why calibrate with a calibration disk vs. receiver's test tones?t (1 Viewer)

[Scott Page]

Allen,

Avia is recorded at 10 db's "louder" than VE and most receiver tones. Therefore, you calibrate to 85 and not 75, however, both should "theoreticaly" result in the same output levels when playing a movie.

 

[Vince Maskeeper]

Isn't 75 db (bot 85) reference level?

Ref level is not "75 db". If it was 75db peak, you would be struggling to hear the sound at all.
Dolby defines ref level as 105db PEAK of SPL from any single speaker (115db PEAK from the sub)-- as measured at the listening position.
So how do you know if peak level is 105? Well, you could take a DVD that has a tone that is LOUD AS POSSIBLE (this loud as possible level is encoded, in the digital world as 0db)... this tone encoded at 0db would then be played back to your speakers and you turn them up till they measure 105db on a SPL meter.
But that would be painful. Sustained tone of 105db would be enough to make you sell all your HT gear!
So, calibration discs like Video Essentials, instead, provide a tone that is 30 steps below the loudest possible tone (in the digital world known as -30db or -30dbfs)... If you play that tone back and remember that it is actually 30db below maximum, you can use a meter to set your system 30 steps below maximum: 75db
105db max minus 30db steps below max = 75db. If you set your stsem with this -30 VE tone, and it measures 75, then when you get maximum output it is 105!
The 75db number is only relative because the tones on VE are 30 steps below the maximum level. It has no other real meaning, so when people refer to it as "75db ref level", this is false-- and when people (like Mike Knapp for example) go into a mixing studio and ask to hear 75 db level- they are referring to a ref point specific to VE tones- and the engineer will have no clue what you mean.
The Avia tones, for example, use the same idea- only their tones are set 20 steps below the maximum (-20dbfs). So the max is supposed to be 105, minus 20 steps, is 85. So if you use AVIA they want you to set your levels to 85. This doesn't mean it will be LOUDER than it was with VE- they should be right about the same... all that is happening is Avia's tone are encoded at a higher level and thus will measure at a higher level (85db spl) on a properly calibrated system.
So, If you get a calibration DVD like Video Essentials or Avia:
On VE if you use their calibration tones, and set it so that every channel measures 75 on the meter- that is dolby ref level.
On AVIA if you use their calibration tones, and set it so that every channel measures 85 on the meter- that is dolby ref level.
You can find more discussion on ref levels here, many might give you new understanding:
http://www.hometheaterforum.com/htfo...threadid=20707
http://www.hometheaterforum.com/htfo...threadid=50867
http://www.hometheaterforum.com/htfo...threadid=38751
http://www.hometheaterforum.com/htfo...threadid=30186
http://www.hometheaterforum.com/htfo...threadid=18703
http://www.hometheaterforum.com/htfo...threadid=18058
http://www.hometheaterforum.com/htfo...d=79788&t=4063
http://www.hometheaterforum.com/htfo...threadid=33208
-Vince

 

[Mike Knapp]

And 2 of 3 of those are stereo 2 channel playback... so speaker balance of 6 channels are somewhat moot

A good processor will allow you to balance each channel seperately, including the left and right mains.

If you have a processor that adjusts the L/R channels as one unit, it is time to look for a new processor.

So....the balance struck by the internal tones is very important. I use the internal tones exclusively.

Your mileage may vary.

Mike

 

[ColinM]

I have a good processor!

 

[James Bergeron]

Hmmmm, makes you wonder what the level is for "The Ultimate DVD, Platinum Edition" I bought this disc for calibrating it has everything BUT no explanation!

It says, adjust all speakers to be the same then starts playing tones, they are LOUD! VERY LOUD! I tried my friends VE disc it was nowhere near as loud as this disc.

Anyone know what it is for this disc?

It's also a stupid disc because it has video adjustments like VE and Avia but they are different and with NO explanation! GRRRRRRRRR.

 

[BruceD]

Mike,

If you have a processor that adjusts the L/R channels as one unit, it is time to look for a new processor.

Ouch!! Not necessarily true, though. If you amp has per channel volume adjustments like many THX certified amps, you can adjust the Left to Right balance there.

 

[Rick Radford]

Here's an interesting (and lengthy) thread that gets into the difference between using a calibration DVD and the receiver's test tones.
Vince, I'm curious as to your thoughts.
BTW, how do you post a link to a thread and get it to go to a specific msg in that thread vs just being a link to the whole thread?

 

[Vince Maskeeper]

BTW, how do you post a link to a thread and get it to go to a specific msg in that thread vs just being a link to the whole thread?

You have to know the post number. For example, a link to this post would be:
http://www.hometheaterforum.com/htfo...979#post488310

 

[Mike Knapp]

Vince,
Any output variance at the processor level would be an exception, not the norm. Perhaps the Onkyo you speak of is incorrect, but that is a design flaw in that particular unit and should not be used as a yardstick with which to judge other processors / receivers.
By using the internal tones (if they are correct as MOST are) you assure a balance between all inputs not just the one in the source device path....wouldnt you agree? (he asks almost knowing the answer already )
Mike

 

[Vince Maskeeper]

By using the internal tones (if they are correct as MOST are) you assure a balance between all inputs not just the one in the source device path....wouldnt you agree? (he asks almost knowing the answer already )

I think you know my opinion on that.
I'm curious where your claims that "most are" correct come from? I can only speak for what I've tested- and the results weren't good.
No offense, but after your story about asking a mix engineer to set the sound "75db level", I take some of your thoughts on calibration and related arts with a small grain of salt
If the tones were right on- then it would be an option to use them, as it would create median level for all modes (not necessarily "correct" for any specific device but a median for all).
However, my findings point to incorrect levels for the internal tones- making such point moot.
Even if the tones were correct- I would probably personally use VE tones as my guideline bacause in my system the only 6 channel source is DVD. I would rather calibrate the rest of the system around the "incorrect" levels of DVD- since this would be the same incorrect levels effecting every disc played.
But again- if you take VE or AVIA and measure the levels at the preamp output with your speaker settings set to neutral- you'll probably find they are identical at the preamp stage across all 6 channels.
-V
PS: Mike, since you're hanging in the newbie area now- you should check out this thread:
http://www.hometheaterforum.com/htfo...threadid=53605
Seems right up your alley.

 

[Rick Radford]

You have to know the post number.

Ok. Now how do I determine the post number?
Thanks.

 

[Brian E]

So do you need Avia? Are the THX tests on a disc like T2: UE not as good or something? If so how? I assume they are since people are paying $30-$50 for Avia. What about the various Ultimate DVD discs (Platinum, Gold, Silver) and the Sound & Vision disc? Are they inferior to Avia? I'm going to buy a disc soon, just want to make sure I get a good one.

 

[Vince Maskeeper]

I'm going to buy a disc soon, just want to make sure I get a good one.

Avia and Video Essentials are both excellent- I usually recommend owning both. AVIA is easier to navigate- but some of VE's test patterns for video I find easier to use, and more accurate. There are pros and cons to either- but the big con is that VE is now "out of print" in preperation of "DIGITAL VIDEO ESSENTIALS" that should be coming in late spring or early summer.
You might check these recent threads:
AVIA vs. VE:
http://www.hometheaterforum.com/htfo...threadid=53557
http://www.hometheaterforum.com/htfo...threadid=18337
http://www.hometheaterforum.com/htfo...threadid=24743
http://www.hometheaterforum.com/htfo...threadid=43911
http://www.hometheaterforum.com/htfo...threadid=35792
http://www.hometheaterforum.com/htfo...threadid=25740
Digital Video Essentials, coming soon:
http://www.hometheaterforum.com/htfo...threadid=17508
http://www.videoessentials.com/dve.htm
http://www.hometheaterforum.com/htfo...threadid=30562
http://www.hometheaterforum.com/htfo...threadid=12200
http://www.hometheaterforum.com/htfo...threadid=15359
http://www.hometheaterforum.com/htfo...threadid=25652
General Avia info:
http://www.hometheaterforum.com/htfo...threadid=28110
http://www.hometheaterforum.com/htfo...threadid=11364

 

[Brian E]

Thanks Vince. I think I'll just get Avia to start off with.

 

[Brian E]

If anyone needs a Sound Meter, the analog one is on sale at Radio Shack for $29.99 right now I just picked one up.

 

[James Zos]

I have also read a post from a Dolby rep. claiming that you should use receiver test tones rather than disc tones...(no, sorry, I don't have a link either, but I think it might have been on another forum. I do remember people getting excited that someone from Dolby was posting). I am NOT saying this is correct--I use a disc--just backing up the other poster who mentioned that he saw this.

I would quibble with you Vince on one point though: having borrowed a friends Avia disc and found it very helpful, I set out to buy my own. The Sound and Vision disc is a much more basic product--but if the speaker balancing tones are just as reliable, then I am happy to have only spent 12 dollars or so, versus the 40 for the Avia disc (I don't use it for video).

The only problem I see is that there was one sonic test on the Avia that I might miss, and that had to do with the way sound traveled from one speaker to another...I think it was helpful to track gaps in the soundfield. Do you have an opinion on the importance of that particular test?

 

[Harry Lincoln]

On the subject of the Ultimate DVD Platinum having no instructions, there is a 'test description' at the bottom of the page for each test, click on this and you will be coached through the tests and given examples of how to use them. I found the instructions to be very good and I had no probs with the disc.

Has anyone compared the Ult DVD plat to either VE or AVIA (do they agree or not?).

Until recently I used an old SPL meter with no C weighting setting, so it was only good for the 5 main speakers, not the subs, I recently picked up a RS meter and ran the calibration again. According to the Ultimate DVD Platinum my sub was running at about 8db too low. I boosted the level to 3db above the mains as the instructions said, and there was that much bass it wasn't funny. Just curious if anyone else has noticed this?

Harry.

 

[ColinM]

Harry - Do you know about the RS meter's compensation chart? When measuring subs, you must add 3-6db's to what you are reading on pink noise. Specifically -
10Hz +20.5
12.5Hz +16.5
16Hz +11.5
20Hz +7.5
25Hz +5
31.5Hz +3
40Hz +2.5
50Hz +1.5
63Hz +1.5
80Hz +1.5
100Hz +2
125Hz +0.5
160Hz -0.5
200Hz -0.5
250Hz +0.5
315Hz -0.5
400Hz 0
500Hz -0.5
630Hz 0
800Hz 0
1KHz 0
1.25Khz 0
1.6KHz -0.5
2Khz -1.5
2.5Khz -1.5
3.15Khz -1.5
4KHz -2
5KHz -2
6.3KHz -2
8KHz -2
10Khz -1
12.5KHz +0.5
16KHz 0
20KHz +1
On my VE sub noise, the needle wavers from 74 to 76 due to the fact that the noise oscillates from deep to deeper, showing the effect of the meter's ability to pick up deep bass.
So if I assume an average (75) I know in reality I'm probably 2 or 4 db's 'hot, since the meter needs correction.
Of course, if you DO know about this, I'll just STFU

- CM

 

[Allan]

This weekend I recalbirated using Avia's test tones. It seemed to me that after doing so, the sound was better. (But then again, maybe I just convinced myself that it should, so it did.)

In any evetn, thanks a lot Vince for all you insight and knowledge on the topic.

Allan

 

[Harry Lincoln]

Colin, I do have the correction values but the sub test signal is white noise, not a sinewave.

Harry.