Speaker Boundary Interference Response

[sabertooth222]

Ok friends, I'm lost and confused.

I'm losing bass (as in the sound gets quiet at these frequency ranges) between 70-90hz, somewhere around 120-140hz, etc. AKA ranges of bass to upper levels of bass are weak or lost. This happens both with my tower speakers and my subwoofer. My assumption is that this is due to speaker boundary interference response, aka, bass waves are bouncing into eachother and effectively "cancelling" themselves out.

Now here's where I think I am confused. The room I am using is 25'10"x10'6", with the speakers along the 25'10" wall facing the couch opposite of it (which is the other 25'10" wall). So basically the width is much larger than the depth. I know, definitely not ideal already. 3 of the walls are standard drywall, the fourth wall (one of the 10'6" walls) is basically a large window (for around 7' of it). I know, also very terrible. Currently, the apartment has cheap plastic blinds on the window. The floor is carpet, and the ceiling is around 10' tall.

So, my question is would it help much to put acoustic drapery over the blinds/window so that the sound gets absorbed more? I wouldn't want to go to all the trouble of putting holes in the wall and buying acoustic drapes if it really didn't do anything. Is there something else that might help more? Am I on the right path?

Thanks for any help!

Specs:

Receiver: Onkyo Tx-nr545

Towers (2 front): Polk tsx550t

subwoofer (1, sorta halfway away from the window and close to the wall): SVS sb-1000 12"

 

[everettT]

You have fairly large room. The svs might not be enough for your size . Unless you takes some measurements its really hard to say. Guessing the problems by ear will not be helpful. How did you determine the sub location?

Ok friends, I'm lost and confused.

I'm losing bass (as in the sound gets quiet at these frequency ranges) between 70-90hz, somewhere around 120-140hz, etc. AKA ranges of bass to upper levels of bass are weak or lost. This happens both with my tower speakers and my subwoofer. My assumption is that this is due to speaker boundary interference response, aka, bass waves are bouncing into eachother and effectively "cancelling" themselves out.

Now here's where I think I am confused. The room I am using is 25'10"x10'6", with the speakers along the 25'10" wall facing the couch opposite of it (which is the other 25'10" wall). So basically the width is much larger than the depth. I know, definitely not ideal already. 3 of the walls are standard drywall, the fourth wall (one of the 10'6" walls) is basically a large window (for around 7' of it). I know, also very terrible. Currently, the apartment has cheap plastic blinds on the window. The floor is carpet, and the ceiling is around 10' tall.

So, my question is would it help much to put acoustic drapery over the blinds/window so that the sound gets absorbed more? I wouldn't want to go to all the trouble of putting holes in the wall and buying acoustic drapes if it really didn't do anything. Is there something else that might help more? Am I on the right path?

Thanks for any help!

Specs:

Receiver: Onkyo Tx-nr545

Towers (2 front): Polk tsx550t

subwoofer (1, sorta halfway away from the window and close to the wall): SVS sb-1000 12"

have

 

[sabertooth222]

I don't think it's a problem with subwoofer power/output. Low frequencies like 20hz-60hz are very powerful and fine. It's when it gets to pockets like 70-90 or 120-140 where the sound just diminishes. The same thing happens when I turn off the subwoofer and put the tower speakers on full band.

 

[Pogre]

I don't think it's a problem with subwoofer power/output. Low frequencies like 20hz-60hz are very powerful and fine. It's when it gets to pockets like 70-90 or 120-140 where the sound just diminishes. The same thing happens when I turn off the subwoofer and put the tower speakers on full band.

I have a slightly larger room than you, but not too far off. I'm using 2 SB1000s and am toying with the idea of upgrading. How did you come up with your sub placement? Where do have your crossovers set between the sub and main speakers?

I've found through advice and experimentation that positioning your speakers/sub is a lot more critical than I realized. I just tweaked things in my room recently and feel like I upgraded. it really did make a noticeable difference.

 

[sabertooth222]

Crossover is 100hz. Does subwoofer placement really affect specific frequency ranges? Because I have toyed around with that already and found a good spot for it. I really think it has something to do with the acoustics of the room. My main question still is whether or not drapery over the window would help.

 

[Pogre]

Okay. The speakers you have report a f3 of 26hz. they should be very capable of playing down to 60 or 80 hz. Have you played around with your crossover settings? I'd recommend 80, but you might like it even lower. Your speakers are big enough to handle it.

Subwoofer placement is very critical to get the right bass response in your seat. The issues you're reporting are happening right around the crossover point you're using. Have you heard of the sub crawl?

 

[sabertooth222]

Have you played around with your crossover settings?

It has nothing to do with crossover settings. As already stated, putting the tower speakers on full band produces the same result.

Have you heard of the sub crawl?

Yes, I already did that.

 

[j_garcia]

Absolutely curtains will help with how you have it setup. I have not heard it called boundary interference, but you have a room mode around that point and it has to do with the way you oriented the setup. In a long room, it is better to have the system facing the long way. The seating position itself within the room will also affect where the room modes are. Curtains will not solve the dips/nulls IMO.

 

[shadyJ]

First of all, 100 Hz is too high a crossover frequency for that sub with those speakers. Unless it just sounds better to your preferences with that high of a crossover, take it down to 80 Hz, or maybe even lower.

Secondly, that dip at 120 to 140 Hz is likely due to something called the Allison Effect. This is where reflections off of the floor cancel out direct reflections from the woofer. The only way to get around this is to either move your listening distance from your speakers (which will only shift the dip to a nearby frequency) or to raise the subwoofer crossover to 200 Hz or so. Your sub is already too diminutive for that task, and it would greatly increase localization, where the sub draws attention to its position. 80 Hz and below is where frequencies become deep enough that human perception is unable to localize the source. One workaround on this is to get another identical sub and place it on an adjacent side of the room.

I would get another sub and use a high crossover point, maybe 160 Hz or so. Move the subs around the room and measure the results. Keep the placements that produce the flattest results.

There are no acoustic room treatments that can help in frequencies this low, so you don't have to worry about any of that.

 

[vsound5150]

Ok friends, I'm lost and confused.

I'm losing bass (as in the sound gets quiet at these frequency ranges) between 70-90hz, somewhere around 120-140hz, etc. AKA ranges of bass to upper levels of bass are weak or lost. This happens both with my tower speakers and my subwoofer. My assumption is that this is due to speaker boundary interference response, aka, bass waves are bouncing into eachother and effectively "cancelling" themselves out.

Now here's where I think I am confused. The room I am using is 25'10"x10'6", with the speakers along the 25'10" wall facing the couch opposite of it (which is the other 25'10" wall). So basically the width is much larger than the depth. I know, definitely not ideal already. 3 of the walls are standard drywall, the fourth wall (one of the 10'6" walls) is basically a large window (for around 7' of it). I know, also very terrible. Currently, the apartment has cheap plastic blinds on the window. The floor is carpet, and the ceiling is around 10' tall.

So, my question is would it help much to put acoustic drapery over the blinds/window so that the sound gets absorbed more? I wouldn't want to go to all the trouble of putting holes in the wall and buying acoustic drapes if it really didn't do anything. Is there something else that might help more? Am I on the right path?

Thanks for any help!

Specs:

Receiver: Onkyo Tx-nr545

Towers (2 front): Polk tsx550t

subwoofer (1, sorta halfway away from the window and close to the wall): SVS sb-1000 12"

I'm just tossing this out there as I'm new to this and going through similar challenges.

What about using an active EQ to attenuate the low amplitude freq. points and also clean up other areas of the band if needed. Probably good to have an EQ around for ease of adjustments when treating the room comes with costly unknowns.