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

From: Fernando Lopez-Lezcano <nando@email-addr-hidden>
Date: Wed Aug 04 2010 - 09:11:28 EEST

On Tue, 2010-08-03 at 21:38 +0200, fons@kokkinizita.net wrote:
> On Tue, Aug 03, 2010 at 08:17:03PM +0200, Jörn Nettingsmeier wrote:
>
> > sending high-passed WXYZ and full-range higher orders to the tops
> > won't work well, i guess. if you want to take care of the
> > band-splitting in your mixer, your best bet would be ganged
> > high/low-pass filters for all the orders. if you have the time,
> > gear, and expendable ph.d. student labor at hand, it would be fun to
> > try three- or four-way systems with an increasing number of speakers
> > as the frequency goes up.
> > but since the most expensive part for massive ambi systems is the
> > amping, that's probably an economic dead-end, at least for now.
>
> A separte VLF decoder is one of the features I want in the next
> generation Ambdec.

That would be great... right now I'm using a HPF/LPF pair for my tests
(butterworth 12dB/oct, supercollider) and placing them high enough that,
well, maybe both the loudspeakers and the subs are in a region that is
not right where they are transitioning (~70Hz).

But I'm not really sure how I can actually measure the bloody thing...

> The question I'm asking myself is how much
> 'configurability' this requires. It's no problem adding the
> filters that would perform a 'perfect' split of VLF and the
> rest. But then you have to consider the response of the units
> themselves - many subs have their own filters, and the LF
> response of the 'full range' speakers can't be assumed to be
> really flat in the crossover region. A really good xover has
> to take into account the response of the two systems it is
> driving. All suggestions are welcome...

No easy answer. It looks like a complicated affair if you want to solve
it "perfectly". I would start with a "perfect" filter (assuming nice
loudspeakers) and leave further tweaking for other programs.

> Another question to two (Joern and Fernando) AMB nerds: does
> a multicnannel AMB aware dynamics processor make sense ? When
> would you use it ? I'm asking because one of the plugins I'm
> developing could be exactly that. ATM it's just compression
> (with real RMS response), but the full version will have a
> noise gate as well, Do you need such a thing ? Current plans
> are that the full version will be mono/stereo only.

This one I never thought about, but I guess it would become
indispensable once your native capture format is ambisonics. It would be
nice to have it but I don't have an application screaming for it right
away.

Unrelated question, does ambdec do third order vertical? Will it?
(I'm going to have zenith and nadir speakers in the Listening Room so it
would be able to do 3rd order h and v).

-- Fernando

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Received on Wed Aug 4 12:15:02 2010

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