Two subs - how best to use them?

m4rky_m4rk

Well-known Member
Hi,

I have two subs :D

At the mo I have a REL B1 attached to the front hi level and low level LFE. The B1 is located mid way behind the front speakers and in a corner. Diagonally opposite in the room, also in a corner and mid way between the rears, I have a REL Stadium 1 hooked up to the hi level for the rears. It's old, before DD5.1, and has no low level.

I was wondering if this is the best configuration for two subs? How do others use two subs. I could have both running of the fronts for the hi level or one on the fronts and one on the rear as I have it now.
 
B

bobby1961

Guest
I can only speak from my experience I tried it and it didnt work until I got an SMS1 for Christmas. Having 2 boxes that have their own tuning plus the room having its own input made it almost impossible to integrate correctly with the main speakers. And that as I found out is the most important part of getting a sub to sound good.
 

KelvinS1965

Distinguished Member
Have you got your rear speakers set to 'large' in the amp's setup menu? Otherwise you won't get much bass going to the rear sub. Some amps don't allow large rears if the fronts are set small, so that might also limit things.

Generally when people use two subs, they are sent the same LFE signal and then balanced to give the correct level verses the main speakers. By having two subs it can help reduce or at least smooth the natural peaks and troughs in the response caused by room acoustics. However it is quite involved setting up two subs and I've often seen it said that one good sub is better than two cheaper ones. In spite of this, I'm considering recycling my older XLS200 sub to see if it will help with a 40Hz dip I have in my main listening position....but it might be a long process even if it does acheive my aim.

PS: A two channel EQ device like my Beringer DEQ2496 can help EQ each sub differently, but would be difficult to use without a low level input on both subs.
 
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cribeiro

Well-known Member
OK, this is generally speaking, but I think it is necessary to say...

The advantages of two subs are

1. More headroom (but this would not be a good argument to get 2 subs)

2. A more even frequency response and less room mode problems

The latter can only be achieved with two identical subwoofers properly placed in the room.

So no real advantage for you, I believe...

Someone here reported of using two subs working at different frequency ranges, which is also a possibility, but that is not an easy setup to adjust... And someone here also investigated the topic "2 subs vs. 1 sub within the same budget", arriving to the conclusion that 1 better sub is usually the best option.
 

THE_FORCE

Banned
Hi Mark. It's generally considered that if you're running 2 subs, then it's best to place them in the front of the room. Each as close to your main speakers as poss so as to integrate them into your system and allow a smooth transition from mains to subs as poss. Unless anyone can prove me otherwise ?
 
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recruit

Guest
Running 2 subs can and will work very well if setup correctly, to get it right you really need to know how well they work when postioned in the room, this is tough enough with one but two make it all that more complicated.

As mentioned above and from my own experience I have also found that they give good results when positioned close to the main Left and Right speakers, but depending on the room it may or may not give great results and will usually require tuning with some form of EQ, the worst senario is that one sub can cancel out the other and will give less bass than with just one :eek:

Make sure you know the response from both locations and then work from there, this can usually be done with EQ and an SMS1 would do the trick nicely and make it a lot easier to integrate into you're system.

Another option could be co-location and that means to use both subs in the same position or stacking if possible, this will also give more SPL and cut out the hard work when positioning seperately from each other...

Good Luck :smashin:
 

m4rky_m4rk

Well-known Member
Have you got your rear speakers set to 'large' in the amp's setup menu? Otherwise you won't get much bass going to the rear sub. Some amps don't allow large rears if the fronts are set small, so that might also limit things.

Generally when people use two subs, they are sent the same LFE signal and then balanced to give the correct level verses the main speakers. By having two subs it can help reduce or at least smooth the natural peaks and troughs in the response caused by room acoustics. However it is quite involved setting up two subs and I've often seen it said that one good sub is better than two cheaper ones. In spite of this, I'm considering recycling my older XLS200 sub to see if it will help with a 40Hz dip I have in my main listening position....but it might be a long process even if it does acheive my aim.

PS: A two channel EQ device like my Beringer DEQ2496 can help EQ each sub differently, but would be difficult to use without a low level input on both subs.

Hi, thanks for the input Guys.

To answer a few questions:

The subs are not identical because I bought a new REL B1 recently and already owned an old REL S1. I recycled the S1. Its been a very good sub and is still reliable. Its 10-15yrs old now and sounds great but its not as good as the B1. For now I decided to use the Stadium 1 for rear bass duties but I could have also have used it on the fronts for Hi level as wellas the B1. Not sure which is best which is the point of my post. Two subs running off Hi level fronts with rears set to small or one sub supporting rear hi level and the other supporting front hi level and rears and fronts set to large. I guess nromaly there isn't that much call for v.low bass output to rears and old REl S1 maybe thankful for that. If both the subs where connected to the front then then the bass performance, rear to front, could be uneven even if I set the rears to small? As I have it set up now the two subs only come into play for films 5.1 etc. For music only the fronts are used of course unless I set the crazy disco option on the amp

I have spent hours, days moving the subs around in the room. Its quite a tricky thing getting the bass to smooth and even. Using my ears and the graphical output of levels from my LX81 amp. I think I have the room positioning and levels setup quite good now. The REL S1 doesn't have low level LFE input. B1 has both Hi and low level. All speakers are set to Large except centre which is Small with 100hz crossover. So now I have effectively very good bass from fronts and rear Hi level with LFE going to the front sub.

I found that placing the B1 close to a front speaker caused the bass to become uneven with respect to left and right reinforcement. A similar thing happened with the rears. So now I have placed the subs more less equidistant from the speakers and in the corners of the room. My speakers are not positioned paralell to any wall but are symmetrical about the daigonal from one corner of the room to the other. ie lots of space behiind the speakers to place subs in corners. Roof isn't even flat. Its sloped so the room is far from box shaped.

Recently by accident I had the rear Stadium 1 sub connected to the front Hi level and vice versa. It sound quite good actually so I think this confirms that I have the levels etc pretty well set up and front vs rear bass is balanced as best it can be.

edited to add:

Instead of just pondering I decided to actually try it out. Now much easier for me to do with the recent addition of banana plugs instead of bare wire. The result so far only tested for music. It wasn't that dramitic a change and quite hard to quantify. I think some frequencies were reinforced while others maybe cancelling. Hard to say but I think, so far, I prefer just one sub on the fronts... B1 of course. Back to the listening to convince myself its a real effect............
 
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