Axiom Home Page Forums General Discussion Home Theater Center Channel overkill?

hi,

it's great to have discovered a forum of great experience breadth and intelligent discussion.

my question involves use of the center channel speaker. in the old days of stereo (last week), i used the "dialog enhancer" function of the DVD player to mix the center channel into the left & right speakers. it worked very well.

with the receipt of my axiom system, that function was turned off, and the center channel enabled in the AV receiver - and volume set per instructions.

to me, the sound from the center channel seems very localized. in other words, with eyes closed, it's very easy to locate the center speaker. the dialog of people on-screen seems "shifted" towards the center speaker, even if they were slightly off-center.

when i was running things in "dialog enhanced" (no center speaker, dialog merged with left & right speakers), the sound was MUCH more "buried" in the screen. the stereo speakers were fine at creating the soundstage. IMHO, it seemed they did a better job.

soooo, here's my question: has anyone ever observed this before? is there a solid reason (other than architecture) that the center channel should be preserved?

i'm going to make a few tweaks with the next movie, but turning the center sound downwards would seem to only bury the dialog.

all comments appreciated, thanks.

Elden

How far apart are your mains ? My experience was that a center channel wasn't really needed when the mains were only a few feet apart straddling a normal sized TV, but as the system and spacing grew the center channel became more important.

It might just be that the center channel level is turned up a few dB too high.

Hi,

this spider's eye view might describe things better:



about 11.5 feet betwixt the towers. the front of the center channel is 13 inches from the back wall.

a projected image appears between the sconces (8 feet across horizontally, not diagonally) maybe 2 feet above the center channel

...and that's last weekend's snowfall

any other comments on speaker placement welcomed.

Thanks,

Elden

Hello Sidereal,

Your DVD player's "dialog enhancer" function that mixes the dialog into both speakers in a stereo setup works very well so long as you sit exactly on-axis between your main speakers. If you move to the left or the right, or if someone else is viewing the movie and sitting to one side (off-axis), then the dialog will collapse to the left or right speaker, whichever is closer to you or the off-axis viewer.

This is the intrinsic flaw of stereo. Virtually all vocal pop, jazz and rock recordings (not operas) are mixed with the vocals pan-potted to the center, which is great if you are sitting midway between the front speakers. When you move to the left or right of the room, the stereo image largely collapses, and the vocal shifts to the speaker nearest you.

Yes, a center-channel speaker "localizes" the dialog--indeed anchors it--to the center speaker, just as it does in a movie theater, to the center speaker behind the screen. If it didn't do that, half the audience to the left or right of the theater would hear the dialog coming from the left or right side of the screen, respectively. No good.

So, here's the trick. Locate your center as close as possible to your TV screen. If it's more than 2 feet away, the dialog may seem disembodied from the actors on-screen.

Independently adjust the center-channel volume, so you get a natural mix of the dialog with the stereo left-right music and effects. That's a huge advantage of having a dedicated center-channel speaker. You can control the mix--of dialog vs. music and effects. You can't do that with your DVD player's "center-channel enhancer".

I even tweak the center-channel balance of singers when I play back stereo vocal CDs or opera CDs in Pro LogicII or H/K's Logic7 (or dts's Neo6).

Regards,

Elden,

Nice photo.
A further addition to my comments. With the center 2 feet away from the projected image, you are on the margin, which is likely why you find the dialog localized to the center speaker.

Sometimes mounting the center directly above the screen image, aimed down, will help. In many situations like yours, the solution is to run two center speakers in parallel, in mono, one mounted above and one below the screen. They will then form a phantom image of the dialog in the center of the screen. And you can still control the level of the center-channel mix.

Regards,

Wow, nice room! And I thought *I* had window issues with a projector. Do you have shades that lower or do you only do movies at night? Just curious (and envious!).

Do you have an SPL meter? Use it to level match all of your speakers. That might help.

Fantastic room!

The toe-in of the M80's looks a little extreme to me. They also seem quite far apart, and fairly close to the back wall. Are you completely satisfied with their positioning for pure stereo? It seems to me that the interaction of the M80's with the room might be as important to your overall satisfaction as tweaking of the center channel. Just a thought.

Thanks for the pic. Cool.

Edit: you might also consider pulling the VP150 forward a bit to avoid coloration from it either being too close to the wall or getting early reflections from the table. It's also good to have the L/C/R on about the same plane (rather than having the center recessed as it is now).

Elden, that is a fantastic room. Are you happy with how the horizontal 600 performs in there?

I have to agree with Tom - the toe-in does seem a bit agressive, but that may be because of the eleven and a half foot separation. I might try pulling each of them in about 6 to 10 inches, and easing up on the toe-in. The great thing is that if you don't like it, you can always put them back.

Here is a picture of my 80's, ~8 feet apart, with seating ~10ft back. This seems to work fairly well in that room.

Also, I would try pulling the 150 right to the front of the table. This will eliminate any reflections you are getting off the top of the table. Don't forget to adjust the speaker distance and level settings in your receiver.

You didn't mention what type of receiver are you running. Some have extra settings for the centre speaker. (centre EQ/dialogue "raise"/dialogue enhance) Have fun playing around with them!

As tomtuttle mentioned, the L/R speakers appear to have too much toe-in. I think you are dealing with a narrow soundstage as a result. Try facing them with minimal toe in. I guarantee you will get a WIDER soundstage, and the center channel will then fit in nicely. Let us know how it turns out!

Hi,

THANKS for the various inputs.

the room was designed around astronomy. i wanted to see the southern stars from the couch. of course, they make an excellent background to a movie or listening. i wasn't thinking about home theater back then (about 7 years ago).

it's a bit too hard, and some "dampening" will have to take place.

to answer as many of the above:

PeterChenoweth - yes, movies only at night. many other things to do during the day.

Real80sman - YES, the 600 performs admirably. i had once calculated the resonant frequency of the room to be 31hz (or so). thanks for the pictures. they'll be helpful.

the receiver is due late this week / early next week - a Denon 4806CI. i'm still slogging through the PDF of the owner's manual.

tomtuttle, Nachosgrande - toe-in & position noted. i have little experience with 'box' designs. my previous speakers were Allison: Ones, and their placement was well spelled out & documented by the designer.

Alan - thanks for the attention. it's not too often i can get the resident expert to poke his nose into my living room and make suggestions !

again, all the input is appreciated. your collective experience is truly valued.

Elden