[LAD] what does "full range" mean with regard to ambisonics and speakers?

[Jörn Nettingsmeier]

On 07/31/2010 11:14 PM, "Bearcat M. Şandor" wrote:

> Thank you.  I think i understand all that, but let me take this apart to
> make sure.  What you're saying is that having full range speakers only
> effects the playback quality of the music not the ambisonics and
> that ambisonics itself does not *need* full range speakers, but that
> having full range speakers is better than not. Is that correct?

ah, no, sorry. as fons remarked earlier, that mail was kind of sloppy. 
it's just that when you embark on the ambisonic trip, there are many 
high-end stereo truisms you should be prepared to let go of.

worse yet, ambisonic systems have some clear disadvantages that would 
not be accepted in high-end stereo circles - different localisation 
ambiguities, sometimes coloration, sometimes extreme phasing, etc.

and there is no reason to accept them in stereo.
at the same time, there is no reason to reject a system that displays 
them, because it's the price of good surround sound. you don't reject 
stereo for its lack of rear localisation, either...

> I think part of my confusion is that i'm still thinking of it as having
> 6 or 8 or more *channels* when that is not the case.  The speakers are
> not steered, they are driven. So you are not going to have a situation
> where the speakers behind you are only reproducing high to midrange
> information as was the case with Dolby pro-logic or something. Right?

no, never.

> I am planning on subs that have their own low-pass filters. I have a
> pair of Anthony Gallo Reference 3.1s but for this ambisonics set up, i'd
> get 4 pairs of the Anthony Gallo Stradas and 4 T3 subs.  stradas:
> http://www.roundsound.com/reference-strada.htm  t3:
> http://www.roundsound.com/tr-3-subwoofers.htm  Most of the stuff on
> those pages is marketing of course, but the satellites have a range of
> 45 Hz - 20 Khz +- 3 db and the subs go down to 22 Hz (no variance given).
>
> That push-pull idea sounds fantastic. I would love it if you'd show me
> how to create a set up for a system like that using ambdec, if you have
> the inclination and the time. That's what i was planning on using anyhow.

basically, you take fons' example for the octagon, set the speakers up 
at the correct angles and then enter the actual distances into the 
matrix, so that delay and near-field compensation is correct for your 
setup. then you take the example square for the subs, set them into the 
corners of the room and again enter the correct distances.

at this point you have two ambdec instances running, one for the tops, 
one for the subs. you'd need to adjust the relative loudness with 
ambdec's faders. once you've determined the correct relative levels, you 
can factor them into the matrix coefficients of the sub decoder and run 
both ambdecs at 0dB. now you can hack both matrices into one and end up 
with a 12 channel ambdec configuration: 8 tops and four subs. easier to 
start up in daily use.