[Mark Hunter]

I got this much (classic 5.1 setup):


* Two L/R direct-radiating front speakers

* One direct-radiating Center front

* Two dipolar (usually) Side Surrounds


* Are the final 2 speakers behind the seating? Directly behind? Or off to the back corners? Are they Dipole? Bipole? Monopole (direct)?


I know that this may be variable...I am just looking for the "textbook" answer.


What changes when going from 5.1 to 7.1 in an ideal situation?


------------------

Mark Hunter

 

[Mark Hunter]

Hmm...Since no one was able to answer this question, I went out and did some actual research. I am posting the reply to my own question in case anyone was following this thread...


I found the "recommended" solution for a 7.1 channel system in a Home Theater magazine last night.



First, a quick "WHY" of the 7.1 channel setup. In a 5.1 channel setup, it is difficult for movie producers to create an "image" behind the listener to accurately place objects there. For instance, when a space ship flies over the listener, a 5.1 movie setup will "smear" the sound of the ship to the diffuse sides as it approaches the listener. Surround sound is awesome for "diffuse" effects (rain, wind, etc.) but not so good when trying to localize an image.


Picture a ship flying towards you with this setup (the sides are dipoles for movie watching) and what happens as the ship approaches the listener. The sound gets more diffuse, and smeared to the sides.

http://www.milori.com/ht/fivechan.gif


The 7.1 channel system was designed to help with this problem by allowing a discrete rear channel that can form an image, if needed by the movie. There are a couple of dozen movies that use the 7.1 format today (THX EX or DTS ES).



Here is my picture of this magazine's recommended way to set up a 7.1 system:

http://www.milori.com/ht/sevenchan.gif


1. 3 Front channels - as they always are.

2. For the side and rear surrounds, use 4 identical dipole.

3. The 2 sides are mounted normally, but the 2 left channels are mounted "inverted", so that no images are produces between speakers except that the two rear channels can produce an image between them. Inverting the speakers should have no effect on their sound since the 2 drivers reproduce an identical source.

4. All the dipoles act as "surround" sources (diffuse, unlocalizable sound) except the rear 2 create an image.

5. For 5.1 recorded movies (Non EX or ES), the REAR 2 speakers should be turned off (returning the system to a 5.1 setup identical to the picture above) to respect the mixer's vision when mixing for a 5.1 setup.

6. For 5.1 recorded MUSIC, the SIDE 2 speakers should be turned off, allowing the music to create a distinct image in the rear.


Does anyone have any critique of this setup? I am considering doing this very thing, so I would be very thankful for any feedback.




------------------

Mark Hunter

 

[Mark Hunter]

Doesn't anyone out there have an EX system? Lexicon people...how do you do your System 7 setup? Denon people, how do you set up your 6.1 surround?


I am interested in hearing feedback from anyone who has "already been there"...I am about to purchase 8 new Atlantic Tech. speakers, and it would be nice to do it right the first time http://www.avsforum.com/ubb/smile.gif

 

[Steve Dodds]

For a contradictory view, you may wish to check out the latest Perfect Vision. They seem to be recommending direct source speakers all around when used with a Lexicon and Logic 7.


Note, however, that they were not playing with EX.


Steve

 

[Rachael Bellomy]

My EX set-up has 4 250 series L/R speakers for L,R,LS,RS and the 250 center and a single 254 SR dipole for the rear center.I have tried other speakers. In my very small room were the rear center is very close,too close really,I like the dipole best.I think most people need only one rear center. I'm using the Smart Jr. to decode.See my recent thread on adding surround EX how? Spizz also has a recent thread on this subject.Hope this helps.....


------------------


Ms. Bitchlist

 

[Will Gibbons]

Mark,


You may wish to check out http://www.smr-home-theatre.org/Interface.html which shows various room setups. You can also find a Lexicon forum at SMR. There are considerable variances in opinion regarding dipole, bipole, and monopole directs for sides and rears. In general, dipoles seem to be preferred for HT, while directs are slightly preferred for localizing effects for music. I have just ordered my Lexicon. I will go with dipoles for the sides and direct monopoles for the rears, which will be the same as my front speakers. Just a question, I did not see a placement for LFE in your room setup. Am I correct in assuming you will be using a sub?


Regards,

Will
Quote:

Originally posted by milori: Doesn't anyone out there have an EX system? Lexicon people...how do you do your System 7 setup? Denon people, how do you set up your 6.1 surround? I am interested in hearing feedback from anyone who has "already been there"...I am about to purchase 8 new Atlantic Tech. speakers, and it would be nice to do it right the first time http://www.avsforum.com/ubb/smile.gif

 

[Ed Csoltko]

I prefer bipole to dipole speakers. I tested both and found bipoler speakers are easier to setup. (Dipole speakers require specific placements on the side walls.) I have four bipolar Def Tech BP30s in each corner, two bipolar BP2s for the sides, CLR2000 for the front center, and CLR1000 for the rear center (EX channel). I also switch my front L & R speakers with my direct radiating Thiel CS3.6s. I also utilize a Mirage BPS400 bipolar sub along with two passive subs. Speakers are very subjective to every individual. Go with what you like because you have to live with the system you create.

 

[Rachael Bellomy]

Oh, the speakers in my previous post are Atlantic Tech....


------------------


Ms. Bitchlist

 

[Irv Kelman]

It depends on which processor you are using.


Yamaha uses direct-radiating front effect speakers mounted high and outside the left and right front speakers.


Denon recommends dipole to the side for movies and direct further back for music.


For Lexicon, THX specifies dipoles to the sides and (2) dipoles in the rear.


My personal experence has been: I have never heard a home theater that sounded better with direct-radiating surrounds. Dipoles produce the best surround envelopment.


I have a Lexicon MC-1 with M&K SS150THX Tripole sides and (2)rear.




------------------

Irv Kelman

We are THX Certified.

 

[Mark Hunter]

Great! Since I posted, I have order the 8 Atlantic Techs (yes, including the PBM 452 15" subwoofer, although it's not in my picture).


The front 3 L/C/R are direct radiating (of course) and both the 2 sides and the 2 rear are identical dipoles.


I am going to be running the ATs with the Onkyo DS989 7.1 THX Surround EX receiver.


I can't wait!

 

[Philip Brandes]

Milori,


Your 7.1 diagram is incorrect. When using rear dipoles for Surround EX, THX recommended placement is for all adjacent drivers to be in-phase. In practical terms, this means reversing the left- and right-labelled dipole speakers in the rear, which will yield opposite driver phasing from that depicted in your diagram.


You seem to indicate this in your write-up that talks about "inverting" the rears, but you don't reflect this in your diagram.


Arranging the drivers as you suggest in the diagram will not facilitate imaging, it will introduce cancellation effects causing gaps in the soundfield and contributing to the problem of exaggerated localization noted elsewhere in this thread. Since the goal of surround sound (and dipoles in particular) is to produce an enveloping soundfield, this would be counterproductive. If you were using monopoles in the rear, you wouldn't wire them out of phase to heighten their imaging; using dipoles is no different.


There is an excellent article on this as well as many other issues related to Surround EX (as well as the limitations of add-on solutions) at this URL:
http://www.homecinemachoice.com/fram...199912EX.shtml


Also, your other diagram, which I assume is meant to depict a conventional 5.1 setup with dipole surrounds, is in error. The side driver arrays should be mirror images (i.e., the "R" should face the front of the room in each case). You got this right in the 7.1 diagram; it should be the same for a 5.1 setup. Your use of "L" and "R" is a little confusing, as this is normally associated with left and right which has no bearing here. It would be clearer to use standard polarity symbols--i.e., "+" instead of "R" and "-" instead of "L" to indicate phase relationships between the drivers.


Cheers,

Philip Brandes


Quote:

Originally posted by milori: Hmm...Since no one was able to answer this question, I went out and did some actual research. I am posting the reply to my own question in case anyone was following this thread... I found the "recommended" solution for a 7.1 channel system in a Home Theater magazine last night. First, a quick "WHY" of the 7.1 channel setup. In a 5.1 channel setup, it is difficult for movie producers to create an "image" behind the listener to accurately place objects there. For instance, when a space ship flies over the listener, a 5.1 movie setup will "smear" the sound of the ship to the diffuse sides as it approaches the listener. Surround sound is awesome for "diffuse" effects (rain, wind, etc.) but not so good when trying to localize an image. Picture a ship flying towards you with this setup (the sides are dipoles for movie watching) and what happens as the ship approaches the listener. The sound gets more diffuse, and smeared to the sides. http://www.milori.com/ht/fivechan.gif The 7.1 channel system was designed to help with this problem by allowing a discrete rear channel that can form an image, if needed by the movie. There are a couple of dozen movies that use the 7.1 format today (THX EX or DTS ES). Here is my picture of this magazine's recommended way to set up a 7.1 system: http://www.milori.com/ht/sevenchan.gif 1. 3 Front channels - as they always are. 2. For the side and rear surrounds, use 4 identical dipole. 3. The 2 sides are mounted normally, but the 2 left channels are mounted "inverted", so that no images are produces between speakers except that the two rear channels can produce an image between them. Inverting the speakers should have no effect on their sound since the 2 drivers reproduce an identical source. 4. All the dipoles act as "surround" sources (diffuse, unlocalizable sound) except the rear 2 create an image. 5. For 5.1 recorded movies (Non EX or ES), the REAR 2 speakers should be turned off (returning the system to a 5.1 setup identical to the picture above) to respect the mixer's vision when mixing for a 5.1 setup. 6. For 5.1 recorded MUSIC, the SIDE 2 speakers should be turned off, allowing the music to create a distinct image in the rear. Does anyone have any critique of this setup? I am considering doing this very thing, so I would be very thankful for any feedback.

[This message has been edited by Philip Brandes (edited July 04, 2000).]


[This message has been edited by Philip Brandes (edited July 04, 2000).]

 

[Mark Hunter]

Thanks, Philip,


I appreciate the dialog! I was hoping for some differing opinions!


I had read the HomeCinemaChoice article before, and I noticed that the recommendation differed from what I had read elsewhere...in fact, that is what prompted the initial inquiry!


Can you tell more about the "cancellation" vs. "imaging" in those rear dipoles? Those 2 speakers are certainly tricky ones to figure out. I think that its safe to build a diffuse array of dipoles in the +/- configuration all the way around, so I was surprised to see the recommendation that I attempted to recreate in the 7.1 picture.


I agree that the "R" and "L" designations in the picture should really be "+" and "-" as they indicate the polarity of the speakers. If we change the "R" to "+" and the "L" to "-", would the picture be correct?


The speaker doesn't need to physically be upside-down, it merely needs to be phase-opposite to achieve the effect.


Please let me know if I helped clarify the idea, or merely made it more confusing.


As a side-note, I haven't implemented either of these configurations yet, as I am still in the construction phase of my HT (just finished painting today). I have the 4 dipoles in their boxes in the closet.



Mark


PS - Yes, I believe that the 5.1 diagram is incorrect. I don't know how that one slipped by.

 

[Philip Brandes]

Hi Mark,


You wrote:


<< Can you tell more about the "cancellation" vs. "imaging" in those rear dipoles? Those 2 speakers are certainly tricky ones to figure out.>>


As I posted in another thread, the acoustic issue is no different from the one involved in configuring a single set of dipole surrounds--namely, adjacent drivers (i.e., drivers firing towards one another) must be in phase to avoid cancellation anomalies. This is why dipoles for side use are specifically labeled "Left" and "Right"--that insures the front-firing drivers are always IN-PHASE with the L-C-R, to create a continuous soundfield free of cancellation anomalies. If they were out of phase, you would wind up with extremely polarized sound at the front and sides with nothing in between.


The exact same issue applies when it comes to side and rear dipoles--if the rear-firing drivers form dipole sides are out of phase with the adjacent drivers from the dipole rears (i.e., the drivers firing outwards towards the walls), you get the same kinds of cancellation anomalies that would occur between out-of-phase sides and LCR. By reversing the left- and right-handed dipoles in the rears, you insure that all adjacent drivers are in-phase.


This will result in a more continuous soundfield free of cancellation effects. Obviously, you will not get the complete dipole effect from the rears since you won't be sitting directly in the null, but you will get a diffuse effect that will blend nicely with your sides.


<< I think that its safe to build a diffuse array of dipoles in the +/- configuration all the way around, so I was surprised to see the recommendation that I attempted to recreate in the 7.1 picture. >>


Yes, it is in error, and has doubtless contributed to the overall confusion about Surround EX. Frankly, I find far too many errors in Home Theater magazine. FWIW, I tend to place the most trust in getting accurate information from The Perfect Vision, followed by Stereophile Guide to Home Theater. I also try to keep track of online articles that provide helpful and accurate in formation, like the one I cited.


<< I agree that the "R" and "L" designations in the picture should really be "+" and "-" as they indicate the polarity of the speakers. If we change the "R" to "+" and the "L" to "-", would the picture be correct? >>


Are you referring to the 7.1 picture? You still need to reverse the rear dipoles. That way the outward-firing drivers would be "-" just like the rear-firing drivers in the side dipoles.


<< The speaker doesn't need to physically be upside-down, it merely needs to be phase-opposite to achieve the effect. >>


Correct. The simple way to achieve this is to swap the speakers from the way they're labelled (i.e., mount the "Left" dipole on the right, and the "Right" dipole on the left).


<< Please let me know if I helped clarify the idea, or merely made it more confusing. >>


I think you understand what the correct orientation should be; I hope other readers do as well.


<< As a side-note, I haven't implemented either of these configurations yet, as I am still in the construction phase of my HT (just finished painting today). I have the 4 dipoles in their boxes in the closet. >>


When the time comes, have fun!


Cheers,

Philip Brandes

 

[Mark Hunter]

Philip,


Email me the .gif and I will put it on my site and send you back the <tag> to display it on the forum. I have done that for a few other folks here as well.


Mark

 

[Philip Brandes]

Quote:

Originally posted by MBelcher: Could someone clarify with yet another diagram? I am also interested in setting this up. But want to make sure I understand how to match 4 dipoles.

I have a .GIF diagram, but no idea how to post it. I don't have a site to link to. If anyone can tell me how, I'd be happy to do so.


In the meantime, this is really simpler than it might appear from all the discussion. Every pair of dipoles is labeled "Right" and "Left." Use one pair for sides and one pair for rears. Mount the sides as labeled, with the "Right" dipole on the right side of the room and the "Left" dipole on the left side of the room.


For the rears, mount the "Right" dipole on the left side of the rear wall and the "Left" dipole on the right siode of the wall. In this discussion "right" and "left" are always relative to facing the front of the room.


Cheers,

Philip Brandes


[This message has been edited by Philip Brandes (edited July 07, 2000).]