More Volume

[murphy3414]

So why is it that as the volume knob is turned up the readout decreases? Also, why do some receivers display volume in this way and others display volume from 0 up.

[will1066]

Some go by the system where 0 is your reference level for movies. It's the level established when setting your speaker levels during setup. At 0 on your dial, normal conversation is about 75 dbl. So when your readout is negative, your below reference level and vice versa. When you then turn it up, the numbers appear to be decreasing, but remember you're in negative scale and you're actually ramping up towards "0".

[Chris D]

Dang, somebody beat me to it!

Will's correct, as long as your system has been properly calibrated to produce 75db at your volume level of "0". I much prefer amps/processors that use this scale instead of a unitless volume knob, so that I can set the volume to exactly where I want it to be before even turning on the music.

[Adz]

The processor I now have says that the proper way to callibrate is to adjust all the speakers in the set-up to match the db reading of the left speaker when its set at -0-. So in my case at my listening position, the left speaker reads 79 dBs, so I set all my other speakers to match 79 dBs. The volume control is inactivated during this process. I wondered why this was different than say what the Rotel tells you to do. Any reason for the difference or is it really the same thing?

[will1066]

Your speaker levels are still matched, but you're a bit hot (hahahaha). As long as your speaker levels are matched, you're good to go. When you watch your movies at your "0" reference, it will be 4 db louder than true reference (75 db). So adjust your knob (haha) to -4.

[Andrew Pratt]

The reason for the negative read outs is that its a more accurate representation of what's actually happening. While this might sound confusing its really not when you stop to think about it. Lets think about a very simple seperates system for a moment where we have a 2 channel amplifer, a pair of speakers and a CD player. Now if you connected the CD players line level outputs directly to the amp what would you expect to happen? Obviously you'd get a song being played back very loudly as the amp would be amplifing a high voltage signal. This is actually the "0" mark on the volume display as the signal from the CD player isn't being adjusted at all. Now since most of us couldn't stand listening to it at that volume for very long we need a way to turn down the volume. This is done with our volume control in the pre amp. Its job is to cut the voltage levels from the CD player down to a more reasonable level. So when you listen to music at -20 dB what its telling you is that you've cut the incoming voltage from the CD's players line level outputs by 20 dB. Now you can have positive gains where the signal is actually amplified above the "0" mark but its rare that you'd ever want to do that.

Of course this assumes that you haven't adjusted the over all levels which most of us do when we calibrate the channel levels. When we do that we typically adjust the volumes so that the "0" mark actually is lowered to the reference levels on our calibration DVD's like Avia or Video Essentials. When this is done the "0" mark now represents this reference level and and cuts displayed on the screen are in reference to that level not the incoming voltage.

[Wayne A. Pflughaupt]

The markings on a volume control have nothing to do with SPL (sound pressure level). If you think about it, it would be an impossible task to assign a particular value of dB/SPL to a volume knob, because highly efficient speakers produce more SPL at a given setting than medium-or low-efficiency speakers.

Thus the calibration of the volume knob has nothing to do with volume level. “0dB” at the top of the scale is the reference for the preamp’s maximum output. In other words, the calibration scale is dBv (voltage), not dB SPL.

Thus the simplest terms, the “backwards” scale means “dBv before maximum gain.” This is why the calibration on the volume knob is given as -dB. Voltage can always be given as a negative figure; obviously sound pressure level cannot.

Regards,
Wayne A. Pflughaupt

[Chris D]

Well, not necessarily, Wayne. Pre/pros use positive values, too, with volume. That way, when your system is properly calibrated for your particular room, speakers, equipment, etc, your system puts out reference volumes at "0". At -10db, it will be less, and with +10db, it will be more.

Will, adjust your own knob!

[Wayne A. Pflughaupt]

If I’m not mistaken, receivers and pre-pros with a 0dB reference with (-) and (+) indicators below and above 0dB are THX certified? THX uses a different calibration reference than receivers marked 0dB at wide open.

Regards,
Wayne A. Pflughaupt

[ThomasW]

Pre/pros use positive values, too, with volume

On my Sony TA-E9000ES, '0' dB is full throttle.

[Andrew Pratt]

Its up to the manufacturer to decide how they want to use it. I know Sony uses "0" as its wide open as Thomas points out where others allow for more flexibility (Denon). THX might come into play in some cases but not the one's that I've used/owned. I will say though that I prefer the negative dB scale to the positive integer system that my Rotel uses.

[Chris D]

Okay, with the personal experiences here, my Parasound Halo C1 uses "0" as the reference level, and it goes all the way up to +15db, I think. (I rarely ever even need 0, much less more) It's THX Ultra2.

[purplepeople]

+15dB is not unusual for pro equipment... typicsal for individual channels on a console. It should mean that the internal circuitry has a gain of 15dB over the input level. The pots normally just "fade" the signal out. Even though the Halo is running some kind of PGA or digital pot, the internals of that chip work the same way, with a maximum gain of 15dB over the input level.

It's actually good to work lower than the reference level, since it usually approaches the noise and distortion specs of the component. Remember the days of setting cassette or reel VU levels to peak at +3dB with an RMS signal of around -3dB. Better gear has more headroom and allows higher peaks over zero. If you use that as your "reference" then setting your max variable amp gain to minimize noise and distortion is relatively easy. It really helps to know the sensitivity of the various inputs in relation to the outputs that they are connected to. Source -> preamp -> power amp. Any overdrive will create the nasty clips that can make things sound horrible, or at worst, wreck things.

Wayne is correct that the 0 reference is more about the specific component on which the 0 is marked. The difference we see is often just the -9dB/+4dB standard output signals for consumer vs. pro equipment.

Okay, with the personal experiences here, my Parasound Halo C1 uses "0" as the reference level, and it goes all the way up to +15db, I think. (I rarely ever even need 0, much less more) It's THX Ultra2.

[chefboy1]

I hoping someone can tell me if my dvd is working properly - I just bought The Sound Of Music dvd and had to set the volume on my Yamaha RX-V1400 to -20dB. I'm worried because I watch most dvds around -30dB (and music around -38dB). I also found myself turning up the volume to hear the singing and cranking it down when the orchestra kicks in. I tried the Night Mode, which helped only a little.

[David Meek]

Hi Dave,

No there's nothing to be worried about. You're just seeing all the variations that are out there in the A/V world. DVDs can be recorded at various levels. The difference between dialog and effects or music on a DVD can be very different. Speakers vary in efficiency. Amps vary in output capability. Your room may muffle some frequencies while highlighting others. Room size can be a factor. And to top it off, each and every one of these (and others) combine in an amazing number of ways to produce your audio environment. 8O So no, it doesn't "sound" like there's anything wrong at all.

FYI, what Nightmode does is compress the overall dynamic range of the soundtrack - ie, the loudest passages aren't as loud and the quietest aren't as quiet.

Also, with my Yamaha RX-V1, I listen at about -35 to -30 for most DVDs, but some "require" cranking up to about -25 or so, and that's in a smallish HT room.