Please explain in english ( 0dbfs )

[noapples]

I don't understand much of this stuff, but I'm trying to learn.

I have a HK135 receiver. I noticed the volume starts at negative. Is 0dbfs the maximum volume playing at full quality the receiver can make? In other words, as it goes beyond 0, the sound should become more distorted,right?

What is 0dbfs equals to in terms of db?~ Maybe this is an incorrect question~ Let's say in a typical 100 watts per channel receiver, would 0dbfs equal to roughly 95-98 db?

Thanks in advance to those who will respond.

 

[mulester7]

I don't understand much of this stuff, but I'm trying to learn.

I have a HK135 receiver. I noticed the volume starts at negative. Is 0dbfs the maximum volume playing at full quality the receiver can make? In other words, as it goes beyond 0, the sound should become more distorted,right?

What is 0dbfs equals to in terms of db?~ Maybe this is an incorrect question~ Let's say in a typical 100 watts per channel receiver, would 0dbfs equal to roughly 95-98 db?

Thanks in advance to those who will respond.

....NoRottonApples, 0 on the volume gain is considered reference level, the level the group actually was, in the studio or onstage....reference level db is, I believe from stuff said here about 75 db at 0....you get 95-98?.....you got some watts hid out?......

 

[agarwalro]

The volume indicated by the receiver is of little importance.

That is because there is no standard scale used by manufacturers to describe volume. For instance, -20dB on a Yamaha receiver is not the same as -20dB on a Denon. In fact, -20dB on a 100 RMS Watts per channel (sometimes called continuous power rating per channel) rated Yamaha receiver will be different from -20dB on a 130 RMS Watts per channel rated Yamaha receiver.

Now factor in the fact that all speakers (even different models from the same manufacturer) have different sensitivity, and now the volume displayed by the receiver is practically meaningless.

But there is a silver lining to the dark cloud. Its called calibration. Say you have calibrated your setup, and your receiver's master volume is at -25dB, and each of your speakers and subwoofers independently are sounding 75dB SPL at the listening position when you play the test tones.

Now you watch a movie and keep the master volume at -25dB, you are listening at reference levels. Assuming your setup is capable of faithfully reproducing the peaks (around 105dB SPL for speakers and 115dB SPL for LFE), you are listening at "DD Reference Level". EDIT: Forgot to metion, these settings pertain to your setup alone. Put your equipment in a larger or smaller room, add an amplifier etc. and the master volume setting on the receiver will be different.

This thread might help.
http://forums.audioholics.com/forums/showthread.php?t=11977

 

[mtrycrafts]

I don't understand much of this stuff, but I'm trying to learn.

I have a HK135 receiver. I noticed the volume starts at negative. Is 0dbfs the maximum volume playing at full quality the receiver can make? In other words, as it goes beyond 0, the sound should become more distorted,right?

What is 0dbfs equals to in terms of db?~ Maybe this is an incorrect question~ Let's say in a typical 100 watts per channel receiver, would 0dbfs equal to roughly 95-98 db?

Thanks in advance to those who will respond.

When you properly calibrate your system to reference level as Agar... mentioned, you should be hearing the sound levels that were used in the mastering stage. That is what is considered 'reference level' going back to the recording reference.

 

[MDS]

Is 0dbfs the maximum volume playing at full quality the receiver can make?

When you write '0 dBFS' you are talking about something a bit different than the 0 dB on the volume scale. 0 dBFS ('full scale') is the maximum sample value that can be stored for a given bit depth.

I always use cd audio to explain because the numbers aren't too huge. CD audio is 16 bits but the most significant bit (msb) is the sign - so there are really only 15 bits for the sample. The maximum negative value you can store in 15 bits is -32768 and the maximum positive value is +32767. A sample value of either -327678 or +32767 is 0 dBFS.

Building on agarwalro's example: If you have calibrated to a known level when the volume dial reads -25 dB, the volume will be 25 dB higher when the digital audio signal is at 0 dbFS (those are peaks and should be few and far between).

0 dBFS for digital audio relates to the 0 dB number on the volume dial in only one way: When you calibrate to reference level and use 0 dB as the reference position on the volume dial, any negative number is x dB below reference level and any positive number is x dB above reference level. As already mentioned, you cannot compare the volume scale from one receiver to another unless both are calibrated to the same level.

 

[tbewick]

0 dBFS is used in digital audio to represent a signal that is at the maximum signal level. dBFS means 'decibel full scale', where 0 is full scale. A decibel is a convenient unit which is used in measuring signal levels. An increase of 4 to 6 dB corresponds to a subjective doubling in volume. Therefore a digital signal of -6 dBFS is half the volume of a signal at 0 dBFS.

There are several measures of volume/signal level which include dBFS, others are measures of changes in voltage in a decibel scale. The indicator on your receiver is most likely the preamp dB change in volts. A change in 1 dB in volts on this scale usually corresponds to a change of 1 dB in sound level.

When deciding what volume to listen to you should set it according to your own personal preferences. If the speakers sound strained or if the woofers are audibly 'bottoming out' then you should reduce the volume level. Reference level does not equal playback level.

 

[Ryan_Lilly]

Ok the most basic explanation.

A volume control does not boost the signal; it attenuates, or limits it. So at zero the volume control lets the maximum signal through to the amp. At zero if you have a 100watt amp, them a full 100watts can be sent to the your speakers. Turn down the volume to a negative number and you get less power.

Essentially when the volume is at zero, it is like hooking you source straight to an amp without a volume, the maximum signal gets through.

 

[tbewick]

Hello Ryan_Lilly,

Are you sure about that? I've heard that it's up to the manufacturers where they set the 0 dbV level or whatever it is. The volume depends on the source you're playing. For example, I've had my Denon receiver (90 watt) up to 16 on the scale when playing a record (phono input), with the maximum level being 18. Other sources are much louder.

 

[MDS]

Essentially when the volume is at zero, it is like hooking you source straight to an amp without a volume, the maximum signal gets through.

Only when 0 is the maximum number on the volume scale. Most receivers nowadays that use the relative volume scale have a max value in the positive range; eg -80 to +10. With such a receiver +10 is the point of zero attenuation - not zero.

The reason this topic is confusing to many is because people confuse 0 db SPL, 0 dbFS, 0 dBV (and others) with 0 on the volume scale. The replies to the original poster have gone off track because he asked about 0 dBFS but the responses are about 0 on the volume scale (which is nothing more than a number between min and max).

 

[jeffsg4mac]

Mule is basically correct. If the receiver in question is THX certified, if you calibrate according to the manufactures instructions, then 0 on the volume knob will be reference level. Meaning that the level will be where the sound engineer intended it to be and there will be enough headroom available for peaks that the signal contains. That is it in a nutshell. Of course, this is also dependent on the size of the room.

 

[MDS]

THX certified or not, you can use any position on the volume scale to be the reference position. Zero is just the convention.

Reference Level has no relation to the level at which the movie or music was recorded as reference level refers to the SPL at the listening position. Likewise, zero on the volume scale is not required for reference level - a receiver that uses the absolute scale can also be calibrated to reference level and zero on that scale is silence.

 

[tbewick]

I read earlier that -25 on the volume scale is equal to Dolby Digital reference level, when 0 is calibrated to 75 dB SPL using test tones. I'm not sure that this is correct. I thought it was 0 itself (is reference level). Listening at this volume has peaks of 105 dB in the full-range channels and 115 dB in the LFE channel. This requires a very high quality system to reproduce these volumes. Also in domestic environments it will probably sound unpleasantly loud. This is why dynamic range compression is useful, as most people don't listen at reference level.

I read somewhere that DTS tracks are 4 dB louder than DD tracks because of DD dialogue normalisation. This is the case unless your receiver corrects this difference. The surest way of making sure that the relative volumes are correct is to run DTS and DD test tones through your receiver.

 

[mtrycrafts]

I read earlier that -25 on the volume scale is equal to Dolby Digital reference level, when 0 is calibrated to 75 dB SPL using test tones. I'm not sure that this is correct. I thought it was 0 itself (is reference level). Listening at this volume has peaks of 105 dB in the full-range channels and 115 dB in the LFE channel. This requires a very high quality system to reproduce these volumes. Also in domestic environments it will probably sound unpleasantly loud. This is why dynamic range compression is useful, as most people don't listen at reference level.

I read somewhere that DTS tracks are 4 dB louder than DD tracks because of DD dialogue normalisation. This is the case unless your receiver corrects this difference. The surest way of making sure that the relative volumes are correct is to run DTS and DD test tones through your receiver.

Your thinking is correct The master volume needs to be set at 0.

 

[tbewick]

Here is a link to the excellent Rane audio site which describes setting your system up and reference volume levels:

http://www.rane.com/note132.html

The reference level is the director's intended volume level but as I said earlier for several reasons this will probably sound too loud at home. The only DVD I've played that sounds enjoyable at close to reference level (i.e. 0 dB full-scale) is Gladiator. Soundtracks are often mixed too loud.

I doubt very much that you can even buy a domestic subwoofer that can reach maximum reference level volumes.