Bosso:

The "pink noise" tone on the Outlaw 950 is the same regardless of speaker setting for the mains, but the subwoofer signal changes depending on the setting of the 950's crossover.

I have output the noise tone of the Outlaw 950, the tone from the Sound & Vision Home Theater Tune Up, and wideband pink noise into my spectrum analyzer so you can see for yourself the frequency distribution of the various signals.

The Outlaw 950 internal test tone: fronts & surround


The Outlaw 950 internal test tone: subwoofer (crossover set to 60Hz)


The Outlaw 950 internal test tone: subwoofer (crossover set to 150Hz)


The Sound & Vision Home Theater Tune-Up


Wideband Pink Noise



As you can see, the tones from the Outlaw 950 and the Sound & Vision disc are heavily biased toward the mid-range frequencies, with very little information in the bass and treble regions, except for the subwoofer test (the low pass of the subwoofer test signal tracks the 950's crossover setting). The wideband pink noise has equal output across the 20Hz to 20Khz band.

You can also see that since the front and surround test tones on the 950 (and all other such pre/pros) cover only a small slice of the audio spectrum (centered at 800Hz), the relative frequency responses of your speakers in this region are very influential on the accuracy of your calibration. If for instance your mains have a hump at the frequency of the test signal, and your surrounds have a dip, the surrounds will end up being set too loud. It is for this reason that to get a really accurate calibration, the use of wideband pink noise is recommended. The "Avia" DVD test disc contains wide band pink noise 5.0 tests for this purpose. Be sure to note that these tones on the Avia disc are recorded at a -20db level rather than the more common -30db, so you need to set your sound level to 85db, rather than 75db SPL.



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The Soundhound Theater


[This message has been edited by soundhound (edited February 26, 2003).]

Soundhound,

Out of curiosity, which spectrum analyzer are you using?

Jeff

It is a software program for Macintosh called "Mac RTA" The sound card is a digidesign Audiomedia.


[This message has been edited by soundhound (edited February 26, 2003).]

Cool beans. I've considered getting a software RTA. Right now, I have the AudioControl one, but obviously, it's not easy to print out copies of the graphs. (I also suspect it's not as tuneable as one implemented in software might be.)

Jeff

The Mac RTA also has an ocilloscope and sound level meter function. It's pretty good, but the program is due for an upgrade. It also has an RPN calculator that allows comparing, adding and subtracting graphs from each other.


[This message has been edited by soundhound (edited February 26, 2003).]

Well, first, I'd probably need a Mac ...

Jeff

My personal habit is to buy fruit from fruit companies, computers from computer companies. YMMV.

TrueRTA is a basic RTA for the PC, and you can get decent MLS stuff from $100 and up.

www.trueaudio.com
www.purebits.com
www.nvo.com

for dispelling dts conspiracy theories:

http://www.wirehedmag.com/archives/00001/sound.html

charlie: as usual the links are right on and appreciated.

Question, does this affect how the 'mix' itself sounds in the final product, - when master volume is less during mixing:

Dolby Digital soundtracks playback several decibals lower than the master volume level due to Dolby’s Dialog Normalization. Therefore, DD is quieter than DTS and the master. So, technically one should be complaining about incorrect master volume level playback on Dolby Digital soundtracks

..or is it just a question of a DD track (if volume is left untouched on your system during playback) being a few dB less than its DTS counterpart?

This is all just AFAIK and etc.....

Dialog normalization is an embedded tag that allows the decoder to 'know' where the level of normal dialog is in a soundtrack. This is helpful when trying to maintain a consistent volume level across a spectrum of different audio programs as well as allowing accurate compression of dynamic range if desired, by allowing sounds louder and quieter than dialog to be compressed to a level nearer the dialog level.

If dial-norm is set correctly all movie (and other programs, such as commercials, etc.) dialog should be at the same level while allowing headroom for loud or quiet passages. In practice a lot of engineers don't set the dial-norm value explicitly in the encoder, so it is generally left in a position (the default value) where the decoder will interpret it as a request to reduce overall gain by 4 db.

So, it is my understanding (possibly all wrong) that it is not the presence of the feature but rather the use (or lack thereof) that causes most DD data streams to be decoded at -4 db.