# MCACC and LFE Channel



## pdxrealtor (Jun 30, 2013)

Does anyone know with certainty if MCACC adds in 10 DB to the LFE channel calibration?


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## tonyvdb (Sep 5, 2007)

MCACC does nothing to the LFE channel it has no filters below 63Hz If I am not mistaken.


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## pdxrealtor (Jun 30, 2013)

It would be to the LFE out as a whole, which is the .1 of 5.1,7.1 etc. 

Oddly enough when I run MCACC it does adjust the LFE channel standing wave control. But I digress.... (And you are right, nothing below 63 hz and I haven't figured if that even affecta the LFE channel) 

what I am is asking is if, at all, there is per Dolby specs a 10 DB + added to the LFE. 

You see, I've done the calibration and ran REW.... No +10 to the subs. They match the the full range @75 db. 

I personally match all my speakers to 75 ( per Dolby) after the calibration, which is why I ran REW in the first place....to see where the mcacc cal set things up. 

Im wondering though if the receiver possibly adds 10db only while playing back dolby direct or matrixed material. This would negate the need for me to add the 10 db, or require the meed to take out 10db while play Dolby content. 

So many settings! Lol


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## chashint (Jan 12, 2011)

I have a Pioneer VSX-23, I researched AVRs extensively before the purchase and have read just about every calibration article available.
I have never heard of this 10dB LFE addition prior to your post nor have I observed any evidence of it while using the AVR.
Please provide a link if possible.

Why would you want to be adding 10dB to the LFE?
That would create a huge imbalance in the system


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## tonyvdb (Sep 5, 2007)

I agree, Im not sure I have ever heard that there is a 10db boost that "should" be added to the LFE channel. I know many people like to boost the level about 10db from the mains but it is dependent on many things.


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## pdxrealtor (Jun 30, 2013)

Done a little research- a couple of links below for your reading pleasure.  

Chashint- since you've researched a lot do you happen to know how the Pioneer is supposed to be configured in terms of the LFE and the +10db? 

Here is a Dolby article- http://www.dolby.com/uploadedFiles/Assets/US/Doc/Professional/38_LFE.pdf

Here is a good post on gearslutz- Post 19, (and item 3 in post 19) cleared up (and should clear up more) a lot for me- although I do admit *I haven't gotten to read the link in that section* - http://www.gearslutz.com/board/post...utting-through-lfe-calibration-confusion.html

There is tons of confusion on the internet and one can easily walk away confused if skimming. How do I know you ask?  

So... there is a +10 added to the LFE, the question is how does your receiver request you set it up so that the +10 is handled properly. 

The answer for my Pioneer, I believe is, in the 'auidio parameter > LFE setting. This is discussed on, I think, pg. 70.

It would seem that my Pioneer accounts for, for lack of better words, the +10db LFE added by the makers. Of course when decoding DD or DTS. 

Which now has me asking another question. Does the matrixed sound (DPLX/NEO:X) add the 10db? I'm thinking so..... but have not confirmed. Hmm.


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## selden (Nov 15, 2009)

The 10dB offset that needs to be compensated is in the (.1) LFE channel's audio in a multichannel recording.

Matrixed surround sound does not include a separate LFE channel: it's normally 4 channels total merged into two audio channels: Right Front and Left Front, with Center and Surround matrixed into them.

Therefore a 10dB offset is irrelevant.

The decodings applied by DTS Neo or Dolby Prologic to create more channels from a 7.1 or 5.1 source also have nothing to do with the LFE channel, so, again, a 10dB offset is irrelevant. They process the fronts and side surrounds in arbitrary ways to produce height, width and/or rear surround channels.

(FWIW, my understanding is that DTS neglected to include the 10dB offset in some of their earliest lossy DVD encodings, which is what has caused all the confusion. All modern encodings do include it.)


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## pdxrealtor (Jun 30, 2013)

I read the same thing RE: some early DTS recordings.


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## chashint (Jan 12, 2011)

Well this is kinda interesting.
After perusing the links that were provided my take on this is the 10dB in question is for commercial cinema calibration and 70mm film mastering.
It is doubtful this would filter down to consumer grade media and electronics because consumers have no standard setups and everything has to be designed so it is relatively easy to achieve good results without needing to know anything about standards.

I only have the VSX23 to reference so keep that in mind.
There is no option to add gain to the LFE channel, but there is an option in the Audio Parameters to reduce the LFE channel in 5dB steps to -20dB. The description of this function indicates it is to be used if the .1 track contains frequencies that the speakers are not capable of producing and audible artifacts are being produced.

There are some THX settings that add curve when enabled, but this is for low frequency room gain compensation not boost.

I am not an authority on the standards, and I don't care to become one, but by inference in the Pioneer if the LFE channel requires 10dB of boost it is built into the decoder algorithms and the end user does not need to attempt any additional compensation to account for it.


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