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#5443 - 12/04/2000 10:32 Frequency Test MP3s
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31563
Loc: Seattle, WA
Since I just moved my Empeg to a new car, and I'm working on the speakers now, I'm messing with my EQ settings again.

At some point, I realized that having tracks with predefined sine wave bursts would help. So I fired up CoolEdit and made some. I'm sure this sort of thing exists elsewhere on the internet, but it was so easy to do in CoolEdit that I didn't bother to look. Also, doing it myself allowed me to customize the frequency centers to match the Empeg's default ones.

If anyone is interested, here are the files:

Frequency Test - Band Centers.mp3 (File size: 1 meg)
Frequency Test - Sweeps.mp3 (File size: 377 k)

Some things you should know about these test files:

1) My voice (which announces the frequencies) is recorded poorly. There are some strange artifacts that sound like MP3 compression artifacts on the voice. Actually, those are the artifacts from the noise reduction algorithm I applied to the voice sections- it was recorded with a bad mic in a room with three noisy computers running, so I had to noise-reduce the voice. But the frequency bursts were created digitally as pure sine waves and weren't post-processed.

2) I compressed these using AudioCatalyst on its highest VBR quality setting. Up through 9khz, they sound great. But the 18khz bursts came out heavily artifacted, so just ignore those. I guess we have to take Xing's claim about it being able to capture high frequencies with a grain of salt. By the way, if anyone wants to know what worst-case high-frequency compression artifacts sound like, listen to those 18khz bursts.

Tony Fabris
Empeg #144
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Tony Fabris

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#5444 - 12/04/2000 13:26 Re: Frequency Test MP3s [Re: tfabris]
eternalsun
Pooh-Bah

Registered: 09/09/1999
Posts: 1721
Loc: San Jose, CA
Tony,

Listen to your frequency test mp3s on Sonique with the CoR's Cosmic Belt visual on. There's one frequency that makes the thing go bonkers! And it's not 18000hz.

Calvin


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#5445 - 12/04/2000 14:07 Re: Frequency Test MP3s [Re: eternalsun]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31563
Loc: Seattle, WA
Oh yeah, I hadn't thought about the implications for vis testing. Cool. I'm going to go run them on a few different WinAmp and Empeg visuals right now. Thanks!

(I don't specifically have sonique or that vis, though.)

Tony Fabris
Empeg #144
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Tony Fabris

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#5446 - 12/04/2000 14:12 Re: Frequency Test MP3s [Re: tfabris]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31563
Loc: Seattle, WA
Holy crap, Hula Hoops made my Empeg reboot like crazy on the frequency sweep one. Anyone else get this?

Maybe it's just an artifact of the fact that I encoded them at the highest available bitrate?

Tony Fabris
Empeg #144
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Tony Fabris

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#5447 - 13/04/2000 02:13 Re: Frequency Test MP3s [Re: tfabris]
rob
carpal tunnel

Registered: 21/05/1999
Posts: 5335
Loc: Cambridge UK
Hula Hoops has a problem at certain frequencies. Hopefully this will be fixed for the next release.

Rob



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#5448 - 13/04/2000 13:25 Re: Frequency Test MP3s [Re: rob]
eternalsun
Pooh-Bah

Registered: 09/09/1999
Posts: 1721
Loc: San Jose, CA
Better test all the visuals while you're doing that!

Calvin


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