Capturing a 5.1 Impulse Response..

[DrummerGuy09]

I need to capture an impulse response of a large circular-shaped room. I'm trying to figure out what software & setup to use.. Altiverb, Apple's Impulse Response Utility or IR-360??


My goal in capturing this room is to place the listener in the center as a virtual "space" as in a "being there" IR. After researching all week & reading posts, i think the set up in the picture below will give me best results. Please let me know what you think.

After capturing, I want to be able to mix through the IR. So if I pan a track to the left-rear speaker, it will faithfully re-create what it would sound like the the "left-rear" section of that room, & so on..

Is this possible? What is the best software/mic placement to use????

[DrummerGuy09]

bump

[David Spearritt]

I am convinced that reverb cannot be used to "position" a source in the sound stage. It consists of incoherent reflected sound, meaning that the arriving cues are too late and too unrelated to the direct path that it cannot be useful in location of sources.

[JonesH]

I haven't done any true surround setups, but I figure as long as the convolution engine supports multiple IR's for true surround we'll be fine. Dunno how altiverb does it, if it's strictly mono->surround, actually.

But recording IR for true stereo is easy; you just record with the speaker centered in respect to the mics first (which is a mono->stereo IR), then move the speaker circular to the mics out to the left (left->stereo) and vice versa (right->stereo). When used together, the left & right IR's can be used to do real, pannable stereo reverb where the early reflections give location cues.

David, I think that early reflections do give location cues. It is used extensively in the System 6000 reverb to enhance localization. It also contributes very much to distance perception AFAIK.

[David Spearritt]

Originally Posted by JonesH

IDavid, I think that early reflections do give location cues. It is used extensively in the System 6000 reverb to enhance localization. It also contributes very much to distance perception AFAIK.

Not convinced as much as you are I guess. I have some "true stereo" IR's from Pinguin but I find they have an almost negligible influence on the location of sources. Fundamental mic technique and direct dry sound from the recording seem to account for a much more significant and dominant contribution.

[JonesH]

Originally Posted by David Spearritt

Fundamental mic technique and direct dry sound from the recording seem to account for a much more significant and dominant contribution.

Yes, I agree of course. TC Electronics, however, have some idea that you should record without a main pair and just use their surround panners and reverb to create the sound stage. Interesting.

[muziekschuur]

Decca Tree.

You need a Phasemeter to setup the tree.