AVS › AVS Forum › Audio › Subwoofers, Bass, and Transducers › Single Subwoofer vs. Dual Subwoofers
New Posts  All Forums:Forum Nav:

Single Subwoofer vs. Dual Subwoofers

post #1 of 68
12/30/12 at 2:16pm
Thread Starter 
Hi,

Is there much of an improvement in the sound if you have 2 subwoofers?

I am thinking of getting another matching sub but not sure if it will really make a huge difference in sound.

I have the SVS PB12 Plus subwoofer.

Thanks for any advice!
Edited by mantaraydesign - 12/30/12 at 2:22pm
Reply
Reply

AVS Top Picks

post #2 of 68
12/30/12 at 3:14pm
Quote:
Originally Posted by mantaraydesign View Post

Hi,
Is there much of an improvement in the sound if you have 2 subwoofers?
I am thinking of getting another matching sub but not sure if it will really make a huge difference in sound.
I have the SVS PB12 Plus subwoofer.
Thanks for any advice!

It would help even out the FR in the room but output wise eh.
Reply
Reply
post #3 of 68
12/30/12 at 5:33pm
Quote:
Originally Posted by mantaraydesign View Post

I am thinking of getting another matching sub but not sure if it will really make a huge difference in sound.
It will. Average output will go up by 6dB (that's the equivalent of 4 times the power) while dual subs spread about the room will smooth room modes that no amount of EQ can fix.
Reply
Reply
post #4 of 68
12/30/12 at 5:45pm
Quote:
Originally Posted by Bill Fitzmaurice View Post

It will. Average output will go up by 6dB (that's the equivalent of 4 times the power) while dual subs spread about the room will smooth room modes that no amount of EQ can fix.

Will it only go up if you colocate the subs? What if he spreads them around the room and than calibrates with some sort of room correction? I thought that would give more headroom? *Just trying to understand* biggrin.gif
Reply
Reply
post #5 of 68
12/30/12 at 6:10pm
Interested in this topic also. I myself and putting 2 of these in my room 14x14x8 in stereo config. 6bd is awesome, where did you get that figure??
Reply
Reply
post #6 of 68
12/31/12 at 7:20am
Quote:
Originally Posted by pokekevin View Post

Will it only go up if you colocate the subs? What if he spreads them around the room and than calibrates with some sort of room correction? I thought that would give more headroom? *Just trying to understand* biggrin.gif
In an anechoic room it will go up by precisely 6dB in that zone where they're less than 1/4 wavelength apart. But since rooms aren't anechoic it will vary throughout the room. The average will still be 6dB, 3dB from the doubling of cone area, 3dB from the doubling of power.
Reply
Reply
post #7 of 68
12/31/12 at 8:20am
Quote:
Originally Posted by Bill Fitzmaurice View Post

In an anechoic room it will go up by precisely 6dB in that zone where they're less than 1/4 wavelength apart. But since rooms aren't anechoic it will vary throughout the room. The average will still be 6dB, 3dB from the doubling of cone area, 3dB from the doubling of power.

In theory, but according to actual measurements in typical rooms, the gains vary considerably with frequency and in a few instances the gains can be reduced at certain frequencies. The subs paritally cancel each other out. I think generally two subs are better than one, but the gains one can expect can vary wildly,
Reply
Reply
post #8 of 68
12/31/12 at 8:38am
With my subs if I co-locate them I gain 6dBs, but I have them at 2 different positions and I gain 3dBs. Used an SPL meter to get those numbers... I prefer them spread out to smooth out freq resp, plus I really didn't need that much headroom.
Reply
Reply
post #9 of 68
12/31/12 at 12:13pm
Quote:
Originally Posted by mantaraydesign View Post

Hi,
Is there much of an improvement in the sound if you have 2 subwoofers?

Having two or more subwoofers dramatically reduces standing waves as well as providing better bass at all listening levels.
The bass benefits can be especially true when décor concerns force you into using a less than optimal location for the first sub.

By using multiple subwoofers, you can greatly increase the room’s modal density, largely filling in the peaks and dips, giving a smooth, articulate bass sound.
This improves the overall consistency of bass response from seat to seat.
Reply
Reply
post #10 of 68
12/31/12 at 12:28pm
Quote:
Originally Posted by coolcat4843 View Post

Quote:
Originally Posted by mantaraydesign View Post

Hi,
Is there much of an improvement in the sound if you have 2 subwoofers?

Having two or more subwoofers dramatically reduces standing waves as well as providing better bass at all listening levels.
The bass benefits can be especially true when décor concerns force you into using a less than optimal location for the first sub.

By using multiple subwoofers, you can greatly increase the room’s modal density, largely filling in the peaks and dips, giving a smooth, articulate bass sound.
This improves the overall consistency of bass response from seat to seat.

I would caution that a more accurate statement is that multiple subwoofers have the potential to reduce the frequency response peaks and valleys through the room and most importantly at the listening position. This is not a certainty, and is dependent on if the subwoofers are in complimentary locations in the room, followed by being set up for best integration. Case in point is for many cases where the "multiple subwoofers" are set on the front wall of a left-right symmetrical room. In such cases it is more likely for the response to be very similar for 2 subwoofers vs. a single, where interaction with the length of the room will be a dominant factor and will be constant for 1, 2, or 4 subwoofers along the front wall. In a large sampling of rooms I find that subwoofers at different depths in the room to be most advantageous and complimentary. If not along the depth, often along the dimension where there is structural asymmetry such as windows vs. solid wall or foundation wall vs. stud & drywall.
Reply
Reply
post #11 of 68
12/31/12 at 12:39pm
Quote:
Originally Posted by Mark Seaton View Post

I would caution that a more accurate statement is that multiple subwoofers have the potential to reduce the frequency response peaks and valleys through the room and most importantly at the listening position. This is not a certainty, and is dependent on if the subwoofers are in complimentary locations in the room, followed by being set up for best integration. Case in point is for many cases where the "multiple subwoofers" are set on the front wall of a left-right symmetrical room. In such cases it is more likely for the response to be very similar for 2 subwoofers vs. a single, where interaction with the length of the room will be a dominant factor and will be constant for 1, 2, or 4 subwoofers along the front wall. In a large sampling of rooms I find that subwoofers at different depths in the room to be most advantageous and complimentary. If not along the depth, often along the dimension where there is structural asymmetry such as windows vs. solid wall or foundation wall vs. stud & drywall.

It sounds like the scenario you describe here involves subs at variable distances to the listeners. In installations like that, is it possible to get good results without dedicated EQ hardware? I have total freedom to arrange my listening space however I want, but I don't think I have it in me to spend a bunch of money on calibration equipment.
Reply
Reply
post #12 of 68
12/31/12 at 2:57pm
Quote:
Originally Posted by SaviorMachine View Post

Quote:
Originally Posted by Mark Seaton View Post

I would caution that a more accurate statement is that multiple subwoofers have the potential to reduce the frequency response peaks and valleys through the room and most importantly at the listening position. This is not a certainty, and is dependent on if the subwoofers are in complimentary locations in the room, followed by being set up for best integration. Case in point is for many cases where the "multiple subwoofers" are set on the front wall of a left-right symmetrical room. In such cases it is more likely for the response to be very similar for 2 subwoofers vs. a single, where interaction with the length of the room will be a dominant factor and will be constant for 1, 2, or 4 subwoofers along the front wall. In a large sampling of rooms I find that subwoofers at different depths in the room to be most advantageous and complimentary. If not along the depth, often along the dimension where there is structural asymmetry such as windows vs. solid wall or foundation wall vs. stud & drywall.

It sounds like the scenario you describe here involves subs at variable distances to the listeners. In installations like that, is it possible to get good results without dedicated EQ hardware? I have total freedom to arrange my listening space however I want, but I don't think I have it in me to spend a bunch of money on calibration equipment.

So long as the distance difference isn't extreme, particularly one being arm's reach of the listener, the timing adjustments are more a matter of further optimization. You can also use an automated device like the Antimode 8033 or the Antimode dual-core which can adjust for 2 separate subwoofers. In many cases you can get very good results and significant improvement without having to adjust distance/delay settings. The AntiMode or using Audyssey XT32 are the best "hands-off" approaches, but if you have plenty of time to try and listen for improvements, you can get by with experimentation and often make significant improvements. Of course with any measurement setup it makes choices and adjustments much more clear and possible to confirm you are in fact improving the end result. I would say measurement capability is even more important than EQ to get good results. I have seen a few odd-shaped rooms where adding a sub at the rear without additional processing resulted in a big hole in the response. This was with 2 JLF113s where the phase control and low pass filters on board were not enough to do the trick. Such case is more an exception than a rule, but statistics don't help much if your room happens to be the exception.
Reply
Reply
post #13 of 68
12/31/12 at 3:27pm
Quote:
Originally Posted by SaviorMachine View Post

Quote:
Originally Posted by Mark Seaton View Post

I would caution that a more accurate statement is that multiple subwoofers have the potential to reduce the frequency response peaks and valleys through the room and most importantly at the listening position. This is not a certainty, and is dependent on if the subwoofers are in complimentary locations in the room, followed by being set up for best integration. Case in point is for many cases where the "multiple subwoofers" are set on the front wall of a left-right symmetrical room. In such cases it is more likely for the response to be very similar for 2 subwoofers vs. a single, where interaction with the length of the room will be a dominant factor and will be constant for 1, 2, or 4 subwoofers along the front wall. In a large sampling of rooms I find that subwoofers at different depths in the room to be most advantageous and complimentary. If not along the depth, often along the dimension where there is structural asymmetry such as windows vs. solid wall or foundation wall vs. stud & drywall.

It sounds like the scenario you describe here involves subs at variable distances to the listeners. In installations like that, is it possible to get good results without dedicated EQ hardware? I have total freedom to arrange my listening space however I want, but I don't think I have it in me to spend a bunch of money on calibration equipment.

You could get ok results with no eq but it would take a lot of effort I expect. A spl meter would be the minimum needed plus pen/paper.
Reply
Reply
post #14 of 68
12/31/12 at 4:06pm
Quote:
Originally Posted by Mark Seaton View Post

So long as the distance difference isn't extreme, particularly one being arm's reach of the listener, the timing adjustments are more a matter of further optimization. You can also use an automated device like the Antimode 8033 or the Antimode dual-core which can adjust for 2 separate subwoofers. In many cases you can get very good results and significant improvement without having to adjust distance/delay settings. The AntiMode or using Audyssey XT32 are the best "hands-off" approaches, but if you have plenty of time to try and listen for improvements, you can get by with experimentation and often make significant improvements. Of course with any measurement setup it makes choices and adjustments much more clear and possible to confirm you are in fact improving the end result. I would say measurement capability is even more important than EQ to get good results. I have seen a few odd-shaped rooms where adding a sub at the rear without additional processing resulted in a big hole in the response. This was with 2 JLF113s where the phase control and low pass filters on board were not enough to do the trick. Such case is more an exception than a rule, but statistics don't help much if your room happens to be the exception.

Thanks. I don't doubt that the Anti-Mode products are excellent, but they demand the kind of expense I'm trying to avoid. I'm game for a SPL meter, but once I've taken measurements, what can I do with them? Do you mean, I should re-locate subs in the room to get a better response per my measurements?
Quote:
Originally Posted by sputter1 View Post

You could get ok results with no eq but it would take a lot of effort I expect. A spl meter would be the minimum needed plus pen/paper.

Same as above--do you mean I should be taking response measurements with subwoofers at different positions? I should mention that I do technically use EQ, but it's just Audyssey MultEQ.
Reply
Reply
post #15 of 68
1/1/13 at 8:04am
Summary - Two subs are better though both at the front would be less optimal. Spacing the subs in depth is good. However, do not have a a distance difference of the the subs to the listener otherwise distance,delay adjustment is needed.

-- Does this rule out positioning one sub up front and another in an "end table" relative to the listening position?

-- It would seem the above criteria would recommend putting a sub at each end of the room?
Reply
Reply
post #16 of 68
1/1/13 at 7:42pm
This is a very interesting topic. I'm also thinking about getting a second sub, mainly to even out the FR, and I hope it's ok to hijack this thread a bit. I have a pretty standard room so this question should be applicable for others aswell. Enclosed is a quick layout of my HT. Blue box in the front is my current sub. I would like to put the second sub on the location marked with "1" but if I understood Mark's comments correctly that's not the best place. Correct? Other possible locations would be numbers "2" and "3". Is number "3" already too close to the listening position? Where else would be a good place for the second sub?


Reply
Reply
post #17 of 68
1/1/13 at 8:25pm
Quote:
Originally Posted by sawyerthecat View Post

-- Does this rule out positioning one sub up front and another in an "end table" relative to the listening position?
No, because the need to use delay to compensate for the difference in distance is slight, if there's any at all. Time align is critical in the midrange, where your ability to hear time issues is quite good. In the subwoofer frequencies the wavelengths are too long for you to perceive time issues unless the distances involved are on the order of 30 feet or more.
Quote:
I would like to put the second sub on the location marked with "1" but if I understood Mark's comments correctly that's not the best place. Correct?
Correct. That results in the rear wall reflective node from both subs being the same. You'd probably get best results with position 2, though sidewall may work well too.
Reply
Reply
post #18 of 68
1/2/13 at 3:06am
Quote:
Originally Posted by Bill Fitzmaurice View Post

No, because the need to use delay to compensate for the difference in distance is slight, if there's any at all. Time align is critical in the midrange, where your ability to hear time issues is quite good. In the subwoofer frequencies the wavelengths are too long for you to perceive time issues unless the distances involved are on the order of 30 feet or more.
Correct. That results in the rear wall reflective node from both subs being the same. You'd probably get best results with position 2, though sidewall may work well too.
My room is very similar. Assuming the front subs cone is facing the couch. If one was to choose sidewall placement, is there an optimal firing direction for placing a front firing, front ported sub (Klipsch RW-12d in my case)? Does it even matter? I understand this is a very general question.
Edited by Bond 007 - 1/2/13 at 4:30am
Reply
Reply
post #19 of 68
1/2/13 at 6:14am
Quote:
Originally Posted by Bond 007 View Post

My room is very similar. Assuming the front subs cone is facing the couch. If one was to choose sidewall placement, is there an optimal firing direction for placing a front firing, front ported sub (Klipsch RW-12d in my case)? Does it even matter? I understand this is a very general question.
Subwoofers radiate omni-directionally. They tend to work best down-firing or aimed at the wall. Front firing sells best because typical customers don't know that subwoofers radiate omni-directionally.
Reply
Reply
post #20 of 68
1/2/13 at 6:26am
Quote:
Originally Posted by Bill Fitzmaurice View Post

Quote:
Originally Posted by Bond 007 View Post

My room is very similar. Assuming the front subs cone is facing the couch. If one was to choose sidewall placement, is there an optimal firing direction for placing a front firing, front ported sub (Klipsch RW-12d in my case)? Does it even matter? I understand this is a very general question.
Subwoofers radiate omni-directionally. They tend to work best down-firing or aimed at the wall. Front firing sells best because typical customers don't know that subwoofers radiate omni-directionally.

How come your plans aren't down firing if they are the best?
I doubt front firing or down firing matters to many here as we want the best for our given budget/room constraints. Also, atleast one company here has stated there isn't any difference between their df vs their ff subs.
Reply
Reply
post #21 of 68
1/2/13 at 6:36am
The biggest improvement is in the frequency smoothing. You will also get greater output but if you are calibrating the level to match your speakers , unless your current sub is inadequate, you won't see a huge impact here. You will lessen the stress on each sub though as you can lower the amp gain on each. I have 5 subs. The totality of them hits the sweet spot at about 77db. My mains are at 75. ( I like my subs a little hot) since there are 5 of them , none of them sweat on even the heaviest of bass scenes so I never worry.
Reply
Reply
post #22 of 68
1/2/13 at 9:12am
Quote:
Originally Posted by sputter1 View Post

How come your plans aren't down firing if they are the best?
Horns are a totally different animal. My subs may be placed with the horn mouth downfiring if desired. But since they have THD far lower than direct radiators there's nothing to be gained from it.
Quote:
I doubt front firing or down firing matters to many here as we want the best for our given budget/room constraints.
Which way the driver faces should have no relationship with price.
Quote:
Also, atleast one company here has stated there isn't any difference between their df vs their ff subs.
Measured response charts with the same sub front, rear and downfiring would be definitive. If there aren't any then all you're getting is an unsubstantiated subjective opinion, which is OK if it comes from a user, not so much from a manufacturer.
Reply
Reply
post #23 of 68
1/2/13 at 9:43am
Quote:
Originally Posted by Bill Fitzmaurice View Post

Subwoofers radiate omni-directionally. They tend to work best down-firing or aimed at the wall. Front firing sells best because typical customers don't know that subwoofers radiate omni-directionally.
Thanks. That's pretty much what I expected. Just thought I'd ask.
Reply
Reply
post #24 of 68
1/2/13 at 9:46am
Quote:
Originally Posted by Bill Fitzmaurice View Post

Horns are a totally different animal. My subs may be placed with the horn mouth downfiring if desired. But since they have THD far lower than direct radiators there's nothing to be gained from it.
Which way the driver faces should have no relationship with price. Measured response charts with the same sub front, rear and downfiring would be definitive. If there aren't any then all you're getting is an unsubstantiated subjective opinion, which is OK if it comes from a user, not so much from a manufacturer.

Interesting take Bill and I am a big fan of horn subs. I had some Danley Tapped Horns that were under my rear row riser and although the tactile effect from them was good, I felt the bass energy coming from behind in my seat in the front row was distracting. Tom Danley referred to sitting on top of those horn subs as being "within the horn bubble" and when sitting directly on top of them I agree but the row in front of them took a pounding from behind even though the horn exits were to rooms back corners.

Turns out, I much prefer the bass energy to be enveloping but also hitting me from the front (i.e. from the screen image).
Reply
Reply
post #25 of 68
1/2/13 at 11:29am
Quote:
Originally Posted by sputter1 View Post

Quote:
Originally Posted by SaviorMachine View Post

Quote:
Originally Posted by Mark Seaton View Post

I would caution that a more accurate statement is that multiple subwoofers have the potential to reduce the frequency response peaks and valleys through the room and most importantly at the listening position. This is not a certainty, and is dependent on if the subwoofers are in complimentary locations in the room, followed by being set up for best integration. Case in point is for many cases where the "multiple subwoofers" are set on the front wall of a left-right symmetrical room. In such cases it is more likely for the response to be very similar for 2 subwoofers vs. a single, where interaction with the length of the room will be a dominant factor and will be constant for 1, 2, or 4 subwoofers along the front wall. In a large sampling of rooms I find that subwoofers at different depths in the room to be most advantageous and complimentary. If not along the depth, often along the dimension where there is structural asymmetry such as windows vs. solid wall or foundation wall vs. stud & drywall.

It sounds like the scenario you describe here involves subs at variable distances to the listeners. In installations like that, is it possible to get good results without dedicated EQ hardware? I have total freedom to arrange my listening space however I want, but I don't think I have it in me to spend a bunch of money on calibration equipment.

You could get ok results with no eq but it would take a lot of effort I expect. A spl meter would be the minimum needed plus pen/paper.

My take is that you find the best spot using the meter without EQ then allow EQ work. imho
Reply
Reply
post #26 of 68
1/2/13 at 11:46am
Quote:
Originally Posted by sputter1 View Post

My take is that you find the best spot using the meter without EQ then allow EQ work. imho
I've always wondered how you can tell what the best spot is from an SPL meter without graphing the response. Is it the spot with the most SPL?
Reply
Reply
post #27 of 68
1/2/13 at 11:51am
Quote:
Originally Posted by dominguez1 View Post

I've always wondered how you can tell what the best spot is from an SPL meter without graphing the response.
You can't. SPL will be different at different frequencies and listening positions, so charting it is a necessity. Doing it one frequency at a time with a meter will work, but it will also take forever. Frequency response charting software makes it a 30 second job.
Reply
Reply
post #28 of 68
1/2/13 at 11:57am
I agree with you, but isn't this the often recommended sub crawl method?
Reply
Reply
post #29 of 68
1/2/13 at 12:08pm
Quote:
Originally Posted by dominguez1 View Post

I agree with you, but isn't this the often recommended sub crawl method?

Yes but it's more accurate using a meter with the sub at your seat and move around the room using pink noise Graphing would take more time this way.eek.gif
REW ftw
Edited by sputter1 - 1/2/13 at 12:13pm
Reply
Reply
post #30 of 68
1/2/13 at 1:00pm
Quote:
Originally Posted by dominguez1 View Post

I agree with you, but isn't this the often recommended sub crawl method?
The sub crawl traditionally relies on your ears, which is OK if those are the only tools you have to work with. Measuring software allows you do put the sub in the LP and then take FR graphs at as many room locations as you wish. Whichever gives the best result is where you put the sub. Then you EQ at the LP.
Reply
Reply
New Posts  All Forums:Forum Nav:
  Return Home

AVS Top Picks

AVS › AVS Forum › Audio › Subwoofers, Bass, and Transducers › Single Subwoofer vs. Dual Subwoofers