Subwoofer Placement (1 Viewer)

[manders8855]

I started off with 2 inexpensive Polk PSW505 subs. Not bad but I had them turned up pretty high and they would make the wind noise with lower frequencies. So I added an old JBL 250W down firing sub up front. Not much of a difference so I removed it. I bought a DB meter and did the sub crawl. I found placing them next to the couch firing towards the front of the room produced the highest levels. Placing anything in the front was just awful. I put a sub in the middle seat and went along the walls with the meter.

I decided to give an SVS SB2000 a shot. It's best placement appeared to be in a corner, at a 45 degree angle, facing the wall.

In the center listening position, at normal loud movie volume running a freq app at 40Hz, I was reading 80db with the 2 polks and 84db with just the SVS. All 3 measured 87db total when all were on.

I guess I was expecting a bit more wow from the SVS. It's really loud about a foot above and behind it measuring 95db. Anything else I can do or am I just having high expectations? My wife says she can't hear the TV in the room above the theater but I don't think moving the subs up a floor is going to do any good.

Thanks!

 

[Robert_J]

How big is your room? Is it open to other rooms?

I built clones of the older SVS Plus cylinder subs and two of them were not enough in my 12 x 25 x 9 room. I have very high expectations.

Finally, SPL meters are great when you have a flat sub response. Rarely do you have a flat response in your room. When I set my speaker levels, my sub was extremely weak on the lower frequencies. I then plotted my in-room frequency response from 120hz to 10hz only to find a 12db peak at 55hz. That's the loudest frequency so that's the level everything was using. I added a parametric EQ to tame that peak and now my sub is + or - 3db from 120hz to 17hz with usable output to 15hz.

 

[manders8855]

How big is your room? Is it open to other rooms?

The room is 13'x15'x7.5'. It is closed off completely. There are really no 90 degrees corners, if that matters. Each of the 4 corners of the room extend out a few inches then run at a 45 degree angle for 15", if that makes sense. Drywall and carpet tiles. At this point, I would have expected a peak of 100+ db but that doesn't seem to be happening.

Literally, if I place the SVS sub or the pair of polks up front, I can watch them pound and hear almost nothing from them and my hearing is still pretty damn good. The spl meter agrees.

I ordered an Extech SP meter with an analog output and created a LabView program so I can run it through a sweep and graph the data.

I haven't recalibrated the receiver yet. Would that help?

 

[Wayne A. Pflughaupt]

Ditch the sub crawl. As Robert mentioned, it will only tell you at what point in the room any peak in frequency response is loudest. Download Room EQ Wizard and get a $100 calibrated measurement mic from Cross Spectrum. Then you can accurately measure response. Otherwise you’re just guessing at the best placement.

If you wanted maximum “oomph,” you should have got the PB2000. Still, the SB2000 should have no problem filling a room that size. Typically you get the best output and best frequency response (after equalization) with corner placement.

Regards,
Wayne A. Pflughaupt

 

[manders8855]

Thank you. I'll give it a shot today. Hopefully I'll encounter some sweet spot.

Plan B might be to return the SB-2000 and get a pair of PB-2000s.

 

[manders8855]

I ran each one separately, plus I ran the svs in it's current position to the right Polk position. I also ran them all at once.

If I'm reading this right, the svs has a better low response, either Polk has slightly higher mid response. All together, something bad happens around 32hz.

 

[JohnRice]

Literally, if I place the SVS sub or the pair of polks up front, I can watch them pound and hear almost nothing from them and my hearing is still pretty damn good. The spl meter agrees.

Plan B might be to return the SB-2000 and get a pair of PB-2000s.

If I'm reading this right, the svs has a better low response, either Polk has slightly higher mid response. All together, something bad happens around 32hz.

Your first comment makes me think something is being cancelled out, which frequently happens with subs, especially when you start just throwing random subs into a room.

Regarding your second comment, a single better sub will almost always be better than two lesser ones. With SVS, a single Ultra will be better all around than two PB2000s.

On your third comment, what is the placement? Corner placement, in the front, as Wayne said, is usually best. Just avoid it being equal distance from two surfaces. Moving it just a couple inches from one of the walls can make all the difference in the world. That could be your 32Hz dip. Don't put it next to the sitting area, no matter how cool the graph looks. Drop-off depending on viewing position is too severe.


Finally, put down the meters and graphs for a while. You'll psych yourself into never liking anything you do. You shouldn't be hearing the sub, you should feel it. When it's set up right, with a good sub, it can almost feel like someone pointed a fan at you when a soundtrack cranks up. You feel it. If you're consciously hearing it, something is wrong.

 

[manders8855]

If I put them up front, they are loud when I'm standing.

I have 1 next to each outside seat which is about 2 or 3 feet from the each back wall corner. Moving it closer to the back wall makes it weaker. The SVS is placed at 45 degrees in the back corner behind one of the other subs. The front corners are a dead zone no matter how they are placed. I will definitely try shifting one, offsetting it from the other.

I'll admit, I'm a bit OCD when it comes to being symmetrical so before you posted, I ordered 2 PC-2000s. My new theater seats are going to span from wall to wall and that kills the side spots and limits the space behind.

On a side note... For what those Polks cost, they are fantastic cheap subs...just a bit muddy and windy at times.

 

[JohnRice]

The front corners are a dead zone no matter how they are placed. I will definitely try shifting one, offsetting it from the other.

Sounds like a phase problem to me, more than a placement problem. I'm not sure you understand how easy it is for things to cancel each other out when it comes to subs. You can completely erase the output of a sub. If you say you can see a sub going like crazy, and you can't hear or feel anything from it unless you stand next to it or in specific locations in the room, you have phase cancellation.

 

[Wayne A. Pflughaupt]

A floor plan showing your placement locations would help us figure out the problem and make recommendations. Much better than trying to figure out what descriptions like” the svs in it's current position to the right Polk position“ mean.

Also, that little camera icon above the graph left side will let you save the graph as a .jpg. No need for camera screen shots.

Regards,
Wayne A. Pflughaupt

 

[manders8855]

Left Polk

Right Polk

SVS

Front

False ceiling.

I had this when I was building it. Yes it is another phone picture. The room is 15 X 12. The recliner couch will have cupholders between the seats in a few weeks (backordered) so it will pretty much extend from 1 side to the other and I'll have to relocate everything again.

The phase issue that John pointed out sounds like a good thought and maybe I'll try shifting one or another away from 0.

Like I said... 2 new subs on order and I'll be returning the SVS and making new homes for the 2 polks. With the recliners getting wider, I'll be limited on location.

I've also tried front sides. That also had a weak output. I think the current location has the best result, but I haven't tried shifting one a few inches, phase shifting, or just rotating in different locations.

 

[manders8855]

The 2 SVS subs appeared to solve the issue. Playing the scene from Dredd when the chain gun comes out used to max out at 95db with the last setup at the standard "movie volume level". Now it maxed out at 118db, same volume, and was much cleaner, and shook the couch. The lower frequencies really came out with these. This was without moving them around, just placing them in the same spot the Polks were in.