Looking for help on room acoustics

[sootshe]

Running a set of La Scala 2's & the bass response varies at different positions in the room. The listening position is probably the worst spot for the most extended bass response. If I stand up from the listening position the bass becomes a lot fuller & subjectively more extended. My room is 9 metres x 7m x 2.7 metres. I have tried the speakers in different positions....When they are forward of the rear wall the bass is reduced...when they are pushed back against the rear wall the bass is increased....so I have them almost against the rear wall, toed in about 15 degrees & 400mm away from the corners. Any clues as to how to get the bass response I get when I stand up from the sitting position.

Thanks,

John

[Chris A]

I would guess that you are sitting or standing in a strong floor-ceiling room mode (i.e., 1.3 metres, 0.9 metres, etc. above the floor or down from the ceiling). If true, I would move my listening position to some other height, and possibly your x-y position in the room. You could be sitting at a double or triple null point.

Having the LS's in the corners is good - you are coupling to the lf room response, thus picking up bass extension and smoothing overall bass response.

Chris

[seti]

Are the bass bins backwards? That would be an issue.

[sootshe]

Are the bass bins backwards? That would be an issue.

No, I've turned them back to the normal position. After some extended listening I found that I was missing some of the high frequency info & a lot of the imaging with the bins turned into the wall (go figure). The bass was awesome with them turned around though.
I'm thinking I need some room treatment of some sort but not quite sure where to start. The floor is tiled & I have thrown a large rug on the floor, but I guess the room would be fairly live even though the sound is nice & smooth & not overly bright.

I agree I'm probably sitting in a room mode position where the bass is probably sucking out butit's impractical to raise the seating position as the bass sounds best when you are standing fully upright no matter where I am in the room.

[seti]

Are the bass bins backwards? That would be an issue.

No, I've turned them back to the normal position. After some extended listening I found that I was missing some of the high frequency info & a lot of the imaging with the bins turned into the wall (go figure). The bass was awesome with them turned around though.
I'm thinking I need some room treatment of some sort but not quite sure where to start. The floor is tiled & I have thrown a large rug on the floor, but I guess the room would be fairly live even though the sound is nice & smooth & not overly bright.

I agree I'm probably sitting in a room mode position where the bass is probably sucking out butit's impractical to raise the seating position as the bass sounds best when you are standing fully upright no matter where I am in the room.

I added a rug, thick oversized curtains, and some wall mounted cd racks. It really took some of the livelyness out of my room. IBSlammin brought over some room treatment panel and that was really cool. He moved them around the room a few times. I'd still like a couple of those.

[sootshe]

"I added a rug, thick oversized curtains, and some wall mounted cd racks. It really took some of the livelyness out of my room. IBSlammin brought over some room treatment panel and that was really cool. He moved them around the room a few times. I'd still like a couple of those."

I don't think the liveliness is a problem but I think I need some of those room treatment panels or maybe those bass traps. Are the bass traps for removing excessive bass? Or might they distribute the bass more evenly throughout the room?

[Chris A]

The bass traps will remove energy from ~175-500 Hz - mid-bass. They will help with room "boom" issues, help to smooth out the sensitivity in listening position (i.e., moving your head by small amounts in x-y dimensions and hearing big differences) and help to EQ the overall response.

The deep bass will be unaffected by virtually anything that you do - the shape and dimensions of the room will determine its deep bass response. That's the reason for advice to move your listening position to hear deep bass.

Chris

[sootshe]

The bass traps will remove energy from ~175-500 Hz - mid-bass. They will help with room "boom" issues, help to smooth out the sensitivity in listening position (i.e., moving your head by small amounts in x-y dimensions and hearing big differences) and help to EQ the overall response.

The deep bass will be unaffected by virtually anything that you do - the shape and dimensions of the room will determine its deep bass response. That's the reason for advice to move your listening position to hear deep bass.

Chris

Thanks Chris,

I don't think I need to go to bass traps then. I've tried other positions but none seem to work unless I'm standing up. Seems I'm stuck with a bad room mode. Might have to bring out the EQ again!....or go back to reversing the bass cabs.

Many thanks,

John

[wuzzzer]

How close to the middle of the room are you sitting?

[sootshe]

How close to the middle of the room are you sitting?

Yes, about the middle of the room. Tried closer forward & further back, as well as to the side, but still get the same response. Bass is always weaker when sitting down than when standing up. The room is not strictly speaking 9m x 7m x2.4m rectangle. It is open to one side to another area. I'll post a diagram of the floor plan soon.

Thanks,

John

[sootshe]

Here's the floor plan

PLAN 4.pdf

[wuzzzer]

Looking at the floor plan it looks like the LaScalas have a pretty huge area to have to reproduce sound in since its such an open floor plan. Looks like you are sitting right in the middle of the room as far as the distance from the Dining room wall behind you and the wall in front of you behind the LaScalas. The middle of the room usually has the least amount of audible bass. Artifically EQing wouldn't be my answer. Dividing the room into thirds and sitting in either the 1/3 or 2/3 distance of the room from the speakers has been recommended for the smoothest bass response.

[Chris A]

One approach might be to construct a small false corner (actually half of a false corner) for your right speaker to give it more connection on the lf end to the room boundaries.

 

However, the most intriguing thought would be to place a backstop room divider just behind your listening position - with its top as high as you might like to go. That would certainly have a positive effect on your bass response. The larger, the better, but a backdrop the size of the couch (but taller than your head while seated) may be good enough. I'm thinking about the movable backdrops used on stages for orchestras, bands, and choirs, but in this case, you might like to have some acoustic damping material on it. Just a straight-wall backdrop would be sufficient. Of course, if you live with a "wife-unit" this may be a difficult thing to do. However, I don't think it's impossible and it may actually help set off the room a bit more as a conversation area.

 

"Just a wild thought."

 

Chris

[sootshe]

Looking at the floor plan it looks like the LaScalas have a pretty huge area to have to reproduce sound in since its such an open floor plan. Looks like you are sitting right in the middle of the room as far as the distance from the Dining room wall behind you and the wall in front of you behind the LaScalas. The middle of the room usually has the least amount of audible bass. Artifically EQing wouldn't be my answer. Dividing the room into thirds and sitting in either the 1/3 or 2/3 distance of the room from the speakers has been recommended for the smoothest bass response.

Thanks Wuzzer,

I agree....every other room that I've had has had the seating position nearly up to the back wall...certainly much closer than this situation. Great advice as I don't really want to go down the EQ path again...it never sounds quite the same.

[sootshe]

One approach might be to construct a small false corner (actually half of a false corner) for your right speaker to give it more connection on the lf end to the room boundaries.

However, the most intriguing thought would be to place a backstop room divider just behind your listening position - with its top as high as you might like to go. That would certainly have a positive effect on your bass response. The larger, the better, but a backdrop the size of the couch (but taller than your head while seated) may be good enough. I'm thinking about the movable backdrops used on stages for orchestras, bands, and choirs, but in this case, you might like to have some acoustic dampening material on it. Just a straight-wall backdrop would be sufficent. Of course, if you live with a "wife-unit" this may be a difficult thing to do. However, I don't think it's impossible and it may actually help set off the room a bit more as a conversation area.

"Just a wild thought."

Chris

Thanks Chris,

Already have the false corner idea on the drawing board...should have had that done when the house was built...it was one of those many details that got overlooked. Will be able to get this up fairly soon.
Love the idea of the backdrop & it would be up tomorrow if it wasn't for the WAF. Will work away at that, as I think you have come up with a top idea here & I think it would look good too.

Thanks,

John

[Chris A]

Well,

It's very interesting how the subject of horn-loaded speakers dovetails so nicely into the subject of room acoustics:

I tried out the idea of a barrier behind my listening position (my room is ~4.7 w x 12 l x 3 h metres, and I listen about 4.5 m back from the front wall). I stacked four "super bass traps" so that the top was of the stack about 1.8h and about the same width, and about 0.75m behind my couch.

All I can say is that I would have to reprogram my XTi amplifier EQ to back off on the low end by ~3-6 db if I left those traps where they are now. I also tried using just three traps at 1.2 M height and got about half of that effect.

[]

Chris

[Colin]

turn your set-up 45 degrees so that both speakers are in the corner,

and a sub-woofer.

[Chris A]

Colin,

If you were talking to me, and since I'm already running two Jubs in full corners (see profile), I don't think that would help very much. But if you are talking generically, then I think that I get your point.

I believe that Floyd Toole mentions this technique in his articles on HTs as a way of avoiding the effects of room modes.

Chris

[sootshe]

One approach might be to construct a small false corner (actually half of a false corner) for your right speaker to give it more connection on the lf end to the room boundaries.

However, the most intriguing thought would be to place a backstop room divider just behind your listening position - with its top as high as you might like to go. That would certainly have a positive effect on your bass response. The larger, the better, but a backdrop the size of the couch (but taller than your head while seated) may be good enough. I'm thinking about the movable backdrops used on stages for orchestras, bands, and choirs, but in this case, you might like to have some acoustic dampening material on it. Just a straight-wall backdrop would be sufficent. Of course, if you live with a "wife-unit" this may be a difficult thing to do. However, I don't think it's impossible and it may actually help set off the room a bit more as a conversation area.

"Just a wild thought."

Chris

Thanks Chris,

Already have the false corner idea on the drawing board...should have had that done when the house was built...it was one of those many details that got overlooked. Will be able to get this up fairly soon.
Love the idea of the backdrop & it would be up tomorrow if it wasn't for the WAF. Will work away at that, as I think you have come up with a top idea here & I think it would look good too.

Thanks,

John

Tried the backdrop idea today....got my better half to hold a piece of 2400 x 1200 board on top of a cabinet behind the seating couch. It improved the sound of the bottom end by at least 80%. So now to get the WAF we are throwing around the idea of a storage cabinet approx. 2.4m wide X 2.2m high which will effectively achieve the result I am looking for & satisfy my better halfs storage needs, Win Win.

[LarryC]

Have you tried the pair in the corners 90 degrees to the left, to give fuller corners to both? Intuitively, I prefer the speakers facing, overall, from the main room toward the offshoots, and would be concerned about the right one being next to the hallway entrance and facing in the opposite direction. IMO, you should try to face the pair somewhat in that direction, not 180 degrees away from it. My suggested location still faces the dining room somewhat, and I suspect the Las are non-directional enough for that position not to be that much of a problem.

My $0.02, of course, & YMMV.

Larry