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purchased new ht about 3 weeks ago, had been watching lotrfor and tt at about -28 on my bk avr 507. yesterday read a thread about bass reference discs a couple of which were in my collection the haunting, and u-571. i played the scenes mentioned and thought ok that's not bad but nothing spectacular. then i played fotr and for some reason the volume was at -20 and it blew me away. i couldn't believe how good eveything sounded and the sub was vibrating everything. it was just so cool. i was wondering how to know if you are playing a dvd at reference level. i know what reference level is, i just dont know how to tell where i am in relation to it. thanks keith
 

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you have to calibrate your speaker levels with a sound level meter. Discs arent all mastered at the same level, however, so you still occasionally have to adjust up or down depending on what you want. FOTR (non EE) is an example of a dvd with a super-hot mix. It's all relative. Using Avia's test tones I have my processor default to 75 dB at my seating when you turn it on. For most movies that's just fine. That theatrical FOTR at that level is way too loud.


Anyway - get a setup disc like Avia and a sound level meter. If nothing else its necessary to balance all the channels so they are the same volume at your seats, whatever the overall volume level is.
 

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The reference level is 0. This is for all DD and DTS dvd recordings.

In theory all dvd's should sound the same, but to me this is not the case.

Some are louder than others. Also some say that DTS in recorded 3db higher.


If you turn your system up to 0 then you have reached the reference level.

In most cases that will be too loud.


It all depends on the equipment you have. If the processor/amp(s) and

speakers can take it then give it a go.


But don't blow your speaker !

:mad:
 

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Quote:
The reference level is 0.
0 what?


-Jon
 

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Quote:
Originally posted by davefrohnwieser
The reference level is 0....

:mad:
0db :confused: could only be achieved in the vacuum of space. Dolby use 85db weighted pink noise as as reference for theater SPL adjustments.
 

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0dB displayed on your reciever/processor, assuming it displays volume with regard to deviation from reference. Because you say you set it to -20, I believe yours does use such a numbering scheme.


As was mentioned above, you must first calibrate your system. To do so you use a to a test signal of some known volume and adjust your system until it is outputting the expected volume when set to 0dB. Discs vary, but the test signal is usually 85dB, 75dB in some cases. Your equipment will have instructions for how to use it's internal test tone should you not have a test disc (You probably at least have a movie with THX Optimode on it). That will get you close enough. The advantage of a test disc is it will test your entire system, from source to speakers, rather than starting with an unknown signal at the receiver.
 

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Guys,


Remember that "reference level" is not a specific level of sound, but rather a means by which we can match the gains in our system to that which the movie was mixed at. IE that is the level they listened to when they designed the soundtrack. What this requires from the electronics and speakers in terms of power and SPL depend entirely on your room and system layout. By using a -30dB test signal calibrated to 75dB, we know that the maximum recorded signal can be 30dB higher in peak level. Whether or not your system can produce the additional 30dB (equivalent of 1000 times the input power to the speakers) is another question.


Consider this: if your room is not terribly reverberant, and you are ~13' away from your main speakers, you would need a speaker which was ~87dB @ 1W/1m to produce 75dB at your seat with 1W of input power. Unfortunately this means that if your gains are set for reference level and there is a recorded full scale peak, you need 1000W available, presuming zero power compression. In reality it is rare to see levels at more than -3dB from reference, which does cut power requirements in 1/2, but considering common power in home theaters, and speaker sensitivities, it is no wonder most consider reference level "too loud." Finally, consider that if you have a seating distance of 26' you would then quadruple the required power for the same levels.


It is too loud... too loud for their system to cleanly reproduce.
 

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Mark,


Right on, man. Right on.


-Jon
 

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I still don't understand how i calibrate to refernce level, using a sound pressure level meter i recorded 105decibels as the average when watching Blade2 some time ago, but i still don't understand refernce level is there a dummies guide available ?
 

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I think this started as such:


The "reference level" keith jay asked about is the ability to match the volume used when mastering the audio (or a presentation in a "reference" theater or such) to the level used when listening at home. i.e. if I hear an explosition at a theater and measure it as being 75db, how can I ensure that when I listen to the same explosion at home I hear 75db there as well.


The issue has a bit more to it, though, which is good to understand.


Using a test signal (from an audio setup DVD or CD or such) with a known level (say, 75db as is common on some calibration discs, which was specifically and carefully recorded and mastered as such), you'd want to adjust 1) each loudspeaker and 2) your preamp/amp such that the audio heard at your listening spot is at a level of 75db. This is the calibration Mark Seaton spoke of - the idea is that you're taking your entire system into account (CD/DVD player, interconnections, preamp, amp, speakers, room) to ensure that 75db as encoded on the test disc results in a 75db signal at the listening point.


When this is achieved, the volume position of your preamp/amp could be considered the "reference level" for your preamp/amp. It has _nothing_ to do with where your volume knob/level is. I've seen preamps where the level was about -15 degrees from top center. I've seen preamps which said it was at -6db. Does the position/value mean anything? Not really. Is the position significant in that it represents a calibrated state? Yes.


Remember that the preamp/amp are only single components in an audio system (which beings with the recording and mastering of the disc, and ends at your ears) - the number/position of the volume only states the state of calibration to make the preamp/amp fit in with the rest of the chain.


Someone please correct me if I missed something...


:D


-Jon
 

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When this is achieved, the volume position of your preamp/amp could be considered the "reference level" for your preamp/amp. It has _nothing_ to do with where your volume knob/level is.
exactly. someone above mentioned "it's 0 dB" The 0 dB readout on your volume display usually means "zero attenuation of the input signal" but what that translates to in decibels at the listening position depends on many other factors. So calibrate with a meter!
 

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To break it down....


Get an SPL (sound pressure level) meter. Turn on the test tones in your receiver. Most receivers are set so absolute 0 equals 75dB from the test tones, however, some are set so that 0dB is 85. Check your manual. Then play each test tone and set each speaker level accordingly on your receiver until it equals 75dB (or 85). This applies to your sub also.


Now you can use the AVIA disc or VE disc on your DVD player to double check your reciever. On AVIA the tones are 85dB. So if you now set your reciever to 0dB volume you should get a 85dB reading on your SPL meter. If you turn your reciever down to -10dB it should now read 75dB on the meter.


Now to play a DVD at reference (theoretically, as some DVDs differ), set your receiver to "absolute 0". With all speakers and sub going you could get up to ~120dB of bass at reference volumes. Movies like Lords of the Rings, Blade II are incredibly dynamic and have overcooked bass while movies like Star Wars Episode I were recorded a bit lower than reference, and may need to be turned up a bit in order to get the same impact. I typically listen to most of my DVDs at around -9dB...or 9dB below reference. Hope this helps.
 

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Quote:
Originally posted by MaxC
To break it down....


Get an SPL (sound pressure level) meter. Turn on the test tones in your receiver. Most receivers are set so absolute 0 equals 75dB from the test tones, however, some are set so that 0dB is 85. Check your manual. Then play each test tone and set each speaker level accordingly on your receiver until it equals 75dB (or 85). This applies to your sub also.


Now you can use the AVIA disc or VE disc on your DVD player to double check your reciever. On AVIA the tones are 85dB. So if you now set your reciever to 0dB volume you should get a 85dB reading on your SPL meter. If you turn your reciever down to -10dB it should now read 75dB on the meter.


Now to play a DVD at reference (theoretically, as some DVDs differ), set your receiver to "absolute 0". With all speakers and sub going you could get up to ~120dB of bass at reference volumes. Movies like Lords of the Rings, Blade II are incredibly dynamic and have overcooked bass while movies like Star Wars Episode I were recorded a bit lower than reference, and may need to be turned up a bit in order to get the same impact. I typically listen to most of my DVDs at around -9dB...or 9dB below reference. Hope this helps.
How does "dial norm" fit into this? I sometimes see this flash on my receiver's display as a DVD loads up:


dial norm: -4 db


Doesn't that mean that internally, the dolby decoder bumps UP the volume by 4 db, to account for the -4 db the DVD was recorded (relative to reference) as shown by dial norm?


So if you have a receiver with "dial norm" (most THX receivers) -- theoretically it shouldn't matter what level the DVD was recorded, because dial norm corrects for that -- is that right?
 

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Quote:
Originally posted by yubyub
caesar1,


This link might help: http://etvcookbook.org/audio/dialnorm.html


-Jon
Thanks, but that link doesn't really answer my questions regarding the home theater environment. Anyone know?
 

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Quote:
Originally posted by caesar1
How does "dial norm" fit into this? I sometimes see this flash on my receiver's display as a DVD loads up:


dial norm: -4 db


Doesn't that mean that internally, the dolby decoder bumps UP the volume by 4 db, to account for the -4 db the DVD was recorded (relative to reference) as shown by dial norm?


So if you have a receiver with "dial norm" (most THX receivers) -- theoretically it shouldn't matter what level the DVD was recorded, because dial norm corrects for that -- is that right?
Yes and no...


It depends on if you are listening to a track in DTS or DD. Most DD tracks are encoded at the same dialnorm, so if you have this turned on it should adjust for differences in volumes between different movies. However, this will not change DTS movies or incorrect DD movies....and it may not be related to reference if you did not set your levels with AVIA or VE, so just make sure your speakers are level with reguards to each other and listen to what levels you are comfortable with for each movie . :D


This will also depend on what type of DD decoding you are using...I believe. For instance are you listening in DD 5.1, 5.1 EX, THX Ultra2Cinema, THX Ultra2 Music, THX EX?
 

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You can turn off dial norm? I didn't see any way to do that in my receiver (Onkyo TX-SR701). I think it is purely iformational in my case.


Anyway, I believe that my receiver (like many THX Select receivers) does adjust for DTS by automatically applying -4 db attenuation (internally) to any DTS track.


Although it does not say it in the manual (nor do I see dial norm flash on my receiver's disply for DTS DVDs), I noticed that I now play my DTS DVDs at about the same level as my DD 5.1 DVDs.


For example, on my old Onkyo TX-SR700 (which is not THX Select -- and no dial norm) -- I played most DTS DVDs at about 60 -- while I played DD 5.1 at about 63 on my volume display.


With my new Onkyo TX-SR701 (THX Select) -- it seems that I'm able to play all DVDs at virtually the same volume setting on my receiver. Thus, whether DTS or DD 5.1, I put my receiver at about the same volume level. Before, I had to have the volume lower for DTS.


This leads me to think that DTS is automatically adjusted on these receivers. I read in a review that DTS is adjusted on the Onkyo 800 (a THX receiver) -- so it may also happen on the 701.


Anyone notice that Monsters Inc. is recorded really low? I always had to bump that up alot on my old receiver -- now I know why. It shows dial norm as -7 db on my new receiver when I load Monster's Inc. Wonder why that was recorded so low?
 
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