Dual Centers for Front Projection?

Dennis Gardner

I have seen alot of setups that have 2 center speakers across the front of the bottom of the screen. I understand this type of setup giving you a wider center image. My question is what happens when you use a speaker above and below a large screen to center the voices within the picture. I am aware of comb filtering, but can this be pulled off with success?

I have an 8 foot wide 4:3 ratio screen and have been using the CS-350LS below it with nice results. I am moving to a 16:9 builtin screen similar to this.
Built-in Screen


I will have enough space above and below for the CS350s.


Your thoughts are appreciated,

Dennis

scottvamp

Hi Dennis, I have done the above and below center on an 8.5' screen and it worked VERY well. The key was the custom braket i built for the top center. It gave me the ability to angle the speaker. So i was able to angle the top speaker directly to the seating position. It worked very well. I may have some pics somewhere but I'm not sure. Using the same speakers it is not an issue - it actualy feeled the large srceen much better than a single position.
Go for it and have fun!!!

Dennis Gardner

Scott,

I'll be able to adjust the angle of both centers. I will be building them into shelves above and below with grill cloth fronts.

Having the center below my current 69" tall 4:3 for widescreen DVDs puts the voices at chest level at best even with it tilted up.
The center is actually only around 12" off the ground as it is today. Going 16:9 will allow it to be almost a foot higher.

Thanks for the response,

Dennis

scottvamp

It should rock! Enjoy!:cool:

Larry Chanin

Originally posted by Dennis Gardner
I have seen alot of setups that have 2 center speakers across the front of the bottom of the screen. I understand this type of setup giving you a wider center image. My question is what happens when you use a speaker above and below a large screen to center the voices within the picture. I am aware of filter combing, but can this be pulled off with success?

Hi Dennis,

I'm wondering whether you've seen this thread that I started on the subject?

Stacking Dual Center Channel Speakers?

This is precisely what I plan on doing using CRS+ for the dual centers. Refer to the attachment.

As I discuss in the thread, I believe that comb filtering can be avoided if the primary listening area is equidistant from the two stacked center speakers. If you only have one row of seating there should be no problem at all. I will have two rows of seating so one row might be subject to comb filtering.

Having said that, I am still somewhat sceptical that comb filtering is a real problem in the first place.

Scott: If you have any pictures of your arrangement, I would be very interested in seeing how you achieve the angling of the speakers.

Thanks.

Larry

Dennis Gardner

Larry,

"Can of Worms" or solid acoustical theories? Who knows. Our
theater rooms are far from anechoic chambers. Questions like ours brings out all the "experts".

Just as you did, I simply wanted to know if anyone has had any luck trying this before I go far in my building of my screen enclosure.

Good luck and let me know how your CRS+ centers work out.

Thanks,

Dennis

Larry Chanin

Originally posted by Dennis Gardner
Larry,

"Can of Worms" or solid acoustical theories? Who knows. Our theater rooms are far from anechoic chambers. Questions like ours brings out all the "experts".

Hi Dennis,

It's not that I don't necessarily believe that comb filtering exists, just the contrary. I believe that it's a natural part of our acoustic environment. So much so that a little extra comb filtering is not likely to be recognized especially in a multi-channel home theater.

For example, in normal everyday life, one thing is absolutely certain, sounds will bounce off the floor or ground. This ground bounce is an unavoidable natural occuring phenomenon. So what happens when the reflected sound and the direct sound reaches the listener? Comb filtering. After a lifetime of being emersed in it our hearing expects it as the norm.

Just my two cent's worth.

Larry

Sami

I think I will be doing this as well. I was thinking of getting one extra LSi7 and using it for centre but most likely I will go with just 5.1 instead of 7.1. That would leave me with two LSi7's for each centre, front and surround.

Y-cable from the receivers centre channel to external stereo amp and from there to the speakers. I don't think I would want to run two 4ohm speakers from one receiver channel...

I will be moving next month and I can't wait to finally get all-around LSi HT/music setup. Corner lot and the entertainment room will be on the corner side, just so the new neighbours don't mind the SVS PC Ultra.

gmorris

http://www.legacy-audio.com/reviews/legacy-system-rvw.pdf

Here is a link to a review. There is a picture in the review with a center channel speaker above & below the screen. It looks very nice.

wlrandall

Hmmm...interesting. To me, this would present the same set of problems that occur with multiple sub locations. Once you get out of the sweet spot, I would think that there would be all kinds of weird things going on. Personally, unless this is a theater for only oone or two people, I'd do a horizontial array below the screen.

Just my .02.

scottvamp

Originally posted by scottvamp
Hi Dennis, I have done the above and below center on an 8.5' screen and it worked VERY well. The key was the custom braket i built for the top center. It gave me the ability to angle the speaker. So i was able to angle the top speaker directly to the seating position. It worked very well. I may have some pics somewhere but I'm not sure. Using the same speakers it is not an issue - it actualy feeled the large srceen much better than a single position.
Go for it and have fun!!!

Like I said - been thier done that - it sounded very good.
NO cancelling - No acoustical traps - No tiny sweet spots. Not any more than running a single center anyhow. Where do you guys come up with this stuff? Hardly anyone owns a FP system - little lone tried such a setup.
Sorry RANT*
Anyway that time period of my theater has no pics. I soon went to 7.1 and 3 center channels across the bottom of the projector screen . Which filled the sound across the screen much better.
:cool:

DarqueKnight

You could call several local cinemas and ask how they arrange their center channel speaker(s).

Larry Chanin

Originally posted by scottvamp
Like I said - been thier done that - it sounded very good.
NO cancelling - No acoustical traps - No tiny sweet spots. Not any more than running a single center anyhow. Where do you guys come up with this stuff?

Hi Scott,

We're not coming up with this stuff, it's the experts telling us comb filtering is a problem.

Larry

Larry Chanin

Originally posted by Dennis Gardner
Larry,

Just as you did, I simply wanted to know if anyone has had any luck trying this before I go far in my building of my screen enclosure.

Good luck and let me know how your CRS+ centers work out.

Thanks,

Dennis

Hi Dennis,

Well, I just completed my screen shadowbox. I went ahead and purchased a pair of CRS+ to use as centers and ran a second set of speaker wires to the upper center. I purchased a Parasound HCA2200 amplifier (220 watt per channel). I'm using this to power my main (SDA-1Cs) speakers. This freed up my Parasound HCA2003 (200 watt per channel) to power the CRS+s.

You can see the physical arrangement by clicking on the concept drawing.

I hung one CRS+ over the screen tilting down at about 15 degrees. The other is under the screen tilting up at about 10 degrees. It is set further back so that it is about as far away from the primary listening area as the mains and the upper center channel (which is almost 9 feet in the air.)

My speakers are sitting on a stage that is filled with about a half a ton of sand. The main speakers and the lower center channel speaker are sitting on solid concrete block stands covered with carpet. The mains are elevated about 15" so that their tweeters are centered vertically on the screen. The two centers project a sonic image centered horizontally on the screen.

Anyway, I've only had this setup for a day and I've only listened to two movies. However, so far things sound very good. Even though I've recalibrated the centers to ensure all levels are the same, the addition of the two CRS+s provides a much fuller front soundstage. It will take some getting used to the new dominance of the center channel. The bass of course is much more pronounced than my CS400i could provide and the timbre is now perfectly matched with my mains.

So...life is good!!:cool:

Larry

scottvamp

That's cool Larry, I would like to see some pics and equipment list.
Sounds like a killer HT rig.

Larry Chanin

Originally posted by scottvamp
That's cool Larry, I would like to see some pics and equipment list.
Sounds like a killer HT rig.

Hi Scott,

Thanks for the interest. My camera hasn't been working too great. Give me some time and I'll see what I can do regarding photos of the current status of my home theater.

As far as equipment goes, here's a link to a current list:

Larry's Home Theater Equipment

Larry

scottvamp

Dam Larry, you must have the most killer HT setup on the forum.
My first FP was an Infocus, those screenplay's are very nice. I just could not afford a FireHawk for the size screen I had.
Ya da man!!!!!

Larry Chanin

Hi Scott,

Thanks you're very kind.

I'm new to front projection, but I'm quite happy with the InFocus ScreenPlay 7205 and the FireHawk screen.

My home theater is still under construction. The only thing that is completed is the stage and screenwall/shadow box.

I don't have a digital camera so I'll have to expose and develop a roll of film. If the pictures turn out I'll start a new thread showing my "Almost All Polk Audio Home Theater".

Larry

Larry Chanin

Hi,

For those interested I've started a thread with some photos of my home theater showing stacked center channel speakers.

Almost All Polk Audio Home Theater

Larry