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

On 07/31/2010 03:03 AM, Jörn Nettingsmeier wrote:

> first, as initial shock therapy to the (ex-?) audiophile: ambisonics is
> not full-range in the usual sense. its localisation mechanism only works
> in a very limited frequency range. the idea is to use that small range
> to produce such good cues to the brain that it conveniently ignores that
> the rest is garbage ;)
> i'm taking localisation only - timbre reproduction must of course happen
> from 20 to 20k...
>
> if you want eight speakers, that would fix you up for up to third order.
> since i assume you're not much into computer-generated music (which
> would provide some source material), and since i know that higher-than
> 1st-order recordings are rare (because i've personally made at least 1%
> of them...), it could make sense to go for 6 speakers initially. very
> good for first-order replay, very good for "super-stereo", easily
> accommodates 5.1 content with only minor placement errors, easier to
> place, and 25% cheaper. unless you choose a very exotic brand and model,
> it should be no problem to extend this setup to eight or more later.
>
> it's no problem (and in fact customary) to use subwoofers with
> ambisonics for low-range extension. you can either forego localisation
> in that band and just use a mono sub (perfectly ok), use 2 and have some
> l/r signal in ithem, or you can use 4 subs in the corners of the room
> and drive them with a special horizontal decode. that's pretty awesome,
> because you can do a decode such that one speaker pushes while the
> opposite speaker pulls. of course that wastes quite some amp power, but
> it makes your room effectively infinite volume, which means you can fit
> very long waves into it without weird effects, and you will win a nice
> trouser-flapping effect without boominess and that obnoxious pressure on
> the ears.
>
> if you're going to use ambdec for decoding, i can show you how to create
> two separate configurations for the full-range speakers and the subs,
> and to combine them into a single matrix (that's assuming that the subs
> themselves do their own low-pass filtering - if not, you'd need to do
> that with a plugin, but that means you will have to use another
> application in addition to ambdec).
>
> best,
>
> jörn
Jörn,

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?

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?

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.

Thank you very much Jörn

Bearcat
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Received on Sun Aug 1 00:15:02 2010