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PeterRoos
10-09-2002, 01:54 PM
I just discovered a disappointing feature of Acoustic Mirror, which I believe very much reduces its value as a \"reverb\" application.

When you pan the input signal hard left or right (e.g. just mute the R or L channel in SoundForge) and then apply Acoustic Mirror, the output is also hard completely panned left or right. Not a single bit of sound leaks into the virtual room.

I find this really odd; I\'d expect to hear normal stereo reflections. Is this indeed intentional behavior? Cannot imagine AltiVerb also behaves this way.

Bruce? Ernest? Hasen?

Tom Hopkins
10-09-2002, 03:15 PM
Peter,

This is true. My workaround for the last couple of years has been to render the completely wet impulse version to a (stereo) audio track. The impulse is applied to a temporary version of the mix that has the instrument placements significantly narrowed toward the center of the stage. I then use the resulting stereo impulse track as if it were a reverb return and adjust its level relative to the dry (and fully panned) version of the mix. Instruments panned far left and right now have reverb contributions in both channels. Experiment with the amount of narrowing in the mix you use for the rendered impulse tracks. Works for me.

Tom

Tom Hopkins
10-09-2002, 03:31 PM
One more thing: I was assuming (in my reply) the use of a multi-track audio program in addition to Sound Forge. It can also be accomplished from within Sound Forge by making a second copy of the fully panned version of the mix, narrowing the stereo stage on the copy, applying the impulse (100% wet) to the copy and merging the resulting file with the original mix. Adjust the relative balance of the two during the merge.

Tom

PeterRoos
10-09-2002, 03:42 PM
Thanks Tom, nice tips. Will check them out in Logic and SoundForge. The bottom line is indeed if it sounds good and not if the solution is correctly modelling the original hall.

Peter

Beckers
10-10-2002, 03:46 AM
Just to add to that, FWIW, I \'ve found that for a heavily panned (esp. solo) instrument it pays to have two wet tracks, using the same impulse, but set for different room sizes: one a little shorter, the other with reduced early reflections and darker. The shorter one you pan to the side of the instrument, but keeping it more central, the other you pan to the other side but more lateral, then tweak the relative volumes, the latter needing at least -6db.

Although easy to overdo, this gives you a better image with a real sense of space.

In fact I keep a time stretched copy of my favourite impulses, to use on the far side to avoid having to shorten the original impulse for the near side. I imagine this sound even better (probably no different)

I haven\'t tried this with an instrument totally panned 100%, I can\'t imagine a situation where that would apply

PeterRoos
10-10-2002, 04:02 AM
The 100% lateral positioning was just to illustrate the problem, which I believe must be a serious design error. images/icons/frown.gif

Beckers
10-10-2002, 04:34 AM
Sorry, yes of course.

The same happens with Room Simulator (the impulse convolver in Samplitude). If you apply any effect to a channel with no signal would you expect any output?. Or have I misunderstood the problem?

Hasen
10-10-2002, 05:18 AM
Yeah it doesn\'t happen with Altiverb. The hard pan goes through but is nowhere near as hard in the wet signal. Is this a bug with Acoustic Mirror then?

PeterRoos
10-10-2002, 05:37 AM
Originally posted by Beckers:
Sorry, yes of course.

The same happens with Room Simulator (the impulse convolver in Samplitude). If you apply any effect to a channel with no signal would you expect any output?. Or have I misunderstood the problem?<font size=\"2\" face=\"Verdana, Arial\">The hardware and plugin verbs I know provide at least some stereo diffusion, so that a completely lateral sound (when entered as stereo feed) results in added, wet sound on the other \"side\".

If I put a trumpet player next to the left wall in the Concertgebouw hall (site here (\"http://www.concertgebouw.nl/ce_main.htm\")), and record with a stereo mic setup, I do expect to pick up a lot of signal also with the right mic...

Now wouldn\'t we just love to have a similar effect with Acoustic Mirror (and the Gos impulse)? images/icons/wink.gif

Cheers,
Peter

PS: check http://www.audioease.com/IR/VenuePages/Concertgebouw.html (\"http://www.audioease.com/IR/VenuePages/Concertgebouw.html\") for some cool photos of that beautiful hall. Accidentally on the AudioEase website... images/icons/wink.gif

See those chairs on the stage? Yes, you can actually enjoy a concert 1 meter away from the players, within the orchestra!

lex
10-10-2002, 07:43 AM
You can control this to some extent with Response Width controler. As soon as you go over 50 the signal starts to leak in the opposite chanel....

Alex

PeterRoos
10-10-2002, 08:16 AM
Yeah, your\'re right. But this unfortunately only creates/adds a very unrealistic mono tail... (list to the wet-only sound). Well, for me Acoustic Mirror was just a free toy with SoundForge. I should stop complainin\' images/icons/cool.gif

Thanks for all the reactions!
Peter

Hasen
10-10-2002, 09:24 AM
Originally posted by PeterRoos:
The hardware and plugin verbs I know provide at least some stereo diffusion, so that a completely lateral sound (when entered as stereo feed) results in added, wet sound on the other \"side\".

If I put a trumpet player next to the left wall in the Concertgebouw hall (site here (\"http://www.concertgebouw.nl/ce_main.htm\")), and record with a stereo mic setup, I do expect to pick up a lot of signal also with the right mic...
<font size=\"2\" face=\"Verdana, Arial\">

Yes that does indeed happen with Altiverb which is why the hard pan becomes slightly more centralised as you hear its reverberation around the hall. The thing is with Altiverb is that in the usual stereo to stereo mode there is a left and right for _each_ side. So the left and right inputs are treated individually with the impulse from each side of the hall in stereo, for a true stereo output.

Unfortunately though you can\'t use Stereo to Stereo with the GOS impulse.....but its still great despite that. images/icons/smile.gif

csduke
10-10-2002, 01:51 PM
Originally posted by PeterRoos:

See those chairs on the stage? Yes, you can actually enjoy a concert 1 meter away from the players, within the orchestra!<font size=\"2\" face=\"Verdana, Arial\">OT: The recently renovated Orchestra Hall in Chicago has some new close seating behind the orchestra. My favorite cheap seats.
Pic1 (\"http://www.kirkegaard.com/images/1161-3.jpg\")
Pic2 (\"http://www.saflex.com/Case_Studies/cs08.htm\")
Pic3 (\"http://www.kirkegaard.com/images/1161-8.jpg\")

PeterRoos
10-10-2002, 03:52 PM
Ah, cool pictures Craig!

BTW: great illustrations for those of us who want to do some midi panning images/icons/wink.gif

DaleB
10-14-2002, 03:57 AM
Originally posted by csduke:
</font><blockquote><font size=\"1\" face=\"Verdana, Arial\">quote:</font><hr /><font size=\"2\" face=\"Verdana, Arial\">Originally posted by PeterRoos:

See those chairs on the stage? Yes, you can actually enjoy a concert 1 meter away from the players, within the orchestra!<font size=\"2\" face=\"Verdana, Arial\">OT: The recently renovated Orchestra Hall in Chicago has some new close seating behind the orchestra. My favorite cheap seats.
Pic1 (\"http://www.kirkegaard.com/images/1161-3.jpg\")
Pic2 (\"http://www.saflex.com/Case_Studies/cs08.htm\")
Pic3 (\"http://www.kirkegaard.com/images/1161-8.jpg\")</font><hr /></blockquote><font size=\"2\" face=\"Verdana, Arial\">We\'ve had a pair of those seats (stage right, to the left in these pictures) for the last three seasons - they are spectacular - you can look Mr. Barenboim in the eye. And now that more folks have discovered their virtues, they are not that cheap any more!

PolarBear
10-21-2002, 06:00 PM
Well... Just got three things...

1.) csduke, thx for the pics - do you see the following in pic3: Almost all instrument players are sitting/standing on a podest. This is a trick to capture the low end of the instruments and have it better \"delivered\" (for the lack of a better word) to the listener\'s seats. Just wondering why they have this in a Concert hall... And for the hole orchestra...

2.) Couldn\'t you go around this hard panning issue, if you only use lets say 90% of the stereo field in production? I personally do not like the hard panned orchestra instruments, as it would find it for some drum loops or pads a nice effect or at least be acceptable.

3.) Just got the idea of constructing a \"Impulse Library\". What if you capture lets say 7-10 (shown with 5) impulses from a Concert Hall or place of your choice, capture them with three mics like this:
<pre>
O


X

X X

X X



O O



</pre>
So you can place the instruments with a placement tool, and add render the tracks with the proper (in the stereo field), different impulses.

Well, knowing that it is very difficult to get only one impulse to work right with sample libraries, I know 10 is just out of sight. But - what do you think, would this be the appropriate way to add \"real\" reflections?

Thanks for stopping by...

Hansi