[djh]

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.