why do amps and stuff have vol in negative db?

[dpopiz]

what does it mean?
I mean that does the negative db number measure?

 

[Trygve]

The dB numbers on the scale represent dB. (Decibels)

Negative numbers are smaller than zero. So, if 0 is the maximum, -12dB is 12 dB less than 0.

(Note that, strictly speaking, dB measures only relative volume on a logarithmic scale. Absolute measurements reference some standard 0, e.g., dBmV represents a logarithmic scale where 0 is one millivolt across a 75 ohm load.)

 

[Joemonkey]

"0 dB is defined as the THRESHOLD OF HEARING, and it is with reference to this internationally agreed upon quantity that decibel measurements are made. In some situations, such as tape recording, a given intensity level is assigned 0 dB, and other levels are measured in negative decibels in comparison to it. "

From here

ain't google grand?

 

[dman]

Nigel Tufnel: The numbers all go to eleven. Look, right across the board, eleven, eleven, eleven and...
Marty DiBergi: Oh, I see. And most amps go up to ten?
Nigel Tufnel: Exactly.
Marty DiBergi: Does that mean it's louder? Is it any louder?
Nigel Tufnel: Well, it's one louder, isn't it? It's not ten. You see, most blokes, you know, will be playing at ten. You're on ten here, all the way up, all the way up, all the way up, you're on ten on your guitar. Where can you go from there? Where?
Marty DiBergi: I don't know.
Nigel Tufnel: Nowhere. Exactly. What we do is, if we need that extra push over the cliff, you know what we do?
Marty DiBergi: Put it up to eleven.
Nigel Tufnel: Eleven. Exactly. One louder.
Marty DiBergi: Why don't you just make ten louder and make ten be the top number and make that a little louder?
Nigel Tufnel: [Pause] These go to eleven.

 

[dpopiz]

Originally posted by: Joemonkey
"0 dB is defined as the THRESHOLD OF HEARING, and it is with reference to this internationally agreed upon quantity that decibel measurements are made. In some situations, such as tape recording, a given intensity level is assigned 0 dB, and other levels are measured in negative decibels in comparison to it. "

From here

ain't google grand?

yeah, so I'm just wondering what the reason is for assigning a certain level to be 0

 

[CptObvious]

Originally posted by: dman

Nigel Tufnel: The numbers all go to eleven. Look, right across the board, eleven, eleven, eleven and...
Marty DiBergi: Oh, I see. And most amps go up to ten?
Nigel Tufnel: Exactly.
Marty DiBergi: Does that mean it's louder? Is it any louder?
Nigel Tufnel: Well, it's one louder, isn't it? It's not ten. You see, most blokes, you know, will be playing at ten. You're on ten here, all the way up, all the way up, all the way up, you're on ten on your guitar. Where can you go from there? Where?
Marty DiBergi: I don't know.
Nigel Tufnel: Nowhere. Exactly. What we do is, if we need that extra push over the cliff, you know what we do?
Marty DiBergi: Put it up to eleven.
Nigel Tufnel: Eleven. Exactly. One louder.
Marty DiBergi: Why don't you just make ten louder and make ten be the top number and make that a little louder?
Nigel Tufnel: [Pause] These go to eleven.

I :heart: Spinal Tap

 

[Trygve]

Originally posted by: dpopiz

yeah, so I'm just wondering what the reason is for assigning a certain level to be 0

It's convenient. For sound waves, it makes some sense for 0dB to be the quietest sound you can hear. For a tape deck, it makes sense to set 0dB to the sound level that will fully saturate the tape formulation. (In some cases where the same deck can handle several different types of tape, like "metal" audio tapes, the 0dB point is not changed to fit the saturation of the medium, but this is still the general idea.) For an amplifier, you might set 0dB to the maximum level the amp can output without clipping (given a full-level input signal), and for a preamp, you might set 0dB to zero gain.

When you design an amplifier or signal processor, you can pick 0dB to be whatever you want.

Why is 0 degrees (F or C) 0 degrees? (That's a rhetorical question; I know the history.) Every unit of measurement is based on some arbitrary standard, except for natural constants like the speed of light or Planck's constant.

 

[Evadman]

Originally posted by: Trygve
Why is 0 degrees (F or C) 0 degrees? (That's a rhetorical question; I know the history.) Every unit of measurement is based on some arbitrary standard, except for natural constants like the speed of light or Planck's constant.

Don't forget 0k

 

[Calin]

If they want to make gradations on the volume button (or dial), then the only way for consistency is to make the measures relative. The dB scale fits. And more, the dB scale is somewhat linear to hearing (it is exponential in fact - 3 dB is about twice the power - but human hearing is also somewhat logarithmic, so it compensate).
The relative scale is used for the wildly different volumes of IN - highly different even from one audio CDto another, not talking about other sources

Calin

 

[memo]

Originally posted by: CptObvious

Originally posted by: dman

Nigel Tufnel: The numbers all go to eleven. Look, right across the board, eleven, eleven, eleven and...
Marty DiBergi: Oh, I see. And most amps go up to ten?
Nigel Tufnel: Exactly.
Marty DiBergi: Does that mean it's louder? Is it any louder?
Nigel Tufnel: Well, it's one louder, isn't it? It's not ten. You see, most blokes, you know, will be playing at ten. You're on ten here, all the way up, all the way up, all the way up, you're on ten on your guitar. Where can you go from there? Where?
Marty DiBergi: I don't know.
Nigel Tufnel: Nowhere. Exactly. What we do is, if we need that extra push over the cliff, you know what we do?
Marty DiBergi: Put it up to eleven.
Nigel Tufnel: Eleven. Exactly. One louder.
Marty DiBergi: Why don't you just make ten louder and make ten be the top number and make that a little louder?
Nigel Tufnel: [Pause] These go to eleven.

I :heart: Spinal Tap

:thumbsup:

 

[Demon-Xanth]

For reference:
In the electronics world, "dB" is gain. +3db==double the power, -3dB=half the power. It's a logrithmic scale.

 

[spidey07]

Originally posted by: dpopiz

Originally posted by: Joemonkey
"0 dB is defined as the THRESHOLD OF HEARING, and it is with reference to this internationally agreed upon quantity that decibel measurements are made. In some situations, such as tape recording, a given intensity level is assigned 0 dB, and other levels are measured in negative decibels in comparison to it. "

From here

ain't google grand?

yeah, so I'm just wondering what the reason is for assigning a certain level to be 0

that is the reference or maximum gain. Hence anything below the reference is (-) db.

For example in home theater gear you can calibrate 0 db on the pre-amp at a reference level of 75 db at listening position. Then when you listen to a movie at 0 db it is how it was mixed in the studio.

 

[Shockwave]

Originally posted by: Calin
If they want to make gradations on the volume button (or dial), then the only way for consistency is to make the measures relative. The dB scale fits. And more, the dB scale is somewhat linear to hearing (it is exponential in fact - 3 dB is about twice the power - but human hearing is also somewhat logarithmic, so it compensate).
The relative scale is used for the wildly different volumes of IN - highly different even from one audio CDto another, not talking about other sources

Calin

3db is twice the power. However, human hearing actually needs about 10 db to be percieved as twice as loud. THus, a true +3db, while twice the power, wont sound twice as loud.

 

[Calin]

Originally posted by: Shockwave

Originally posted by: Calin
If they want to make gradations on the volume button (or dial), then the only way for consistency is to make the measures relative. The dB scale fits. And more, the dB scale is somewhat linear to hearing (it is exponential in fact - 3 dB is about twice the power - but human hearing is also somewhat logarithmic, so it compensate).
The relative scale is used for the wildly different volumes of IN - highly different even from one audio CDto another, not talking about other sources

Calin

3db is twice the power. However, human hearing actually needs about 10 db to be percieved as twice as loud. THus, a true +3db, while twice the power, wont sound twice as loud.

I beg to differ - the human hearing is also logarithmic (while you hear someone's whisper at 5m, 100 persons whispering at 5 m (in a circle around you) won't sound 100 times as loud

Calin

 

[Mallow]

I bet it has to do with the definition of a decible. 0 db does not mean the absence of sound. You can have sound at 0 db. I think it is a relative number; relative to what I don't know.

 

[spidey07]

Originally posted by: Calin

Originally posted by: Shockwave

Originally posted by: Calin
If they want to make gradations on the volume button (or dial), then the only way for consistency is to make the measures relative. The dB scale fits. And more, the dB scale is somewhat linear to hearing (it is exponential in fact - 3 dB is about twice the power - but human hearing is also somewhat logarithmic, so it compensate).
The relative scale is used for the wildly different volumes of IN - highly different even from one audio CDto another, not talking about other sources

Calin

3db is twice the power. However, human hearing actually needs about 10 db to be percieved as twice as loud. THus, a true +3db, while twice the power, wont sound twice as loud.

I beg to differ - the human hearing is also logarithmic (while you hear someone's whisper at 5m, 100 persons whispering at 5 m (in a circle around you) won't sound 100 times as loud

Calin

Has nothing to do with human hearing. sound pressure is measure in decibels which are a log scale.

Mallow - it is relative to a reference volume or full gain.

 

[NightCrawler]

When we use 0 db we mean that is the maximum without distortion. Then the needles go into the red and it starts to distort.

It's the recording level on tape or cd.