D

Dave2121

Audiophyte
Can some techie explain 'Reference Levels' to me please. I have looked on this site and can not find it. I went into a store for a demo of the 4806 and I noticed the display show -15db. The salesperson said it is supposed to be set at 0db - if it was set at 0db, I suspect it would have blown my ears off. At -15db, it was loud enough. Is this 0db setting 'reference level'?

Does this have any bearing on the products sold as 'Reference Series'?

Hope this is not too dumb a question.

Dave
 
GlocksRock

GlocksRock

Audioholic Spartan
It has no bearing on anythign being sold as "reference Series", it has to do with how loud you calibrate the receiver to play. When the receiver is at a -xx db setting, that means the volume is playing at -xx db below reference level. You set the reference level at the volume you desire by adjusting the level of each individual speaker by playing test tones and calibrating using an SPL meter. Generally reference level is set anywhere between 75db and 85db.
 
M

MDS

Audioholic Spartan
GlocksRock has it right but let me further clarify. We really need two different terms: 'reference level' and 'reference volume'.

Reference Level has a well-defined meaning. It is defined by Dolby as 105 dB PEAKS at the listening position for the main channels and 115 dB PEAK for the LFE channel. You calibrate the receiver to achieve that level. The reason you calibrate to 75 dB or 85 dB is because the test tone you use to do the calibration is at either -30 dB (internal receiver tone, DVE calibration disc, THX standard) or at -20 dB (AVIA calibration disc). If eg., you use the receiver's test tone at -30 dB, you would have to calibrate to 75 dB to achieve Dolby Reference Level because 75 + 30 = 105.

Reference Volume (my term) is the number on the receiver's volume dial that achieves Reference Level. By convention, 0 dB on the dial is used because it makes it convenient to tell the level just by looking at the screen. If you calibrate so that 0 dB on the dial is reference level, then -15 dB is 15 dB BELOW reference level. There is no magic to the 0 dB reading - it is just a point near the max range of the volume dial. On receivers that use absolute volume display (0-80 for example), you can of course still calibrate to reference level - the reference volume will just be a positive number (mine happens to be 60).
 
D

Dave2121

Audiophyte
More clarification??

I had to read both 2-3 times - I think I got it, but want to restate please.

Equipment that say 'Reference Series' is only a marketing name - nothing technically referring to 'reference levels' - GOT IT.

When I install the system, I calibrate it to the specified levels MDS mentioned. (I assume all recievers have some sort of calibration control that I can tweek so the meter reads the correct db level.) IF when I do the calibration, my VOLUME control is set to 0db, then 0db is MY reference level. I can then play the sound at any VOLUME I want +/- db from 0db (my reference level). DO I HAVE IT?

NEW QUESTION
Is the reason to calibrate it so that I have 'balanced' sound from all speakers at the listening positon?

This forum is fantastic. Really helping me understand what I am getting into.
 
M

MDS

Audioholic Spartan
Yes, you've got it. It's good to see that you get the concept that it is YOUR reference level. You can choose any level you want and any position on the volume dial (except for those receivers that automatically play the test tone at 0 dB). Dolby Reference Level and 0 dB is just the standard and we all try to use it so we are comparing apples to apples when we say 'I listen at 20 dB below reference'.

The main purpose of calibration is to balance the levels of all the channels and that is more important than any particular SPL.
 
D

Dave2121

Audiophyte
A Big Thank You

G R E A T -
Now it actually makes sense.

Great big sincere thanks

Dave
 
J

Johnd

Audioholic Samurai
Dave2121 said:
Equipment that say 'Reference Series' is only a marketing name - nothing technically referring to 'reference levels' - GOT IT.
Further clarification: reference series usually equates to that manufacturer's best, or at least, their higher end equipment. So it is a comparative term usually, but meaningful only within that manufacturer's scope of offerings (nonetheless a relative term). Paradigm's Reference Series was their best until last year when they came out with their Signature Series. Cheers.
 
G

greenhill

Audioholic Intern
good question Dave.

MDS said:
GlocksRock has it right but let me further clarify. We really need two different terms: 'reference level' and 'reference volume'.

Reference Level has a well-defined meaning. It is defined by Dolby as 105 dB PEAKS at the listening position for the main channels and 115 dB PEAK for the LFE channel. You calibrate the receiver to achieve that level. The reason you calibrate to 75 dB or 85 dB is because the test tone you use to do the calibration is at either -30 dB (internal receiver tone, DVE calibration disc, THX standard) or at -20 dB (AVIA calibration disc). If eg., you use the receiver's test tone at -30 dB, you would have to calibrate to 75 dB to achieve Dolby Reference Level because 75 + 30 = 105.

Reference Volume (my term) is the number on the receiver's volume dial that achieves Reference Level. By convention, 0 dB on the dial is used because it makes it convenient to tell the level just by looking at the screen. If you calibrate so that 0 dB on the dial is reference level, then -15 dB is 15 dB BELOW reference level. There is no magic to the 0 dB reading - it is just a point near the max range of the volume dial. On receivers that use absolute volume display (0-80 for example), you can of course still calibrate to reference level - the reference volume will just be a positive number (mine happens to be 60).
This is a great Explanation MDS.... Thanks, man... I have a Yamaha RX-V757 and recently set my 5.1 set-up to 75 dB using the recievers internal test tones and a RadioShack SPL meter.... I set my volume level to "0" and adjust the individual speaker trims to 75 dB...

I did'nt know that the "pink noise" averages -30 dB below reference and I also did realize that true reference is 105dB peaks for mains..... this is all starting to make a lot of sense!!!!! Thanks again.....

I wander what other Audioholics usually set there volume level for movie listening???..... At reference???? or below?????
I watched the LOTR Fellowship of the Rings recently at about
-17dBs below reference... There is now way I could listen to that movie at reference.... it would just be WAY TOO LOUD!!!!
good question DAVE!
greenhill.
 
M

MDS

Audioholic Spartan
Reference level is way too loud for me too. 60 gives me reference level and I rarely have the volume past 40. I also use compression ('late nite' on the Onkyo). Guess my ears just don't like high volumes anymore. :)

Note that the test tones are not 30 dB below reference. They are 30 dB below 'full scale digital'. Full Scale Digital is 0 dBFS - that is the digital samples are at their maximum. That 0 dB is not to be confused with the 0 dB on the volume display. When the soundtrack has samples at 0 dB and the volume display reads 0 dB, the SPL will be at reference level.
 
G

greenhill

Audioholic Intern
MDS said:
Reference level is way too loud for me too. 60 gives me reference level and I rarely have the volume past 40. I also use compression ('late nite' on the Onkyo). Guess my ears just don't like high volumes anymore. :)

Note that the test tones are not 30 dB below reference. They are 30 dB below 'full scale digital'. Full Scale Digital is 0 dBFS - that is the digital samples are at their maximum. That 0 dB is not to be confused with the 0 dB on the volume display. When the soundtrack has samples at 0 dB and the volume display reads 0 dB, the SPL will be at reference level.
allright, now I'm confused again....thanks, alot! :)

I don't understand Full Scale Digital? I hav'nt heard of this yet? still kinda new here..... How does Full Scale Digital compare to Reference???? or how are they related???? i guess what i did was turned down all the individual speaker levels.... then set my Volume Level to "0" (Yamaha not being an absolute volume machine.) .... then played the internal test tones (pink noise) through each speaker....and using my SPL meter (RS analog) increased each speaker level to 75dBs...(C weight, slow response) ....so "0" on my Recievers display is "my" reference point........Right??????
greenhill
 
M

MDS

Audioholic Spartan
Greenhill, you calibrated correctly to (Dolby) Reference Level.

Remember Dolby Reference Level is 105 dB PEAK. A peak occurs when the digital signal is as high as it can be and that point is known as 0 dBFS (0 dB 'Full Scale'). The test tone you used has an average level of -30 dB or 30 dB below full scale. When you played that tone, you adjusted the channel trims on the receiver until the SPL meter read 75 dB. Thus when playing a signal with an average level of -30 dB, you get 75 dB SPL at the listening position. [Incidentally, the 'standard' (although not universally followed) for dialog level in a movie is -31 dB, which is why I personally prefer to use the receiver internal test tones].

All of this is when the volume display reads 0 dB because that is the point you chose:

When the signal hits a peak (loud music transients, explosions, etc) it will be higher than -30 dB. As the signal gets 'hotter', its digital level gets closer to zero. When it hits 0 dB, you get 75+30=105 dB SPL. Let's say the music of the soundtrack suddenly gets a little louder, but not quite full scale, so the level is now -20 dB - at that point you get 75+10 = 85 dB SPL (the input signal is now 10 dB hotter than the one you used to calibrate). When the soundtrack's average level is around the level of the tone you used, the SPL at your listening position will be around 75 dB.

Play a CD where the average level is MUCH higher than a movie soundtrack (average -10 dB these days) and your SPL will be 125 dB when the music hits 0dB because remember you calibrated with a -30 dB tone and are now playing something that is 20 dB hotter to begin with. That is why you don't have to turn the volume up as much when playing CDs compared to a movie.

One of these days I'm going to take screenshots of the waveform in Sound Forge from various songs on CD so people can better understand all of this junk.


This is why people find digital audio confusing:
0 dB SPL - threshold of hearing; practically silent.
0 dB FS - maximum level of a digital signal.
0 dB relative volume display - arbitrary point near the max range of the volume control, but once calibrated it relates to a specific output SPL given you know the level of the input signal.
0 dB channel level - the point at which the input signal is neither boosted nor attenuated. After calibration, these are rarely zero - they can be either plus or minus - whatever it took to get the output SPL you were looking for on the SPL meter.
0 dB on a fader or mixer -the point at which the input signal is neither boosted nor attenuated.
 
G

greenhill

Audioholic Intern
MDS said:
Greenhill, you calibrated correctly to (Dolby) Reference Level.

Remember Dolby Reference Level is 105 dB PEAK. A peak occurs when the digital signal is as high as it can be and that point is known as 0 dBFS (0 dB 'Full Scale'). The test tone you used has an average level of -30 dB or 30 dB below full scale. When you played that tone, you adjusted the channel trims on the receiver until the SPL meter read 75 dB. Thus when playing a signal with an average level of -30 dB, you get 75 dB SPL at the listening position. [Incidentally, the 'standard' (although not universally followed) for dialog level in a movie is -31 dB, which is why I personally prefer to use the receiver internal test tones].
[/i]
Again, Well explained.... Thank you very much... you made it easy to understand..... this is good stuff!! Ok, Next... regarding your comment on Dialog and Center channel.... why did you say you prefer the internal test tones regarding Dialog level??? Internal test tones as oppose to what???? Avia, DVE??? Should we be calibrating the Center channel on average 1 dB hotter than the rest???? for Dialog purposes??? (to make up for the -31dB standard).......

Also, I wander how I can find out exactly how many dBs below full scale my Yamaha's internal test tones are??? (out of curiosity) We are assuming 30 dBs....... Is that a pretty fare estimate as far as general A/V recievers go???? I suppose they can vary a little.... Contacting Yamaha may be the way to get that info.... Unless there is a listed Spec that i'm not aware of....Probably not that important, however, I love the tweaking process.

Also, out of curiosity.... Is there a DTS Reference level??? different than Dolby Reference Level...

Another Question.... (sorry) Does the Movie Theater industry have a Standard for Speaker settings.... are they playing at "reference"?????

allright, I'll stop.
thanks again.
greenhill.
 
M

MDS

Audioholic Spartan
-31 dB is another Dolby standard for the average level of dialog in a movie. A Dolby Digital bitstream may include a value called 'dialnorm' (for 'dialog normalization'). The value is supposed to indicate how the actual level varies from -31 dB. It's ok for mastering engineers to make the level louder or softer but they are supposed to include a dialnorm value to tell the processor how to adjust the level to match the standard. So, if the actual level is -27 dB, the processor will attenuate the level by 4 dB so it becomes -31 dB to match the standard. I figure since the level of movies is usually around -30 dB (+/-) it is better to use test tones at that level for calibration.

Not that it matters all that much anyway. Dolby Reference Level actually specifies -20 dB as the test signal. -30 dB is a THX standard and as far as I know all receivers, THX certified or not, use that level for the internal test tones. [I suppose the reasoning is that 85 dB is annoying loud and you would have to use that if the test tone were at -20 dB, so they specify -30 dB so you can use 75 dB which isn't quite as annoying. That's just my theory though - there may be an actual technical reason that I am unaware of].

Movie Theaters are supposed to play at Dolby Reference Level, which is why some people say that reference level is the 'level at which it was intended to be heard'. I've never heard of a specific DTS reference level, but I assume it is the same as DD. The delivery format doesn't matter because we are talking about output Sound Pressure Levels.

I personally don't make the center level louder than the other channels, but that is another personal preference thing. There is no right or wrong answer, although if the dialog is hard to understand it is usually a problem with the mix or room acoustics.
 
G

greenhill

Audioholic Intern
MDS said:
-31 dB is another Dolby standard for the average level of dialog in a movie. A Dolby Digital bitstream.....................
Thank You MDS.... my questions are answered. I appreciate your time.
take care.

Dave, thanks for the Thread.

greenhill.
 
D

Dave2121

Audiophyte
No Title

Now after this thread has run it's couse and others asked questions, I do not feel I asked such a stupid question, but I can definitely say there are poeple out there like MDS and others that are doing a great service by being willing to take the time to share.

Thanks
Dave
 
mtrycrafts

mtrycrafts

Audioholic Slumlord
greenhill said:
allright, now I'm confused again....thanks, alot! :)

I don't understand Full Scale Digital? I hav'nt heard of this yet? still kinda new here..... How does Full Scale Digital compare to Reference???? or how are they related???? i guess what i did was turned down all the individual speaker levels.... then set my Volume Level to "0" (Yamaha not being an absolute volume machine.) .... then played the internal test tones (pink noise) through each speaker....and using my SPL meter (RS analog) increased each speaker level to 75dBs...(C weight, slow response) ....so "0" on my Recievers display is "my" reference point........Right??????
greenhill

That is what I was about to mention to your other post; glad I saw this.

0 dB fs is the highest audio signal recorded on a DVD and CD. That is the reference level, max level, and that would equate to 105 dB spl.

Now, you don't use that signal to level match your speakers for obvious reasons. You'd go deaf before you finish calibrating:D or nearly so.

So, on a theater mastering stage, they use a -20dB FS signal, 85 dB spl(105 - 20= 85) to calibrate and do the dialogue. But, this is still too loud for home to calibrate and level match your setup, so most/many test DVD and THX receivers use -30 dB FS signal, 75 dB spl. As MDS explained, when you set the master volume control(THX receivers I know about advances the master volume automatically to 0 when testing engaged) -30dB FS test tone should produce 75 dB spl at the listening position or trim it to achieve it with each channels.

Then, if you are in the mood to experiment, no neighbors to contend with, you can try some movies with the master volume control at 0 but I would slowly advance it towards this 0 as it will be very loud overall. Many listen way less than this level.
 
MACCA350

MACCA350

Audioholic Chief
mtrycrafts wrote:
Then, if you are in the mood to experiment, no neighbors to contend with, you can try some movies with the master volume control at 0 but I would slowly advance it towards this 0 as it will be very loud overall. Many listen way less than this level.
Also listen for clipping or distortion. Depending on room size and equipment used many systems can run out of steam at those levels, the last thing you want to do is pop a driver.

cheers:)
 
S

stanrozenfeld

Audioholic Intern
I have a question too.

I am trying to set levels on my player's 5.1 analog out for multichannel music. My subwoofer is set at thx, and my receiver is at '0', just like when I set receiver's levels. Unfortunately, with my player's subwoofer levels, I can do no better than 67db, so I trimmed the rest of the channels by 8 or 9 db to make it even. I compensate for lower levels, by turning up receiver's volume control as necessary.

Is there anything wrong with this option? Can it cause clipping more readily? What about noise floor? I notice that when I turn up the volume without music, the noise floor increases, so if I turn up volume control to compensate for lower levels, will it increase the noise?

Any help or advice is much appreciated,

Thanks,
Stan
 
mtrycrafts

mtrycrafts

Audioholic Slumlord
stanrozenfeld said:
I have a question too.

I am trying to set levels on my player's 5.1 analog out for multichannel music. My subwoofer is set at thx, and my receiver is at '0', just like when I set receiver's levels. Unfortunately, with my player's subwoofer levels, I can do no better than 67db, so I trimmed the rest of the channels by 8 or 9 db to make it even. I compensate for lower levels, by turning up receiver's volume control as necessary.

Is there anything wrong with this option? Can it cause clipping more readily? What about noise floor? I notice that when I turn up the volume without music, the noise floor increases, so if I turn up volume control to compensate for lower levels, will it increase the noise?

Any help or advice is much appreciated,

Thanks,
Stan
Can you increase your sub level? I am thinking that if you can, you may be able to increase it so you don't have to adjust the other channels. This is because when you go back to DD5.1 operation, your levels will be off and will need recalibration. Better to move one, the sub levels around to a known setting than all other channels.
 
MACCA350

MACCA350

Audioholic Chief
stanrozenfeld wrote:
I am trying to set levels on my player's 5.1 analog out for multichannel music. My subwoofer is set at thx, and my receiver is at '0', just like when I set receiver's levels. Unfortunately, with my player's subwoofer levels, I can do no better than 67db, so I trimmed the rest of the channels by 8 or 9 db to make it even. I compensate for lower levels, by turning up receiver's volume control as necessary.
Most Players that have bass management for multichannel music(SACD/DVD-A) have an option to increase the sub level by 10 or 15db(this is on top of any normal adjustment) also many receivers have this for External Inputs. check you players and receivers manual for this option in their bass management, as doing it this way will not effect your other inputs on the receiver.

cheers:)
 
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