Subwoofer and Bass Gurus (1 Viewer)

[sfyalek]

I've posted before on this but my room is a square 15' x 16' x 8' with a hallway opening forward right of speaker system and kitchen opening to the right side of the speaker system, both opening up with a larger door size opening (no doors btw) by the right speaker and subwoofer. The subwoofer is behind the right speaker. To the forward left of my speaker system is a foyer about 4' x 4' with my outside door. This subwoofer position is the best in my room. I've moved the subwoofer all over the living room and where it sits now offers the most accurate and deep bass out of any position. It really does sounds very good there. The good listening areas are at any seating position on my sofa which is about 1/2' from the back wall or to the sides of the sofa going into the corners but with a bass rise of 6 decibels from 75 to 81, but sound quality is still good.

My question is that at my listening area and my entire sofa area, I get a SPL of 75 decibels. To the sides of the sofa going into the rear corners of the room, I have 81 decibels of SPL. Also just a 5 feet forward of my listening position, I have a bass null in the lower frequencies even though the SPL is still at 71 decibels. Sounds much worse than 4 decibels. Will adding an identical subwoofer behind my left speaker help equalize the SPL (sound pressure levels) at my sofa and corners?? Also will the 2nd subwoofer help at all with the null about 5' in front of the listening position. Weird as the 5' in front of the listening position is the only area that has this significant null. Just to the sides of it are fine.

I will not be using any DSP or anything. I just was wondering if the 2nd subwoofer would help with equalizing the Sound Pressure Levels. I know that a 2nd subwoofer is usually for smoothing the bass but that honestly sounds good, just the differences in SPL is what bothers me as I would like to add some corner seats but not drown out the movie speech with bass.

BTW, I may be able to stick a 2nd sub in either rear corners but it will be a hardship with furniture and cosmetics.

The reason I ask is that prices came back down on my Klipsch R-120sw and if it will truly help, grabbing one now may be the thing to do. However I'm short on money and don't want to buy another sub if it won't correct these SPL issues.

Thanks for your help.
View attachment 149894

Please don't mind my poor drawing skills. I drew this up quickly on scrap paper.

Mike, I want to throw in some information about audio even you got quite a few useful information from the forum.
Treble is uni-directional so the treble speakers should aim to the listener' ear level. Both speakers should be in the equal distance from the listener. Also treble is attenuate much faster than base. Thus, the distance of the speakers to the listener is critical. Bass is non uni-directional so the sub can be placed at any location but preferable closer to a wall or any construction and use the wall to bounce the sound back to the room.
I know you mentioned that you prefer to put the sofa close to the wall. However, part of the sound will bounce from the wall behind you to your ears and this delay could affect the clarity of the sound, depends on the type of material of the wall.
Sound power is calculated by the logarithm. For doubling the energy, it will increase the sound level, presume the placement in the same distance, for 3dB.
I personally do not think you need to add another sub-woofer, just experiment with the placement should do the job.

 

[Mike Up]

Mike, I want to throw in some information about audio even you got quite a few useful information from the forum.
Treble is uni-directional so the treble speakers should aim to the listener' ear level. Both speakers should be in the equal distance from the listener. Also treble is attenuate much faster than base. Thus, the distance of the speakers to the listener is critical. Bass is non uni-directional so the sub can be placed at any location but preferable closer to a wall or any construction and use the wall to bounce the sound back to the room.
I know you mentioned that you prefer to put the sofa close to the wall. However, part of the sound will bounce from the wall behind you to your ears and this delay could affect the clarity of the sound, depends on the type of material of the wall.
Sound power is calculated by the logarithm. For doubling the energy, it will increase the sound level, presume the placement in the same distance, for 3dB.
I personally do not think you need to add another sub-woofer, just experiment with the placement should do the job.

Thank you for the comments. I've been installing and setting up home theaters for family and friends now for about 25 years now. I have a lot of home theater setup tools as well.

I've never had issues with bass setup like I have with these square rooms. Most rooms I've had in the past, and setup have all been rectangular never like the squares I have in my living room and media room. I never had the issues with bass like I have in these rooms.

One common thing that I've read over and over is that DSPs are good for taming standing waves but they are not good for nulls. Nulls are said to be best dealt with subwoofer location which I have tried over and over. Nulls are my biggest problem. I have finally found a happy solution. I have position my couch on the center of the back wall which has good bass sound quality. Moving my couch off the wall by 1 foot puts me in the main null if I lean forward where my head is at the edge of the couch seat. It's about a 6 or 7 db null. If I boost output up, it sounds like normal so I just make sure I don't get into that null by keeping the couch on the center back wall. The only way to be off the back wall and not in the null is to put the couch in the center of the room which does not work in any way or form.

In all my seating positions, I have good bass. In every seat on the couch and in my corner chair. I pulled the corner chair out a lot so it's not in the standing waves of the corner but not up far enough to be in the null. So I have 4 -5 good seats that have the bass output levels within +3db of the main listening seat. I can live with this. Ironically, the media room shape is just like the living room but smaller and the standing waves and nulls are roughly in the same spots. My far seating position of my couch is in the corner but the standing waves are not as bad (loud) so it works out the same as the living room. I guess I'll be happy as my systems now have never sounded better with the newer speakers and setup.

BTW, I do understand logarithms, I use them for my job when calculating power and voltage gain along with speaker setups.

Thanks

 

[Doug2000]

Your problem is almost certainly the square room. A square room in audio is a special case and a death-null.

Here's a video on square rooms:

Just amazing how many sub makers push dual subs when results could be bad.

I would not extrapolate anything about the viability of dual subs in general based on the fact that dual subs didn't work in your square room.

 

[Mike Up]

Your problem is almost certainly the square room. A square room in audio is a special case and a death-null.

Here's a video on square rooms:


I would not extrapolate anything about the viability of dual subs in general based on the fact that dual subs didn't work in your square room.

That's a great video!

Well on one wall I do have bookshelf cabinets but they don't take up the whole wall but a good portion. I also have shelves installed on the walls for photos from the bookshelf cabinets to the corner but only 2 shelves. The other side of the bookshelf cabinets is an opening into the kitchen on the side and an opening into the hallway following forward from that wall. The opposing wall has a large picture window which takes up pretty much the entire wall except the very corner on one side and a foyer on the side. Front wall is between hallway and foyer and is TV and home theater equipment. Rear wall is sofa (ottoman in front), chair and table. You can see a rough drawing in earlier posts. So in some ways that room is broken up with items. Right now at my listening position, I have very good sound. Excellent. Off to the sides is also very good but with a few decibels higher in bass at the extreme. Right in front of the by ottoman, a huge null with no bass. In the corners, tons of muddy, bloated bass. Subwoofer is located on front wall behind right speaker which is sit's left of the hallway opening. In this position I have excellent bass at listening positions. In the corners I get bloated, one note, muddy, bass. On the side walls, 3' away from rear corners, I get bad hollow bass that has no punch or real low bass.

Right where it's at on the front wall, I get sub 30 Hz bass, articulate and musical bass. It just drives me nuts having a huge null in front of the sofa, near the center of the room. Same with my media room but not quite as bad even though there are both roughly square rooms.

As I said I tried 2 subs and it sounded bad. I'll just lick my wounds and be happy I have good sound quality in my listening positions and look past the large null outside of the listening positions and 3 decibel elevated bass at the extreme listening positions.

Thanks for the video, I guess I'm lucky I'm getting as good sound quality as I am!