Now, if someone has thoughts on shelf filters for higher orders...there is some stuff in Daniel's
PhD thesis, but...
On 15/12/2011 19:19, Richard Lee wrote:
http://ambisonic.info/info/ricardo/shelfs.html
This is now only of historical interest. My latest thinking on Shelf Filters is
encapsulated in BLaH3 "Is my decoder Ambisonic?" where Aaron's clarity puts me
to shame and explains why I'm still a beach bum.
The only useful info there which isn't in BLaH3 are the UHJ Shelf Filters.
(There's loadsa now useless info)
Fig 3.3 shows them in the form that Ambdec uses; matched gain at LF.
So 'order gain' at LF is 1.0 for both.
At HF, 'order gain' is
3.7dB for W
and
-2.1dB for X& Y
This is "exact" for regular horizontal speaker layouts. (Actually I'm just
reading off my Fig 3.3)
In theory, rectangular layouts should have slightly different values but these
are known to work well subjectively. I daren't ponitificate on Guru Fons'
individually matched Shelfs for his 5.1 layout [1] but suggest these might work
well too.
You'll excuse me if I dodge the "Shelf Filter for Forward Preference" question.
My brain hurts.
[1] I think he derives another matrix at HF by an iterative process. BLaH4 is
our attempt at this for non-regular / non-diametric opposite layouts.
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