[LAU] Jconv

alex stone compose59 at gmail.com
Thu Mar 26 20:15:39 EDT 2009

On Thu, Mar 26, 2009 at 9:51 PM, Fons Adriaensen <fons at kokkinizita.net>wrote:

> On Tue, Mar 24, 2009 at 08:52:07PM +0300, alex stone wrote:
> This does not make any sense. Early reflection are
> the first 80-100ms of a room's response. There will
> normally be a number of reflections in this interval,
> and they come from all directions. In a good concert
> hall there will be some strong ones from the sides.
> Reducing them to mono and giving them the same direction
> as the direct sound does not correspond to any real
> acoustic process. A jconv setup meant to reproduce ER
> should at least be stereo if your mix is stereo. You
> just mix it directly into the stereo master bus.
> Most stereo reverbs will just produce one set of ER,
> while they should be different for each source position.
> If you separate the ER from the reverb tail there are
> some things you can do to have more variation. One is
> to create a second set by just swapping L and R, or for
> an AMB reverb, by rotating it. Much more interesting
> is to play with delays and levels. For a close source
> the ER will be weaker and arrive later. For a more
> distant source the ER will be close to the direct
> sound, and stronger.
> An alternative is to use a reverb that provides a
> number of different ER patterns. The reverb I captured
> in the concert hall of la Casa della Musica does
> provide this, IIRC there are at least 4 ER patterns
> corresponding to different on-stage source positions.
> In the jconv configuration they have separate inputs
> (as does the reverb tail), and a common output. Nothing
> is lost by the common output, as separate ones would
> just all be mixed into the master bus anyway. You can
> enhance the set of 4 by using different delays.
> On each channel you should have a post-fader send to
> set the level of the ER and a second one for the reverb
> tail, and insert a short variable delay into the direct
> sound path (after the point where the delay send is taken).
> Or you put the delay into the reverb send and use it
> in the opposite sense.
> Of course doing this in Ardour is a nightmare as you end
> up with three of four plugins per channel. For a typical
> orchestra this means you'd have something like 50 plugin
> windows on screen, or being forced to re-open and close
> them for each adjustment.
> I'm developing a mixer app that has a more ergonomic
> layout for this sort of thing. It wil also do ambisonics
> and provide filters, dynamics, equaliser and delays on
> each channel.
> --
> FA
> Io lo dico sempre: l'Italia è troppo stretta e lunga.
Fons, you're right, it doesn't make any sense, and i've found that out for
myself. (I did learn something in the effort though, so it was worth

I also have the recent experience of trying to create as many sends as
required in Ardour with another IR, and got past 50 down to the trombones,
before i called a halt to it.

I shall have a go at the sala IR tomorrow, and see what happens. Hopefully i
can find a balance between as 'real' as possible, and within a reasonable
template that runs without a problem. When i add 70 tracks, and 40 busses to
Ardour, and then add 50 odd sends, it takes a little while to make all the
connections on startup, so i'll need to compromise somewhere, i think.

It's good news about your mixer project. I can see something like that
taking at least some of the hard work out of a standard orchestral setup.

I wait with barely controlled excitement for the release.

Thanks again for all the tips, and user friendly technical advice. I'm
certainly learning a lot, and that's no bad thing at all.


Parchment Studios (It started as a joke...)
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