Reference level suprise. (1 Viewer)

[Dan Kaps]

Today, I wondered how close to reference volume (75db) my usual movie watching is. On my Outlaw 1050, I usually set my volume to 58 when viewing DD material (53 for DTS). This always seemed to have plenty of impact in my medium sized room and what I consider to be pretty "theater-like".
So, out of curiosity, I got out my VE disc and my sound level meter and checked what reference level read on my dial since I didn't pay attention to the displayed number when I originally calibrated based on 75db. The display read 71! I then checked the actual db level at my normal 58. I was around 55 db, a full 20db short of reference!
Of course my next step was to view a few minutes of TS2 at reference. Holy cow! I was a rock drummer for about 15 years so my tolerance for volume is pretty high I think. My speaks held their own pretty well and didn't sound as strained as I thought they might (NHT 1.5's and AC-1). My sub however, couldn't quite keep up (HSU VTF-2...still an excellent sub mind you). It never clipped or distorted but it got buried here and there.
How many people actually listen at reference levels in the home?

 

[Will Ernst]

From reading a lot of threads on this topic, I think the concept of reference level is misrepresented. I don't think that movie theaters deliver 115dB to the seat. I believe that is what they put out near-field, but due to the large space of the theater, what you hear is a substantially lower. I went to a couple of movies this weekend for the first time in a long time, and I know that it was somewhat lower that what I listen at home. I normally listen between -10dB to -7dB.
But, this is just my observation, so I'm probably wrong

-will
[Edited last by Will Ernst on July 17, 2001 at 09:09 PM]

 

[Jack Gilvey]

I believe it's reference level at the seats. I closed my eyes recently at a boring action flick to concentrate on just how loud it was, because it just didn't seem as loud (whatever that means). After a while, I concluded that it was actually much louder than I listen at home, which is about ref. -10db.
[Edited last by Jack Gilvey on July 17, 2001 at 09:12 PM]

 

[Charbel]

I go to 74/75 on my dial. Whatever that is? I know that does`nt really tell you anything but maybe with this other info... Onkyo 787 (100wpc) Studio 40`s CC and Servo 15 sub. I like to listen pretty loud. Although I don`t have it that loud ALL THE TIME. I wish I could but my neighbors... I`m actually insulating the outside of my house so I can put the sound up without bothering the neighbors.
I`m looking into more power like the Parasound 200+ wpc x5 amp. Can`t wait. btw my hearing is pretty good.

 

[Mario_C]

I like listening to ref levels during the dialoge, but as soon as the action starts I back down to 5 to 10 decibles.
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[DanG]

The 75db figure represents the THX reference level which will produce a maximum SPL of 110dB during DVD playback. As others posting to this thread for movies I am -10 to -15 db down and for music -5db down or 0. Got "Lucky Man" from the DVD-A to clock at 106db, very impressive sounding!
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[Mario_C]

reference level will produce 105dB for the main channels and 115dB for the LFE.
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[Lewis Besze]

The 75db figure represents the THX reference level which will produce a maximum SPL of 110dB during DVD playback

Ok here we go again!
The 75db figure refers actually to the dialog level at reference,so test tones on VE are recorded at -30db.If you add 30 to 75 you get 105.that's exactly the peak level that Dolby and THX advocates from the 5 main speakers.[105db] togheter.The sub gets a 10db boost at the the DD DTS decoding stage so it should kick out 115db at reference level,so now you know why TV advocates about high SPL's at reference level from the sub.All figures should "read" at the main seating position.
FYI Avia uses test tones recorded at -20db which yields the target level of 85db for calibration,but that shouldn't make any difference.[85+20=105,+10=115].
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"You Hungarians always disagree"

 

[Jack Gilvey]

The 75db figure refers actually to the dialog level at reference

Really? I've never heard that.

 

[Will Ernst]

Actually, Charbel's 75 dial reading doesn't mean much of anything other than a benchmark. He's referring to what the volume is set to.
Charbel:
In order to compare volume readings, you'd have to calibrate your speakers to reference level with either Avia or Video Essentials.
Link Removed . I suggest reading through it.
-will
OT:
So the Edit times are displayed on posts finally!

 

[Jay Mitchosky]

I usually listen 5-10db lower than reference. Reference is LOUD!

I am the same. Reference levels are downright scary, and depending on the content can be system threatening (Saving Private Ryan, The Haunting DTS come to mind). Not to mention the potential ear damage from long exposure. But it's fun for kicks once and a while. I find that the "manufactured" soundtracks like Toy Story or Titan A.E. perform best at these volumes as their fidelity is so high.
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--Jay
"No one can hear when you're screaming in digital."
My Home Theatre Pictures...
"You're no mesiah. You're, you're a movie of the week. You're a ... t-shirt, at best."

 

[Mike OConnell]

I have a Denon 5800, Paradigm Reference Series speakers, and a Velo HGS-18 sub. I have not calibrated the sound levels with VE or Avia, but have used the internal tests tones.
That said, for TV viweing, I am usually at - 20 dB to -25 dB on the volume, and for movies, usually at -14 dB to -18 dB on the volume.
I have tried reference level (0 dB on the volume) for brief periods on a few of movies - T2 dts, SPR dd, ID4 dd - and althought I had absolutely no distortion and very clear sound, it was WAY too loud for me in my home. (I have to admit the sound, or rather the feel, of the bass coming from the sub was really an experience).
I have tried to turn the subwoofer volume up instead of the receiver volume to get the same feel during movies, but the sound field just is out of balance and have gone back to the calibrated settings.
I feel that the sound is too loud when I go to movies and sometimes feel like I should be wearing earplugs, but then you could not hear the dialogue very well.
Mike

 

[Vince Maskeeper]

The 75db figure refers actually to the dialog level at reference,so test tones on VE are recorded at -30db.

Well, Lewis is CLOSE to right on this.
I don't know if this is why VE used the 75db point as their specific tone level- I think it was just ease of use (loud enough to be over background noises- quiet enough not to get complaints)...
But, average Dolby level for dialog IS right around -30. Actually- if you use a dolby encoder- it seems to imply that the average level for dialog is EXPECTED to be -26db (or -27, I forget).
The reason I say it IMPLIES that this is the "correct" average level for dialog is if you tell the encoder that your average Dialog level is -26, then it encodes with 0db dialog normalization offset. If you tell it your dialog it -25, then it encodes with an offset of -1 (reducing your -25 to -26)... tell it your avg dialog level is -20, it sets the offset to -6, etc...
So Dolby's dialog norm offset seems to want to stick avg dialog levels right around -26 (or it might be -27, it's been a while since I've had my hands on an encoder).
But, this seems to be a coincidence regarding VE's decision to use -30db level for their calibration tones-- But Lewis is basically right- average dialog level, according to the encoder settings, is intended to hover right around -26db, which would equal 79db in a properly calibrated ref level system.
But again, I think this fact and the choice of -30db calibration tones (thus equalling 75db SPL playback) by VE is simply coincidence. I think they figured -30dbfs was a good level for tones- and so they used -30. I think it's just happenstance that this is around the level dialog playback is supposed to be...
Vincent
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http://www.musicianassist.com
AIM: VinceMaskeeper
"If you want everything to be cheap then you're in the wrong hobby." -Rob Gillespie
Got Remo?
[Edited last by Vince Maskeeper on July 18, 2001 at 03:31 PM]

 

[Lewis Besze]

Vince,
I should have said that Dolby[and THX] advocates that the avarage dialog level is around 75db,hence the -30db test tones that almost all THX certified products use including built in pink noise generators in receivers,and softwares.
DVD spectecular which was a collaboration of Dolby and Delos,also use the same level.VE while isn't THX certied[not with Banned From The Ranch,on the cover],could be using the the same level,by coincidence,but some reason I doubt it.
Also I didn't calculate any of the dialnorm off sets since it seems vary sometimes and it could have very well induce more confusion to the subject.
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"You Hungarians always disagree"

 

[Chip E]

I have all this good equiptment but, i really am clueless how to calibrate any of it.. I do have Avia. Can anyone spell it out for me, lol.. (or direct me somewhere to find out how) My room is small -11'2" X 10'6"
Thanks!
- Chip
Mitsubishi 46807
B&K AVR-307
Dish 6000 HD receiver
Sony S900ES dvd player
Sony M-333ES mega changer
Panny junkbox vcr
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PSB Stratus Silveri main's (gloss black)
PSB Stratus C6i center channel (gloss black)
Infinity QPS1 surround's (changeing to PSB Image 10S's)
SVS 20-39PC
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[Jay Mitchosky]

Chip
If you don't already have one go to Radio Shack and buy a sound pressure level (SPL) meter. It's around $30ish and is among the best HT dollars you'll ever spend. I would also recommend a tripod - it will make your life much easier.
I'm an advocate of first balancing the channel levels using the receiver's internal test tones. The advantage is that it balances the system for your other sources, stereo w/ sub, etc. Once you're done this use Avia to calibrate DD channel levels for your DVD player (more accurate when coming from the source).
Either way the process for the SPL is the same. Make sure you turn the SPL on to the '80' mark on the dial (if I recall - don't have mine handy), set weighting to 'C' and 'Slow'. The meter should be located at the main listening position, tilted slightly forward of vertical. Activate the test tone starting in the front left channel and turn the AVR-307's volume up until the readout indicates -00-. This will be reference in the future, but typically you will play back movies at around -10 as suggested above. You adjust each channel's output so that it reads (in the case of Avia) 85dB, or (in the case of your receiver's tones) 75dB using the channel level settings, not the volume control. Repeat for the other channels. Engage THX mode and do it again - in my experience everything will be the same except the surrounds will need a couple of additional dBs.
Side note: Avia does not include tones for rear surround channels. Your AVR-307's internal tones do (I have to assume). In keeping with my strategy above you can either a) note the difference between the calibrated levels of the different channels from the receiver's test tones vs. Avia, and then add/subtract an average value for the rear surrounds, or b) once you've done the initial Avia calibration connect the rear channels to the side surround outputs and re-run the test tones for just those channels. I'm certain others in the same predicament could offer other suggestions.
Once you have done that you will have a properly balanced system for channel levels. You also need to properly set the delay levels for each channel relative to the mains. Note your average distance to the main speakers. Compare the distance to the center, and average surround distances. Factor in delay at 1ms/foot difference in distance. Some receivers simply ask you to enter the different speaker distances and it calculates the delays automatically - the 307 may work the same way, check your manual. Measure from your ear to the tweeters. I haven't done this in awhile (equipment hasn't moved) so if I've missed something somebody please speak up. While a millisecond here or there may not seem like such a big deal, the end result is that one sound arriving earlier than another (regardless of the margin) will be perceived as louder. If the delays are off than channel balancing won't be as effective as sounds will be arriving at your ear too early or too late.
Finally, the AVR-307 is unique among the current crop of super-receivers in that it allows you to properly adjust crossover points and slopes, as well as equalization for a problem frequency. Search out other 307 users and ask how they have adjusted these settings. You can make a huge difference in performance by defining the best crossover point where frequencies go to either the sub or the speakers, and how sharp/gradual the transition. Plus, if you have a nasty frequency spike at your listening position you can flatten it out for a more balanced sound (and more detailed as it may drown out the surrounding frequencies). The latter adjustment is reasonably easy to identify using your trusty SPL meter, a frequency sweep (series of test tones at different frequencies played back at the same volume), and some graph paper. Measure the output of each frequency at the listening position to graph a response curve and eyeball which frequency is most elevated compared to the others (you can't really fix dips effectively through equalization), how much is it elevated, and how many adjacent frequencies does it cover? That information can be thrown into your receiver and it will attenuate (reduce) the volume of the frequency every time it occurs. Regraph using the sweep, confirm the results, and fine tune. Avia has such a sweep but I think it only runs automatically top to bottom. You need one where you can manually switch from frequency to frequency with enough time to measure the output of each. It seems to me that the 307 offers this capability internally for just such an excercise - again, consult your manual. Remember that they were all recorded at the same level. Any volume differences you here are entirely the result of room interactions.
Good luck.
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--Jay
"No one can hear when you're screaming in digital."
My Home Theatre Pictures...
"You're no mesiah. You're, you're a movie of the week. You're a ... t-shirt, at best."
[Edited last by Jay Mitchosky on July 19, 2001 at 09:01 AM]
[Edited last by Jay Mitchosky on July 19, 2001 at 09:04 AM]

 

[Grady Hollums]

Well I watch all my movies at reference level 75db calibrated using VE and my receiver Kenwood VR-407 is set at -21 sound level.
When I do watch movies I have gotten the sub to reach 114db, and man in my small room it is amazing!
All I have to do to watch a movie is ask my wife's permission and call my up stairs neighbors if they don't mind their floor shaking every now and then during the following 2 hours. (Man, I love my SVS)
I wonder if I should calibrate my receiver to -30 sound level and then use VE and change the individual speaker levels?
Does it matter what the should level(according to the receiver) is at as long as the Radio Shack Sound Level Meter says 75db for speakers and 80db for sub?
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In Him,
GH
My Home
Theater

 

[Stevie B]

Just out of curiosity I wonder if anyone has taken their SPL meter into a theater to see what they are actually delivering to the seats.

 

[Will Ernst]

Just out of curiosity I wonder if anyone has taken their SPL meter into a theater to see what they are actually delivering to the seats.

Yes people have, it was mentioned earlier in this thread even.

-will

 

[Chip E]

Thanks so much Jay... This is just the kind of help i needed. I'll head down to Radio Shack this weekend and pick up an SPL meter and give it a whirl. Thanks again.
- Chip
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