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Old 21st October 2002, 12:02 AM   #1
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Exclamation FREE Audio Test CD!!!

You got all excited and were about to yell SPAM!!! weren't you?

So here's the deal:

There was a thread talking about breaking in drivers. Petter mentioned he used Sound Forge to make sine waves for this purpose. I happen to have Sound Forge and I want to make a driver break-in/test cd.

I was wondering what I should put on it?

I know I can do sine/square/saw/triangle waves.

There is also a "noise" setting which can be used to produce white noise. You can set the low pass cutoff frequency, so I think you could produce a "pink" noise by setting the frquency to 10kHz. Does this make sense?

You can also do some frequency modulation and DTMF stuff, but I'm not sure how useful that is.

Because I am a "musician", I figured I would use frequency which are actual musical notes(27.5Hz, 55Hz) as opposed to "random" frequencies. Any thoughts?

Also, since I figured I'm going to spend at least a few hours making this, I thought I could share. However, I don't have a website which people could download off of. Is anyone willing to put it on their website?

I could *.zip up the wav files into small sections and it could be passed around by email...

Any thoughts or suggestions would be appreciated.
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Old 21st October 2002, 06:29 AM   #2
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A few signals that are useful

Swept sine waves, covering the whole frequency range, or portions thereof

Impulse power test signal: a 1kHz signal that is quite low in amplitude (say -60dB), but increases to full amplitude for a short period (100mS) every few seconds, useful for testing the peak power of an amplifier

997Hz signal instead of 1kHz. 1kHz at 44.1kHz only uses 4410 sample levels of the 65536 sample levels available from a CD, so distortion measurements may be skewed. 997Hz uses all levels and does not repeat.

Also, zipping .wav files results in poor compression (especially with the 997Hz signal I suggested above). Use a dedicated lossless audio compressor. I think the current best one is Monkey Audios Program http://www.monkeysaudio.com/ If you can get past the name, it is a very good program.

Cheers, Adrian
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Old 6th December 2002, 09:16 PM   #3
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Does anyone know what level (-db) I should record the steady tones at? I have a feeling that doing it at 0db might be a bad plan.
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Old 7th December 2002, 12:38 AM   #4
halojoy is offline halojoy  Sweden
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Thumbs down Musical notes or Frequencies

Quote:
Originally posted by seangoesbonk

Because I am a "musician", I figured I would use frequency which are actual musical notes(27.5Hz, 55Hz) as opposed to "random" frequencies. Any thoughts?
Any thoughts or suggestions would be appreciated.
According to what I read and publish in
"Least offensive crossover"
there is no such thing as musical notes.

Only to think of the western worlds music
there can be an A tuning from 430-444 Hz.
If we go to India or Africa or Arabia
or the naitve tribes community in the deep forrests
I am sure you find that music made by humans (often taken from nature)
uses whatever for making this thing we define as "music".

What makes music within us, seems to one component be
cultural - not inherited.
But certain kind of sounds, mainly very "primitive"
is inherited. This can be sounds that we associate to
eating/signal of pleasure or to
warning/signal of danger.

Also heartbeats is very much a primitive sound that everyone knows.
One of the first sounds we can grasp, is our mothers heart rhytm.

This is reflected in humans liking of a marked rhytm, like drums or
bass rhytms. This is very basic, you can say we are stamped with this. Like with many first experiences.
First impression you know.
Elvis, the Rock'n Roll Music and The Beatles were very
fortunately gettin some advantage of this.

Perhaps also liking into moving our body, called dance,
can get out of the fact that our mother carried us inside.
It seems to be universial.
And with her every step we were rocked by her every twostep.
Even her skeleton gave us sounds of that two beat rhytm
through the connected bones.

All this is my own thinking. I have have not read this anywhere
but it is very likely to be some truth in it.
Most of my observations indicates that.

/halojoy
may be copied
in fact it should
for common knowledge - common good
------------------------------------------------
My old Mama sure knows how to ROCK&ROLL
She has given birth to 5 girls and 5 boys, I am one
------------------------------------------------
"Cotton Fields" Creedence Clearwater Revival

When I was a little bitty baby
My mama would rock me in the cradle,
In them old cotton fields back home;

It was down in Louisiana,
Just about a mile from Texarkana,
In them old cotton fields back home.

Oh, when them cotton bolls get rotten
You can't pick very much cotton,
In them old cotton fields back home.
-------------------------------------------------
http://www.creedence-online.net/
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Old 7th December 2002, 01:36 AM   #5
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Default Re: Musical notes or Frequencies

Quote:
Originally posted by halojoy
According to what I read and publish in "Least offensive crossover" there is no such thing as musical notes.
ooooooooooookaaaaaay...

I wasn't implying that I thought certain frequencies are more "musical" sounding than others.

I just thought it would be "convienient" to have the frequencies fall on a standard scale, so that I could identify certain notes as "the lowest note of a piano" or "the lowest note of a double bass".

I was not implying that our mothers skeletal womb music wasn't some good tunes to listen to...


P.S. Before I was born, I was annoyed by a 12db peak at 3kHz in womb gain. I had to rearrange the placenta in order to construct a diy bass trap. The womb treatments made for a more enjoyable pre-birth skeletal listening session.
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Old 7th December 2002, 04:04 AM   #6
halojoy is offline halojoy  Sweden
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Quote:
My mom says I'm a catch!!!
What is a catch?
Are you contagious?
Can't catch you.

Did you see the piano scale I had posted?
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Old 7th December 2002, 06:06 AM   #7
hifiZen is offline hifiZen  Canada
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This may be of interest to you:

S. Linkwitz's tone-burst test CD page
Publications Page - search for the word "burst" on this page, and you'll find a couple of paragraphs with some sound files and other goodies.
System Testing Page - towards the bottom of this page, you'll find an interesting explanation of the tone burst signal.
Site Index - This index shows all the pages and files on the site... which could be useful for you.

These signals are quite useful for testing speakers and room acoustics.
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Old 7th December 2002, 01:23 PM   #8
dhaen is offline dhaen  Europe
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Quote:
Does anyone know what level (-db) I should record the steady tones at?
I have a European professional test CD in front of me.
The octave and spot frequencies are recorded at -14dB FS.
0dB FS is only used for checking "headroom".

NB
Test CD's from other parts may be recorded at -12dB FS.
It really won't make much difference which is used.
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Old 15th May 2005, 10:37 PM   #9
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I was looking for "test cd sine noise" on the forum, to see what I should include in the Test CD I'm going to make with the SPLmeter I bought a few days ago, and this old thread is what came up.

Here are some ideas I have come up with. (I have a sine generator, and I can also make white noise with that. I just haven't figured out how to get pink noise yet.)

If anyone has ideas for the implementation of my suggestions, or some additional test signals, please feel free to help:

Should be on CD:

--> CALIBRATION:
- 50Hz tone for 2.83 Volt at speaker. (Most accurate freq on Multimeter.)
- 60Hz tone (idem above, but for US.)
- 1000Hz tone (is usually ref. freq. for distortion and dB measurement.)


--> TONAL TESTS:
- white noise
- pink noise
- *two possibilities*:
- 1/3 octave pink noise at various freq. -- OR --
- 80Hz - 8000Hz sinewaves in steps of 3Hz [mains/sattelites], and 10Hz - 80Hz sinewaves in steps of 2Hz [subwoofer/room gain]

(for SPL and freq. curve measurement)


--> RESONANCE, DISTORTION & BANDWIDTH TESTS:
- slow sweep from 20Hz-20000Hz (exite room modes - intermit/bleep each octave for reference.)
- slow subwoofer sweep from 10Hz-80Hz.(intermit each octave for reference.)
- HF sweep from 20000Hz - 8000Hz (intermit/bleep each octave for reference. -- hearing test?)
- 2nd harmonic distort. test (1sec 40Hz - 1sec 20Hz - 40Hz - 20Hz - 40Hz - 20Hz)
- 2nd harmonic distort. test (1sec 60Hz - 1sec 30Hz - 60Hz - 30Hz - 60Hz - 30Hz)
- Various bursts as discribed on Linkwitz-Riley's web page.
- Square waves at most common X-over frequencies. (Only usefull for oscilloscope )


--> IMAGING TESTS:
- Stereo pink noise
- Mono pink noise
- out-of-phase pink noise

--> DYNAMIC RANGE TEST:
- white or pink noise @0dB,-3dB,-6dB,-10dB,-12dB,-18dB,-24dB in 3sec interval.
- low level chime ("A small metal chime was recorded at a relatively high initial level and reduced digitally so it peaks at about -40 dBFS. You can leave the system turned up from the previous tracks and hear what your D/A converter does with a delicate acoustic sound at very low levels. [EBM]")
- Ouverture 1812 (cannon fire test. )
- power compression test (pink noise at -10dB for 20 sec to heat up VC, then 1 sec burst at -6dB, at -3dB, at -0dB, then again -3dB and at -6dB. Then 5sec -10dB and 1 sec at 0dB.)


--> VARIA:
- Picket fence test ("A sum of sine waves at all 1/3 octave centers from 20 Hz to 20 kHz, except for omitted 1.25 kHz to 3.15 kHz. It is a severe test for bit-reduced systems (like MP3) since it contains energy spread across the spectrum. [DBH]"
- Multitone test ("An in-band test for high frequency distortion suggested by Robert Cordell and discussed in the 9/81 AES Journal. It comprises three equal amplitude tones at 20.00, 10.05, and 9.00 kHz. The distortion components are at 950 and 1050 Hz. Unlike the CCIR test with 19 and 20 kHz, it allows easy measurement of both even- and odd-order distortion without the use of a spectrum analyzer. The suggested test fixture comprises two 3rd-order low pass filters at 2 kHz followed by a 4th-order bandpass filter centered at 1 kHz, with gain in between each filter pair.
Cordell notes: "Because the test does not resort to unrealistically high rates of change to stress the amplifier under test, good subjective correlation can be expected." [DBH]")

One last word about suggestions: the more "artificial" sounds, the better. I don't want to get into "this piece of music is better recorded than ..." discussions (let alone copyright issues -- classical music is safer for that), and I think distortion is more detectable by ear if your brain is not distracted that much by a melody or instrument. Real music tracks will be used later to fill the CD.
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Old 16th May 2005, 02:30 AM   #10
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Well, a sad time indeed; Halojoy seems to be back. I guess we can all look forward to a future of random ramblings that offer absolutely nothing toward the tasks at hand.
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