question about imaging

motorstereo

Hello; I have a question about my sda's that I'm sure some of polk gurus can answer. I have a pair of polk sda 2.3s with the tweeter upgrade and bass brace. The speakers are out from the wall about a foot and are about 9' apart. I like the sound very much but I recently had a good friend over who's much more of a critical listener than I am. He pointed out that there's a big hole in the middle of the soundstage. Yesterday I did some critical listening and yes he's right. Compared to my other conventional speakers there's quite a gap in the middle of the imaging. As soon as you unplug the sda interconnect the image falls into place. Is this the way these speakers are designed or is there something amiss somewhere? My speaker phasing is correct and I'm running them with a bose 1800 power amp. I haven't done the crossover upgrade yet but it is on the want to do list. I'm wondering if the crossover might be really tired or is this the nature of the beast to have the image spread out; so to speak?

Ricardo

Two hints here:

-Move them a bit closer together (how far from the speakers is your luistening position?)
-Don't bring your friend any more

george daniel

^^^^what he said^^^ and you may want to tweak your listening position if you cant move the speakers.

Deadof_knight

the sweet spot is the same distance from your speaker as the distance they are apart on the sda isnt it .

Mix-no-mo

Try to position them in an equilateral triangle with you being the third point. From there, you can tilt them in towards each other until you get the best soundstage.

ben62670

Mix-no-mo wrote:

Try to position them in an equilateral triangle with you being the third point. From there, you can tilt them in twords each other until you get the best soundstage.

This is usually the correct answer for most speakers, but SDA's are a lot different. They need to be at least 3 feet from the side walls, and 6-8 feet apart. Try to avoid toeing in your speakers, they should be parallel to the walls. Also experiment with the distance from the walls. SDA's like to be closer to the walls than most. 6 inches to 1 foot. All this info is direct from the Owners manual. Unless you are in a wide room put them unnaturally looking close together and work your way out.

Enjoy
Ben

DarqueKnight

motorstereo wrote:

The speakers are out from the wall about a foot and are about 9' apart....I like the sound very much but I recently had a good friend over who's much more of a critical listener than I am. He pointed out that there's a big hole in the middle of the soundstage.... As soon as you unplug the sda interconnect the image falls into place.

The SRS's in my home theater are 7-1/2 feet apart and there is no problem with center fill.

You really did not provide enough information about your listening environment.

1. What are your room dimensions and what is the length of the wall that the SDA's are placed in front of?

2. How far are the speakers from side walls? Reflections from side walls can mess up the imaging. Since you say the center image fills in when the SDA cable is disconnected, it appears that something in your room is interfering with the dimensional drivers' dispersion patterns.

3. How far is your listening position from the front of the speakers? According to the manual, for optimum imaging, the listening position should be equal to or greater than the distance between the speakers.

4. Is there a wall immediately behind your listening position? Depending on your room size and ceiling height, reflections from a rear wall, coupled with reflections from side walls, could mess up your imaging.

hearingimpared

These speaker definetely must not be toed in with the SDA interconnect is use. Placing them a bit closer together is good advise. Also, someone noted that the sweat spot is the distance from center as the speakers are apart. In my room, that sweet spot would be 6'3" because the speakers are exactly that measurment apart. However, I like to sit about 6' 10" because the imaging and sound is more natural to me. Sitting in this position however can cause the center imaging to appear a little weak to me on certain recordings to I move a little closer accordingly.

The recommended speaker spacing from each other in the manual is 6 to 8 feel apart. Nine feet may be too far.

Experiment. . . it sounds like you have plently of space in your room to move things around.

motorstereo

Wow! Thanks for all the responses guys. Lots of helpful hints here. Ok I got out my measuring tape and here's the exact dimensions. They're exactly 8' apart. One of them is very close to a side wall and the other has about 4'. They're 9" away from the rear wall. And the room size is 15'x20'. I have my equipment rack between the 2 speakers. This comes up 4' high and out 2'. I do try to listen to them in an equilateral triangle. Meaning about 6 to 8' out from dead center. Moving them anywhere within the room really isn't an option. I pretty much built my equipment rack to accomodate these big guys. I could toe them in slightly but I remember reading the set-up and they recommend not to do that. I do love these speakers but now the center image or lack of it has me wondering if there may be something askew or if this is how they were designed. They seem to spread the image outward which is nice but now that I'm aware of the hole in the middle it makes me wonder.

hearingimpared

motorstereo wrote:

Wow! Thanks for all the responses guys. Lots of helpful hints here. Ok I got out my measuring tape and here's the exact dimensions. They're exactly 8' apart. One of them is very close to a side wall and the other has about 4'. They're 9" away from the rear wall. And the room size is 15'x20'. I have my equipment rack between the 2 speakers. This comes up 4' high and out 2'. I do try to listen to them in an equilateral triangle. Meaning about 6 to 8' out from dead center. Moving them anywhere within the room really isn't an option. I pretty much built my equipment rack to accomodate these big guys. I could toe them in slightly but I remember reading the set-up and they recommend not to do that. I do love these speakers but now the center image or lack of it has me wondering if there may be something askew or if this is how they were designed. They seem to spread the image outward which is nice but now that I'm aware of the hole in the middle it makes me wonder.

Here is a biggy. . . the front of the drivers MUST be at least two inches in front of anything between the speakers. When I first connected up my rig I didn't have them out that far and there WAS a huge hole in the middle of the image. that may be your problem right there.

Don't worry about coming out from the back wall too far right now. Get the imaging right and then there are other things you can do to get the bass straightend out.:) Hope this solves your problem.

ben62670

"One of them is very close to a side wall"
You really need to get that one at least 3 feet from the side wall, or it won't be right. I have one of mine 3 feet from the side wall, and there is no wall for the other one. Even with that scenario I get annoying high frequency reflections. I am looking for egg crate foam to treat the wall on that side to help compensate for bad room acoustics.

Enjoy
Ben

hearingimpared

ben62670 wrote:

"One of them is very close to a side wall"
You really need to get that one at least 3 feet from the side wall, or it won't be right. I have one of mine 3 feet from the side wall, and there is no wall for the other one. Even with that scenario I get annoying high frequency reflections. I am looking for egg crate foam to treat the wall on that side to help compensate for bad room acoustics.

Enjoy
Ben

Ben if you have a Calico Corners in your area or any fabric outlet for that matter you can get a six foot piece of very dense 3 to 4 " thick foam that works very well in the corners on the speaker side of the room. I have a six foot piece on the left side of the room and a 3 foot piece on the right and it works very very well. I think my wife got them for like $34 all told. . . she really knows how to haggle with merchants. All I really have to do is cover them in some type of fabric to make them more WAF acceptable.

BTW three feet from each wall is the absolute minimum. Mine are a little over five feet from the side wall and it is almost perfect.

ben62670

hearingimpared wrote:

Ben if you have a Calico Corners in your area or any fabric outlet for that matter you can get a six foot piece of very dense 3 to 4 " thick foam that works very well in the corners on the speaker side of the room. I have a six foot piece on the left side of the room and a 3 foot piece on the right and it works very very well. I think my wife got them for like $34 all told. . . she really knows how to haggle with merchants. All I really have to do is cover them in some type of fabric to make them more WAF acceptable.

BTW three feet from each wall is the absolute minimum. Mine are a little over five feet from the side wall and it is almost perfect.

Thanks again for yet even more good advice. I whole heartedly agree with 3 feet being the minimum. Trying to convey this train of thought to newbies with SDA's(myself included) is tough. Its almost as bad as explaining wire differences.

hearingimpared

ben62670 wrote:

Its almost as bad as explaining wire differences.

Oh no . . . you may have released the Kraken!!! WAAAAAAAAAA

motorstereo

Thanks again guys for the all the quick responses. I guess I'll have to live with the hole in the middle. I didn't realize that putting one sda up against a wall would make that much of a difference but I guess it must. My equipment rack is slightly forward of the speakers so that may have a detrimental effect on them as well. Only one thing left to do; tell the Mrs. we need a new building so we can listen to the big polks at they're intended to be listened to. On second thought maybe I will try to figure out a way to move them around somewhat. Unfortunately my listening room has to double as a motorcycle garage, a workshop, and a gymnasium. Space is precious indeed so truthfully I think I may have to turn to other sources for the times that I desire precise imaging. Thanks again for the help guys.

ben62670

Treat your walls like H said that will help quit a bit.

NJPOLKER

Its simply amazing!! After reading this thread, I have read the manual too, I moved my SDA's apart another foot to about 7' and to about a foot from the rear wall. I generally sit about 7' from the center point of the speakers. They sound even more amazing!! The thing I did not take into account was my television that sits between the speakers, it was about 6'' in front of the faces of the SDA's and this made a huge difference in the sound stage.