Dual Subs

[Yeha-Noha]

Originally Posted by tbizzle

Haha no problem man. As for the sub on the wall, I think it should sound as good as if it was in a corner. It might seem to have a little less output than a corner, but not necessarily. Subs generally don't sound boomy by being in a corner, it's when they're too close to the wall that it can get boomy or muddy.

LFE waves like to interact with walls, so a sub should be placed near one as opposed to in the middle of a room. At least that's my understanding of it, I'll let the pros chime in on this stuff though [edit: BD swooped in while I was in the bathroom ]. I'm just speaking from personal experience I've had with this stuff in the last year and from with what I've learned here on the forums.

Ok, I won't placed them too close to a wall. That's some sound advice man!

[rpatt]

My HT room doesn't allow the middle of left right/front rear walls placement. I used the 25% of wall length which is "very good" in BDs diagrams. This placement coincided with my front speaker placement so I put the subs in front of the speaker stands. I'm very happy with the results. Try this arrangement if you can't make the others work.

[Yeha-Noha]

The 1/4 distance along the front wall won't work for me. I don't have a wall on the right side. The HT area opens directing into the dining room and there's another 15 ft to the dining room's corner. Actually where I have placed my first sub is about 1/4 from the corner if there were a corner on the front right side. There isn't enough space to put it 1/4 L on the left. My only choice is on the left side wall about 1/4 L from the corner or FP which is in the left corner.

[350gt]

A quick sketch of how I moved the subs around. I like that the def tech doesnt rumble as much as when I had it in the front right corner but now I can barely hear it.
I didnt get dimensions but I know from the screen to where the ac is it is 17ft. There is some pics in my gallery. Do you think this is the optimal placement for the room and I might just have to do a little better job at calibrating?

Or would you recommend I move them...?

P.s. its a horrible sketch but I did it in a few minutes...but its almost right on...

[edubb5]

Originally Posted by Big Daddy

This question has been asked and answered in multiple threads. With two subwoofers, it is best and easiest to have identical subwoofers from the same manufacturer. However, with a little patience and experimentation, you can make two different subwoofers work with each other. The bass response in a room can be very uneven. Depending on the position of the sub or your listening position, you may experinece cold and hot spots. This due to interation of low frequency sound waves with the room boundaries and creation of standing waves. An easy solution is to use two subwoofers. In almost all cases, two subwooferes are preferred to one. Placement of the two subs is very important. Research has shown that the best positions for tow subs are:

1. Middle of the side walls.
2. One in the middle of the front wall and one in the middle of the rear wall.
3. The two right and left front corners.
4. When you have different subwoofers and one is stronger than the other one. Put the bigger (better) sub up front in a corner and put the smaller subwoofer on the side or behind your sofa (a few feet away). With this arrangement, the bigger sub up front will give you deeper and lower frequency bass sound and the smaller sub will give you the upper frequency and louder bass sound.

It is very important that you adjust the level of each sub independently.

1. On the back of the subs, turn their levels to 50%-60%, no higher than 75%.
2. On the back of the subs, turn their crossovers all the way up to their maximum point. You set the crossover in the receiver.
3. In the receiver's menu, set all speakers to SMALL.
4. In the receiver's menu, set the crossovers of all the speakers to 80Hz. You can deviate from 80Hz depending on the low frequency extension of your speakers. Make sure the crossover is always set at least 10Hz-15Hz higher than the minimum frequency response (+-3dB) of your speakers.
5. In the receiver's menu, set the crossover frequency of the LFE channel to 120Hz.
6. In the receiver's menu, set the level of the subwoofers to zero.
7. Turn off one subwoofer.
8. Play the test tones through the subwoofer that is on and measure its response with an SPL meter or your ears. Adjust its level on its back (not the receiver) so that you get approximately 75dB.
9. Turn on the other subwoofer and turn off the previous subwoofer.
10. Run test tones through it and adjust the level on its back so that you get approximately 75dB.
11. Now, turn on both subwoofers and do not touch the levels on their back.
12. Run the calibration program again or use an SPL meter.
13. If you are using an SPL meter, when the time comes to adjust the subwoofers, move the SPL meter slighly to the right and slightly to the left and average the dB level that it registers.

Hopefully this will work. If you move the subwoofers or move your listening position, don't be surprised if the level of the subwoofers change drastically.

Read A Guide to Subwoofers (Part II). Post #2 in that thread discusses positioning and the importance of using identical subs.

Should the Spl meter be turned toward the speakers? Or Up? Like a sound mic for Mcacc or Audyssey

[jomari]

@350GT,

id prefer to have the def tech close to the R speaker, almost parallel to your current jbls.

have you tried moving the jbls opposite of the def techs?

Originally Posted by edubb5

Should the Spl meter be turned toward the speakers? Or Up? Like a sound mic for Mcacc or Audyssey

the spl meter should be facing 45 degrees up as bd has mentioned in his sticky, calibrating with your spl meter.

i prefer to use it facing almost straight up.

[Fors*]

Originally Posted by jomari

@350GT,

id prefer to have the def tech close to the R speaker, almost parallel to your current jbls.

have you tried moving the jbls opposite of the def techs?



the spl meter should be facing 45 degrees up as bd has mentioned in his sticky, calibrating with your spl meter.

i prefer to use it facing almost straight up.

jomari, do you get a slightly different reading when in this position? I'm curious if you do and why you do position it straight up.....

[jomari]

for me, it avoids inconsistencies in readings, avoiding room reflections and/or other variables.

gasping results? not really. better? in my opinion it worked in a number of rooms ive used it in.

it may be unorthodox, but my preference nonetheless.

[Fors*]

Originally Posted by jomari

for me, it avoids inconsistencies in readings, avoiding room reflections and/or other variables.

gasping results? not really. better? in my opinion it worked in a number of rooms ive used it in.

it may be unorthodox, but my preference nonetheless.

Well, since I need to switch my surrounds to make room for the projector, I was going to pull out the SPL meter anyway, so perhaps I will try it this way just to see what happens......

[erict]

Originally Posted by forsberg21

Well, since I need to switch my surrounds to make room for the projector, I was going to pull out the SPL meter anyway, so perhaps I will try it this way just to see what happens......

Are you going to switch you're room around with the new projector?

[Fors*]

Originally Posted by erict

Are you going to switch you're room around with the new projector?

No, just the surrounds as I need the shelf space behind me for the projector. I have the bipoles there and they take up a lot of horizontal space, that the Polk's dont'. The projector is going along that shelf and with both both bipoles up there right now, it wouldn't work. Thus the 30's free up the space needed for where the pj is going.

By the way, my wife was home from work sick today and must have fallen asleep, as the FedEx guy had to take my projector back with him, because he needed a signiture and my wife must not have answered the door.

[jomari]

Originally Posted by forsberg21

Well, since I need to switch my surrounds to make room for the projector, I was going to pull out the SPL meter anyway, so perhaps I will try it this way just to see what happens......

some use the spl meter facing directly at the speakers themselves, others point at 45 degree angle, some facing the ceiling.

its a matter of preference and experimentation. as much as the radioshack spl meter is golden considering its price point, its noted as well that not all of the spl readings are deemed accurate, some due to unit discrepancies, others due to the microphone built in em.

[350gt]

Originally Posted by jomari

@350GT,

id prefer to have the def tech close to the R speaker, almost parallel to your current jbls.

have you tried moving the jbls opposite of the def techs?

.

Thanks for the long awaited answer...LOL

But ya what I did try was positioning the JBL behind the rear couch and it sounded way better. I am going to move the DEF. tech back to the right side where it was.
It seems like the JBL now fills the rear of the room with bass and as soon as I move the def tech back the front of the room will be right where i want it.
I also plan on getting some risers for both subs, I would build them but I am not to handy with tools ..