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Subject:SF7 : creating impulse
Posted by: Pol Davril
Date:11/14/2007 12:48:52 PM
Hello, I am trying to create an impulse with a decay time > 12 seconds, with the 48 seconds test tone. The resulting impulse is truncated to 5.944 seconds,so that the reverb is gated. Why ? How can do make a longer impulse ? |
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Subject:RE: SF7 : creating impulse
Reply by: Pol Davril
Date:11/15/2007 1:09:31 AM
Furthermore, I would like to know how convolution reverbs really work. I mean, how the plug-in can generate all frequencies, starting from an impulse file that seems to contain one single "noise" only, which is sometimes of a low level. Any web site or any other documentation about the process is welcome. Thanks ! Message last edited on11/15/2007 1:14:20 AM byPol Davril. |
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Subject:RE: SF7 : creating impulse
Reply by: Kennymusicman
Date:11/15/2007 3:19:13 AM
I'm going to over simplify how it works here, but hopefully this will get you started. Look at a waveform in SF. It looks like noise, or a sine,square,whatever wave form doesn't it? It's a complex waveform that is the result of several waveforms interacting and combining, through addition, multiplication, subtraction and so on. FM synthesis works on this basis, same with ring modulation and many more. Manipulate a waveform by using another. Even phasing has it's key basis formed by this. So you have your waveform A (as in your original dry waveform) and you have another B, which is your impulse. Now multiply A with B and you get output C, which is the result. Google and wikipedia will offer plenty of fairly accurate and technical info on the how's and whys. If you want to see phasing at it's best. Create a simple, stereo sine wave. (at most -6dB level). Copy channel 2 (R) and mix with channel 1 (L). What do you get? - you should see channel 1 effectively double in volume (6dB gain increase). Now undo, back to stereo waveform. Invert 1 channel (not both!). Now repeat the copy of channel 2 and mix with channel 1. What do you get this time? Should have nothing/silence. Interesting huh? Welcome to the world of balanced signals, and the key principle behind balanced signals. HTH Ken |
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Subject:RE: SF7 : creating impulse
Reply by: Pol Davril
Date:11/15/2007 6:07:00 AM
Thanks Ken ! Does anyone has explanations about a 6 seconds limit in Acoustic Mirror ? How can I create an impulse with 12 seconds reverb decay, for example ? |
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Subject:RE: SF7 : creating impulse
Reply by: Pol Davril
Date:11/16/2007 2:59:25 AM
Hi, As I'm stuck with this issue, can someone tell me about the limit of 6 seconds impulse in Acoustic Mirror ? Or do I miss something ? Thanks in advance. |
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Subject:RE: SF7 : creating impulse
Reply by: WavetableMaker
Date:11/16/2007 2:28:22 PM
I'm not sure convolution can be properly understood without exposing yourself to some fairly serious signal-processing theory. For me it's been over 20 years since I had a fresh grip on things like moving from the time domain to the frequency domain and back again, which underpin numerous DSP operations. If you're feeling brave, go here: http://www.dspguide.com/ It's a complete book on DSP for scientists and engineers. You can download chapters (#6 is on convolution) or the whole book if you like. |
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Subject:RE: SF7 : creating impulse
Reply by: Pol Davril
Date:11/19/2007 2:34:38 AM
BUMP. Just for the 6 seconds limit in Acoustic Mirror when creating an IR file. Any idea ? |
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Subject:RE: SF7 : creating impulse
Reply by: Pol Davril
Date:11/21/2007 1:38:04 PM
In the meantime, I will have a look at Voxengo utilities. |