decibel level question

[debs67]

Hi!
I'm new here and new to home cinema.
I have a Yamaha RX 650.
I have no problems with the sound.
Why does the decibel/volume indicator on my receiver show the levels at minus?
Is that normal or have I set something wrong?
Thanks,
Debs

 

[Red]

Its Normal

Almost all newer receivers have volume set that way. I've never really had it explained to me but I believe it works like this: Check to see what the number is when you have the volume turned all the way down, e.g. -80. What I think this means is that when you turn the volume up to 0 the receiver is putting out 80db SPL (sound pressure level). So if you have the volume set at -30, it means the receiver is putting out 50db SPL.

Like I said, I've never had it explained but that is the conclusion I came up with. If I'm wrong, someone on the forum will provide the right answer

 

[Leprkon]

Is that normal or have I set something wrong?

I think somewhere along the line (mid eighties), one of the really high-dollar comapnies like McIntosh or somebody did it, and every body else decide it looked cool...

 

[debs67]

Ok! Thanks!
You learn something new everyday!
Debs

 

[mtrycrafts]

Ok! Thanks!
You learn something new everyday!
Debs

It is all referenced to full power, full scale. Hence, anything below is -

 

[warpdrive]

^^ What he said.

0 dB is supposed to be 100% power (assuming with inputs also at 100% level), and everything else is a below that, hence the minus scale

 

[nibhaz]

Different theory

^^ What he said.

0 dB is supposed to be 100% power (assuming with inputs also at 100% level), and everything else is a below that, hence the minus scale

I'm not sure about this...because my receiver will go +18db over the 0db position...how can you go over full power? I've found that with pink noise test tones that 0db on the dial puts out 85db...which happens to be the reference level at which most DVD soundtracks are mastered, so I've always thought that the -(whatever)db was relative to the reference level of 85db...but I could be wrong....logic only goes so far in this hobby

 

[shokhead]

0db i dont think would be full power but maybe reference.

 

[Jimd43]

Debs,

I'm really glad you asked this question. I have been confused about this ever since I bought my receiver. (Yamaha rx v750) It was always my understanding that 0dB would mean no decibel level at all so that any sound one could hear would, by definition, have to be positive.

When my receiver's volume is set on 0dB, its onscreen bar display indicates not quite half volume.

If 0dB is full power, why does the volume continue to increase when I go over 0dB into positive?

 

[Francious70]

0db i dont think would be full power but maybe reference.

This is true. 0dB is their reference level. It should state what the level is in the manual.

Paul

 

[MacManNM]

Usually 0db is 25% of total rated output power. so +3db would be 1/2 power, +6db would be full power. +18 would be clipping, blowing out your speakers, or using your unit as an arc welder.

 

[MasterChief]

Usually 0db is 25% of total rated output power. so +3db would be 1/2 power, +6db would be full power. +18 would be clipping, blowing out your speakers, or using your unit as an arc welder.

lol i guess thats why people ask y u have to turn it up so much. damn i kno 0db is the refrence level but only 25% hmm. no wonder

 

[Buckeyefan 1]

Usually 0db is 25% of total rated output power. so +3db would be 1/2 power, +6db would be full power. +18 would be clipping, blowing out your speakers, or using your unit as an arc welder.

1 word... NICE. Arc welder. My side hurts.

 

[mtrycrafts]

I'm not sure about this...because my receiver will go +18db over the 0db position...how can you go over full power? I've found that with pink noise test tones that 0db on the dial puts out 85db...which happens to be the reference level at which most DVD soundtracks are mastered, so I've always thought that the -(whatever)db was relative to the reference level of 85db...but I could be wrong....logic only goes so far in this hobby

Which test disc? Test discs or for that matter receiver test tones are not recorded at 0dB full scale but at -20 or -30 dB below FS, hence your 85dB spl when the volume control is at 0. That is so a 0dB FS signal will give you 105 dB spl. Your test tone seems to be recorded at -20dBFS.
A +18 is probaly used for vely low level recordings. Certainly not for 0dB FS signals. That will be the end of that tune

 

[mtrycrafts]

0db i dont think would be full power but maybe reference.

Well, it is reference level because calibration test discs and test tones are not recorded at 0dB FS but -20dB or -30dB FS. That way, when your volume control is on 0, you will get full scale, 105 dB spl when a 0dB FS signal is recorded. LFE runs hot by 10dB.

 

[mtrycrafts]

lol i guess thats why people ask y u have to turn it up so much. damn i kno 0db is the refrence level but only 25% hmm. no wonder

Before you accept his explanation, you need to know what happens at 0, reference level, if your master volume control is automatically goes there. The test signals are not recorded at 0dB FS but either -20dB or -30dB FS.
So, at 0, with a 0dB FS signal you would be getting a 105dB spl.

 

[nibhaz]

So is there any chance that my receiver could clip at listening levels below 0db, say at -10 or -5db? Just curious as to how hard I'm pushing things...

Obviously, I'm just looking for some educated speculation...thanks.

 

[MasterChief]

Before you accept his explanation, you need to know what happens at 0, reference level, if your master volume control is automatically goes there. The test signals are not recorded at 0dB FS but either -20dB or -30dB FS.
So, at 0, with a 0dB FS signal you would be getting a 105dB spl.

Indeed, i get it ..

 

[mtrycrafts]

So is there any chance that my receiver could clip at listening levels below 0db, say at -10 or -5db? Just curious as to how hard I'm pushing things...

Obviously, I'm just looking for some educated speculation...thanks.

Might depend on your speaker load, impedance and sensitivity.

 

[nibhaz]

Might depend on your speaker load, impedance and sensitivity.

Here's what I'm working with...

Amplifier Section Onkyo TX-SR800
Power Output* (8 ohm, 20 Hz-20 kHz, FTC)
Front L/R 100 W/Ch
Center 100 W
Surround L/R 100 W/Ch
Surround Back 100 W/Ch (L/R)

B&W 604 S3

Nominal Impedance: 8 ohms (minimum 3 ohms)
Sensitivity: 90dB spl (2.83V 1m)

I'm only asking about driving my front channels in stereo, based on the information provided previously and this information, can a reasonable speculation be made, or is the answer always going to be "it depends?"