Subwoofer Placement (split from Rotel Pictures)

[Andrew Pratt]

Very nice:T

(admin. note, this thread was split from the Rotel Pictures thread, so the discussion will seem to start from the middle.)

[BlazeMaster]

John G., can I ask you where you put your sub? Very nice layout.

[John G]

John G., can I ask you where you put your sub? Very nice layout.

I currently don't have a sub but I just purchased a new center, L, R front speaker and sub. The new speakers will be about the same size as my existing ones in the picture and will use the same stands. The sub will fit between the AV rack and one of the front speaker stands after the AV rack is moved a bit to one side.

Any ideas on what side would be better? I was thinking of putting it on the left side to keep it more in the center of the room.

Here's a different angle.



Should I also keep the front and center channel speakers set to large when I get the sub in there and setup?

[Martinf]

John,

You should definitely set all your speakers to "small" with a crossover point in your receiver (and also in your DVD player) set at about 80Hz. Looking at the size of them, I doubt they are able to kick out anything below 60Hz.

N.B. With the sub (and with bass management engaged) you should notice a HUGE difference in the sound.

As for positioning the sub, I find that putting it in the furthest corner from you gives the best results. In your case, try putting it to the left of your record/bookcase, or right in the far corner -- see pic. The interconnect cable could come across and then down from the ceiling.

[BlazeMaster]

you'd have to run a longer cable run to that corner, not sure if that path is used alot, but a cable in the way could be annoying. How about putting it behind your couch? It would complety hide it away for a cleaner look and at the same time, maintain the nice symetry that you have in the front. I was thinking about doing the same by, putting the sub behind the couch and facing the center. I have the PB12plus/2 so I need about 3 feet of clearance from the couch to the back wall for it to work.

[John G]

My understanding was that the best place for the sub was between the front left and right speakers. To me it makes sense as that is where the majority of the sound is coming from. Conveniencewise it's a good place for me as it keeps the A/V gear all in the same general area and out of the way of the rest of the room. The sub is only 12 inches wide so should fit nicely in the limited space I have there. It also has a sealed enclosure (non-ported design) which makes it less fussy about placement.

I'll have to experiment with the large and small settings for the front L/R and center channels as well. I've been told to leave all them set to large as well, the speakers I'm getting are more than capable of handling the signal sent to them, they're pretty robust speakers.

[Martinf]

John,

I'm not sure where you got that information from about putting the sub in the middle. The sub needs room to breathe. The wavelengths are long, and you will only really hear the lowest frequencies properly when the sub is as far away as possible from you and preferably coming from a point source in the furthest corner.

N.B. True 'sub-bass' -- which you can "feel" -- means frequencies of about 80Hz and lower. (In contrast, subs that are set to put out sound up to 100Hz can sound horribly boomy). I actually like my sub to kick-in only from 60Hz and lower. At these frequencies the sound is non-directional, so it's irrelevant to position the sub where "the majority of the sound is coming from" -- to use your phrase. Moreover, being in the corner, means that all the sound comes uniformly from a point source, and it will therefore minimize destructive and constructive wave interference (the formation nodes and anti-nodes).

If you put a sub in the middle of the room, then the waves will reflect off the four walls simultaneously with unpredictable results. i.e. you may get no bass ('suckout') when you sit at one end of a sofa, whilst in another location you may get far too much bass resonance. I know. I tried all possibilities when setting up my system. See the attached photo. (Note that the sofa on one side "corners" the sound into the alcove which turns it into a kind of point-source acoustic chamber).

>> the speakers I'm getting are more than capable of handling the signal sent to them, they're pretty robust speakers. <<

That may be the case, but whether they actually produce the full frequency audio spectrum is an entirely different matter.

b.t.w. In case you are wondering, somebody put a black shoebox (with CDs in it) right in front of my downward-firing REL sub which is actually a perfect cube of about 1ft x 1ft x 1ft.

[PewterTA]

Okay first off...

A sub will not sound boomy at 100Hz and up...you can easily locate the sub, but it doesn't mean that it will be "boomy." A boomy sub can happen with frequencies at 80Hz ,60, 40, 20, etc, and anything in between. My friend's B&W ASW600 is extremely boomy and he has the cross over set at 80hz (might be 60, can't remember). It has very very much to do with Frequency response and room acoustics that will cause the sub to be boomy.

You will often increase the db output of a sub upwards of 3 - 6dbs when you cornerload the sub. But there is NO reason that a sub can't sound good in the middle of a wall or placed in elsewhere throughout the room. In fact, a lot of people prefer their subs this way. It's all listener based.

To get the wave lengths to hit the listener position you can do two things. Correctly set the phase on the sub (most good subs have this), so that the sound wave hits the listener at the same time as the rest of them. Another thing you can do to easily find the best place for your sub (and quickly find the best location for sound waves per one's room) is to place the sub at the listener position, then walk around the room until you find the best spot to place the sub.

The third (and best thing) you can do is get something like the Behringer Feedback Destroyer (BFD) and then go through and create a flat FR curve for your room. This is the best way to make your sub sound phenominal as you will have no peaks and valleys in your Frequency Response and have a more useful sub. This will kill any "boominess" to a sub. Remember on this you really only want to cut down on the peaks, not raise the valleys (nulls). Also needed to do this is a SPL meter (properly calibrated for low frequencies).

[Martinf]

>> You will often increase the db output of a sub upwards of 3 - 6dbs when you cornerload the sub <<

No. But you can LOSE 3-6db by putting the sub in a less-than-optimal location -- such as in the center of the room.

There's no magic in sub placement. Have you ever done the "ripple-tank" experiment in your high-school physics class? It's exactly the same principle with soundwaves. i.e. emit a point-source wave from a corner, and an arc of waves travels diagonally and uniformly towards the center of the room, and along the walls rather than perpendicularly into them.

But if you put the point source at the center, then waves radiate outwards and hit the four walls head-on (perpendicularly), and reflections then bounce around all over the place.

And if you need that "feedback destroyer" contraption, then you've got your sub placement wrong.

As for 100Hz. Well, that's definitely NOT sub-bass. That's lower/mid bass. A sub shouldn't really be used for that (unless the main speakers are really tiny).

[Martinf]

I see your "room" is not a typical square shape. Looks a cool place to chill-out though!

You basically need to try out what works best for you. By the way, I think that given the large distances involved between the two "rooms", I don’t think that using the one sub for both systems would work too well. There will be too many logistical and sonic compromises. Besides, your 2-ch system will (probably) not have a line-level sub output (i.e. at pre-amp stage), and you’d need to take a high-level feed from one of your main speakers. (b.t.w., RELs have both high and low (line / LFE)-level inputs for this purpose).

You would also need time-alignment (speaker distance settings either in the DVD player when using its RCA analog outputs, or in receiver/processor when using the SP/DIF coax / Toslink) to correct for the distance displacement — which, again, your 2-ch system won’t have.

In short, I think each system should really have its own co-located sub.

For your A/V system, I still think the far corner (or immediately next to the record shelves) as I originally illustrated would sonically be the best place for the sub. I don’t think that sandwiching it between all your other equipment would be good. especially as it could also make your other equipment rattle by being so close.

However, you should nevertheless try all possibilities and see what works best for you in what is quite a "complex" room layout. Anyway, for me, experimenting is one of the great things about this hobby. And be prepared to allocate a whole day to try all sub-placement possibilities.

By the way, here’s an interesting link I found just now, and I see that it explicitly says in the first bullet point: "The worst place for a subwoofer is in the middle of a room".

http://www.audioholics.com/techtips/...ementguide.php

[John G]

For your A/V system, I still think the far corner (or immediately next to the record shelves) as I originally illustrated would sonically be the best place for the sub. I don’t think that sandwiching it between all your other equipment would be good. especially as it could also make your other equipment rattle by being so close.

Thanks for the advice. Behind the record rack near the corner is a stairway that goes to the upstairs. I'm thinking that maybe a problem with noise going up there and bothering the rest of the house. I have a corner on the left side near that closet door where it would be easier to run cables and it has a AC outlet nearby that would be more convenient. I think I prefer putting it there and forego having to mess with moving the front speakers and rack until I've experimented a bit along the left corner and wall.

I'll stick to using it with the AV setup for the time being.

[Andrew Pratt]

Guys can we get this thread back on track as a picture gallery thread. If you want to talk sub placement please start a new thread in the HT area.