I found the following quote on another forum and wonder what people here think of it. It was taken from a thread where they were arguing whether it was more accurate to use internal test tones or tones froma disc like Avia....I'm of the school of thought that a test disc such as Avia or VideoEssentials is the best way to calibrate, as it's coming from the exact machine you'll be doing most of your viewing on, i.e. the DVD player!

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That makes perfect sense when the signals are analog. But these test tones are all recorded in Dolby Digital, so they don't exist as PCM until they reach the decoder chip. There's nothing that your DVD player can do to in any way to alter or affect those signal levels. All it can do is not play them, or play them perfectly.

That same chip is where the internal noise is generated, so there's nothing about the external signals that's any better or worse, assuming they have the same frequency spectrum. Some noise signals have a wider bandwidth, like th THX Optimode signals, and these will sound and measure differently in most cases. They will be wrong if they measure differently, because it only means the various speakers are not identical in response.

Dolby makes sure the internal noise is calibrated in level and meets certain spectral requirements.

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Roger Dressler
Dolby Laboratories
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This is contrary to everything I have been told.

Yeah, dosen't really matter where you get your signal from, the internal one, a test DVD, or an actual pink noise generator. It's really the quality of the generator that matters. Like Roger said, the player is in the digital domain, either all or nothing!

Well, maybe it's only a matter of my comfort level, or maybe the interconnects affect it, even optical digital? All I can say is:

First, my channels do NOT balance at the same levels when using the Avia tones that they do when using my receiver's internal test tones.

Second, I tend to trust the Avia tones more. For one theing, because they are coming from the same DVD player that will be sending my movie signals. For another, because I think Avia might have placed just a bit more emphasis on producing accurate tones: after all, it's their job, not just "another circuit we have to include in the receiver at the lowest cost possible."

I would think that if the Avia tones were inaccurate in any way, someone would have caught on by now.

-Bruce

Obviously Mr. Dressler has never been acquainted with the Panny RP-91.

I don´t think there is a right or wrong in this subject.

If you think a test cd with pink noise works better than the internal test, you should use it.

It´s the enviroment in your livingroom that has to be compensated with the test, not the speakers.

And there is´nt any livingroom that look or "sounds" the same.

A test that work perfect for mr.X does´nt necessery work for mr.Y

It´s all comes down to your ears.
After all, you bought the stuff it´s you that should be satisfied with the soundstage.

/Jocke

A thought:
Would it not be logical to expect for brand A to have tones in its tone generator that would show its product in the best lite & leave any short comings in the shadows?? Therefore would it not be best to use another non brand biased tone source?
Dougofthenorth

Someone correct me if I am wrong, but I don't think the Avia test CD useds Pink noise. They use a different signal that is supposed to take room acoustics more into account. That is one of the ways they refute the claims like the one listed in the first thread here.

Actually i never heard of the Avia test CD.
I just assumed that it had a Pink noise track.

Can someone fill us in on this CD?

Thinkly,

You are correct. I'm pasting this from the AVIA FAQ.

Q: "Calibrating my audio system using built-in test signals gives different results from using AVIA's test signals. Why?

A: The acoustic characteristics of rooms and frequency responses of speakers vary. For this reason, AVIA DVD uses an audio test signal with the recommended shape spectral distribution for setting speaker levels. This shaped noise is designed to be minimally affected by the differences between main, center, and surround speakers. Other audio test signals, such as pink noise, don't have the same spectral distribution and consequently result in different speaker level settings."

"Another reason to use AVIA DVD's test signals rather than built-in tones is that doing so checks your entire playback chain from source to speakers. Setting your system to play back AVIA's test signals correctly compensates for variances caused by your playback equipment."

That second paragraph is naturally from a biased source since they want you to buy their DVD, but the logic makes sense to me so I'll go along with it. :)

jocke: The Avia disc is designed to assist the HT owner with optimizing system setup, including calibrating tones for audio and patterns for video. It's actually a DVD rather than a CD. For more details, see http://www.ovationsw.com

This message was edited by Bruce Burson on 12/28/01 05:02.29.