Author Topic: 60/120Hz ballast noise/transformer MP3 sample request  (Read 2493 times)
Flurofan96
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60/120Hz ballast noise/transformer MP3 sample request « on: February 02, 2017, 09:55:52 AM » Author: Flurofan96
Hi all  :)

Heres the thing what I did, I sampled the 50/100Hz buzzing/humming noise from my FL fixture in my bathroom (one with the 90s OSRAM tube) using microphone and Logic Pro then I edited the raw recording file to make the sound suitable for a loop effect.

To all US members and those who live with a 60Hz mains frequency, can someone at least sample/record a FL fixture or an HID lantern that has a magnetic ballast that produces a loud enough volume to make a good sample of the 60/120Hz for my music use please ?

The 50/100Hz make the note of G whereas the 60/120Hz make the note of B flat

Thanks and all the best  :) :)

Flurofan96 :) :)
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Medved
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Re: 60/120Hz ballast noise/transformer MP3 sample request « Reply #1 on: February 02, 2017, 01:20:35 PM » Author: Medved
Speed the record you have up (by factor 1.2)...
A pretty low end way (if you do not have any editor capable to do such operations) is:
Save it as an uncompressed "wav" file, open it in a hex editor, locate the position of the sample rate (it is in the byte header, you should be able to locate it when you know the sample rate you have used for recording) and change that number to  "OriginalSampleRate"/1.2.
Then most audio mixer-editors should be able to "save that as" a file with the sample rate you finally want.
The second operation will do the actual signal processing (anti-aliasing and resampling).

The thing here is, most editor authors do expect a need to convert a file from one sample rate to another one, so do implement the required processing.
But many of them never thought about anyone needing to speed up and/or slow down a sound, so they do not offer that functionality directly, although it means exactly the same operation with the raw sound data...
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Ash
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Re: 60/120Hz ballast noise/transformer MP3 sample request « Reply #2 on: February 02, 2017, 03:04:00 PM » Author: Ash
"The second operation will do the actual signal processing (anti-aliasing and resampling)."

What Anti aliasing is needed for frequencies on the order of 60Hz + assume 10 lowest Harmonics (which are still audible) with 48K sample rate ? It would have nearly no effect anyway i think
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Flurofan96
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Re: 60/120Hz ballast noise/transformer MP3 sample request « Reply #3 on: February 02, 2017, 07:16:28 PM » Author: Flurofan96
Ah I know what I'll do I'll can do that with my application


Thanks for the info  :)
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