Speaker imaging

[Paul Joppa]

It's only 9 per side - the 10th is the active crossover.

Four woofers, 1 amp each, all Paramounts.

Inefficient midrange with four amps in an unusual arrangement to combine their power, more Paramounts.

One tweeter amp - was originally an SR45, more recently ... another Paramount!

[drewh1]

This thread inspired me to try some experimentation.  I have a 14x18 ft room with a fireplace in the middle of the speakers. the fireplace is not centered on the wall. The right speaker is 2 ft from the wall, the left speaker is 3 ft. The right wall is flat drywall, the left has a door and window. speakers are 32 " from the back wall.  I also have my gear behind the right speaker on a rack, the only place I can currently fit it.

In this configuration, my soundstage is shifted to the right speaker.  I have absorption panels on the front and back walls.  I thought that the problem was the right speaker being closer to the wall. So I experimented putting some sound absorption there (in this case a very thick comforter, not sure what the technical specs are  This made the shift more apparent. So I tried the absorption on the left wall and voila, the soundstage opened up to the left in a not very subtle way. Quite surprising and a bit counterintuitive for me. What was a dead zone of sound is now filled with voices and instruments.

So it is definitely worth getting some serious room treatments in place and experimenting with placement. I am going to continue to experiment and try some assymetrical treatments as well. I did try moving speakers around and even centered them at one point without as much impact.

Anyway, I hope this gives you some ideas and good luck with it.

[proud indian]

Get into near field listening. Once you get closer to the speakers, the room reflections etc will take a back seat. Try it.

shreekant

[ssssly]

I'm only 10" from the speakers. So os fairly near field.

Pulling the speakers away from the wall eliminates all bass below 90hz. They are rear loaded horns and use the wall as part of the horn expansion. So pulling them away from the wall isn't really an option either.

[Jim R.]

Guys,

I've had nothing but difficult, assymetrical rooms, and as Doc says, start with the front wall, and the first reflection points, but after that the thing I have found to work by far better than anything else is diffusion panels instead of absorption.  And you can do an awful lot with just a few panels -- I've typically found them to be best behind or off to the side of the speakers, and one overhead on the ceiling. 
The only other thing that worked, but I eventually abandoned as it was just cumbersome, was a diagonal room setup.  But of course my rooms have all been fairly small, so I was pretty limited in how far out into the room I could pull the speakers.

Drew, I'd deefinitely go with that diffuser panel first -- it will also give you something to build ;-).

I think there was a post in the speakers section by another guy here who had a similar issue with his Lowther speakers and found a homemade diffuser panel to do the trick.

I'm starting out on my new room with the Michael Green RoomTune pack, but I will probably still need a diffuser or maybe two at some point.  This room is asmall, so I'm pretty cautious about over damping the room with too many absorption panels.  I'm certainly no expert in this, but I do have a good amount of experience playing around with small assymetrical rooms, and have been able to achieve some incredible listening spaces where the room walls virtually are not there and with amazing soundstagging... but it tookk a whole lot of time and experimentation and super critical speaker placement as well -- and the speakers were in a perfectly parallel stance when all was said and done.

-- Jim

[sl-15]

check out Jim Smith Get Better Sound. i bought the book a few years ago and think it is full of useful setup tips. this would not be a quick fix but might be worth it. i think by now he has several different books and even a setup DVD. good luck tweaking

[proud indian]

I'm only 10" from the speakers. So os fairly near field.

Pulling the speakers away from the wall eliminates all bass below 90hz. They are rear loaded horns and use the wall as part of the horn expansion. So pulling them away from the wall isn't really an option either.

I also use horns and have pulled the speakers 5 feet from the wall and used a sub. But, if I may give you a new direction..........are your cables broken in?  You may laugh because you have put in a few hundred hours on them, but with single drivers, I have found that it does take a lot of breaking of all cables to get the sound stage right...... just my experience.

shreekant

[4krow]

I think the following may apply to this topic of room treatment. It is as much a question as anything. I have been thinking about how different materials for absorption handle different frequencies, and I have wondered in cases where a room needs a lot of absorption on one side, whether or not 'memory foam' would be more useful than other materials.  Your thoughts everybody.

[Paul Joppa]

A standard sound-absorbent material has the optimum flow resistance - that is, it is harder than air and softer than wood.  :^)  You can blow through it with moderate effort, more like a pillow than a fiberfill comforter. It will absorb sound pretty well when the material is more than a quarter-wave thick. A wavelength at 1kHz is about a foot (34cm actually) so a 3" pad is good down to 1kHz. The memory foam I've seen is very hard or impossible to blow air through, so it would not be a good absorber.

That's from the simplest theory. Clever material designers can push this lower, maybe as much as an octave, by exploiting more subtle material parameters and/or non-uniform materials. And a thinner pad of higher resistance will absorb less energy but do it down to a lower frequency.

I have left out bass traps which get to much lower frequencies but only in a more narrow frequency range, by exploiting resonances.

[4krow]

Thank you Paul, Everything has a song when it comes to resonance.  I have long been interested in acoustics, as things are not as you might expect. This leads me to constant curiosity.