imaging and speaker placement with tv in center


I have a long room 27 wide by 15 deep which is my music room (8' ceilings). I have my speakers 10 ft apart with the stereo cabinet (CWD lowboy) between them and slightly recessed from the speakers which are 26 inches from the back wall. My 36 inch behemoth Proton tv sits on the lowboy. The imaging is great, with soundstage larger than the speakers and at times depth farther back than the wall itself. I get pinpoint imaging that seems to eminate from where the tv is in the centered position.

The speakers are Von Schweikert Vortex Screens (somewhat similar to the VR4's) low driver 28 " off the floor and mids and highs mounted in separate cabinet section above. These speakers have a transparent nature to them, they sound like sound eminating in space, with no hint of cabinet coloration - even though they are 4.5 foot tall monsters. By walking around the speakers one can determine that they do not radiate sound off axis 90 degrees so I don't see that TV between them would interfere with the image, as it's slightly recessed back from the side axis of the speaker. Sometimes the cabinet doors are open for ventilation which could affect the imaging a little (I can always take these off, no spousal unit or gf to confound things cosmetically)

I am in a near field setup. Speakers 11 ' from me and 10 feet apart, 28 inches from speaker backs to the wall (speakers 14" deep). Speakers toed in an inch. My couch is against the back wall, so no back wall reverberation. The side walls are 9 and 6 feet away for cosmetic and traffic flow reasons.

I use the system primarily for music, but it also serves as a great two channel movie setup (not into 5 channel HT).

I have three questions
1) should/does the tv disctract from the imaging?

2) how far from the backwall?

I checked the archives for speaker placement and saw the Cardas setup. His depth to backwall calculation of width x .447 seems ridiculous or only applies to setups where the speakers are along the short wall. For my setup 27' x .447 says the speakers should be 12' off my back wall, or 3 feet from me. Or 6.7 feet if the width is really the short wall distance for calculations, still well out into the room

My setup seems to be very nice from an imaging standpoint, but I would like to fine tune things if possible. I don't have any special room treatments - carpeted, some posterboard music posters on side and back walls

3) does anyone have room placement formulas or recommendations for placing speakers on the long wall like my 27x15 setup? the cardas setup doesn't seem to hold here, except the equilateral triangle end

thanks

Tom
128x128audiotomb
I hate to be someone going against the grain here; however, I have never thought of the "golden rules" as having anything to do with imaging. I would suggest prior to even trying to fine-tune imaging, checking frequency respones with a test cd. If your speakers can remain flat, at your listening position, you will do more for realistic sound than worrying about your TV interferring with imaging. In my experience, I haven't had that much trouble dialing in imaging once I found good frequency response. Besides, if imaging and soundstage are a high priority, try Synergistic Research's Designer's Reference interconnects with active shielding. I believe Garfish will support me on this--you will take imaging and soundstage to whole nother level.

I could be off the mark here but I thought I would throw out my 2 cents.

Gregg
Since I've already said that I put a 7-tube Room Lens copy in front of my TV set (which sits between Quad ESL 63's), let me add that I had previously tried several layers of a thick blanket, and the Room Lens worked MUCH, MUCH better. This could be because my room is on the edge of having too much absorption, and might not apply to all rooms. But if you can try a row of wine bottles, say, raised to a suitable height, I'd compare that with the blanket. They'll diffuse without absorbing, and that could be what's best for you.
I agree with those above who say "if it ain't broke....etc". But if you'd like to try something else, I like the Vandersteen formulae which is an "odd dimensions" placement.

Measure the rooms length and width in inches, then divide these measurements by 1/3, 1/5, 1/7, 1/9 etc. Put the speaker center at one of these distances from the long and short walls. Of course the 1/3 line puts your speakers well out into the room, and this is often not acceptable for various reasons. But, I was able to use the 1/5 line which put the speakers about 54" from the back wall of my 14 X 22' room (speakers on short wall).

If you have your speakers placed on the 27' wall, this formula would have them 36" from the back wall using the 1/5 placement, 1/5 X 180" = 36". Interestingly, the 1/7 line, which in your case is 25.7" from the back wall is almost identical to your present placement of 26" out. Happy Tweaking. Craig
I agree with Moonshyn, with a pair of Quad 63's and a 28" TV between, one can clearly hear the difference by covering up that big piece of glass with a blanket. My center image is much more "dense" and have moved the speakers according due to too much centerfill (better extended on the sides now). Bass (or maybe more accurately in the Quad's case - midbass) actually improves, too.
When you're just listening to music try putting a heavy woolen blanket over the TV.It's easier than moving the TV out and in many cases it makes a big difference.
I admit I'm a bit extreme, but every time I want to do some serious listening I wheel my 32" TV outta there to open up the space between my speakers. The difference is night and day and well worth the effort given the sonic rewards. Everything opens up and breathes better and the bass becomes tighter, and a 3D soundstage appears--this all gets hidden with the TV there. If at all possible I'd try to get the TV on some kind of stand with wheels and show it the door when it's time to listen. It takes some effort and I have to undo/redo a few connections each time I move the TV, but the results are so much better I don't mind doing it. Maybe get a friend to help you remove the TV to see if it might be worth it for you too. Failing this, you might try draping a comforter or thick blanket over the TV which may help minimize any diffractions/reflections the TV may cause. Well, I'm off the the chiropractor(man this hobby takes a toll). Best of luck.

Tim
Anything placed in the room can alter reflections - good and bad - including a TV between the speakers. But remember, the "image" does not exist between the speakers, it exists between your ears.
I agree with the "if it's not broken ..." comment, but for whatever use it may be to you, I have a large TV set pretty well on the floor between my speakers, back from their plane about 1.5', and found that things improved if I put Argent Room Lenses (actually my own DIY imitations) in front of the TV. I found that two Lenses were better than one, so I made a 7-tube Lens, with tubes a bit higher than the TV. It's easy to move for TV watching, and did help the sound quite a bit. Reflections come from everywhere, roughly, and while you don't want to eliminate them completely, most do more harm than good, especially in a smallish room, I think.
It sounds as though your setup sounds great to you, so why mess with it.
My room is 25X15 with large speakers (B&W800's). I originally set them up 5 ft from the back wall (using the "rule of thirds." My speakers are along the long wall, and about 9+ feet apart. My seating possition is about 1.5 ft from the wall behind me. The speakers and I form an equalateral triangle.
This is how I set them up 9 years ago, and although I have made many electronic changes, the system always sounded great, so the speakers have NEVER been moved.
IF IT'S NOT BROKEN, DON'T FIX IT
my system is posted in the virtual systems under
work in progress

cal, evs millenium, arc D200 and ls2 mk II

looking to upgrade the preamp to something serious
After much experimenting, I have placed my Maggies as such, which is nowhere near the Cardas setup: tweeters on the inside, inner edge 44 in. from back wall, outer edge 48 in.
from back wall and inner edges 56 in. apart

I also use my system for 2 channel only DVD. My Sony HDTV in the middle disrupts the central imaging, but I have minimized the damage by carefully moving the TV 1/4 in. at a time. There is a spot about 32 in. from the back wall to the front of the TV where there was the least problem. It is not as good as no TV, but it was well worth the time of experimentation. With good source music, you should be able to place your TV in one evening. You can even use broadcast TV sound to double check, as its highly compressed center image is ideal for this type of test.
Good Luck!