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Topic: IR Creation

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  1. #1
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    IR Creation

    Hey Everyone,
    Does anybody have any advice on creating IR's for gigapulse? I've made some myself, but they're not top notch. I'd like specifically to know exactly what sort of audio signal to use-2ms of white noise? Sine sweep (tried it-must've dones somthing wrong)? Longer burst of noise? I know how to import wav. to GPulse, but I need to know what wav. to output in order to create the IR.
    Some of you have indicated an understanding of how this is done (One poster: "Creating IR's is easy"), but no one (least of all tascam) is giving up the goods.

    So how 'bout it?

    Belbin

  2. #2

    Re: IR Creation

    Hi Belbin,

    I seem to recall that Larry Seyer moderates a non-NSS forum regarding GigaPulse impulses and the like. If anybody can offer advice on the subject, it would be Larry.

    Let us know what you learn!

    -JF

  3. #3
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    Re: IR Creation

    Quote Originally Posted by JonFairhurst
    Hi Belbin,

    I seem to recall that Larry Seyer moderates a non-NSS forum regarding GigaPulse impulses and the like. If anybody can offer advice on the subject, it would be Larry.

    Let us know what you learn!

    -JF
    Thanks Jon, I will.

    Belbin

  4. #4
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    Re: IR Creation

    A great forum on this topic is Noisevault. Since you didn't mention it here I wasn't sure if you already knew. Also, your questions seem to pertain more toward IR capture than Gigapulse itself.

    The site's founder wrote a detailed article about IR capture here:

    http://www.noisevault.com/index.php?...d=22&Itemid=33

    Also there is much discussion on the subject in their forums.

    One one hand you might prefer a very quick, loud, clean transient (like a starter pistol, see article above). On the other you might want to excite the space with a full range of frequencies (like a sine sweep).

    The raw impulses included with Sonic Foundry Acoustics Modeler I believe combined a very quick spike with a sine sweep for 24-48 seconds.

    Also, a nice 2-channel AD converter is pretty much key. The fidelity of your impulse capture will be a significant factor in how well it deconvolves to an IR.

    For the record, I have never created any impulses. But I'm interested in the subject, and happen to be satisfied with the existing IRs available out there. Or at least, the thrill of making my own can wait for now.

    RE: Gigapulse, I have these steps saved to my computer. I think I copied them off NorthernSounds at one time:

    =======

    This applies mainly to GS3 versions before 3.1, after which GigaPulse gained a better import feature.

    1, insert a GigaPulse instance and select New... from the file menu button
    2, specify a name for your .iis file in the dialog
    3, select the appropriate ticks in the middle (LFront, RFront, and others if you are in surround)
    4, push on the Add button
    5, select the tick "enable this source placement"
    6, specify a name for the source placement
    7, in the middle, push the "..." button to insert the wave files to the "LF" and to the "RF" channels, answer the arising question if you selected a stereo file
    8, push "Done"
    9, select "Done" again and specify a file name
    10, select a bank file name
    11, specify a Preset name
    12, select OK and you are done

    =======

    There are other, non-reverb modeling aspects of GS I know next to nothing about. Larry's Gigapulse-enabled libraries may well make use of those.
    Some experts learn more and more about less and less, until at last they know everything there is about nothing at all.

  5. #5
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    Re: IR Creation

    Quote Originally Posted by Alewis
    A great forum on this topic is Noisevault. ....... Larry's Gigapulse-enabled libraries may well make use of those.
    Thanks, I never knew about that one. Definitely seems like the place to be for this kind of stuff.

    Some background: My jazz quintet is in the studio right now working on an album. I am tickled pink with some of the room sounds we are getting. If I could impulse these it would be fantastic. I also just got a Beautiful Laney VC 100 guitar amp at a steal of a price. It sounds unbelievable, but frikkin' unbelievable in the ISO booth. It will probably sound FREKKIN' unbelievable when we put it in the tracking room for alternate takes/overdubs. I want to take all those neumanns and rodes and rooms and settings home with me!!!
    I think if there's any time left I'll ask the drummer to play a few pages worth of one-shots for me. Will post examples soon.

    Thanks for the tips!

    Belbin

  6. #6
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    Re: IR Creation

    Sounds like fun! You could definitely take impulses of that space. Why not just grab them while the mics are in place, and worry later about how to turn the recordings into IRs?

    Use the clean channel on that Laney to play your test tones. Make a CD of the test tone sequence, set up a reliable position and settings for the Laney, and just get in the rhythm of recording it through each mic position.

    I'd say make sure it's at least as loud as the loudest sound you're recording. Get a nice clean recording of it, and then you can come back later to edit and deconvolve the samples.

    Here's a useful thread at the Noisevault forum where various folks discuss how to create IRs:

    http://www.noisevault.com/elephantta...asc&highlight=

    Which in turn references this helpful guide:

    http://www.acoustics-engineering.com/files/TN001.pdf
    Some experts learn more and more about less and less, until at last they know everything there is about nothing at all.

  7. #7
    Senior Member james vogts's Avatar
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    Talking Re: IR Creation

    I'm having alot of fun w/ the examples I got in GS3. I have tweaked all of them at least a dozen times and came up with some unique results. Try the pedal down model on a good acoustic stringed instrument. Or the catedral's mic placement and decay.

    This IR really works for me.

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