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|   dual subs, optimal placement? | sumdumgi
Nov 30, 2001 9:52 PM | | I have dual subs in my system and only one corner to load off of. The other sub is kind of centered in the room and pretty close to the TV. Bad thing? What are the best placement options for my situation to get bass as uniformly as possible throughout the room? I heard that stacking subs is good? I have some photos of my system at this URL: http://www.geocities.com/trustnoho/htframes.html to get a better idea of how it's laid out. Thanks. |
| re: dual subs, optimal placement? | Doug C.
Dec 1, 2001 5:43 AM | | I have dual SVS subs. Stacking or putting both subs in the same corner will provide maximum overall bass output capability. This may be best if you lack output.
I found co-locating my subs (after experimenting to find best location) produced some localized low frequency peaks at various listening positions (not really an issue for HT but poor for music).
Placing one sub in each of the front corners results in better low frequency uniformity throughout the listening room (in my room). My best advice is to experiment with placement to see what the best results are in your specific room. Experiment with different crossover settings also.
Good Luck!
Doug C. |
| Richard Greene, a little help here? | bigwally
Dec 1, 2001 6:34 PM | | "Placing one sub in each of the front corners results in better low frequency uniformity throughout the listening room (in my room)."
Mine too (vs. both in one corner). I'm at a loss to explain why. Theoretically there should be a deep null at 43Hz (566/13') in my room with this type of placement but it didn't happen. Yes, the overall output is down a couple of dB as would be expected, but the response is much flatter. |
| Okay, this is an easy question | Richard Greene
Dec 3, 2001 12:50 PM | | Bass energy in a typical home listening room will never be even no matter where you place your subwoofer, due to standing waves caused by surface-to-surface reflections. This is not a problem in auditoriums and other very large venues -- but it is a serious problem in many home listening rooms.
Using two or more subwoofers at different locations ("stereo") will almost always make the bass frequency response worse than a single corner subwoofer ("mono").
One advantage of using two subwoofers, one in or near the left front corner and the other in or near the right front corner, is that this will make the subwoofers more sonically invisible than stacking both in the same room corner (this especially applies to subwoofers with significant output above 80Hz.)
The only way to measure bass frequency response variations is with a slow sine wave sweep tone such as the five-minute long sweep from
1Hz. to 100Hz. on the Stryke Audio Basszone test CD. Using a watch with a second hand, you can actually estimate the frequency of each audible bass resonance (each minute of the sine wave sweep track
covers about 20Hz. -- use the elapsed time to estimate the frequency of the bass resonance -- for example; at 1.5 minutes into the 5 minute sweep, the frequency should be at about 30Hz.).
The best subwoofer position will usually be the one with the smallest bass frequency response variations -- usually a room corner subwoofer location offers the smoothest possible bass frequency response at a variety of listening positions. Corners alway provide the loudest SPL and lowest harmonic distortion.
Bass frequency response measured at your listening position using a slow sine wave sweep tone tone will usually be +/- 10dB or worse due to standing waves. With equalization the best I've measured is
+/- 6dB. (Don't compare these measurements with measurements made using pink noise or warble tones -- those tones don't remain at the same frequency long enough to excite standing waves).
According to JBL VP Floyd Toole, it is theoretically possible to place two subwoofers in different positions resulting in
a frequency response better than a single corner subwoofer ...
but only in SOME listening rooms ... and only for ONE listening position. The odds of finding these two subwoofer positions by ear (trial and error) are slim -- you would need to use sophisticated test instruments.
The most likely location for the smoothest possible (smoothest nfrequency response, at a variety of listening positions, will be from one subwoofer, playing mono bass, placed in or near a room corner. If your room is well shaped, (not square or near-square), a smooth bass frequency response measured using a slow sine wave sweep tone will usually be +/- 10dB or worse .
Two subwoofers stacked in the same corner will have a smoother frequency response than two subs in two corners. The destructive interference between the two subs will reduce output by 1 to 3dB versus the same two subs stacked in a single corner. Two subs in two different corners (right and left of the main speakers) should not excite the side-wall-to-side-wall room resonance very much (they excite that resonance out of phase and cancel each other out) so there should be a narrow but deep hole in the frequency response centered roughly at the frequency of the side-wall-to-side-wall axial room mode (566/width of room in feet).
All of this theory works well for a rectangular room made of solid cement with no doors or windows! For real rooms just use a sine wave sweep tone to measure bass frequency response -- the test CD I mentioned is $10 and your ears should hear the bass resonances
(a sound meter is more accurate but not mandatory)... and almost everything in your house, including the walls and floor, will resonate at certain frequencies (try to quiet everything that rattles).
In the pictures I noticed a window and |
| Depends on your main usage, and the crossover setting | Dougman
Dec 1, 2001 1:00 PM | | IMHO, if you are mostly using them for music, I would put them as close to your main front speakers as possible. I use a pair of 10" KEF subs in conjunction with a pair of Mission 773e speakers in a system used almost completely for music, and I have set the crossovers at around 80Hz. In this situation, I find that I get the best matching with the main speakers, and the best stereo separation by setting each sub just outside of the main channel speaker that it crosses over to.
On the other hand, if you are using them predominantly for home theater, and/or if you have the crossover set below around 50Hz, there is very little separation effect anyways, so you probably want to position them in such a manner as to minimize wave cancellation effects - for the tightest and biggest bass. In that case, I would put them right near each other. If they are front firing, you probably want to stack them, but if they are downward firing, you should definitely NOT stack them (the top one will screw up the bottom one's response if they fire downward). |
| Depends on your main usage, and the crossover setting | sumdumgi
Dec 2, 2001 3:43 AM | | My subs are used for 90% music, 10% HT. I have the low pass filter set at 50Hz on one, and 70Hz on the other. Both are forward-firing. My problem is not output, but uniform output in the room. Thanks. |
| Based on your usage, You're probably already set up pretty well | Dougman
Dec 2, 2001 8:59 AM | | I'm not sure that you could get much better than your current placement, in terms of uniformity and optimizing the soundstaging.
The only question I have is, are the subs shielded, and if not, have you been completely free of Gaussing effects on your screen in the lower corner near one of the subs? It looks pretty close and over time, you might start to see some color distortions on the set if that speaker is not shielded.
BTW, I like the poster above the TV |
| re: dual subs, optimal placement? | ibarr
Dec 2, 2001 11:39 PM | | I read an article in Stereo Review/Sound and vision.....I believe it was written by Julian Hirsch. He said the most even response would be gained by an arrangment such as the one you have now, with the subs in different areas of the room, but for 3dB more bass, stack the two one on top of the other in the corner location. |
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