Running two different subs?

mr. doom · 24th February 2011, 04:57 PM

What problems occur when operating two separate BR subwoofers other than peaks at overlap. One box is tuned to 48hz the other at 55hz.

I am shooting for a nice 60hz bump.

AllenB · 26th February 2011, 02:08 AM

I don't see a problem with them in general. Room modes will probably outweigh your plan for a hump, (or help you create one or even extend the bass a little).

Top Shelf · 27th February 2011, 12:41 AM

Hmmm how come I've read posts that claim up to -5 db difference when using two different subs? Not that I'm disagreeing with you because I've never run two different subs on the same system. It would make sense that the sum would be additive though.

AllenB · 27th February 2011, 01:43 AM

Room modes.

Perhaps if you imagine your room as a minefield of hot/cold spots. Where you place your sub and where you listen will each have an effect on the response. Unless you listen in a corner and put your sub in another corner, you'll have an issue. Some bass will be boosted and some won't couple well to your listening position.

Putting a second sub somewhere makes the interaction more complex, but has the potential to improve the total bass transfer to your listening position. Where and how is important.

weltersys · 27th February 2011, 02:59 PM

Quote:

Originally Posted by mr. doom

What problems occur when operating two separate BR subwoofers other than peaks at overlap. One box is tuned to 48hz the other at 55hz.

I am shooting for a nice 60hz bump.

The different tunings will result in different phase response, so they will not have a + 6 dB summation.
This will result in uneven response across the room, LF comb filtering in addition to room problems.
I'd suggest stacking the subs to minimize the problem. A differing time delay and EQ for each box would be deeded to correct the phase difference.

The 55 Fb box will need a 7 Hz higher HP than the 48Hz box to keep from tearing up the cone, which further changes the phase response, unless you HP both at around 50Hz, in which case you loose the extension the 48 Hz box would give.

Have fun!

revboden · 27th February 2011, 08:18 PM

Well there's no way to tell until you try it. Phase weirdness will probably rear its head so distance tuning (moving them closer/farther apart) will be necessary. Stacking might work to couple the subs a bit but then you'r stuck with source phase cancellation (i'd spread them out). I say give it a go and see what happens.

24th February 2011, 04:57 PM	#1
mr. doom diyAudio Member Join Date: Mar 2006 Location: glacier	Running two different subs? What problems occur when operating two separate BR subwoofers other than peaks at overlap. One box is tuned to 48hz the other at 55hz. I am shooting for a nice 60hz bump.

27th February 2011, 12:41 AM	#3
Top Shelf diyAudio Member Join Date: Apr 2010 Location: Midland, Ontario	Hmmm how come I've read posts that claim up to -5 db difference when using two different subs? Not that I'm disagreeing with you because I've never run two different subs on the same system. It would make sense that the sum would be additive though. __________________ JEREMY M_________________________________ I like it loud, BUT NOT TOO LOUD!.... Hey do you hear that high pitched ringing sound ?

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26th February 2011, 02:08 AM	#2
AllenB diyAudio Member Join Date: Oct 2008	I don't see a problem with them in general. Room modes will probably outweigh your plan for a hump, (or help you create one or even extend the bass a little).

27th February 2011, 01:43 AM	#4
AllenB diyAudio Member Join Date: Oct 2008	Room modes. Perhaps if you imagine your room as a minefield of hot/cold spots. Where you place your sub and where you listen will each have an effect on the response. Unless you listen in a corner and put your sub in another corner, you'll have an issue. Some bass will be boosted and some won't couple well to your listening position. Putting a second sub somewhere makes the interaction more complex, but has the potential to improve the total bass transfer to your listening position. Where and how is important.

27th February 2011, 08:18 PM	#6
revboden diyAudio Member Join Date: Feb 2011	Well there's no way to tell until you try it. Phase weirdness will probably rear its head so distance tuning (moving them closer/farther apart) will be necessary. Stacking might work to couple the subs a bit but then you'r stuck with source phase cancellation (i'd spread them out). I say give it a go and see what happens.

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