[David Hunker]

"Kevin McMurtrie" wrote in message
...

In article ,
"djh" wrote:

I got a Yamaha RX-V750 7.1 AV receiver this past weekend. I have it
configured for 5.1 surround sound and use an over-the-air television
antenna
for viewing local programming (no cable). The audio signal I receive from
NBC fluctuates significantly, this occurs in programs as well as
commercials. An example would be while watching the local news the volume
will be at a normal listening level throughout the entire news cast but
when
the station goes to commercial the sound level drops to a far less audible
level for some of the commercials, not all. When the news resumes the
sound
level returns to normal. It is not limited to commercials only. It drops
the
sound level for certain programs such as The Tonight Show. When I try to
watch The Tonight Show I turn the volume up to a normal listening level
but
the sound has a muffled quality to it. I do not have this problem with
the
other national networks. Although I have noticed some distinct sound
variations on other networks such as background sound is somewhat
diminished during some programming as well as commercials, but certainly
not as pronounced as NBC. I had a Sony 5.1 AV receiver but replaced it
with
the Yamaha but I did not have this sound trouble with the Sony. Am I
missing something in the setup of the receiver? I've followed the setup
guide to balance the speakers using the microphone. I'm using optical
cable
to connect the television to the receiver. Has anyone else run into this
problem? Thank you for any help or advice you might have.

It sounds like Dolby Dialnorm problems with AC-3 decoding. It's a
headroom adjusting hack designed accommodate low and high dynamic range
programs.

A perfect receiver will not fix the problem. Many TV stations don't
pass through the correct Dialnorm value. Even when they are, it's
probably wrong from the program too. The Tonight Show with Jay Leno is
an excellent example of how Dialnorm should not be used. It uses a high
dynamic range profile but it's recorded with a very compressed dynamic
range. In a feeble attempt to create a "live" atmosphere, people mixing
the sound crank up the volume for a moment when they notice that the
crowd is reacting.
--
I will not see posts from Google because I must filter them as spam

Thank you for pointing dialnorm out to me. I found a post at
hometheaterforum.com that described my predicament precisely. My thanks to
Michael Reuben for his insight.
"The theory behind dialnorm is to allow DD signals to be adjusted so that
dialogue is always at a constant level when switching among soundtracks. The
dialnorm setting achieves this by instructing the decoder to raise (or
lower) the overall volume by a set amount. The feature would be useful in
things like TV broadcasts, where it could be applied to maintain a constant
volume across different channels -- if only it were used correctly. But it
almost never is. For example, I receive one cable channel that has a
dialnorm setting of 0 DBFS, because some idiot in the broadcast chain
obviously thinks that's a "neutral" setting, when in fact it drops the DD
volume by 31db (27 more than a typical DVD), which makes it almost
inaudible."
Again, thank you for your time and pointing out this answer for me.