives and so on. >> -------------- next part -------------- >> An HTML attachment was scrubbed... >> URL: >> <https://mail.music.vt.edu/mailman/private/sursound/attachments/20140806/e445ee8b/attachment.html> >> _______________________________________________ >> Sursound mailing list >> Sursound@music.vt.edu >> https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit >> account or options, view archives and so on. > > ______________________________________ > Prof. Dr. David Worrall > Emerging Audio Research (EAR) > Audio Department > International Audio Laboratories Erlangen > Fraunhofer-Institut für Integrierte Schaltungen IIS > Am Wolfsmantel 33 > 91058 Erlangen > Telefon +49 (0) 91 31 / 7 76-62 77 > Fax +49 (0) 91 31 / 7 76-20 99 > E-Mail: david.worr...@iis.fraunhofer.de > Internet: www.iis.fraunhofer.de > > Senior Adjunct Research Fellow, > Australian National University. > david.worr...@anu.edu.au > > > > > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <https://mail.music.vt.edu/mailman/private/sursound/attachments/20140807/2c52bf76/attachment.html> > _______________________________________________ > Sursound mailing list > Sursound@music.vt.edu > https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit > account or options, view archives and so on. _______________________________________________ Sursound mailing list Sursound@music.vt.edu https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on.
