# Blu-ray Audio Tracks..



## Prof.

Can someone please explain to me why there are variations in audio quality, when playing different discs that use DTS-HDMA.!!

Case in point...
When I play "Race to Witch Mountain" on DTS-HDMA, I get great dynamic sound with very good bass..
But when I play "Knowing" on DTS-HDMA, there is a total absence of dynamics, but bass is not too bad..
However, If I change to Dolby TRUE HD on that disc..I get incredible dynamics with room shaking bass!!..
The Plane crashing scene just about blows me out of the chair!!:yikes:

Why would there be so much variation? :scratch:
With DVD's that had a DTS sound track, you would always get better dynamic sound than the Dolby track..


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## tonyvdb

Are you sure that Knowing has both DTSMA and TruHD? I dont think so, you either get one or the other. You may be simply using the DTS track and that where the difference may be.
Also some Tru HD audio kick on the nightmode setting on some receivers I would look to see if it does that.


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## Prof.

I should have mentioned Tony that both disc's are UK releases..
"Knowing" on Region B does have both tracks..
"Race to Witch Mountain" just has DTS-HDMA..

Could it be that theses variations only occur with Region B disc's?

Edit..I didn't know that the night mode might be affected with TruHD!.I'll certainly check that..


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## tonyvdb

Hmmm, I dont know. I've never seen both uncompressed formats on on BluRay.


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## Prof.

I have several other region B Blu-ray's that have both formats..
So you don't get a choice with Region A disc's?


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## tonyvdb

No, I have not seen any and I have about 25 BluRays


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## Prof.

That's very interesting..I'll have to look very closely at any Region free disc's that I might purchase from the US, as to what format they are using..

Maybe if someone else who has Region B disc's, might like to throw some more light on the matter..


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## tonyvdb

Like I said earlier the TruHD sometime turns on nightmode so that could also be an issue.


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## Prof.

TruHD turning on night mode is not the problem.
It's the TruHD audio that's giving brilliant uncompressed sound..
The DTS-HDMA is the one that's not up to the standard with this movie and is the compressed sound track..which is surprising since DTS-HDMA normally has the uncompressed sound..

It also appears that the US release is by Universal, whereas the Region B release is by Icon!!

I also posted this query on an Australian HT forum and everyone is saying the same thing..
The DTS-HDMA track is severely compressed..
It must just be an anomaly with Icon..


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## tonyvdb

very odd, It would be interesting to hear from others on this.


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## Sir Terrence

This sounds to me like an encoding error, because the region A version is hardly lacking in dynamics. Encoding errors do happen, and to illustrate this, Remember the Jurassic Park LFE issue as a reference.


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## victor tubeman

Hi Prof,
I have, Knowing on bluray which has both HD tracks(only one with both out of 90 blurays),generally I find DTS MA soundtracks approx 4db louder than dolby True HD as my system is analog out,with 3 pre amps I have set vol for movies.System set -8db from ref 75db with lots of power.3.2m from front stage.

Dolby True HD average dialog level 59db to 62db with peaks 99db.

DTS MA average dialog level 62db to 64db with peaks 103db.

Prof,how are you listening to HD tracks,what is decoding the HD audio etc.

Cheers Victor.


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## Prof.

Hi Victor,

My problem was that the Yamaha receiver I was using at the time didn't have the necessary audio codecs to process True-Hd or DTS HDMA..
Since then I've bought a new Receiver which has all the HD codecs through HDMI..and no more problems..
I also found that the DTS-HDMA track on Knowing is the better of the two now..and that applies to most BD movies..

Cheers..

Edit.. That's some crazy gear you've got there!!:T


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## victor tubeman

Hi,
Thankyou,
That is what I thought was the problem,yamaha no HDMI,and samsung cannot do DTS ma.Glad it,s ok now.

When I watched Knowing with friends,that plane crash scene woke and scared them,and yes people ask why all these big boxes on the ground etc.

Cheers Victor.


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## Prof.

I can't imagine how good Knowing would sound on your system!! :yikes:
Even on my meager system it sounds absolutely brilliant...The most powerful sound of all my BD's!
It's become a demo disc for me..


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## victor tubeman

Hi Prof,
A well set up system(most are not) can sound good,I find most systems can do explosions etc thats easy.Subleties in movie soundtracks,low level detail 25db to 50db ,and real instruments recorded in real space is what excels on my system.I have found most movies have good and above rating,concert blurays are all not that good,compressed and like 99% of cd,s lacking.

I,m guessing it is the mastering,mixing process and due to the ultra high resolution of the speakers and amps all faults are noticed.In movies I do notice eq changes,dialog ,space of recording studio changes with dialog and more.This passes and does not distract me from most movies.
Concert audio is totally different story.I am finding so many faults,that are so glaring,most to do with visual cues,and audio not tying together.(If only audio would not be as obvious).This is caused by no set way to mix surround sound,unlike movies,and maybe a lack of quality control?As I only have 4 concert blurays,they all much louder than movies 90db to 95db ave levels,so now have 2 vol levels on 3 pre amps -10db from ref for movies,and -25db for concerts with ave levels now 75db to 80db but still little dynamic range.As I get more concert blurays I hope this will change?
Cheers Victor.


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## Prof.

victor tubeman said:


> Hi Prof,
> A well set up system(most are not) can sound good,I find most systems can do explosions etc thats easy.Subleties in movie soundtracks,low level detail 25db to 50db ,and real instruments recorded in real space is what excels on my system.I have found most movies have good and above rating,concert blurays are all not that good,compressed and like 99% of cd,s lacking.


Yes..This is the only part I feel is lacking in my set up at the moment..that clean extended bass!
Plenty of punch from my sub now, but lacking a bit in the very low register..

To that end, I'm planning to put in an IB sub system in the near future..to pick up some of those very low bass notes you can find on some BD's..


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## Sir Terrence

victor tubeman said:


> Hi Prof,
> A well set up system(most are not) can sound good,I find most systems can do explosions etc thats easy.Subleties in movie soundtracks,low level detail 25db to 50db ,and real instruments recorded in real space is what excels on my system.I have found most movies have good and above rating,concert blurays are all not that good,compressed and like 99% of cd,s lacking.


Wow, when I read that last statement, I was floored. Have you really watched any Blu ray concert videos? I was a reviewer at Blu ray.com, and my specialty was music. Out of all the reviews I have done, I only encountered one concert that didn't have either a DTS-HD Master Audio lossless, or Uncompressed PCM. All others had either or both for audio. On most of the titles I reviewed(or have watched) the audio was above average to excellent. Even the one with the compressed audio sounded quite good. I heard no sound of audio compression(not what is apart of the codec)on any of the disc I reviewed, or have watched since I stopped reviewing. 



> I,m guessing it is the mastering,mixing process and due to the ultra high resolution of the speakers and amps all faults are noticed.In movies I do notice eq changes,dialog ,space of recording studio changes with dialog and more.This passes and does not distract me from most movies.


I want to clear up a misconception here. First(as a audio engineer and sound designer) rarely does one change studios during post production mixing or mastering. Once in post production, a mixer is usually married to the studio he mixes in(we are assigned studios to work in). Most of the time ADR is done in a single studio, and if it is not, changes in studio equipment can usually be equalized as to match all of the dialog elements we receive. 



> Concert audio is totally different story.I am finding so many faults,that are so glaring,most to do with visual cues,and audio not tying together.(If only audio would not be as obvious).


What you see as a fault, is not really one. With the cookie cutting editing style of most concert videos(you have to break up your shots), there is no way for audio to follow along, or it will sound as choppy and uneven as the visuals can sometimes look. We choose one audio perspective that best represents what is on stage, regardless of how the video is edited



> This is caused by no set way to mix surround sound,unlike movies,and maybe a lack of quality control?


There is a set way to mix surround for audio. You capture it as if you were in the auditorium. Band up front, audience surrounding you. 




> As I only have 4 concert blurays,they all much louder than movies 90db to 95db ave levels,so now have 2 vol levels on 3 pre amps -10db from ref for movies,and -25db for concerts with ave levels now 75db to 80db but still little dynamic range.As I get more concert blurays I hope this will change?
> Cheers Victor.


We mix concert videos at a higher level because the dynamic range of a concert is much less than a movie. There is nothing peaking ten or twenty decibels above average in music recording, so it requires less bandwidth and can afford a higher mastering level. There is no set mixing or mastering levels in audio, but most engineers generally use 79db average program level for monitoring, and 83-85db for mastering. The dynamic range is represented by real concert levels of which there is not a lot of dynamic range in the first place. 

I have over 110 concert videos on the Blu ray format, and I have found them to have very high production values for the most part. They are not perfect by no means, but not so imperfect that they are distracting to watch.


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## victor tubeman

Hi Terrence,

Thankyou for your detailed reply,from someone in the industry.May I assume that movie soundtracks would involve far more steps to the final audio master,than concert live audio soundtracks to the master?(less effects etc )

When I mentioned compression,regarding raising low vol,and reducing louder vol,reducing dynamic range from their natural vol levels.(there are cd,s with no compression,no eq etc).

I have only 5 concert blurays(so far),when reviewing did you try the 2 chan mixes?This is where I find large errors.Roy orbison black and white night.

"Watched this b/ray again today and found what had bothered me the first time unconsciously. 
System used analog out 5.4/ 2 channel as I mentioned 1st post dts MA track too loud 91db plus average,so listen to 2 channel 24/96khz track,
Pioneer LX-71,analog out to pre amp BAT vk-5 to Audio Research Reference 600mkIII monoblocs to Martin Logan prodigy,s crossed over to subs 80hz,2 revel B15 and 2 genesis 900 subs Rears (centre is Logos,rears are Requests, amps for centre Krell Theatre Amplifier Standard 5 chan,mono for centre 1600w 4ohm,rear amp BAT VK-500).
Listen to at 81db average levels,quality of audio is good,a purity very clean tight bass,highs and midrange have great body,air and bloom on high notes from Roy.String section which is clearly on far left,are mixed into right channel?Backup singers who are clearly on far right are mixed into centre stage.
Drum kit is very well done correct height and behind Roy.Electric Guitars and acoustic are not all audible in later songs but at least on correct side of stage when audible.
Very little dynamic range maybe as a result of tv special,amps ref 600 output was 0.01 to 0.05 watt average,600 to go.
On the fly I did change to DTS MA, and it does add depth and increases soundstage,2 channel was still relatively flat,not much depth on stage but did feel audience space and rear of room.Sound levels much higher 90 plus db so not on equal terms did notice on tracks backup singers are mixed all into 2 rear channels and very audible,maybe 2 channel is derived from 5.1 MA track.
So I wonder how the 1 of the best mastering engineers remixed this,with some instruments reversed?Maybe the original master had a mic,incorrectly placed mixed?
I will try to reset levels for DTS MA,so I can compare.
I will try to grab cd of this to check too,
IT does sound pretty GOOD,1 thumb up,
Cheers Victor. "

As you can see this really is not acceptable from one of the top mastering engineers?

The 2 channel mix on concerts is a seperate mix from the 5 channel surround mix would that be correct?Mixing 5 channels into 2 is no doubt difficult,but not impossible?

I found interesting audio is mastered at 4db to 10db above movie tracks,on my system they are all 20db to 25db above movie tracks(and my system is -8db from ref 75db) at 3.2m from front stage.)which is far louder.I have new settings for concert blurays so now 5.1 is approx 75db to 80db,now I can enjoy 5.1 surround mix as intented.

I have listen to 4 concert blurays in 5.1 surround and ,the Andrea Bocelli Live in Tuscany is bye far the best with greater dynamic range(could do with more easy) and well mixed(subtle) piano is quite good.George Michael live in london,is also well recorded in 5.1 and 2 channel(thats a change).

Regards Victor.


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## Sir Terrence

victor tubeman said:


> Hi Terrence,
> 
> Thankyou for your detailed reply,from someone in the industry.May I assume that movie soundtracks would involve far more steps to the final audio master,than concert live audio soundtracks to the master?(less effects etc )


You would be correct. 



> When I mentioned compression,regarding raising low vol,and reducing louder vol,reducing dynamic range from their natural vol levels.(there are cd,s with no compression,no eq etc).


Sometimes this is a necessary evil to help balance the individual elements with each other. The object is to use it in a subtle fashion - just enough to get the balance, but not enough to make it obviously audible. It is a balancing act that must be carefully monitored to get the best result. 



> I have only 5 concert blurays(so far),when reviewing did you try the 2 chan mixes?This is where I find large errors.Roy orbison black and white night.


We have to review all of the audio formats on the disc. The problem with using the two channel mixes as a reference is that they are often mix downs of the 5.1 track with no additional tweaking and minimal monitoring of the end result of that mix down. In other words, it is not optimized for two channel reproduction. The 5.1 mix should be the reference, as it is optimized and monitored with greater scrutiny. 



> "Watched this b/ray again today and found what had bothered me the first time unconsciously.
> System used analog out 5.4/ 2 channel as I mentioned 1st post dts MA track too loud 91db plus average,so listen to 2 channel 24/96khz track,


I find the comment that the Dts MA track to loud is a bit amusing. Right at your finger tips you have control of the volume knob, so it really does not matter what average mastering level is used. As long as the recording is not constantly bumping against 0 digital reference levels, or having its peaks clipped, the average level is irrelevant. 



> Pioneer LX-71,analog out to pre amp BAT vk-5 to Audio Research Reference 600mkIII monoblocs to Martin Logan prodigy,s crossed over to subs 80hz,2 revel B15 and 2 genesis 900 subs Rears (centre is Logos,rears are Requests, amps for centre Krell Theatre Amplifier Standard 5 chan,mono for centre 1600w 4ohm,rear amp BAT VK-500).
> Listen to at 81db average levels,quality of audio is good,a purity very clean tight bass,highs and midrange have great body,air and bloom on high notes from Roy.String section which is clearly on far left,are mixed into right channel?Backup singers who are clearly on far right are mixed into centre stage.
> Drum kit is very well done correct height and behind Roy.Electric Guitars and acoustic are not all audible in later songs but at least on correct side of stage when audible.
> Very little dynamic range maybe as a result of tv special,amps ref 600 output was 0.01 to 0.05 watt average,600 to go.


This sounds like the polarity is being reversed somewhere in the recording, mixing or mastering chain. It is rather obvious to me that QC was not in the production teams head when the master was approved. 

The movement of the vocals to center was perhaps for clarity sake. Sometimes an audio engineer has to make editorial decisions on the audio separate from the video. It will often make the audio sound more clearer, but create a discontinuity with the visuals. 



> On the fly I did change to DTS MA, and it does add depth and increases soundstage,2 channel was still relatively flat,not much depth on stage but did feel audience space and rear of room.Sound levels much higher 90 plus db so not on equal terms did notice on tracks backup singers are mixed all into 2 rear channels and very audible,maybe 2 channel is derived from 5.1 MA track.


Most two channel mixes on concert videos these days are derived from 5.1 masters using down mixing algorithms from their respective codecs. These kinds of recordings are going to have a bit of a flattened sound stage because they are tightly miked which eliminates any phase information. Sound stage depth is derived from phase information as the signals hit the microphones at different times. 



> So I wonder how the 1 of the best mastering engineers remixed this,with some instruments reversed?Maybe the original master had a mic,incorrectly placed mixed?
> I will try to reset levels for DTS MA,so I can compare.
> I will try to grab cd of this to check too,
> IT does sound pretty GOOD,1 thumb up,
> Cheers Victor. "
> 
> As you can see this really is not acceptable from one of the top mastering engineers?


As I stated before, either there was a polarity problem in the mixing and mastering chain, or it was an editioral decision made for clarity sake. It is impossible for me to know for sure. 



> The 2 channel mix on concerts is a seperate mix from the 5 channel surround mix would that be correct?Mixing 5 channels into 2 is no doubt difficult,but not impossible?


Usually the 2 channel mix is derived from the 5.1 mix using mix down algorithms. Rarely are there two separate mixes created and optimized for each delivery system. 



> I found interesting audio is mastered at 4db to 10db above movie tracks,on my system they are all 20db to 25db above movie tracks(and my system is -8db from ref 75db) at 3.2m from front stage.)which is far louder.I have new settings for concert blurays so now 5.1 is approx 75db to 80db,now I can enjoy 5.1 surround mix as intented.


Mastering levels are irrelevant unless they create a problem. In the end you have ultimate control over what level you will listen to. 



> I have listen to 4 concert blurays in 5.1 surround and ,the Andrea Bocelli Live in Tuscany is bye far the best with greater dynamic range(could do with more easy) and well mixed(subtle) piano is quite good.George Michael live in london,is also well recorded in 5.1 and 2 channel(thats a change).
> 
> Regards Victor.


Victor, you have a lot of listening to get to as there are now more than a hundred concert Blu ray videos out there.


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## Prof.

Sir Terrence said:


> I find the comment that the Dts MA track to loud is a bit amusing. Right at your finger tips you have control of the volume knob, so it really does not matter what average mastering level is used. As long as the recording is not constantly bumping against 0 digital reference levels, or having its peaks clipped, the average level is irrelevant.


This is where I need to chime in...

Just turning the volume down on some of these DTS-HDMA tracks, won't solve the problem..
"Knowing" is a good example of this..You can set the volume so that the peaks are still at a reasonably high level with out going over board, but then the whispered voices (as when they are in the car with the children sleeping in the back) are almost unintelligible ..
If you turn up the volume a little to be able to hear what they're saying, then the peak levels are over the top!!

The first time I watched this movie, I had the volume set for normal voice listening levels, and the peaks were so loud that I thought my speakers would be damaged..and if I hadn't quickly grabbed the remote to turn down the volume, I'm sure they would have been!!

That sort of dynamic is a bit over the top in my opinion..


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## Sir Terrence

Prof. said:


> This is where I need to chime in...
> 
> Just turning the volume down on some of these DTS-HDMA tracks, won't solve the problem..
> "Knowing" is a good example of this..You can set the volume so that the peaks are still at a reasonably high level with out going over board, but then the whispered voices (as when they are in the car with the children sleeping in the back) are almost unintelligible ..
> If you turn up the volume a little to be able to hear what they're saying, then the peak levels are over the top!!
> 
> The first time I watched this movie, I had the volume set for normal voice listening levels, and the peaks were so loud that I thought my speakers would be damaged..and if I hadn't quickly grabbed the remote to turn down the volume, I'm sure they would have been!!
> 
> That sort of dynamic is a bit over the top in my opinion..


Knowing is a soundtrack that has all of the theatrical dynamic range transferred to the Blu ray disc. It requires a room where the ambient level is very low to preserve the dynamic range, but keep the viewer from having to "ride" the volume control for comfortable listening. I have found no such problems when I play this soundtrack back on at least three of my home theater system, as the ambient room levels in these rooms meet THX theatrical standards.(about NC-25). 

This problem can also exist where the sensitivity and the ultimate power level of the center speaker is very different from the L/R mains(and other channels as well). This is an area where completely matched identical speakers, and amp channel capacity shines.


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## Ricci

Hmmm. Sounds like I may need to pick that disc up. Is the movie any good?


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## Prof.

Sir Terrence said:


> This problem can also exist where the sensitivity and the ultimate power level of the center speaker is very different from the L/R mains(and other channels as well). This is an area where completely matched identical speakers, and amp channel capacity shines.


That's very interesting to hear, inasmuch that my centre channel speaker is far more efficient than my L&R speakers..
When balanced to 75dB. the L&R speakers trims through MCACC are set to +1.5dB and the centre channel is -4.0dB!!

I would have presumed on that basis that the centre channel would produce low level voices very clearly..but I find the opposite..
It's almost like there's a certain volume level where it works very efficiently, and go below that and it starts to drop off quickly!

Edit: I should also mention that the ambient sound level in my theatre, is like that of an anechoic chamber!!


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## Prof.

Ricci said:


> Hmmm. Sounds like I may need to pick that disc up. Is the movie any good?


If you can handle watching Nicolas Cage's wooden acting!..then it's a very good movie..:R


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## victor tubeman

Hi Terrence,
Thankyou,with regard to master vol levels,in my system it is a problem,I have three vol controls.Therefore I need to use test disc to reset levels for 3 pre amps with the sub level at nearly the min for -8db from ref 75db(movies),and -25db from ref for concerts in surround mode.

Having a low NC in a room is very important,as most systems do not have the amp headroom to cope with 40db plus peaks.My main system has a NC of 35db plus due to audio research mono,s each have 4 fans but I do have plenty of power for front stage.My other system has a NC of 20db with Avantgarde Duo,s and the low level detail 25db to 50db most systems miss this completely,and being 104db/watt also helps :T

Cheers Victor.


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## Sir Terrence

Prof. said:


> That's very interesting to hear, inasmuch that my centre channel speaker is far more efficient than my L&R speakers..
> When balanced to 75dB. the L&R speakers trims through MCACC are set to +1.5dB and the centre channel is -4.0dB!!
> 
> I would have presumed on that basis that the centre channel would produce low level voices very clearly..but I find the opposite..
> It's almost like there's a certain volume level where it works very efficiently, and go below that and it starts to drop off quickly!
> 
> Edit: I should also mention that the ambient sound level in my theatre, is like that of an anechoic chamber!!


While the auto setup processing is handy, I would not take their results as accurate until I check behind them after they go through their set up routine. My experience has taught me that their end results can often be quite inaccurate for a number of reasons. I use the Audussey system, and after it was finished calibrating, I rechecked its settings with a real time analyzer and SPL meter just to verify accuracy. I have had to tweak some of the settings after calibration, but not that often. 

Is your center speaker voiced or matched to your L/R mains? If they are from different manufacturers or non matched models, the frequency response difference can effect the rendering of low level detail when the L/R are reproducing signals. There are a lot of things that can effect low level detail, such as the S:N ratio of amps, pre-amps, and various other things. Some signal chains do not have the resolution to clearly render low level detail. Our perception and belief of things, and the reality of things are sometimes at opposite ends of the spectrum.


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## Prof.

Sir Terrence said:


> While the auto setup processing is handy, I would not take their results as accurate until I check behind them after they go through their set up routine. My experience has taught me that their end results can often be quite inaccurate for a number of reasons. I use the Audussey system, and after it was finished calibrating, I rechecked its settings with a real time analyzer and SPL meter just to verify accuracy. I have had to tweak some of the settings after calibration, but not that often.


I should have mentioned that I do check channel levels after running MCACC, and they are generally way off the mark and need to be set manually to 75dB. 



> Is your center speaker voiced or matched to your L/R mains? If they are from different manufacturers or non matched models, the frequency response difference can effect the rendering of low level detail when the L/R are reproducing signals. There are a lot of things that can effect low level detail, such as the S:N ratio of amps, pre-amps, and various other things. Some signal chains do not have the resolution to clearly render low level detail. Our perception and belief of things, and the reality of things are sometimes at opposite ends of the spectrum.


Unfortunately they are very miss matched, inasmuch that the L/R are Acoustic suspension types and the centre is bass reflex..They are also from different manufacturers..

I did some further experimenting with the MCACC yesterday, and put the calibration setting to "Front Channel Adjust", whereas previously I had used "All Channel Adjust"..
For what ever reason, this has improved low level centre channel balance to L/R quite significantly..
I did need to make a few minor adjustment to the L/R EQ bands over the MCACC settings..but 
the end result is that I'm now very happy with the overall balance..


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## Sir Terrence

Prof. said:


> I should have mentioned that I do check channel levels after running MCACC, and they are generally way off the mark and need to be set manually to 75dB.
> 
> 
> Unfortunately they are very miss matched, inasmuch that the L/R are Acoustic suspension types and the centre is bass reflex..They are also from different manufacturers..
> 
> I did some further experimenting with the MCACC yesterday, and put the calibration setting to "Front Channel Adjust", whereas previously I had used "All Channel Adjust"..
> For what ever reason, this has improved low level centre channel balance to L/R quite significantly..
> I did need to make a few minor adjustment to the L/R EQ bands over the MCACC settings..but
> the end result is that I'm now very happy with the overall balance..


Excellent!:T

The setup programs IMO tend to work better when you have taken care of some basic acoustical issues before running them. I found that after doing some basic room treatment, and then running the Audussey, I never needed to tweak after running the setup. The less pretreated the room was, the more off the settings would be(this may not be everyones experience). I also found that if your speakers are already equidistant to the listening position before running the calibration, the more accurate the settings were. My smallest theater (a 7.1 system mini monitor and sub system) has the room pretreated, and the speakers equidistant, and the Audussey calibration was spot on. I didn't even need to tweak the EQ, it hit is right on the bat.


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