Q:What's a real world ref level in home sound (1 Viewer)

[Jack Gilvey]

I just had to experiment. Fwiw,I'm using an Onkyo 575x receiver.
I calibrated to 85db using Avia. This was with my master volume set at "+10", since setting it at "0" didn't leave enough gain in the individual adjustments (only go to "+12") to get to 85db. After calibrating to this level, I found that lowering the master volume to "0", or a 10db decrease in level according to the master display, did indeed result in a 75db reading on the SPL meter for each channel on Avia's tones, or "ref -10db" so they do seem to track quite linearly.
So, now I know where exactly "reference" level is. Like I said, I listen at 10db below this (which is now "0" on my display, although I knew where it was before also). I found it important to know exactly where this "comfort level" is, so I can set it when putting in a movie and know things won't be too loud or too soft.
Interestingly (maybe just to me), playing the Onkyo's internal test tones on the system calibrated to reference (85db with Avia)showed them to be "recorded" approximately 5-6db lower than Avia, and also read slightly different relative channel levels. In addition, the THX Optimode tones on my Phantom Menace DVD read about 5db lower than the Avia tones. So, as with Phil's findings, my internal tones seem to basically jive with the Optimode tones, but not with Avia. In short, when Avia reads 85db, the other sources read about 80db.
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[Edited last by Jack Gilvey on October 25, 2001 at 10:39 AM]

 

[Scott Page]

Ok guys,
I agree digital is digital, but how come calibration via AVIA is different than calibration via the reciever? I have calibrated both ways and they are not the same. Based on what your posts have said, the AVIA test tones are not correct. Note: I do have an optical connection between the DVD player and my Denon.
This is important because the surround channels in particular are way different between the two calibraton methods. Yes I know that AVIA is calibrated to 85db and the Denon to 75db which both are supposed to result in "reference level" peaks of 105db and +10 for LFE.
Is a DVD player truly and perfectly "transparent" as to channel levels?
Are the AVIA test tones incorrect and not true to Dolby levels?

 

[Jeremy Anderson]

I've done this with my Onkyo 595 as well. With Avia, calibrating all channels to 85db and then using internal tones, the internal tones read as 80db left main, 78db center, 80db right main, 78db right surround, 78db left surround, (and here's the shocker) 90db subwoofer. What's up with that?
[Edited last by Jeremy Anderson on October 25, 2001 at 11:11 AM]

 

[Phil Iturralde]

OBI - Your welcome, . . . I've learned so much here from you and all the fine members in HT Forum that to obsorb all this great INFO, at times it becomes necessary to save selected important verified documents for future reference, which is why I had Roger's contributed information on Dolby's vs. DVD test tones.
As for the other following questions by Scott Page & Jeremy Anderson, here's another 'quote' by Roger Dressler, different Receiver, but principle comments apply . . .

Topic: Strange SPL results w/ Denon 5800...
I don't have the AVIA disc on hand, but maybe the test tones are recorded -20dBFS and are supposed to be set for 85dB SPL (THX ref level), whereas the 5800 and other test discs use -30dBFS noise for calibrating at 75 dBSPL (as irt is less jarring on the nerves). Both methods give the same end result. But if you try to use the -20dBFS tones to get a 75dB reading, you will have to reduce the gain of all channels by 10dB, as you did.
This all assumes the AVIA is really 10dB louder. You can easily tell if, when you turned off the internal noise and played the AVIA it sounded twice as loud.
By the way, the reason Dolby requires test tones in decoders is so you don't need to use a test disc to set the levels. Always believe the internal tones if there is any doubt or discrepancy.
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Roger Dressler
Dolby Laboratories

Hope this helps,
Phil
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My HT Enthusiasts Website
[Edited last by Phil Iturralde on October 25, 2001 at 11:23 AM]

 

[Scott Page]

Yes I realize that when calibrating using the Denon, I calibrate to 75, when calibrating using AVIA calibrate to 85 and when using VE, calibrate to 75. All of those should produce the same reference peaks of 105db +115db LFE.
But they don't of course. Ok, I guess there are two schools of thought. I was hoping the Guy Kno (I think that's his name) would be watching and would comment on why the test disks differ. So Dolby says trust the internal tones not the calibration disks.
Ok, I can live with that. I'd just like to know WHY AVIA does not come out the same.
[Edited last by Scott Page on October 25, 2001 at 11:35 AM]

 

[Jack Gilvey]

In short, when Avia reads 85db, the other sources read about 80db.

I'm quoting myself just to follow up. I don't assume that all the tones should read the same, that would depend on their recorded levels, but I did kind of expect them to read 85db or 75db, depending on level (-20, -30), so I'm wondering what I may have gotten wrong.
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[Edited last by Jack Gilvey on October 25, 2001 at 11:39 AM]

 

[Jeremy Anderson]

Well, in my case, I've used both VE and AVIA (VE at 75db and Avia at 85db) and they both match up perfectly at my reference level for all channels.
So at my reference level -- VE reads 75db with all channels, Avia reads 85db with all channels, and internal tones read 80lf/78c/80rf/78rs/78ls/90sub. I don't understand why the internal tones are 5db off from both Avia and VE. I could understand a slight deviation from channel to channel (80 in mains and 78 in center and surrounds) if the internal tones are spectrally different from the VE/Avia tones... but the only way I can account for the +10db difference on the sub tone is that the internal tone generator is using the +10db LFE padding (so people using this tone to calibrate are setting overall bass levels 10db too low).
Maybe Onkyo's internal tones just suck...

 

[Phil Iturralde]

I noted the difference Volume Knob location vs. test sources . . .
Source / Volume Knob Mark** (REF Level 75 dB)
1) Video Essentials / "DOT" between #16 & #12
2) Yamaha Internal Signal / #16
3) THX Optimode / #16
(didn't really use AVIA for Audio Calibration)
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**NOTE: (Yamaha uses a dB Scale Increments)
VOL Marking vs. Clock position (approx.)
# -28 dB = 10 o'clock
# -20 dB = 11 o'clock
# -16 dB = 12 o'clock
# -12 dB = 1 o'clock
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Though the VOL Knob Mark tracks differently between VE vs. Internal/THX, all 5-channel balance are within ±.125 (1/8th) dB from 75 dB.
My listening REF Level, based on 106 dB SPL Fast Peaks, is lower than REF Level . . . for example
1) "Tomorrow Never Dies" / SE = DOT (between 28 & 20)
2) "Star Trek - 1st Contact" = DOT (between 28 & 20)
3) "The Mummy" /UE = DOT (between 28 & 20)
4) "Independence Day"/ SE = #20
5) "Armageddon" / SE = #20
6) "GalaxyQuest" / SE = #20
7) "The Phantom Menace" /SE = #20
Using my Yamaha's/THX REF Calibrate Mark -
1) DVD's #1 to #3 are -8 dB below REF
2) DVD's #4 to #7 are -4 dB below REF
Using VE REF Calibrate Mark -
1) DVD's #1 to #3 are -10 dB below REF
2) DVD's #4 to #7 are -6 dB below REF
Either way, my Listening REF Marks don't vary except by the documented different DVD's listed above, because it's based on my Radio Shack SPL vs. 106 dB fast peaks (hear and feel just right).
So, whenever I sample a brand new DVD, I start @ the DOT (between 28 & 20), and sit back and let the blockbuster movie mayhem, sound impact begin!
Just thought I'd share this,
Phil
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My HT Enthusiasts Website

 

[Guy Kuo]

If you didn't have to account for speaker and room effects on the spectral content, there wouldn't be that odd difference between expected and actual measured levels between one set of test tones to another. The spectral content of the signal is affected by room acoustics and the speakers. Some frequencies get attenuated, others accentuated. If the test tones are not identical in spectral content, you expect some room induced variations. To help reduce this effect, the test tones are normally bandwidth limited to a range which all speakers should perform well. The tones are then set such that their electrical dB level are appropriate, but once you play them in a room, things get thrown off several dB by the acoustics. That's why internal and external tones often don't align exactly with each other even if you know they are the same level or 10 dB apart. The measured results are usually a little off the predictions unless you have perfect acoustics.
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Guy Kuo
Link Removed
Ovation Software, the Home of AVIA DVD

 

[Jack Gilvey]

Just ran Avia and the internal tones again, very carefully.
While Avia reads 85db, I'm still getting 77-79 db readings from the internal tones, which should apparently read 75db (?)if I'm at reference. Oy.
Edit: Just read Guy's post. I thought spectral content could explain some difference, I just didn't think that much. How do we decide which to go with, then, if we wish to have true reference?
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[Edited last by Jack Gilvey on October 25, 2001 at 12:23 PM]

 

[Scott Page]

There he is! Hi Guy. Sorry I got your last name wrong.
As there is no objective way to tell by playing a movie,I guess I may just have to calibrate both ways and see which I think sound more natural.
But not having great confidence in my ears I wish someone could just say with conviction; calibrate using XXXX as it will provide a more accuate presentation of what the DVD sound engineers intend.
Can I rent a Hollywood sound engineer? Only need em for a couple of hours. Any sound engineers watching? If so, how do YOU calibrate your home theater equipment?

 

[Scott Page]

Jack,
I got simular results with my Denon if I remember correctly. About 3-5 dbs difference. The AVIA tones seem hot compared to the internal Denon tones. When I calibrated with the Denon (following an AVIA calibration) my wife commented that the impact was gone. So AVIA seems hot.
In any case actually listening at refenence levels is generally uncomfortable with all except dialog only type movies. I like it about 5 dbs down with DD movies and down a little more with DTS movies which seem louder by 3 to 5 dbs.

 

[Rick Radford]

I find this thread interesting, I really do.
I wish there was a way to reconcile the differences between Avia, VE and the internal signals.
I've learned new conflicting info.. such as I should be using the internal test tones to calibrate with rather than test DVDs. But all I've read in the various fora tell me to use Avia/VE for speaker level calibrations because that takes into account other aspects of the system such as the DVD player and interconnects.
Apparently, even the experts disagree.
IAC, I'm glad to know the calibration method I use is the same as Guy's (MV@-10 dB and SPLs at 75 dB/Avia).
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--RR
[Edited last by Rick Radford on October 25, 2001 at 01:22 PM]

 

[John Kotches]

Eugene Hsieh said

Hehe, I wish I had the moolah to be such a perfectionist.

So do I Eugene, so do I! I just saw this months Visa bill and it wasn't pretty

Seriously, some of the equipment is on loan so it isn't quite as financially draining as it could be... Of course it'll suck when I have to send it back.
Regards,
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John Kotches
Contributing Writer
Link Removed