Which (free) FX to fix aliasing?
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- Banned
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- 228 posts since 3 Feb, 2014
Hearing some bad high-frequency noise from EWQL Choirs, and wondering which FX to use to treat the problem?
A sample of the problem is the 2nd note in this WAV file:
https://drive.google.com/file/d/0B5ZYXb ... sp=sharing
From the zillions of good, free EQ's and filters available, any recommendations particularly suited to this task? Thank you.
Edited to add: If there is an art to this process, anything I should know? Or I just sweep until I locate the problem frequency and apply the steepest, deepest notch possible?
A sample of the problem is the 2nd note in this WAV file:
https://drive.google.com/file/d/0B5ZYXb ... sp=sharing
From the zillions of good, free EQ's and filters available, any recommendations particularly suited to this task? Thank you.
Edited to add: If there is an art to this process, anything I should know? Or I just sweep until I locate the problem frequency and apply the steepest, deepest notch possible?
Last edited by BachRules on Thu Mar 13, 2014 1:10 pm, edited 2 times in total.
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- KVRAF
- 5564 posts since 13 Jan, 2005 from the bottom of my heart
try out the excellent free stuff from robin schmidt @ http://www.rs-met.com/freebies.html
ps. voxengo redunoise is great but not free and 32bit still.
ps. voxengo redunoise is great but not free and 32bit still.
Whoever wants music instead of noise, joy instead of pleasure, soul instead of gold, creative work instead of business, passion instead of foolery, finds no home in this trivial world of ours.
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- Topic Starter
- 228 posts since 3 Feb, 2014
I am a voxengo fan, but I'm guessing this problem is conducive to a free solution. schmidt's products look very nice; I'll try them. Thanks.murnau wrote:try out the excellent free stuff from robin schmidt @ http://www.rs-met.com/freebies.html
ps. voxengo redunoise is great but not free and 32bit still.
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- KVRAF
- 5223 posts since 20 Jul, 2010
Thing is, aliasing doesn't happen at one frequency that you can filter out, it moves depending on the note produced, and it meshes with the musical part of the signal. I don't think I can envision a way of removing alising after the fact that isn't clumsily removing audio and muffling the sound.
http://sendy.bandcamp.com/releases < My new album at Bandcamp! Now pay what you like!
- Beware the Quoth
- 33175 posts since 4 Sep, 2001 from R'lyeh Oceanic Amusement Park and Funfair
Yup.Sendy wrote:Thing is, aliasing doesn't happen at one frequency that you can filter out, it moves depending on the note produced, and it meshes with the musical part of the signal. I don't think I can envision a way of removing alising after the fact that isn't clumsily removing audio and muffling the sound.
my other modular synth is a bugbrand
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- Topic Starter
- 228 posts since 3 Feb, 2014
I'm not sure it's aliasing, but it's high pitched and surely doesn't belong. I don't hear it changing frequencies, so I'm guessing I'll have some success, even if some good parts of the signal get removed in the process. Muffled would be better than high pitch giving me a headache and probably causing permanent hearing loss.Sendy wrote:Thing is, aliasing doesn't happen at one frequency that you can filter out, it moves depending on the note produced, and it meshes with the musical part of the signal. I don't think I can envision a way of removing alising after the fact that isn't clumsily removing audio and muffling the sound.
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- KVRAF
- 7890 posts since 12 Feb, 2006 from Helsinki, Finland
The easy way to identify typical aliasing is to do a slow pitch bend; if there are frequency components moving in the wrong direction, then you are suffering from aliasing. If the artifacts stay fixed, then it might be something else.
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- 228 posts since 3 Feb, 2014
This is a good idea. When I use the pitch wheel, however, I get no pitch bend. I don't know this product well enough yet to know if there's another way to do pitch bend. Thanks for the advice though. I'm trying to pinpoint the location of the noise that's bugging me.mystran wrote:The easy way to identify typical aliasing is to do a slow pitch bend; if there are frequency components moving in the wrong direction, then you are suffering from aliasing. If the artifacts stay fixed, then it might be something else.
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- KVRAF
- 5223 posts since 20 Jul, 2010
If the artifact isn't moving around when you play different pitches, it's almost certainly not aliasing. It could be some other sampled-in artifact. If it's just a ringing tone a notch filter should be able to kill it. Just slowly roll the cutoff around until it fades away. If it's an unwanted resonance from the instrument/acoustics, some gentle EQ cut in the area should help.
http://sendy.bandcamp.com/releases < My new album at Bandcamp! Now pay what you like!
- KVRAF
- 7890 posts since 12 Feb, 2006 from Helsinki, Finland
It could still be aliasing from interpolation in a sampler that has separate waves for each note (and the sampling rate doesn't match the host rate, so resampling is necessary), hence the suggestion to try pitch bend. But yeah, ultimately there's not much one can do beyond filtering.Sendy wrote:If the artifact isn't moving around when you play different pitches, it's almost certainly not aliasing. It could be some other sampled-in artifact.
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- 228 posts since 3 Feb, 2014
Does any besides me hear the problem? Here is a new demo:
https://soundcloud.com/ammonium-nitrate ... -test-file
The file is 5 notes -- g, f, e, d, c. The "e" has the high pitch which is bugging me. The file repeats the 5-note sequence 4 times for convenience.
https://soundcloud.com/ammonium-nitrate ... -test-file
The file is 5 notes -- g, f, e, d, c. The "e" has the high pitch which is bugging me. The file repeats the 5-note sequence 4 times for convenience.
Last edited by BachRules on Fri Mar 14, 2014 11:14 am, edited 1 time in total.
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- KVRAF
- 2032 posts since 15 Mar, 2002 from Seattle, WA - USA
Depending on how severe it is iZotope RX may help. It isn't cheap, but I've managed to seamlessly repair audio that was riddled with high frequency artifacts which would've been nearly impossible to achieve using static notched EQ bands. It has one of the most intuitive spectrum visualizers I've ever seen and in most cases artifacts like that are plainly visible. They can be "cloned" out not unlike tools in Photoshop like the healing brush. Might be worth checking out the demo if you haven't already; I'm pretty sure it's fully functional for 10 days or so.
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- Topic Starter
- 228 posts since 3 Feb, 2014
I pegged it with a narrow notch.
https://docs.google.com/document/d/1Aa3 ... sp=sharing
That solves my problem, but I'm still curious what the noise is; whether it really entered the microphone like that, or whether it was introduced later.
https://docs.google.com/document/d/1Aa3 ... sp=sharing
That solves my problem, but I'm still curious what the noise is; whether it really entered the microphone like that, or whether it was introduced later.
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