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Discussion Starter · #1 ·
I have just bought the first component to my home theatre (Yamaha RX-V1200) , I know it has just been superceded, but i got it for a really good price. All i need now is the Sony HS10 projector some good speakers a component DVD player and an HDTV set top box.


While researching 6.1 sound I have come across a number of references to using two speakers for the Rear Centre (RC). Aparrently this 7.1 setup gives a more diffuse character to that rear channel and helps to counter a psycho-accoustic phenomena called "back to front flipping". The RX-V1200 only has one terminal for the RC and pumps 80 watts RMS.


Is it possible to attach two speakers in series to that one terminal or will I have a major problem with impedance thus upsetting the balance of the sound? I know that there are Amps and Recievers that have a specific seventh terminal for this, but the forums I have read seem to imply that it was possible with the one RC terminal. Then again, I may have completely misinterpreted.


Any help or comment would be appreciated.


TIA


K1w1



:D :D
 

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If the two speakers in question are rated at 8 ohms, you can wire them either in parallel, which presents a 4-ohm load to the amp, or in series, which presents a 16-ohm load to the amp. Either way, your amp will handle it fine. If the speakers are rated less than 8 ohms, wire them in series.


Don't worry about impedance mismatch between channels. Each amp channel is adjustable for volume in the receiver, and the impedance issue will have no effect on sound quality.
 

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 Parasound CSE 6.1


Looks like this might be useful for you. You can use an old amp to power these channels. I think it retails for much less on the internet and might add some surround "processing".
 

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Quote:
Originally posted by k1w1
Aparrently this 7.1 setup gives a more diffuse character to that rear channel and helps to counter a psycho-accoustic phenomena called "back to front flipping".
Correct. After attaching the two surround-back speakers to the one terminal, make sure you place them well apart and as far behind the listening position as your room allows. Also, try to have them as equidistant from the listener as possible; this is important because you want them to be of equal volume level and correctly time aligned, even though you won't have individual control over each of the two speakers.


Good Luck,

Sanjay
 

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6.1 to 7.1 short answer - NO


The 6 & 7 are channels that have their own separate (discreet) info encoded for them. However the in the current 7.1 the 6th & 7th channels are two MONO channels as opposed to front left & right & rear surround left & right which are stereo. In the 7.1 the 6 & 7 are are merely 2 mono channels with slighly different phase shifted/delay processing used.


You can get almost the same by hooking up the 2 centre rears but depending on the ohms of the 2 speakers you have to be carefull of what the setting of the selection switch is set to on the back of your recvr.


The best way to hook the 2 same (I hope) brand size etc speakers is amp out + to + of 1st speaker, the - of the 1st speaker to the + of the second, and the amp - out to the - of the second speaker. You may have to increase the db out to the centre rear channel in the recvr menue. As for distance, I would closely follow the recommendations of a 7.1 system speaker set up which currently exists. Any good dealer will be able to let you know exact measurements.


There is a better way to use 2 centre rears if you have an extra powered DSP unit - put the centre preout from your recvr to the main input of the DSP unit & take the speaker left & right front main outs & connect to your rear centre speakers. The DSP unit will "sense" a left & right nuance from the input & send it to the R&L rear centres accordingly. This would be a MATRIX 7.1 - do the same to your front centre & you got 8.1 MATRIX


Hope this helps further.


Dougofthenorth
 

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Quote:
Originally posted by Dougofthenorth
6.1 to 7.1 short answer - NO


The 6 & 7 are channels that have their own separate (discreet) info encoded for them. However the in the current 7.1 the 6th & 7th channels are two MONO channels as opposed to front left & right & rear surround left & right which are stereo. In the 7.1 the 6 & 7 are are merely 2 mono channels with slighly different phase shifted/delay processing used.


You can get almost the same by hooking up the 2 centre rears but depending on the ohms of the 2 speakers you have to be carefull of what the setting of the selection switch is set to on the back of your recvr.


The best way to hook the 2 same (I hope) brand size etc speakers is amp out + to + of 1st speaker, the - of the 1st speaker to the + of the second, and the amp - out to the - of the second speaker. You may have to increase the db out to the centre rear channel in the recvr menue. As for distance, I would closely follow the recommendations of a 7.1 system speaker set up which currently exists. Any good dealer will be able to let you know exact measurements.


There is a better way to use 2 centre rears if you have an extra powered DSP unit - put the centre preout from your recvr to the main input of the DSP unit & take the speaker left & right front main outs & connect to your rear centre speakers. The DSP unit will "sense" a left & right nuance from the input & send it to the R&L rear centres accordingly. This would be a MATRIX 7.1 - do the same to your front centre & you got 8.1 MATRIX


Hope this helps further.


Dougofthenorth
Im sorry but what did you say?:confused:
 

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Doug,


There is exactly one discrete format with more than 5.1, which is DTS-ES discrete. There is well less than .1% (less than 72 out of 72,000) DVDs released with this encoding.


7.1 implementations of either DTS-ES (discrete or matrix) have monophonic information in the 6th and 7th channels, in other words it is the same.


Further, DD-EX is matrix encoded, not discrete.


Regards,
 

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Discussion Starter · #9 ·
Now i am even more confused.


Dougofthenorth's view on the 6.1/7.1 Rear Centre is completely at odds with the situation as i understand it.


Discrete or Matrixed i believe that the RC channel standard for 7.1 is mono and that there is no 7.1 stereo standard. Is this correct?


If that is the case, i see no problem with a serial or parallel connection to the twin RC speakers. The only issue would be volume, and that can be controlled independantly through the reciever. Is that correct?


You have probably noticed that i am not an electrical engineer, but just know enough to get into trouble.


Once again any comment or suggestion would be appreciated. There must be someone out there that has tried this configuration.


TIA


k1w1
 

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Quote:
Originally posted by k1w1
Discrete or Matrixed i believe that the RC channel standard for 7.1 is mono and that there is no 7.1 stereo standard. Is this correct?


If that is the case, i see no problem with a serial or parallel connection to the twin RC speakers. The only issue would be volume, and that can be controlled independantly through the reciever. Is that correct?
Correct to both!


Best,

Sanjay
 

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Quote:
Originally posted by John Kotches
Doug,


There is exactly one discrete format with more than 5.1, which is DTS-ES discrete. There is well less than .1% (less than 72 out of 72,000) DVDs released with this encoding.


7.1 implementations of either DTS-ES (discrete or matrix) have monophonic information in the 6th and 7th channels, in other words it is the same.


Further, DD-EX is matrix encoded, not discrete.


Regards,
As I stated - perhaps I should have been more clear, I understand 5.1, 6.1 etc., as well as 4.1 (pre 5.1). However there is NO 7.1 encoding format, thus no 7.1 (as an aside- Logic7 is stating centre rear Stereo). As I have stated in other posts, I think selling & stating 7.1 systems is BOGUS. There exists a recognized form of stating 5.1, 6.1 etc but I am arguing that the stating of 7.1 is misleading. it should be stated 7.1 MATRIX, or 6.1.1.


My explanation of the being able to achieve 7.1 & 8.1 (both matrix) gives a more lively appearance to the centre & rear sound fields than does the currently (mistated) 7.1. I also suggest starting with a 6.1 capable system would yield better results as the front & rear centres would be matrixed from a discreet source. I don't know what Matrixing a 5.1 rear centre 6.1 Matrix channel would give, (Matrixing a Matrix).


As for the hook up of extra speakers using the form I suggested does not create as much heat in the amp circuits. Using my SPL meter showed a very small increase to the front centre channel level was required (RX-Z1 recv'r).


k1w1 - I hook up my 2 front centres as I explained in my previous post. As for your using 2 speakers for the centres I would be concerned as well that you try & use 2 of the same speaker models, so as to keep the tonal quality the same. Further, using 2 front centres on top of a wide screen enables a wider sound field, using 2 centres on a narrow (standard) screen presents a not as noticeable effect.


Hope I made it clearer this time! ?


Dougofthenorth
 

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Doug,


Using two speakers up front for the centre channel isn't a good idea because it can result in muddied dialog for off-axis listeners. Contrary to your advice, this becomes even worse with wider screens compared to narrower ones. And, even for on-axis listeners, comb filtering artifacts can become an audible problem.


However, using two speakers for the surround-back channel is a good idea because it deals with front/back reversal and also provides better diffusion while still allowing listeners to locate sounds specifically behind them. k1w1 mentioned both these advantages in his initial post. These are amongst the reasons why companies that have a history of specializing in surround sound (Fosgate, Meridian, Lexicon) recommend 7.1 or 5.1 speaker set-ups, but discourage a 6.1 configuration.


I can understand your concern that the term "7.1" can lead to misconceptions regarding the number discrete channels involved; it can happen unintentionally by uneducated consumers or on purpose by unscrupulous salesmen/manufacturers. But this potential for confusion doesn't make 7.1 speaker layouts somehow bogus or incorrect. In fact, what's incorrect is telling someone that using a single surround-back speaker in a 6.1 set-up is fine and will work just as well as using two surround-back speakers in a 7.1 set-up. That's truly bogus.


Best,

Sanjay
 

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Quote:
In fact, what's incorrect is telling someone that using a single surround-back speaker in a 6.1 set-up is fine and will work just as well as using two surround-back speakers in a 7.1 set-up. That's truly bogus.
I tried another pair of Titans parallel wired and then a CC170...I couldnt notice any difference. It may be bogus to you but thats your opinion.

Yosh70
 

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Quote:
Originally posted by Yosh70
I tried another pair of Titans parallel wired and then a CC170...I couldnt notice any difference. It may be bogus to you but thats your opinion.
It's more than my opinion; it's information based on long established scientific facts about psychoacoustics, as well as the research and practices of pre-pro manufacturers who have remained at the leading edge of surround processing. I've articulated the reasons upon which my opinions are based; please feel free to tell me which particular ones are wrong and why. Meanwhile, your opinions are based on...? Oh right, you "couldnt notice any difference." Well, that'll certainly tear down the walls of Jericho.


Best,

Sanjay
 

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Sanjay,


Thank you for your comments. I withdraw my comment about Matrixing the front centre channel to create the 8.1 Matrix.

Comments on Matrixing the 7.1 rear centre channel?


Based on your comments would it then be prudent to puchase a 2nd speaker for my 6.1 rear centre channel?


However, I cannot agree with your blanket statement that 2 centre front speakers non DSP'd can create problems. I will clarify that they are centered & next to each other not spread out as the 7.1 rear centre configs, therefore in effect they act as 1 speaker.


Further, Yamaha has added its proprietary 2 front L&R Effects speakers.

{set at cieling height 1.5 metres out from front mains.}

RX-Z1 = 6.1.1(+2)


I would also point to the discussion papers between T. Holman & Dr. D. Griesinger whereby he & Holman are discussing the ideal configuration of 10 versus 11 channels. DDX or Dolby10.2. These speaker configs are already in place, albiet few. I think eventually we are indeed heading to a "bank" of speakers front, mid side & rear.


Regards

Dougofthenorth
 

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Hi Doug,
Quote:
Based on your comments would it then be prudent to puchase a 2nd speaker for my 6.1 rear centre channel?
Up to you, but I personally would always use 2 speakers for the surround-back channel, for reasons mentioned earlier by k1w1 and myself.
Quote:
However, I cannot agree with your blanket statement that 2 centre front speakers non DSP'd can create problems. I will clarify that they are centered & next to each other not spread out as the 7.1 rear centre configs, therefore in effect they act as 1 speaker.
For the on-axis listener sitting in the sweet spot, two centre front speakers will probably sound fine; I think it unnecessarily introduces the opportunity for comb filtering (though that may go unnoticed by some listeners and/or not bother other listeners). I'd be willing to deal with this problem if I saw a clear advantage to using two centres up front, but I don't see what I would gain with this configuration.


Now, for the off-axis listener it's a different story. Dialog from the centre channel will arrive at the listener twice, separated by a few miliseconds. That's not enough time for the human ear/brain to consider the second arrival as a separate sound or as an echo of the first arrival. But it is enough time so that the two slightly mis-timed arrivals can muddy the sound. Note that this slight diffusion is desireable in the surround field, but not up front where dialog clarity is critical.


A wider TV means more separation between the two centre speakers. More separation means a greater delay between the two arrival times of the same centre channel information. Greater delay means the dialog will be less focused and more smeared. Like I said, I don't see where two centre speakers would be advantageous over one.
Quote:
I would also point to the discussion papers between T. Holman & Dr. D. Griesinger whereby he & Holman are discussing the ideal configuration of 10 versus 11 channels. DDX or Dolby10.2. These speaker configs are already in place, albiet few. I think eventually we are indeed heading to a "bank" of speakers front, mid side & rear.
It is in some of the writings of Dr. Griesinger (inventor of Lexicon's LOGIC7 processing) that I first read about front/back reversal; it helped explain some weird behaviour I was hearing at the time in my system. Both Holman and Griesinger support five speakers up front, though they differ in configuration. I think this is more useful in movie theatres, where the front spread can be like 40 or 50 feet wide. For the typical listening room at home, I think five speakers up front is a bit of overkill (not that I would turn it down).


Note however (and this is an extremely important point) that in Holman's and Griesinger's "bank" of front speakers, EACH speaker is getting a different sound; this will produce significantly different results than having two or more front speakers that are reproducing the same sound.


Best,

Sanjay
 

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Well my opinions are based on what I am hearing....and yours are based on what?...oh yes
Quote:
long established scientific facts about psychoacoustics
:rolleyes: ....if someone disagrees with ur analytical thesis, do you have to get all snitty about it? Im very sorry that you had some problems "psychoacoustically" but I guess my situation differs from yours.


All my best

Yosh70
 

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Quote:
Originally posted by Yosh70
....if someone disagrees with ur analytical thesis, do you have to get all snitty about it?
Moi snitty? Don't be silly!


I have no problem with people disagreeing with anything I've said, especially in this thread. And speaking of disagreeing with me; I'm still waiting for you to tell me what parts of my "analytical thesis" are wrong and why.


Best,

Sanjay
 

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You can have, read and quote all the theories you want....they may even be correct for yours and other situations.....for me tho, 6.1 works fine for my ears. My Marantz is a 6.1 channel receiver and has pre-outs for a 2 channel amp for 7.1 so I will be doing that down the road. I wouldnt want to have any "pyschoacoustical" effects ya know :D
 

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Sanjay;


Again, I thank you for your comments. Not that I am intending to be argumentative for its own sake.

1) I would have liked it if you would have qualified your answer further, RE

front room width 14 feet should allow for 2 20" front centres placed

side to side on a 54" wide set, thus creating a 40" front centre speaker.

Otherwise, would not it be creating the same effect if a person had a

12" wide front Centre speaker then switched to a 24" wide centre?

2) Further, I would have liked you to have commented quantitatively on

the 2 L&R front effect speakers as (aside from the 2 centres), other

than "you feel ...". The RX-Z1, hence Yamaha does indeed provide this 5

speaker front "bank".


3) As for the 2 centre rears "being as far apart as possible" Can you be

more specific as I intend to follow you advice & would like some

measurements (figures) on the spacing, if you would be so kind to

provide them.


Dougofthenorth (Hope this is still proving useful for k1w1)
 
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