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 <H1>[SC-04-08] About bad frequencies in room calibration (AES-X218,	X219)</H1>
 John Woodgate 
 <A HREF="mailto:sc-04-08%40standards.aes.org?Subject=Re%3A%20%5BSC-04-08%5D%20About%20bad%20frequencies%20in%20room%20calibration%20%28AES-X218%2C%0A%09X219%29&In-Reply-To=%3C48vzVLHZunkRFwrY%40jmwa.demon.co.uk%3E" TITLE="[SC-04-08] About bad frequencies in room calibration (AES-X218,	X219)">jmw at jmwa.demon.co.uk
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 Tue May 14 11:59:53 MDT 2013
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<PRE>In message 
<<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">16B235628D3CC14FB6116D4DD7740604602D5F at server.exchange.local</A>>, dated 
Tue, 14 May 2013, Alberto Pereira <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">alberto.pereira at dms-cinema.com</A>> 
writes:

>I remember when we met in Rome, you said no frequencies would appear in 
>the chain when we calibrate a room (correct me if I'm wrong, I'll be 
>sorry). Is it possible that some inaudible frequencies are amplified 
>and become audible because of some acoustics phenomenon of a particular 
>room ? Some sound systems can induce unwanted harmonics of the original 
>sound, then these harmonics could be amplified in the acoustic chain 
>even if they are inaudible in the begining...
>
>I hope I made myself clear.

I don't think you did, because the responses you received don't seem to 
be quite on the subject you raise. Suppose we have, in a room, a 
loudspeaker reproducing 100 Hz, with some second harmonic distortion at 
200 Hz, at a level of -30 dB relative to the 100 Hz signal. Now the 
room, ***or some object in it*** has a resonance close to 200 Hz. This 
might lift the level of the 200 Hz signal by 10 dB or more (perhaps 
only locally, if due to an object). This *could* happen.

At higher frequencies, the reinforcement of the level of a sound, such 
as an unwanted harmonic, could be much more, but only over a very narrow 
band of frequencies.  The Romans used to embed bottles of different 
sizes in the back walls of their indoor theatres, to boost sound levels 
by acting as arrays of Helmholtz resonators. But they didn't have 
harmonics produced by non-linear sources to worry about.
-- 
OOO - Own Opinions Only. See www.jmwa.demon.co.uk
They took me to a specialist burns unit - and made me learn 'To a haggis'.

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
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 <H1>[SC-04-08] Nonsense</H1>
 John Woodgate 
 <A HREF="mailto:sc-04-08%40standards.aes.org?Subject=Re%3A%20%5BSC-04-08%5D%20Nonsense&In-Reply-To=%3Cr8e3FjHd3nkRFwIQ%40jmwa.demon.co.uk%3E" TITLE="[SC-04-08] Nonsense">jmw at jmwa.demon.co.uk
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 Tue May 14 12:09:33 MDT 2013
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<PRE>In message <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">C8BFD0BF-9548-44DF-BE2A-7FD2FBCE5D7C at taylormadesystem.com</A>>, 
dated Tue, 14 May 2013, Jacques FUCHS TMS 
<<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">jacques.fuchs at taylormadesystem.com</A>> writes:

>this is "just" a confusion between the "X" curve of a B chain in 
>cinemas (ISO 2969 and SMPTE 202) and the "monitor curve" of SPMTE 222 
>for television control and review rooms....

I think that a more detailed explanation would perhaps help to enlighten 
all concerned.
-- 
OOO - Own Opinions Only. See www.jmwa.demon.co.uk
They took me to a specialist burns unit - and made me learn 'To a haggis'.

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
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 <H1>[SC-04-08] Nonsense</H1>
 philip newell 
 <A HREF="mailto:sc-04-08%40standards.aes.org?Subject=Re%3A%20%5BSC-04-08%5D%20Nonsense&In-Reply-To=%3CCAEEhACm-XDp%2BowiWJd10H%2Bb07Runf_arBcMa_o6YtMS2AkNOKw%40mail.gmail.com%3E" TITLE="[SC-04-08] Nonsense">philiprnewell at gmail.com
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 Tue May 14 12:38:45 MDT 2013
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<PRE>Dear John and Jacques,

I was thinking exactly the same thing (as
John), because unless these things are explained fully there is a serious
risk of only adding to the confusion.

Perhaps the little-known SMPTE222 is a
place that we should not go to at the moment. It has already given rise to
some confusion in 'another' corresponding 'B-Chain Group'. It is not really
relevant to this discussion.

Best wishes,

Philip

On 14 May 2013 20:09, John Woodgate <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">jmw at jmwa.demon.co.uk</A>> wrote:

> In message <C8BFD0BF-9548-44DF-BE2A-**<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">7FD2FBCE5D7C at taylormadesystem.</A>**com<<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">C8BFD0BF-9548-44DF-BE2A-7FD2FBCE5D7C at taylormadesystem.com</A>>>,
> dated Tue, 14 May 2013, Jacques FUCHS TMS <jacques.fuchs@**
> taylormadesystem.com <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">jacques.fuchs at taylormadesystem.com</A>>> writes:
>
> this is "just" a confusion between the "X" curve of a B chain in cinemas
>> (ISO 2969 and SMPTE 202) and the "monitor curve" of SPMTE 222 for
>> television control and review rooms....
>>
>
> I think that a more detailed explanation would perhaps help to enlighten
> all concerned.
>
> --
> OOO - Own Opinions Only. See www.jmwa.demon.co.uk
> They took me to a specialist burns unit - and made me learn 'To a haggis'.
>
> John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
> ______________________________**_________________
> SC-04-08 mailing list
> <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">SC-04-08 at standards.aes.org</A>
> <<A HREF="http://standards.aes.org/sc.**cfm?ID=91<http://standards.aes.org/sc.cfm?ID=91">http://standards.aes.org/sc.**cfm?ID=91<http://standards.aes.org/sc.cfm?ID=91</A>>
> >
>
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 <H1>[SC-04-08] Nonsense</H1>
 John Woodgate 
 <A HREF="mailto:sc-04-08%40standards.aes.org?Subject=Re%3A%20%5BSC-04-08%5D%20Nonsense&In-Reply-To=%3CpBwnqkImEpkRFwKL%40jmwa.demon.co.uk%3E" TITLE="[SC-04-08] Nonsense">jmw at jmwa.demon.co.uk
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 Tue May 14 13:31:50 MDT 2013
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<PRE>In message 
<<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">CAEEhACm-XDp+owiWJd10H+b07Runf_arBcMa_o6YtMS2AkNOKw at mail.gmail.com</A>>, 
dated Tue, 14 May 2013, philip newell <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">philiprnewell at gmail.com</A>> writes:

> Perhaps the little-known SMPTE222 is a place that we should not go 
>to at the moment. It has already given rise to some confusion in 
>'another' corresponding 'B-Chain Group'. It is not really relevant to 
>this discussion.

One can argue the other way and say that if 222 could cause confusion, 
its irrelevance should be explained.

Would someone write a short 'tutorial' for SC-04-08 members who are not 
expert in cinema sound and its unique terminology, or point to one in 
AES or on the Web? What is a 'B-chain' and how many links per inch has 
it? If the B-chain has a X-curve, is it a catenary?
-- 
OOO - Own Opinions Only. See www.jmwa.demon.co.uk
They took me to a specialist burns unit - and made me learn 'To a haggis'.

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
</PRE>

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 <H1>[SC-04-08] Nonsense</H1>
 philip newell 
 <A HREF="mailto:sc-04-08%40standards.aes.org?Subject=Re%3A%20%5BSC-04-08%5D%20Nonsense&In-Reply-To=%3CCAEEhACnnAqdSUktkimMXAw-NC4ddYVKWcne2VeBkTE0SMBWFow%40mail.gmail.com%3E" TITLE="[SC-04-08] Nonsense">philiprnewell at gmail.com
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 Tue May 14 13:46:36 MDT 2013
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<PRE>Dear John,

Perhaps a background document/article explaining the status
quo. This could then be used as a discussion document.

If it would be useful and allowable, I could send a paper
that I co-wrote for the London AES convention in May 2011, outlining what
we saw as the principal questions relating to the current situation.

Best wishes,

Philip

On 14 May 2013 21:31, John Woodgate <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">jmw at jmwa.demon.co.uk</A>> wrote:

> In message <CAEEhACm-XDp+owiWJd10H+**b07Runf_arBcMa_o6YtMS2AkNOKw@**
> mail.gmail.com<CAEEhACm-XDp%2BowiWJd10H%<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">2Bb07Runf_arBcMa_o6YtMS2AkNOKw at mail.gmail.com</A>>>,
> dated Tue, 14 May 2013, philip newell <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">philiprnewell at gmail.com</A>> writes:
>
> Perhaps the little-known SMPTE222 is a place that we should not go to
>> at the moment. It has already given rise to some confusion in 'another'
>> corresponding 'B-Chain Group'. It is not really relevant to this discussion.
>>
>
> One can argue the other way and say that if 222 could cause confusion, its
> irrelevance should be explained.
>
> Would someone write a short 'tutorial' for SC-04-08 members who are not
> expert in cinema sound and its unique terminology, or point to one in AES
> or on the Web? What is a 'B-chain' and how many links per inch has it? If
> the B-chain has a X-curve, is it a catenary?
>
> --
> OOO - Own Opinions Only. See www.jmwa.demon.co.uk
> They took me to a specialist burns unit - and made me learn 'To a haggis'.
>
> John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
> ______________________________**_________________
> SC-04-08 mailing list
> <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">SC-04-08 at standards.aes.org</A>
> <<A HREF="http://standards.aes.org/sc.**cfm?ID=91<http://standards.aes.org/sc.cfm?ID=91">http://standards.aes.org/sc.**cfm?ID=91<http://standards.aes.org/sc.cfm?ID=91</A>>
> >
>
</PRE>

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 <H1>[SC-04-08] Nonsense</H1>
 david murphy 
 <A HREF="mailto:sc-04-08%40standards.aes.org?Subject=Re%3A%20%5BSC-04-08%5D%20Nonsense&In-Reply-To=%3CDC98EF6CF2F08F40AA5AA23B3509EDA971160E0F8D%40KRIX-DC.Krix.local%3E" TITLE="[SC-04-08] Nonsense">dmurphy at krix.com.au
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 Tue May 14 17:17:20 MDT 2013
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<PRE>Hi John,
All,
In the good ol' days when everything came for the film, the film image was projected through the lens, etc, and after a short interval the film was passed through an optical head which scanned the variable area stripes alongside the images to get analogue sound track(s) [for the new fangled stereo!). Further developments occurred when some (mono) surround information was encoded into the stereo tracks, and even two surround channels was possible using analogue encoding. After conversion from a variable light signal to a variable electrical signal we have 'audio', and after amplification it is fed to a master volume control. This in effect is the start of the B Chain. Usually there are basic bass and treble tone controls and a 1/3 octave graphic equaliser included in the B Chain, either before or immediately afterwards the master volume control.

Tradition has it that this master volume control is set to '7', so that in a calibrated cinema, the audience will hear the same SPLs etc as the original mixing people.

Then came the digital revolution! The method which won commercial acceptance was devised by Dolby. It used the area between the sprocket holes of the film to imprint a checkerboard pattern. The checkerboard contained multi channel sound and extra digital information for error correction etc. A new optical read head was required to scan the checkerboard, decode the digital patterns and turn it into multi channel digital sound. The CP650 accepts analogue and digital audio signals from the film, and has a fault tolerant system whereby if the digital audio fails, it reverts to analogue multi channel, then analogue stereo, then analogue mono, and as a last resort the by pass audio is used. This important function is across the top of the block diagram, being the bypass fader and by pass output level. In case the system falls over or fails, you can still get (mono) audio through the by pass circuitry and into the centre channel and keep the audience happy.

Depending on the internal details of the processor, there was then EQ and a master volume control (either analogue or digital) and that is the start of the B chain. It is placed towards the top right hand corner of the (hopefully) attached block diagram.
Real life is not quite as simple as that. There are a variety of input sources, capability for two projectors, etc. Some of the audio inputs are called 'non sync', industry terminology for not_from_the_film. This is used for back ground music before the film starts, and/or voice overs for the advertising slide show which usually occurs before the projectors roll. 
Anyway, if the attached jpeg gets through the AESSC upload system, it will repay a bit of study.

The situation is simplified a little for an all digital cinema. In effect the projector output is multi channel AES-EBU data, which is still fed though a master volume control. 
Also in the B chain system are, for _each_ channel there are basic treble and bass tone controls and a 1/3 octave graphic equaliser.

Anyway, I hope this contribution sheds a bit of light on cinema audio practice.
Best regards
David

-----Original Message-----
From: <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">sc-04-08-bounces at standards.aes.org</A> [mailto:<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">sc-04-08-bounces at standards.aes.org</A>] On Behalf Of John Woodgate
Sent: Wednesday, 15 May 2013 5:02 AM
To: Working group on Measurement and equalization of sound systems in rooms
Subject: Re: [SC-04-08] Nonsense

In message 
<<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">CAEEhACm-XDp+owiWJd10H+b07Runf_arBcMa_o6YtMS2AkNOKw at mail.gmail.com</A>>, 
dated Tue, 14 May 2013, philip newell <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">philiprnewell at gmail.com</A>> writes:

> Perhaps the little-known SMPTE222 is a place that we should not go 
>to at the moment. It has already given rise to some confusion in 
>'another' corresponding 'B-Chain Group'. It is not really relevant to 
>this discussion.

One can argue the other way and say that if 222 could cause confusion, 
its irrelevance should be explained.

Would someone write a short 'tutorial' for SC-04-08 members who are not 
expert in cinema sound and its unique terminology, or point to one in 
AES or on the Web? What is a 'B-chain' and how many links per inch has 
it? If the B-chain has a X-curve, is it a catenary?
-- 
OOO - Own Opinions Only. See www.jmwa.demon.co.uk
They took me to a specialist burns unit - and made me learn 'To a haggis'.

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
_______________________________________________
SC-04-08 mailing list
<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">SC-04-08 at standards.aes.org</A>
<<A HREF="http://standards.aes.org/sc.cfm?ID=91">http://standards.aes.org/sc.cfm?ID=91</A>>
</PRE>

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 <H1>[SC-04-08] Nonsense</H1>
 John Woodgate 
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 Wed May 15 01:49:22 MDT 2013
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<PRE>In message 
<<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">DC98EF6CF2F08F40AA5AA23B3509EDA971160E0F8D at KRIX-DC.Krix.local</A>>, dated 
Wed, 15 May 2013, david murphy <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">dmurphy at krix.com.au</A>> writes:

>Anyway, if the attached jpeg gets through the AESSC upload system, it 
>will repay a bit of study.

No attachments do that. You must upload your graphics to the Documents 
page for SC-04-08 on the AESSC web site.

Thank you for the information. Having 'tone controls' in a system makes 
a nonsense of having a 'standard gain control setting' and expecting 
that to set 'loudness'.

I would like to see:

- Why is it called 'B-chain'?

- What is an 'X-curve', and why?

- explanations of probably a number of other terms peculiar to cinema 
sound.

-- 
OOO - Own Opinions Only. See www.jmwa.demon.co.uk
They took me to a specialist burns unit - and made me learn 'To a haggis'.

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
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 <H1>[SC-04-08] B-chain definition</H1>
 Mark Yonge 
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 Wed May 15 04:11:08 MDT 2013
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<PRE>Dear John, and SC-04-08,

I have posted, courtesy of SMPTE, a copy of the current ST202 standard that is the basis of our AES-X215 project, "Liaison with SMPTE project to codify current procedures to calibrate the Cinema B-Chain"

The document is on the SC-04-08 document site and has the filename:
x215-smpte-st0202-130403.pdf

This document, like all the documents posted to the document site, is for AES standards committee use only and may not be distributed further.

A direct login is available at:
<A HREF="https://secure.aes.org/standards/documents/?ID=91">https://secure.aes.org/standards/documents/?ID=91</A>

In ST202, a reference cinema audio chain is is defined in two parts in clauses 4.4, 4.5, and figure 2.

The A-chain comprises the various playback devices.

The B-chain comprises source selection, fader (level control), room equalization, crossovers, power amplifiers, speakers, and auditorium acoustics.

The fader (level control) exists primarily to handle program transitions and is expected to be set to a calibrated position giving a standard sound-pressure level during film playback. Fader calibration is not included in ST202.

The term "X-curve" is defined in clause 4.9 and subsequently - it is the main focus of ST202.

Calibration of the electroacoustic response to produce the X-curve, as I discussed during the Rome meeting, is made using fairly conventional tone controls for overall shape, and third-octave equalizers for more detailed trim. These are not intended to be adjusted arbitrarily like the tone controls on a hifi system. So far as I am aware, there is no prescription for the type of equaliser to be used in this application: modern implementations may have evolved smarter equalization techniques than simple cut or boost in third-octave bands.

Regards,

Mark

On 2013-05-15, at 08:49, John Woodgate wrote:

> In message <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">DC98EF6CF2F08F40AA5AA23B3509EDA971160E0F8D at KRIX-DC.Krix.local</A>>, dated Wed, 15 May 2013, david murphy <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">dmurphy at krix.com.au</A>> writes:
> 
>> Anyway, if the attached jpeg gets through the AESSC upload system, it will repay a bit of study.
> 
> No attachments do that. You must upload your graphics to the Documents page for SC-04-08 on the AESSC web site.The typical cinema audio path is defined
> 
> Thank you for the information. Having 'tone controls' in a system makes a nonsense of having a 'standard gain control setting' and expecting that to set 'loudness'.
> 
> I would like to see:
> 
> - Why is it called 'B-chain'?
> 
> - What is an 'X-curve', and why?
> 
> - explanations of probably a number of other terms peculiar to cinema sound.
> 
> -- 
> OOO - Own Opinions Only. See www.jmwa.demon.co.uk
> They took me to a specialist burns unit - and made me learn 'To a haggis'.
> 
> John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
> _______________________________________________
> SC-04-08 mailing list
> <A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">SC-04-08 at standards.aes.org</A>
> <<A HREF="http://standards.aes.org/sc.cfm?ID=91">http://standards.aes.org/sc.cfm?ID=91</A>>

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 <H1>[SC-04-08] Nonsense</H1>
 Gunter Oehme 
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 Wed May 15 02:30:44 MDT 2013
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<PRE>Hi all,

I seems that the X curve is something like a red rag to a bull thing.
Perhaps we better should sort out what the problem is and how to improve it:
the current measurement method, the target curve or the human factors.

First observation: The idea of cinema standardization always was and
currently is to translate between mixing room and cinema which not
necessarily means that is has to sound identical which might not happen e.g.
due to different speaker quality. It is not really important whether the
achieved response is linear or not, it only should translates. The timbre of
the sound created in the mixing room is an artistic decision and the content
is equalized according to this decision. In fact the intended sound timbre
seems to be different in Europe (e.g. France, Italy and Germany) compared to
the US - voices are expected to sound more bright and direct.

Second observation: At least in Europe the equalization found in many
theatres sucks due to many reasons of bad alignment causing that the
translation to the theatres often does not work out as intended.

Third observation: To my experience the translation between mixing rooms
within the same facility and between different facilities works pretty well.
Again this does not necessarily means that is has to sound identical e.g.
due to different speaker quality. 
The reasons for better translation are that mixing rooms usually are within
the recommendations for RT60 resulting in more similar direct sound level to
total sound level ratios. More advanced people doing the eq for studios and
finally the Dolby consultants ensured that the response complies to the
SMPTE 202 standard. 
Listening the different mixing rooms of the technical tours in Rome to 3
facilities showed pretty much the same timbre of the 2 way JBL 4570 and JBL
4575 installations found there.
Historically the X-curve was created the same response of the screen speaker
compared to a flat monitor in a room of that time. The curve was explained
as result of a level build-up of the reverberant field. The X-curve was
suggested to compensate RTA measurement with steady state pink noise
resulting in flat response.
I am not sure if this ever was the case as only measured that kind of level
build-up in very reverent rooms. In modern mixing room in the RT60 ranges
recommend by SMPTE EG18, Dolby ad THX (they agrees on same RT60 at 500 Hz) I
never measured a level build-up of the reverberant field similar in the
X-curve.

Fourth observation: By the current standards we have a roll-of direct sound
response in the mixing rooms which causes some sort of pre- and de-emphasis
in cinema mixes.
Again it is an artistic decision how much the sound elements are equalized
by listing to the mix in the mixing room.
The RTA measurement was state of the art in the 70s. Today it is outdated
and needs to be replaced as we have better measurement tools and reasonable
eq in the cinema 
Actually I am using time windowed FFT measurement for doing cinema
equalization for about 15 years verifying that the special averaged RTA pink
noise response is reasonable within the X curve tolerance range.

The issue is to improve alignment quality in the field. We should sort out
the aspects and issues involved and work through the issues as a work
program:

Aspect 1: Proper measurement
To my understanding SC 04-08 is about alignment of sound system for
different kind of venues not only bound to cinema application.  
For this purpose standardization of practical far distance response
measurement in the auditorium is required. E.g.:
What are proper time windows to measure direct sound for different frequency
ranges that correlates to human direct sound perception?
What is the impact of diffuse sound for timbre perception? Is there
weighting factor between direct sound and diffuse sound response for timbre
perception?
In modern multiplex cinemas at least in Europe the RT60 is typically much
lesser than the value recommended by SMPTE EG18, Dolby and THX over 125 Hz.
However the RT60 below 125 Hz is much higher than recommended by Dolby and
THX. Due to lacking bass treatment these auditoriums have high bass ratio
values. 
Therefore diffuse sound may have less impact on perceived timbre for higher
frequencies in modern movie theatres compared to other venue types. However
the high bass ratio is an issue for low frequency reproduction and
measurement because there is a build-up in low frequencies.

Aspect 2: Linear curve
How should linear response be defined? 
The difference to music listening at home and music mixing room is a much
higher listening distance. To which extend is the "roll-off" due to air
attenuation at typical humidity expected/compensated? What are the linear
target curves for given distances?

Aspect 3: Cinema target curve
The current multi mic measurement standard should be compared to the new
measurement standard. This should be done for typical mixing room measured
to current standard with several mic positions to determine the typical
current target curve measured with the new measurement process. That is the
target curve which is currently used for content production. A curve similar
to the X curve with some less roll off is expected.
Either this curve is used as target curve for all cinemas. This in fact does
not create any real problem to continue with the current roll off as it is
compensated in the mix as artistic decision.
When changing a linear response this creates a compatibility issue. The
current target needs to be provided for showing existing mixes the theatres
is required. This was done for mono movies when changing to the wider x
curve when introducing cinema sound processors as Academy filter for mono
movies.
The problem is that most of existing sound processors out there do not
provide dual eq features and a lot of processors have been replaced when
changing to digital cinema. So it is not a good timing for changing the
target curve.

Aspect 4: Alignment instructions
For most installers the current procedures suggested by SMPTE 202 are too
complicated, e.g. modification of target curve according to size,
understanding the dos and don'ts of equalization. 
In Europe installers usually have only a short time frame for alignment.
Often only one mic position is used contrary to the current standard. 
This is a human factor problem and I am not too optimistic that the
installer's qualification will improve.
A new standard with too many things to consider for alignment will not be
successful in improving the theatrical alignment quality in the field.
The instructions need to clear, strait forward and easy to follow in order
to change the situation. An automated measurement process could be
implemented to assist the installers perhaps as a realistic approach to
improve the situation.

Best regards,
Gunter

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 <H1>[SC-04-08] B-chain definition</H1>
 John Woodgate 
 <A HREF="mailto:sc-04-08%40standards.aes.org?Subject=Re%3A%20%5BSC-04-08%5D%20B-chain%20definition&In-Reply-To=%3COcD%2BdACqK2kRFw%2BL%40jmwa.demon.co.uk%3E" TITLE="[SC-04-08] B-chain definition">jmw at jmwa.demon.co.uk
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<PRE>In message <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">0DA7A767-9BA5-46BC-AF7B-DE6114954AB7 at aes.org</A>>, dated Wed, 15 
May 2013, Mark Yonge <<A HREF="https://secure.aes.org/mailman/listinfo/sc-04-08">standards at aes.org</A>> writes:

>I have posted, courtesy of SMPTE, a copy of the current ST202 standard 
>that is the basis of our AES-X215 project, "Liaison with SMPTE project 
>to codify current procedures to calibrate the Cinema B-Chain"

Thank you. I am sure this will eliminate much misunderstanding.
-- 
OOO - Own Opinions Only. See www.jmwa.demon.co.uk
They took me to a specialist burns unit - and made me learn 'To a haggis'.

John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK
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