Trying to create my own cab impulse...problem

[::XeS::]

Last week I tried to create for the first time a cab impulse.
So I opened Voxengo -> Test Tone Gen and I generate a sine wave (44100, 24bit, mono, 12 sec).
After that I imported it to Pro Tools, I sent it out of one of my output to the 6505 return and I miced the cab.
At the end I exported this new track and I imported it into Deconvoler, I loaded the original Sine Wave and I created the impulse.
Now, when I load this impulse into a convolution reverb...it's like there is no impulse loaded. I only hear the distorted preamp track....and with other impulses everything works.
Any idea?

 

[id3alism]

I guess i had the same problem when I tried making my own impulses. The newly recorded track needs to be a few milliseconds longer than the test tone file. This can be just silence. Experiment a little bit with it, something like 1-12 ms should be enough.

 

[ForHerDeadEyes]

You shouldn't make an IR of a distorted channel..
But if you're recording a 12sec sweep, then record to at least 14sec.. but I'd record 18 - 20 seconds..
Then convolve it..
And remove the silence that follows the IR.. = Editing the IR

 

[Wild Hades]

You need to keep some silence at the end of the recorded tone.
The length of the IR coming out of Voxengo Deconvolver is going to be equalt to the amount of silence you left of the recorded track. If you have the test tone and the recorded tone of the same length, you're going to get silence out of Deconvolver (just look at the IR file with a wave editor).
Remember that the length of the IR is really important for the frequency response accuracty compared to the real cab, never use less than 1024 samples (2048 should be more than enough for close micing).

Hope it helps

 

[::XeS::]

Thanks guys...Tomorrow I will try.
So when I have my recorded track I have to add some ms of silence at the end...so I have a recorded track a little bit longer than the sine wave track, right?
Another thing....the Line out of the interface is really "hot" so I usually lower the send of the track. If I don't lower the out that goes on my amp..the speakers really blow!
How do you set the output of the line out?

 

[::XeS::]

I just checked the impulses I made that don't work....and there is nothing inside I mean..it's a short file with no wave inside ...
Another thing...how can I make 1024 samples? You mean that after the creation of the short impulse I have to reload and cut it to 1024 samples?

 

[Skaldir]

I just checked the impulses I made that don't work....and there is nothing inside I mean..it's a short file with no wave inside ...

Ah I think I had that problem. Don't downmix the recorded sweep, but bounce it as mono! I think there is no result when you deconvolve a stereo wav.

 

[::XeS::]

Ok...I solved my problems
The key is to play the sinewave but you have not to record the lenght of this track. The recorded signal have to be "n" samples longer than the sinewave. "n" have to be equal to the resolution of the impulse you need.
So if you need a 1024 sample you have to record a track 1024 samples longer than the sinewave track...or just insert 1024 samples of silence at the end.

 

[::XeS::]

Now the problem is that my impulses lack very much the bass frequency...Don't know if it was caused by the low volume recording...anyway I was forced to record with earplugs so it was not that low..
Maybe 12seconds are too short to get a decent analysis?

If you wanna try one of the impulses: http://dl.dropbox.com/u/1436721/2x12-Cone_Pres5_dc.wav

It's a 48Khz impulse. SM57 on axis aiming the cone of the speaker.