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Getting phantom image perfectly centered

This is driving me nuts! I can't get the image centered unless I turn the balance control on the preamp to the 1:30 position. I've tested the system from source to loudspeakers from an electrical standpoint, so I know each speaker is getting the exact same electrical signal with a test tone and each speaker outputs the same dB with the same test tone.

So, it HAS to be the speaker room interaction, right?

I've read http://www.linkwitzlab.com/listening_room.htm and I THINK I understand everything.

All of the following measurements are in inches:
The room is 189 long by 144 wide. (15.75 feet by 12 feet)

The speakers are precisely 45.5 inches from the back wall.
They are each 26.5 inches from the side walls with a caveat. The left speaker is 27.5 inches from the window sash, which is 1 inch deeper than the wall. It's 30 inches to the top panes of glass and 28 inches from the lower panes of glass. But measured from the actual wall, both speakers are exactly 26.5 inches from the wall.

The speakers are precisely 90.5 inches apart.

The listening position is pretty close to 45.5 inches from the back of the room. The back of the room is open to the rest of the house and the wall on either side of the opening is symmetric with each partial wall being 36 inches.

Listening to a recording were I know the voice is dead center, the voice is actually just to the left of centered, and I mean "just". Would you recommend moving the left loudspeaker towards the center an inch or two?

What kinds of techniques to you use to "dial it in" when you've got a really revealing system and you are past the "math" and it's all more art than strict science?

I think you should be able to see a picture of my listening room here: http://orion.quicksytes.com/download/file.php?id=3096

My apologies if this isn't the right sub-forum to post this question to.
marktrav
bmwmcab
63 posts
 
Weebeesdad,

That's also what I thought at first but through trial and error, I found that this method actually worked for me. If the image is not perfectly centered, it really bugs the heck out of me and I would try many things to correct it. The up and back method works to a certain point but it hinders the harmonics and tones. Ymmv.
statman's avatar
statman
285 posts
 
You sir have an issue with your room. Move the speakes all you want but it will still return. That will be eliminated with proper measuring and room treatments. Paying particular attention to the "glass window"! The most likely culprit is your ceiling being untreated. I learned that when I had my room finished using Vicoustics panels throughout the room. In the past there had been trouble locating a clear center image sometimes on playback. Three different sets of speakers, both Electrostatic panels and moving coils have been thru this room. They all did it until I treated the ceiling and walls, especially behind your listening area. Even though it's open there maybe something reflecting behind you causing signal errors. Best of luck to you.
playpen
161 posts
 
Have you measured tweeter height on both speakers from the floor?I found they need to be exactly the same height,not a half inch off but dead even.My brother was having problems till I went over and found his tweeters were a half inch off,that cleared up his complaints.He also suggested putting some carpet on the one side wall which really made an improvement in my system.Mine are dead on now,perfect,and it costs no money.
playpen
161 posts
 
I forgot to mention also to check with a level the tops of the speakers so that they are perfectly level with each other.That bubble is dead on exact same on both my speakers.
marktrav OP
24 posts
 
I found the problem and I feel like an idiot. Remember, these are 4-way active x-o speakers completely built from scratch.

I had mis-wired the polarity of 4" driver from the instructions. I'm not sure how I did that, but I let it go for months chalking it up to bad acoustics, less than top quality electronics, etc. I was starting to wonder if there was another 4" driver that could be substituted because it just sounded brittle in the upper midrange. The upper midrange is why you spend so much money in this hobby! I upgraded to an Ayre QB-9, a Parasound JC-3+ and a few other things. I was about to start considering the amps.

After a glass of wine in a listening session, I just decided to swap the speaker connections on the 4" driver (knowing full well I'd wired it perfectly when I built it!!!! - NOT!) and low and behold, what a glorious sound!

I returned the balance control to the middle position and returned the speakers to their former mirror image of each other and now I'm in heaven. (Again!)

It's funny how good these speakers sounded for the past several months even with that mistake.

I get to enjoy that "new equipment" high all over again. :D
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