8 Jan
2011
8 Jan
'11
3:30 a.m.
On Sat, Jan 08, 2011 at 01:39:17AM +0100, Jörn Nettingsmeier wrote:
That is very well possible. It means that you don't have the real
pressure, not even at the sweet spot. Which is to be expected if
your room isn't free of LF reflections, as most are.
It's just a property of the higher order components in the near
field. If you look at the amplitude and phase plots of the higher
order NF effects, it's very evident that there is quite a large
phase shift even before the amplitude starts to rise by any
significant amount. Even for first order the +3dB point has
45 degrees phase shift - like a first order filter.
Also if you look at Moreau's 'useful bandwidth' filters for
synthesising near sources, you'll see that none of them has
more than 3 or 4 dB gain before going down steeply for lower
frequencies. This means that it is not the very high LF gains
of the higher order components that create a near source, but
the phase shifts.
Not exactly.
For a well-designed decoder the pressure at LF will
be proportional to W, even without NFC, and should not have any
bass boost.
need to double check, but iirc i did hear a very pronounced (read:
unbearable) boominess on my organ recordings when listening to them
on my <4m array in second order without NFC... What you get in
that case is a velocity field that
does not match the pressure in level,
this i understand.
and more important - in
phase, and this sounds very unnatural.
this is news to me. where does this phase delay come from? i guess the myth is more correctly formulated as
"you can't localize
anything except some select and very obvious mid-frequency cues in
AB stereo". of course, bose and friends would jump on this to sell
ridiculously small satellites with woofers going up to 300 hz :)
With Bose you'd be lucky to localize anything at all :-)
Ciao,
--
FA
There are three of them, and Alleline.