FAQ: Center of Room Deadspot for Sub Response

[moovtune]

I've been unhappy for weeks with the lack of low frequency energy from my two subs at my sweet spot, which unfortunately is basically the center of the room. If I stand up I get more low end and if I start to move around the room it seems to increase by 100%.
My question is: should I waste my time trying to find a placement for the subs that will give me what I'm expecting, or is the center of the room always going to be a dead spot no matter where I move the subs to?

[bootman]

Aug 9, 2011 12:01:13 GMT -5 moovtune said:

I've been unhappy for weeks with the lack of low frequency energy from my two subs at my sweet spot, which unfortunately is basically the center of the room. If I stand up I get more low end and if I start to move around the room it seems to increase by 100%.
My question is: should I waste my time trying to find a placement for the subs that will give me what I'm expecting, or is the center of the room always going to be a dead spot no matter where I move the subs to?

This is hard to say without a bit more info.
Where in the room are they placed?
If possible can you provide a layout of your room with their placement?

Something simple done in paint with shapes showing placement of everything will do.

Two Epik legends should fill up most rooms.

Want a good read on sub placement?

www.audioholics.com/tweaks/get-good-bass/subwoofer-placement-the-place-for-bass-part-1

[NorthStar]

Every room have its nuls and peaks, and where you sit will at the end determine pretty much this simple mathematical equation.

And I agree with bootman that two subs well positioned will help equalizing that unbalance.

But listener positioning (1/3rd, 1/5th, 1/7th, 1,9th, etc.) from all room's dimensions (width, length and height) will much more alleviate the bulk of this unevenness.

[moovtune]

Yes, the two Legends have lots of output for the room, but it's not present in the center of the room where I sit. What I'm not sure of is whether I could ever get bass strong in the center of the room no matter where I place the subs. I'm not an acoustic expert nor a mathematician so for all I know I could spend lots of time trying to achieve something that's just not possible. If you're saying it should be, then I'll spend some time doing the subwoofer crawl tomorrow. When I do the crawl, would you suggest just using one sub set in the listening spot and the other one off or both in the sweet spot?

[NorthStar]

Put one at the main listening position and the other one facing the front wall (1/4 way from a corner and 4 inches from the front wall). ...Or right in the middle of the front wall (half way from both side walls).

Then do the crawling trick.

Or put them both at the main listening position, and position one sub at a time while doing the crawling trick.

And if you can, change the main listening position; only if by few inches (sideways or forward or backward).
{Use some of those fractions I told you before: 1/3, 1/5, 1,7, 1/9, 1/11, to position yourself in a three-dimensional space. The Bass will benefit, so are you.}

EXPERIMENT!

[moovtune]

Thanks LOTR. I'll give these suggestions a try for sure.

[flamingeye]

Well it`s a well known fact that the center of a room is the worst place for bass if you could offset your main sitting place back our forewords you will have a better chance of getting good bass

[NorthStar]

Another tip:

The longest wall in your room (without interference from other piece of furniture) is always the best one for a subwoofer; because it permits the bass waves to travel freely and farther, without close object's and closer adjacent wall's confliction.

And NEVER put a sub or a loudspeaker for that matter with the exact same proximity to the front, side walls and floor (use different distances that are NOT multiples).
=> That is when measured from the voice coil of the drivers (woofers).

[jamrock]

Get a sub / room calibrating tool such as MINI DSP, DSPeaker 8033S and place the subs whereever you want.

[Deleted]

Aug 9, 2011 15:55:25 GMT -5 moovtune said:

Yes, the two Legends have lots of output for the room, but it's not present in the center of the room where I sit. What I'm not sure of is whether I could ever get bass strong in the center of the room no matter where I place the subs. I'm not an acoustic expert nor a mathematician so for all I know I could spend lots of time trying to achieve something that's just not possible. If you're saying it should be, then I'll spend some time doing the subwoofer crawl tomorrow. When I do the crawl, would you suggest just using one sub set in the listening spot and the other one off or both in the sweet spot?

".....whether I could ever get bass strong in the center of the room no matter where I place the subs......"

Yes, you can get strong bass. You have two identical subs. I recommend you do the sub crawl using one sub only. Make a notation of the best and the second best position in your test. This is where (or close) to place the two subs. If practical considerations preclude these spots then go with locations 1&3 or 2&3 or 2&4, etc.

[hemster]

Aug 9, 2011 15:55:25 GMT -5 moovtune said:

Yes, the two Legends have lots of output for the room, but it's not present in the center of the room where I sit. What I'm not sure of is whether I could ever get bass strong in the center of the room no matter where I place the subs. I'm not an acoustic expert nor a mathematician so for all I know I could spend lots of time trying to achieve something that's just not possible. If you're saying it should be, then I'll spend some time doing the subwoofer crawl tomorrow. When I do the crawl, would you suggest just using one sub set in the listening spot and the other one off or both in the sweet spot?

Those Eigenmodes can lead to anemic bass but do not give up!

Good advice from others above. Also look at the sub placement article in the FAQ. emotivalounge.proboards.com/index.cgi?action=display&board=subwoofeers&thread=19241&page=1#305416

[bootman]

Aug 9, 2011 18:50:47 GMT -5 jamrock said:

Get a sub / room calibrating tool such as MINI DSP, DSPeaker 8033S and place the subs whereever you want.

Check out his sig.
He already has one. (actually two!)

[moovtune]

Thanks for all the suggestions. I've achieved what I was looking for and it only took about 1.5 hours. I put one sub in the sweet spot, looped a 40hz and a 31.5 hz tone and did the crawl, SPL meter in hand and found a couple of places that registered best bass level. They were both at the front corners (along the longest wall as suggested) and not far from where they had been placed.
Then I moved one sub into position and put the SPL meter in the sweet spot and moved the sub around slightly until I got the highest reading. Then put the other sub in place, turned off the first sub, and moved #2 around until best reading. Then turned them both on and experimented with the phase switch on each, in turn (in-phase was best for both). But I noticed as I approached the couch from behind to look at the SPL meter that I was passing through an audibly louder area.
A little more experimenting showed me that moving the couch back slightly less than a foot increased the level even more. Then I ran the 8033 auto setup for each in their new location and Audyssey after that.
The end result is I finally have the couch shaking "kick" and the feeling of air being pushed that I was missing from the larger and deeper FX in films. In fact I had to lower the levels on both from 12 O'clock to 11. A good film to use for bass energy and LFE testing is the animated film "9" by the way. Not as commonly thought of as other titles but full of good test material.
Thanks to all for your help. I won't have to sell my Legends for bigger subs now.

[bootman]

Aug 10, 2011 12:12:33 GMT -5 moovtune said:

Thanks for all the suggestions. I've achieved what I was looking for and it only took about 1.5 hours. I put one sub in the sweet spot, looped a 40hz and a 31.5 hz tone and did the crawl, SPL meter in hand and found a couple of places that registered best bass level. They were both at the front corners (along the longest wall as suggested) and not far from where they had been placed.
Then I moved one sub into position and put the SPL meter in the sweet spot and moved the sub around slightly until I got the highest reading. Then put the other sub in place, turned off the first sub, and moved #2 around until best reading. Then turned them both on and experimented with the phase switch on each, in turn (in-phase was best for both). But I noticed as I approached the couch from behind to look at the SPL meter that I was passing through an audibly louder area.
A little more experimenting showed me that moving the couch back slightly less than a foot increased the level even more. Then I ran the 8033 auto setup for each in their new location and Audyssey after that.
The end result is I finally have the couch shaking "kick" and the feeling of air being pushed that I was missing from the larger and deeper FX in films. In fact I had to lower the levels on both from 12 O'clock to 11. A good film to use for bass energy and LFE testing is the animated film "9" by the way. Not as commonly thought of as other titles but full of good test material.
Thanks to all for your help. I won't have to sell my Legends for bigger subs now.

Outstanding!

Your post should be stickied as reference for other users that may be having similar issues and hopelessly spending $$$ upgrading when just a good bit of troubleshooting and optimizations was all that was needed.

[Deleted]

Great! I hope you don't have carpet burns on your elbows and knees!

[flamingeye]

good to hear it always pays to do a little experimenting now play with the mains or maybe you already did

[Lsc]

"One sub in the sweetspot" - what does this mean?

[moovtune]

I had two sub's - but using just one of them, I placed it in the spot where I usually sit - the "sweet spot" - in the center of the couch in my case.

[remo]

I had the same issue but could not move my listening position or the subs because of a constricting room layout. Ended up building stands and raising my subs , center of the drivers are 16" from the floor. Solved the issue.

[ansat]

Aug 9, 2011 18:50:47 GMT -5 jamrock said:

Get a sub / room calibrating tool such as MINI DSP, DSPeaker 8033S and place the subs whereever you want.

Plus using dsp to attempt to correct room problems and placement issues never end up well.