Dolby Level

[dr sound]

posted February 02, 2003 09:34 PM
--------------------------------------------------------------------------------

quote:
--------------------------------------------------------------------------------
Originally posted by dr sound:
SNIP...As for band limited pink, I've been told by a few NOT to use it. What do you think guys? I use the pink source in my Martinsound MultiMax. The Dolby guys who set up my room EQ used that as their source.
--------------------------------------------------------------------------------

There are two important reasons for using bandwidth limited pink noise for mains:

1) You avoid problems from low frequency buildup due to standing waves

2) small movements of the microphone can give different readings if audio above 2K is present

The Dolby DP564 decoder offers both bandwidth-limited and full spectrum pink-noise.

--------------------
KK Proffitt
www.jamsync.com
<font size="2" face="Verdana, Arial">K.K,
I will investgate and post my findings here in the next day. I have a manual that states something different so let me check it out first.

[Aquarius]

Hi everyone !

Sorry to answer this late but I've been on holidays a few days to eaze the pressure from my crowded Metropolis !!!
I've read your posts and add my comments these very next days.
Thanks again to all for your support [img]images/icons/smile.gif[/img]

[KK Proffitt]

Originally posted by dr sound:
posted February 02, 2003 09:34 PM

<blockquote><font size="1" face="Verdana, Arial">quote:<hr /><font size="2" face="Verdana, Arial">

<font size="2" face="Verdana, Arial">K.K,
I will investgate and post my findings here in the next day. I have a manual that states something different so let me check it out first. <hr /></blockquote><font size="2" face="Verdana, Arial">I urge you to look at some of the more historical texts such as those by Thomlinson Holman. I've seen many unfortunate misunderstandings by manual writers for equipment.

BTW, calibrating for a dubbing stage involves different considerations than calibrating for a smaller studio or one with a bass management system. There is no "one size fits all". For instance, applying an X-curve in a situation where a mix is meant for DVD that will be played in home theaters would be ill-advised. In fact, some decoders have "anti-Xcurve" functions for those situations where a large theater mix was simply dumped to DVD.

Just because Dolby cal'd your dubbing stage doesn't mean it's correct for a smaller studio. Not to say that Dolby doesn't know what they're doing...I have friends at Dolby, too. I beta tested the Dolby Sound Tools years ago for Digidesign and wrote the review of the DP562-569 pair for either Surround Pro or Mix (I can't remember which and since we moved all my review copies are still in boxes).

When I designed our bass management system for JamSync, it was the Holman texts that gave the most info about calibration and I'd urge you to check them out.

[dr sound]

Member
Member # 4712

posted February 03, 2003 12:47 AM
--------------------------------------------------------------------------------

quote:
--------------------------------------------------------------------------------
Originally posted by dr sound:
posted February 02, 2003 09:34 PM


quote:
--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

K.K,
I will investgate and post my findings here in the next day. I have a manual that states something different so let me check it out first.
--------------------------------------------------------------------------------

KK responds:
I urge you to look at some of the more historical texts such as those by Thomlinson Holman. I've seen many unfortunate misunderstandings by manual writers for equipment.

BTW, calibrating for a dubbing stage involves different considerations than calibrating for a smaller studio or one with a bass management system. There is no "one size fits all". For instance, applying an X-curve in a situation where a mix is meant for DVD that will be played in home theaters would be ill-advised. In fact, some decoders have "anti-Xcurve" functions for those situations where a large theater mix was simply dumped to DVD.

Just because Dolby cal'd your dubbing stage doesn't mean it's correct for a smaller studio. Not to say that Dolby doesn't know what they're doing...I have friends at Dolby, too. I beta tested the Dolby Sound Tools years ago for Digidesign and wrote the review of the DP562-569 pair for either Surround Pro or Mix (I can't remember which and since we moved all my review copies are still in boxes).

When I designed our bass management system for JamSync, it was the Holman texts that gave the most info about calibration and I'd urge you to check them out.

--------------------
KK Proffitt
www.jamsync.com

dr sound replies:
As stated above when asked about what spl for the room I mentioned 83 and some links . As for my findings as soon I ask a few people, I will report here my findings. Having mixed in a Tom Holman design and calibrated room in Burbank, I can tell you first hand what his room sounds like! My particular setup while larger than most people, is no way as large as those on "the lot" here in town. I mix with the "X" curve, so do most of the rooms that do the major work here. So did the Tom Holman room I worked in. Now with the mid field, or near field monitors that are so prevelent in most of the smaller rooms, they typically don't have any monitor EQ, or even Bass Management! Having sent you, KK, a short section of the manual I quoted and stating I would ask around, please give me a moment to find out to respond to your statements. Trying to give assistance is my only motivation here. Like I stated above, I was told not to do band pass Pink, and then asked "what do you think".
You are correct in stating one size doesn't fit all. Having sat in with Tom Hollman as he played back Laserdisks of a TV show a very good friend of mine mixed,as he tweeked the room AFTER it was EQ'd, I understand quite well it's not cut and dry. Mr. Hollman with his knowledge and his
and his books and tapes are an excellent source for those who do not have a staff engineer who is versed in the art of room tuning. Most of the rooms that I've been in that don't have the "X" or" modified X " have been too bright for my ears. As for not using the X, as stated above, it also is not cut and dried. Since this is a subjective medium, one has many choices on what speaker to use, and where to place them, eq or not, bass manage or not. As for your writtings, I have read and enjoyed them over the years and will look forward to more in the future!
Take Care,

[Aquarius]

Hi Dr Sound aka Marti !

As I said in my previous post, I'm back in the studio, working the damn thing round...and round...and round [img]images/icons/tongue.gif[/img]
Well, today I've tried an alternative method to calibrate my room - using the internal full band Pink noise generator (-20 dB FS) from my Tascam unit - and finally achieved the 85 dB SPL measure on the Radio Shack !
I fed it through the speakers one at a time in the correct position [img]images/icons/wink.gif[/img]
Now I have some other questions for you ;
How does this level interacts with the 192 IIO calibration (-20 dB FS) ?
Do I have to recalibrate my interfaces ?
Sorry for those stupid questions but that's my way to get sure I don't make anymore mistakes...
[img]images/icons/rolleyes.gif[/img]

Thanks in advance

[ODC]

Bump....

[dr sound]

Here it is......
I spent a good part of today investigating the Pink or Narrow Band Pink as a standard calibrating tool for room SPL. I talked with Engineers at the top 5 facilities in town and also Dolby. The score Pink 6 Narrow Band Pink 0.
These people oversee the vast majority of Mix to Picture rooms. Not one uses narrow band Pink. I asked Dolby and they said the reason for narrow band pink is for calibrating "Home Receivers" since the speakers and rooms vary so much. There is a different "X curve " for smaller room called the "modified X". It goes out appr. 1 k more than the "X curve" then it decreases 1 1/2 db per octave instead of 2db. It is more for small mixing environments. So people there you have it. Set your room up for -20 at 0= 85 or 83 or. . . I won't get into calibrating your 888's or 192 I/O's. Once again I'm using my background in Post as an example. Use the guidelines in some of the links that I put out above to check your levels. Now, back to mixing at 83, 80 or whatever works best for you all! [img]images/icons/grin.gif[/img]

[KK Proffitt]

Originally posted by dr sound:
Here it is......
I spent a good part of today investigating the Pink or Narrow Band Pink as a standard calibrating tool for room SPL. I talked with Engineers at the top 5 facilities in town and also Dolby. The score Pink 6 Narrow Band Pink 0.
These people oversee the vast majority of Mix to Picture rooms. Not one uses narrow band Pink. I asked Dolby and they said the reason for narrow band pink is for calibrating "Home Receivers" since the speakers and rooms vary so much. There is a different "X curve " for smaller room called the "modified X". It goes out appr. 1 k more than the "X curve" then it decreases 1 1/2 db per octave instead of 2db. It is more for small mixing environments. So people there you have it. Set your room up for -20 at 0= 85 or 83 or. . . I won't get into calibrating your 888's or 192 I/O's. Once again I'm using my background in Post as an example. Use the guidelines in some of the links that I put out above to check your levels. Now, back to mixing at 83, 80 or whatever works best for you all! [img]images/icons/grin.gif[/img]

<font size="2" face="Verdana, Arial">And the speakers and room sizes don't vary for PT mix rooms? A vast majority of the PT mix rooms today are not dubbing stages. They don't use a multiple array of microphones where the signal is averaged because you have to cover such a wide area.

A LOT of PT mix rooms are the size of typical home theaters. They use bass management because they need the ability to move subs around to compensate for room modes. It is this size studio that benefits from bandwidth-limited -20dBFSrms pink noise for setup.

In fact, to give them the same technology for setup as a large environment leads them into an area of imprecise measurement. Many, many of them will use Radio Shack SPL meters for setup. Many of them will simply slam any noise labeled as "pink" through the system, not caring if it is RMS cal'd or not and that begins the long slide down into recordings that do not translate well into other environments.

For that matter, the "big guys" don't seem to be perfection, either. There is wide variance among current releases vis a vis their program levels. Among certain circles "Die Another Day" is known as "Die Another Eardrum".

In any event, my interest in the more than a decade I've been using PT is for small studios who are technologically savvy. We're seeing a lot of them spring up, not only for mixing but for composing in surround to picture. The days where the mega studios ruled are really over. Many of them can't pay off their SSL's.

The PM3 spec addresses this situation, as do several of the manufacturers who now address smaller rooms. I'd caution anyone who is attempting to set up a studio in an environment that is not a dubbing stage to do their homework and learn about the technical basis for measurement in different spaces with different tools. It isn't simple and it's not a matter of voting. It's a complex subject and the very basis of calibration is to use the proper calibration signal for the test path.

OTOH, for every poorly setup room, we get proportionally more work for remix and remastering, so perhaps I shouldn't be giving away the store here.

For more info on bandwidth-limited pink noise, check out

http://www.digido.com/index/pmodule_...der_page_id=59

Appendix 2, the section entitled
"Improved measurement accuracy if narrow-band pink noise is used"

Bob Katz includes a concise review of Holman's theories and practices, but it's also a cogent detailing of
how you get from -20dBFSrms to 83 dBSPL. Good for those who shy away from some of the higher math that serves as a basis for these practices.

[Joel Silverman]

Originally posted by dr sound:
Here it is......
I spent a good part of today investigating the Pink or Narrow Band Pink as a standard calibrating tool for room SPL. I talked with Engineers at the top 5 facilities in town and also Dolby. The score Pink 6 Narrow Band Pink 0.
These people oversee the vast majority of Mix to Picture rooms. Not one uses narrow band Pink. I asked Dolby and they said the reason for narrow band pink is for calibrating "Home Receivers" since the speakers and rooms vary so much. There is a different "X curve " for smaller room called the "modified X". It goes out appr. 1 k more than the "X curve" then it decreases 1 1/2 db per octave instead of 2db. It is more for small mixing environments. So people there you have it. Set your room up for -20 at 0= 85 or 83 or. . . I won't get into calibrating your 888's or 192 I/O's. Once again I'm using my background in Post as an example. Use the guidelines in some of the links that I put out above to check your levels. Now, back to mixing at 83, 80 or whatever works best for you all! [img]images/icons/grin.gif[/img]

<font size="2" face="Verdana, Arial">Why continue to debate the facts about filtered noise? KK has given numerous data points. Here are a few more: I quote from Dolby's 5.1-Channel Production Guidelines (http://www.dolby.com/tech/L.mn.0002.5.1guide.pdf)

"3.4.5 Individual Level Calibration

There are typically two types of pink noise available for speaker/channel calibration:
pink and filtered. For setting relative levels, filtered noise is recommended, as any
room anomalies will not be factored into the level calibration process. For spectral
balance of each channel, pink noise is used with an RTA to adjust the system for
proper frequency response."

Here's another one: I quote from Dolby's DP562 User's Manual (http://www.dolby.com/products/DP562/562_3.pdf) page 26


"There are two settings for test noise in the DP562: “PINK” or “FILTERED.” If no bass
redirection is chosen (“NONE” - default), calibration of the monitoring system should be made
using the “PINK” test noise option. This option uses a full-band pink noise signal.

If a Bass Redirection option other than “NONE” is selected, calibration of your monitoring
system should be made using the “FILTERED” test noise option. This will compensate for the
absence of low frequencies in your main monitoring speakers. These selections can be performed
in the Setup menu. See Section 5.10 for complete instructions."

[dr sound]

KK and Joel,
We disagree, plain and simple. I won't continue here to explain my point. Just a by the way...
I don't mix in a room the size of a football field! The link to the room is
http://www.monkeylandaudio.com/mixingstages.html
I am very aware on the size of the systems and rooms out there. Just trying to do what I love in a town that has been taken over by large corporations. It's very tough out there. That's why I try to assist people here on the DUC with any questions they have on Post. Since I've got 23 plus years invested in it, and it's what I love, it's just not worth getting into a pissing match. Hopefully others here will be helped by you and your knowledge.