Receivers & 7.1 & THX

Curtis2000

Novice Member
Hi,

Some advice needed please...

Regarding the content on this page: http://www.thx.com/consumer/home-entertainment/home-theater/surround-sound-speaker-set-up/

Which is better, 7.1 Surround Sound Speaker System Set Up or Dolby® TrueHD or DTS-HD Master Audio™ Set Up? I'm building a house and I didn't see the later one just the 7.1 setup, so I was having them wire it for the 7.1 configuration since we will have 7.1 wiring, where the back speakers are in the middle, next to each other, firing directly at my head. I thought that was odd when I originally saw this before since you usually always see them on the sides, pointed in the middle. But I trusted what I saw since it came from THX. Did I mess up? Is the later Dolby setup better? I don't know much about sound and if it is like Blu-ray vs HD DVD battle, where one will eventually win as the lasting format and I will regret it down the road since it won't exist and having the speakers so close to each other isn't ideal. If I leave it as is, will I not get as good of sound if I don't go with a receiver that is THX certified? There aren't that many.. Seems like I do as the setup I picked, requires THX technology to take advantage of it.

I was trying to do it right and I think I screwed up now.

Thanks
Curtis
 

dante01

Distinguished Member
There's no specific setup you need to use in relation to DTS-HD Master Audio and or Dolby TrueHD. The 7.1 setup is the same irrespective of the audio encoding and generally what Dolby suggest it to be for 7.1. THX suggest you place the back speakers closer together than Dolby suggest, but this is the only real difference. The THX configuration works with and is intended for use with all audio formats irrespective of which 7.1 encoding is used. THX isn't a format or type of encoding, THX are simply a concern involved in cinema and home cinema audio. There's technically no reason why having the two back speakers in close proximity to one another would be better than having them further apart, but you would position them as suggested by THX if using T THX Advanced Speaker Array, (ASA) speakers and products that support THX-ASA. ASA speakers are designed to work in a way that benefots from how THX suggest you position them. I'd suggest spacing conventional speakers out and leaving at least 2' between back speakers and indeed the rears. If unsure then try before you make any permanent mounting decisions.

THX certification, simply means the receiver was tested by THX and meets certain criteria set out by THX. Many receivers that are not certified both meet and exceed those criteria. Yamaha stopped certifying their products with THX, stating that why do they need to pay THX to do something they can do for themselves? You pay more for a THX certified product, but the product will not include anything you'll not find on non certofied products. In other words, you pay for the badge.

Here's what the certification means:
THX Certification Performance Categories « THX.com

Note that THX is a profit making organisation and not a standard!


If you'd like more info on THX-ASA then look here:
THX Surround Sound Modes « THX.com


Again, the way THX suggest you place the back speakers only comes into play if using THX products and THX-ASA.
 
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Curtis2000

Novice Member
Thank you for the very helpful reply! THX says this on their website:

Surround Back Left & Right Speakers (SBL & SBR)*: The SBL & SBR speakers should be the direct firing type and placed together on the back wall. This allows the THX Advanced Speaker Array, or ASA technology to deliver its maximum effect. If the SBL and the SBR speakers can not be placed together, refer to your THX Certified Pre-amplifier or Receiver’s “THX Set Up” menu for alternative configurations.

Is that a bunch of bs? Nonetheless, my house is getting very close to sheetrock, this week I think. I may be able to move the speaker wires over a few feet before it isn't too late (an hour away from where I live now). Would that be worth it or just leave it where it is?

I attached my layout I gave my builder for when they cut the holes for the cables... This was all based on THX's website.

Curtis
 

Attachments

dante01

Distinguished Member
Their site suggests you need products that incorporate THX tech and THX certification. Their suggested placement doesn't work if not using THX modes and THX-ASA. It is unlikely that the 7.1 audio was mixed in a studio where the back speakers are placed where THX suggest you place them and the engineer wasn't thinking THX-ASA when mixing the audio. When dealing with 7.1 audio then you really need to place your speakers as close to where they were located in the mixing studio, not where THX suggest you locate them to take advantage of THX listening modes. I guess it depends upon how big a THX fan you are? If you have THX kit and always utilise THX listening modes then the way THX suggest you place the speakers is fine, but if you don't then you need to do as Dolby suggest.
 

dhts

Active Member
The particular receiver you are using may have some specific recommendations for placement of rear speakers but the thing I would suggest is that you go crazy whilst the house is at this stage and add additional wiring just in case. For example front height and wides and if you think something like Aura 3d will take off then rear heights and 'voice of God' speakers also. Cable is cheap at this stage but routing additional cables later can be a real pain.
Your centre speaker looks high but not sure what type of screen you are using and I wasn't sure if you had thought about wiring for a sub (or 4).
 

dante01

Distinguished Member
If the room is to be a dedicated cinema room with just a PJ and screen then you should look at using an acoustically transparent screen in order to fascilitate the placement of the centre speaker behind the screen as opposed to having it located below the screen. You may find this of interest as to the reasons why I suggest this:

Home Cinema Design - Mkloudspeakers


The centre speaker ideally needs to be in alignment with the front left and right speakers which in turn need to be in alignment with your seated head height. It is even better if you use a speaker identical to the speakers to either side of it rather than speakers marketed as centre speakers. You may find these articles of interest:

Vertical vs Horizontal Center Speaker Designs | Audioholics

Center Channel Speaker Design Additional Considerations | Audioholics

Vertical vs Horizontal Center Channel Speaker Designs – An Alternate Perspective | Audioholics
 
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Curtis2000

Novice Member
I can't remember where I came up with the height, but was putting the rears 3 feet from the ceiling. Is that too high? I can go there and move the cable over some but it will take up some of what cable is left and there isn't much. Can you buy more audio cable and just connect the two or must be completely reran to my closet where it is all wired to, one complete piece? Insulation is already up...

They wired it to the back corner. They used coxial cable actually. Can a sub-woofer work with coaxial??

I picked above as because of the size of the screen, I didn't think there would be much room below before it was on the ground.

Curtis
 

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dante01

Distinguished Member
As to the height at which you locate rear and back speakers, these should be located 30 - 90cm above you seated head height. Too high and you lose them altogether and too low and they become too localised.
 
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dante01

Distinguished Member
An active sub would require coax as opposed to conventional speaker wire. Placing the sub to the rear of the room isn't the best placement for a sub. It is usually suggested that the sub be best placed approx one third up the room from the front and off to one side.
 

Curtis2000

Novice Member
Boy, information overload. I think I have to do it tonight as I can't ask the builder to do it, not their fault. They already ran the cables where I told them. Can I just buy 16 awg speaker wire and extend it like you do electrical wire with those plastic connector caps? Not sure if I can even buy speaker cable locally easily or where to go & get it. Not sure if I should even mention this to the builder or just do it myself. They may so no and I will just be stuck with where it's at.
 

Curtis2000

Novice Member
I want to say thank you to everyone that posted information, it was all very helpful!

Can anyone provide any input on how I hook my sub woofer up to the coax cable they are installing for it? I do not believe any subs or receivers even have a coax port on them?
 

dante01

Distinguished Member
The coax should be terminated at both ends by an RCA (phono) connector:



 
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dante01

Distinguished Member
Yes, for the active sub then this would be the only way you should coonect it to your AV receiver.. The receiver has a sub pre out to which you connect one end of the cable. The sub itself will have several inputs depending upon make and model, but it will fascilitate you connecting the cable to it via the RCA terminated coax cable. If the sub has stereo RCA inputs then only one need be used to connect an AV receiver because the output from the receiver is mono. It is usually the left low level RCA input that you use to connect an AV receiver.

You can buy subwoofer cables ready made. They are bascally the same as stereo RCA terminated coax cables. but sold as one cable as opposed to there being two of them. Examples here:

Subwoofer Cables - AudioVisual Online - Home Cinema and Hifi Specialists
 

Mark.Yudkin

Distinguished Member
Regarding the content on this page: http://www.thx.com/consumer/home-entertainment/home-theater/surround-sound-speaker-set-up/

Which is better, 7.1 Surround Sound Speaker System Set Up or Dolby® TrueHD or DTS-HD Master Audio™ Set Up?
The first 7.1 setup is for DVD, which only has discrete 6.1, the second for Bluray (misleadingly called "Dolby® TrueHD or DTS-HD Master Audio™"), which has discrete 7.1. I would therefore suggest the setup with the speaker separation.

THX is both certification and a feature set. THX certified receivers contain the feature set from the certification level, non-THX receviers do not (can not), as the technologies have not been licensed, but may provide some other means of achieving similar results.

The THX speaker layout suggestion is in fact not related to either THX certification or THX technologies; it is simply very good advice with universal application.
 

dante01

Distinguished Member
The THX speaker layout suggestion is in fact not related to either THX certification or THX technologies; it is simply very good advice with universal application.
Not according to THX:
THX Surround Sound Modes « THX.com

Both THX Movie and Music modes depend upon you placing the back speakers in the configuration suggested by THX. THX-ASA only works if you abide by THX's speaker layout suggestions.


The close proximity of the two back speakers isn't so much to do with DVD as an attempt to give 6.1 encoded audio output a closer speaker configuration to that which would have been used for 6.1 audio i.e. trying to make the 2 back speakers act as one mono speaker as opposed to 2 individual speakers with their own channels of audio. You can do this without placing speakers in close proximity to one another via phase alignment.
 
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