why when using a receiver is it "negative decibels"?

as in, when i turn it up, it goes from -65dbs to -30dbs? why do they do this?

0 dB is a reference point.

Go through this thread for a more precise explanation:


http://www.avforums.com/forums/archive/index.php/t-76024.html

im fairly certain that the negative decibels mean that the receiver is that much below its maximum undistorted output. thus, when it is in the positivies it should be distortying slightly.
/recalls good old days of putting the marantz up to +10...

Lots of answers in that thread and the guy at the end finally tries to answer the real question. I love it when that happens, only one guys is paying attention to what was really asked.

The volume control is an attenuator. It reduces volume output from maximum. All volume controls work the same way.

Well, positive decibels would be kind of stupid. Even at the same volume setting, you're going to hear different decibel levels in different rooms, with different speaker combinations, etc. So the negative decibels is just how many decibels below the loudest it can go.
As far as I'm concerned, I don't even look at the numbers when I adjust the volume. Adjust it so you can hear it but not so loud that you'll lose your hearing.

It's - of it's max.

You have to understand the way the engineers think. They say this amp has a dynamic range of say 105dB. Now that 105dB could be starting from 0 or starting from 20...all dynamic range is is the range from teh highest level to the lowest level. so the only way to be truly accurate in what your saying is how many dB short of the max of the unit you are pushing.

Plus if it was in positive, you would have to account for speaker loads,and so on. there are too many variables to getting how many dB your setup would put out than most would care to ever think about.

HRslammR said:

as in, when i turn it up, it goes from -65dbs to -30dbs? why do they do this?

Click to expand...

Sound measurement is based on “quiet” or “quieting”, the measurable point of no noise or “no sound”

Way back in the day that “reference level” or point used to be –100db. As you added sound that number decreased as in –50 was louder then –100. The whole point of it being that a given component turned on but doing nothing that measured –98Db was a pretty good piece of gear. Digital has pushed the numbers at both ends of the spectrum but the way it’s measured has stood the test of time.

That’s a bit over simplified but that’s where the negative numbers come/came from.

Think of it this way, what happens when you connect a CDplayer strait in to an amp with no control?

your going to get MAX output. the Volume knob reduces this output from it's MAX state.