[LAD] Determining Phase

Arnold Krille arnold at arnoldarts.de
Sun Jun 26 16:24:28 UTC 2011

On Sunday 26 June 2011 18:05:12 Jörn Nettingsmeier wrote:
> On 06/26/2011 05:47 PM, Arnold Krille wrote:
> > On Sunday 26 June 2011 11:58:54 Jörn Nettingsmeier wrote:
> >> On 06/26/2011 10:50 AM, pshirkey at boosthardware.com wrote:
> >>>> Other than that, I'd make a really cool spectrum analyzer that ran the
> >>>> Fourier analysis on two channels, correlated their phases then made a
> >>>> +/- line vs. frequency for all to see so that the phase of the
> >>>> components of the spectrum could be watched for phase relationships.
> >> 
> >> that is precisely what dual-fft tools for p.a. system calibration do,
> >> and they're extremely useful.
> >> they allow you to constantly monitor the system with _program_ material,
> >> without having to use MLS noise or any other specific measurement
> >> signal. one channel is used for the direct signal from the mixer, the
> >> other is fed by a measurement microphone with delay compensation. you
> >> get instant phase and amplitude response. good systems also give you an
> >> additional "confidence" curve that tells you how much you can trust
> >> which parts of the spectrum. for instance, if your program material is
> >> a boy soprano, the confidence of the measurement in the low end is
> >> practically zero.
> > 
> > I use(d) japa for this :-) Altough that lacks phase display...
> it will do the job nicely in its difference setting, but you have to
> find (and compensate for) the delay manually, like a real man.
> modern p.a. tools allow sissies like yours truly to just click on the
> "find delay" button and be done :-D

The venues I used japa in are small enough and the music slow enough to just 
use the second-slowest settings from japa and call it a day. :-D

But a PA setup helper with speaker-managment and x-over and convolver-engine 
is probably one of the killer apps linux audio is missing.
But then again, real men use jconvolver, drc and aliki to adopt for the rooms 
and PAs defficiencies. Unless they calculate the correction responses by hand...
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