off axis or tilted speaker placement ?


I have a long and narrow L shaped room in the basement where I put my system (30'x 12' x 7'). Played numerous ways of placement but still not happy as there is definitely some kind of room mode comes into play, e.g., some notes in piano solo works just does not sounds right, and imaging is not quite good.

My system: Harbeth Compact 7ES3, Exposure 2010s, SB3 and a Tubemagic D1 DAC. Here is what I tried so far and none works:

1. speaker against short wall with 5 feet to the back wall and 3 feet to the side;
2. pull out speaker further 7 feet even 10 feet
3. put speaker against long wall but since I only have 12', it is quite awkward as my chair is almost backup to the wall.
4. toe in vs no toe in.

Finally last night I decide to try the following: speakers against short wall but about 8/9 feet away, and instead of firing it straight down the L room, I tilt both such that the center of two speakers and listening position forms a line that is not parallel to the long wall but tiled at a slight angle. This seems to improve the room mode and also imaging.

Wonder if this makes sense. Any other suggestions to try ?

I recommend trying the long wall again. Good quality speakers can be spread pretty far apart. I would try as much as 10'-15' apart. You may not get a lot of depth, but you will have a huge soundstage. Since your room is only 12' wide you will need room treatment on the wall behind your listening seat. I would treat approximately 8' of that wall. There should be no need for any further room treatment. The end result should be a full bodied sound with excellent midbass and a big soundstage. Good Luck!
That is more or less what you are supposed to do, if I am understanding you correctly. Keep them away from the side walls as well and point them so a line projected from the centre axis of each speaker meets at a point (eg 10ft) behind your listening position.
Thanks for suggestions above. I have not tried placing the two speakers along long wall and really far apart, as I'm already against the wall. Sound stage seems to be quite good regardless how I place them but there is definitely a difference for standing wave on some notes. For now I settled with tilt everything at a slight angle as that seems to get cleaner sound.
I have a similar room and use a similar setup. My speakers are more omnidirectional/360 dispersion in nature. They tend to fill the front of the room with sound more than project it forward and the result is the short length of the L shaped room up front acts like a soundstage, kind of like what one would hear at a small clus like the Vilage Vanguard in NYC, if you have ever been there. I tend to sit at least 10 feet or more back from the speakers in the narrow section and find that gives a nice lifelike perspective with excellent soundstage overall. If I sit closer up where the front wall to the left is within eyesight, teh soundstage will expand accordingly to the left for a closer perspective with a wider sound stage. I have been very happy with this setup now for a few years.
Try the Audio Physics set-up method. Long wall placement, speakers half-way into the room, listening position against back wall. As Rrog suggested treat the wall behind you. As far as spreading the speakers apart, start at 7' and gradually move them further apart until the center image begins to sound diffuse. Then pull them a bit closer to snap the image back. As for toe-in this is completely experimental and would help if someone could assist you by toeing in the speaker as you are listening so you can dial it in properly. Me, I like the speakers toed in so the axis crosses a couple feet in front of me, but my speakers were designed with this in mind. I know Spendor recommends trying this arrangement and having owned them can say it works but is room dependent. Harbeth may be able to advise you on this as well.
Well, here is my 2 cents... in a basement environment with the size room you have, I'd go with a perfect triangle type set up. If the bottom edge of your tweeters are 9 feet apart, I'd make the tweeter 9 feet to my ear. I'd dampen the wall behind the speakers and on the sides of them if possible. Next assuming that you have hard walls, seeing 7 ft ceilings.... I normally like the bottom edge of the tweeter to be at ear level, in this case, I'd take your tweeter (entire speaker) up a few inches and do a slight tilt downward to alleviate any ceiling interaction. Going wider with your speaker placement should be not problem, as long as you are an equal triange to your listening position and you allow at least 30 inches from your side wall. Imaging should be great. If things are still a bit harsh, I would then slowly start turning each speaker outward an inch or so at a time, this will smooth it up a bit if needed. I hope this helps, Tim
I have my JBL G300's on 35" stands about 5' from each ear. They are in a configuration of about 155 degrees for headphone like stereo imaging. One of them is very slightly tilted. They are secured to the stands w/ bungee cords over the top. JBL lists the FR for bass at only 50 hz but it is much better than that. Not only is a good idea to damp the walls behind a rear port spkr but I have Army blankets tacked up on all the walls of my room to prevent confusion from diffraction.

This keeps the neighbors happy as well.