Volume Regulations (1 Viewer)

[Rotard12a]

Not sure if this is the right area to ask this question, but I've got something of a problem.

I'm watching a movie on TBS that has fairly low volume dialog, so I have it turned up quite a bit to hear clearly. The way my receiver displayed it was "-39.0dB". Then I wonder what's on my university's movie channel, so I switch to it. All of the sudden I'm being blasted with the sound of Saturn V Moon Rocket launching at the epitome volume with EXTREME sound distortion. Well, by the time I get to the mute button (different remote), a driver on one of my front towers is blown out.

Afterwards, while still on the same channel, I turned down the volume to where it was coming out of my speakers at a reasonable listening volume and found it was still ultra-distorted. It was so low that when I changed to another channel I could barely even hear anything of the loudest of commercials, and nothing of regular programming. The receiver read -83.0dB.

Naturally, I was pissed so I call up the station coordinator guy at my school. Guess what he says? "Sorry to hear it. Not our problem. Bye."

Ridiculous.

Sorry for the rant. Point is, I'm trying to figure out if there is an FCC rule that states that those kind of absurd volume levels with such high distortion are illegal. It seems like there would have to be SOME kind of volume regulation, to protect people from me having their speakers blown out for no good reason. Does anyone have any idea?

 

[Lew Crippen]

There is no such regulation.

 

[Allan Jayne]

If the sound is distorted even at low volume, the station technician might have overloaded the studio console amp. This can still result in clipping and an overabundance of high frequency content, enough to blow out tweeters.

Unless the station has a spectrum analyzer, the technician may see only correct readings on the audio meters and let the audio be broadcast that way.

If an AM station broadcasts an overabundance of high frequency content, there is a strong likelihood of interference with adjacent channel stations. But TV sound is FM and such interference is less likely.

The louder station may well be the station that is more correct in terms of overall modulation. Some kinds of audio, notably piano music, have such a wide dynamic range that the overall level has to be set lower so the peaks including short percussive transients are reasonably reproduced.

 

[Rotard12a]

That's possible, though it seems unlikely. I've used all kinds of sources with this receiver, but I've never had to turn it anywhere near this low. Or I may be missing your point.

 

[chuckg]

I _always_ lower the volume to near-off before switching channels or inputs. Call me paranoid, but it is a habit learned from years of pro audio "sound reinforcement." Once I was at a theater rehearsal when an incautious audio guy destroyed several thousand dollars worth of equipment. He was, to say the least, chagrined.