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Gear / Technical Help => Post-Processing, Computer / Streaming / Internet Devices & Related Activity => Topic started by: Steve J on January 09, 2006, 11:59:51 PM

Title: What should these frequency & spectrum analyses tell me?
Post by: Steve J on January 09, 2006, 11:59:51 PM

A question that popped up on another board from a non-taper (although he probably should be!  ;) ). Not quite sure what I'm looking at...other than a large frequency dropout. I figured I'd bring the question here.

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Converting these files to FLAC for personal archiving, I ran an analysis on the wav files. I got a kind of result I have never seen before. Can anyone offer an explanation for these graphs?


(http://city.hokkai.or.jp/~martin/ll92-07-11d2t01_frequency.jpg)


(http://city.hokkai.or.jp/~martin/ll92-07-11d2t01_spectral.jpg)

Title: Re: What should these frequency & spectral analyses tell me?
Post by: mmedley. on January 10, 2006, 12:09:31 AM

http://taperssection.com/index.php?topic=57244.0

 ;D

Looks like compression.  :(

Title: Re: What should these frequency & spectral analyses tell me?
Post by: Steve J on January 10, 2006, 12:23:55 AM

Having listened to other files from the same source (and knowing the quality of the sources frequently put out by a particular seeder), I highly suspected that they might be MP3-sourced files. And of course, if I'd just read a bit more. Thanks!

Now...altogether: "Hello? McFly?!"  :hmmm: :lol:

Title: Re: What should these frequency & spectrum analyses tell me?
Post by: Steve J on January 10, 2006, 04:18:43 AM

I posted back with that info; but it appears the real question is why there's no frequency response from about 8k to 16k with a "stripe" across at 16k. Has anyone seen this type of pattern? There was a suggestion that it might be caused by a problem with the sound card.

For grins, I went back and checked one of the other shows that were seeded. The files have that telltale dropoff at about 16k; but not the big hole in the frequency response. I can't begin to speculate how many generations this source has gone through, as the seed was supposedly created from a cassette transfer...which means somewhere along the line it went WAV>MP3>analog transfer to cassette, and then back again to WAV.  :bawling:

Title: Re: What should these frequency & spectrum analyses tell me?
Post by: RebelRebel on January 13, 2006, 10:12:06 PM

 shoulda read ::)

Title: Re: What should these frequency & spectrum analyses tell me?
Post by: Steve J on January 13, 2006, 10:42:03 PM

No...it's actually a recording of a full band; but I'm sure that it was an MP3 a couple times in its life.