Dipole Speaker Placement w/48" flat panel TV

[dlneubec]

I've been wondering about the optimum speaker (or should I say TV) placement for dipole speakers in relation to a large flat panel TV (say 48" across). The TV would be setting on a stand and have to be at least 12" from the wall, probably a bit more. It can't be hung on the wall. Let's say the speakers are 42" from the front wall and 30" from the sides (see graphic below).

Given that scenario, what would you presume to be the best positioning. With the screen closer to the wall, directly between the speakers, with about 1' clearance or somewhere in between and why?

[Saurav]

Are you not toeing the speakers in at all? I'd put the TV roughly on the line extended from the speaker baffle, since that'll reduce the amount of energy sent to the TV to be reflected off it. So with the speakers toed in, that means the TV is somewhat behind the speakers.

[ThomasW]

The closer to the screen the more issues with comb-filtering.

My Iris dipoles are 29" in front of a 52" LCD. If I place a couple blankets on the screen the soundstage improves. So I'm planning building a removable panel made with OC 703 that sits in front of the screen when the TV isn't being used.

[---k---]

Dan,

My speakers aren't dipoles, but I would imagine the effects of the TV to be similar or even worse with dipoles. My speakers are located with the front of the baffle approximately 24" from the back wall (about 10" behind them). I have a 52" DLP (16" deep and 4" off the back wall) in between the speakers. IIRC there is about 18" from inside edge of the speaker to the outside edge of the TV.



I find that if the front of the TV is in line with the speakers the sound stage depth collapses. There no longer is depth behind the speakers. Sound radiates from a plane between the speakers and in front of them. The presentation becomes flat. You loose some of the performer is right there in the room with you feel. I haven't really noticed a huge change in the tonal balance, but it could be because the difference in the sound stage depth and presentation is so different. Just pushing the TV back about 4" behind the TV makes noticeable improvements. But getting rid of the TV is the best option. Its huge.

I feel good about discussing what I've heard. For an explanation of the physics behind what I hear, I pull crap out of my butt to make myself feel smart. So take the rest with a grain of salt, but the logic makes sense to me.

I think that without the tv the sound waves are able to roll around the speaker and fill that space, and that filling the space with sound gives it a spacious sound. But with the tv, the sound is all radiating from that plane between the speakers and depth can't develop behind the plane because the sound waves can't physically get there.

I would fear that dipoles would be worse, because the back wave would bounce off the back of the speaker and just be trapped behind the speaker.

[dlneubec]

Ryan,

I think that dipoles are quite different in the sense that they naturally have a figure 8 polar radiation pattern, which puts the biggest nulls at the sides of the speakers. That suggests that spl output is lowest in that null area, reducing reflections, which would not be the case for a box speaker like yours. I could be way off here, however.

My initial thinking is that if you can't get enough space behind the dipole to the TV to keep it from acting like a wall and causing first refections too soon, then you would be better off with the flat panel in the null area, to the sides, assuming some minimum clearance between the speaker and TV edges could be maintained. I don't know what the minimm distance would be, however, and I could be entirely wrong about putting the flat panel in the null area. My doubt about it is why I though to post this thread.

Thomas has an interesting option with covering the TV for music, but that obviously has its shortcomings for HT. :W

[Dennis H]

My initial thinking is that if you can't get enough space behind the dipole to the TV to keep it from acting like a wall and causing first refections too soon, then you would be better off with the flat panel in the null area, to the sides, assuming some minimum clearance between the speaker and TV edges could be maintained.

That's my thinking too, Dan, but I'm wondering if you'd lose some of the dipole goodness by blocking the direct front wall reflections with the panel. OTOH, Thomas is absorbing those reflections with a blanket so maybe it's not so bad.

Thomas, can you try moving your TV forward so it's in the null of the dipoles and see (hear) what happens? If it's in the null, there shouldn't be much comb filtering like with a monopole.

[ThomasW]

Thomas, can you try moving your TV forward so it's in the null of the dipoles and see (hear) what happens? If it's in the null, there shouldn't be much comb filtering like with a monopole.

The TV is in a fixed location, and the Isiris are moved as far back as they can go, so there's not much I can do....

[Dennis H]

Okay, how about just sticking a sheet of cardboard or whatever in the null to see what it does to the soundstage? Does it collapse the depth like Ryan said with his monopoles or....?

[ThomasW]

I'll try that in the AM....

[---k---]

Dan,
Like I said, I don't know. Even in the null, I'm thinking like Dennis. I guess we'll find out soon.

[Rudolf]

Given that scenario, what would you presume to be the best positioning. With the screen closer to the wall, directly between the speakers, with about 1' clearance or somewhere in between and why?

My opinion: TV as close to the front wall as possible. Dipoles in the same position as shown, but toed in in such way, that the dipole null is pointing to the mid of the TV screen. Any remaining sound reflected from the TV would have to bounce off the opposite side wall and will reach the opposite ear first, which doesn´t harm.

[AJINFLA]

Get rid of the TV. There's nothing but crap on like 500 channels (ok, with the exception of the NFL network) and you've got dipoles (well, not quite) to listen to.

cheers,

AJ

p.s. if you keep it, I like Rudolfs suggestion.

[ThomasW]

Okay, how about just sticking a sheet of cardboard or whatever in the null to see what it does to the soundstage? Does it collapse the depth like Ryan said with his monopoles or....?

Yes it makes the soundstage more 2D.

[Dennis H]

Yes it makes the soundstage more 2D.

Thanks for doing the experiment, Thomas. :T

[---k---]

Yes it makes the soundstage more 2D.

Well, I guess it sounded good in theory. Thanks.

[dlneubec]

I did a little experimenting last night and have to agree with Thomas. The soundstage was compromized with the TV in between the speakers. They sounded more like box speakers than open baffle speakers. The negative effect of first reflections is reduced, however, to my ear, which was a positive. Overall, I prefered the TV back as far as possible, with the speakers toed in to put the TV a little more in the null area and the speakers moved a little closer to the side walls so they are further from the TV.

This was pretty much Rudolph's and Aj's suggestion.