[Mark Strube]

I am wondering what you guys would recommend for the crossover between my two subwoofers.


So here's the deal... I recently added an extra, smaller subwoofer to my home theater setup, the idea is to fill in the higher bass frequencies so the large one can concentrate on the nice low extension rumbles. I don't know the square footage of the room, but it is a bit challenging because it is a living room that has a vaulted ceiling and is open to the kitchen. The large sub by itself sounds great, but I can tell it's being challenged (I've heard it "pop" a few times... it was being driven hard but the volume level didn't sound unreasonable. I'm sure more power would help but I'm not quite ready to open things up.)


Just for reference, the main speakers are Infinity Primus models, the reported low-end response is as follows: Center 80Hz, Mains 50Hz, Front Height and Surrounds 60Hz. I have the crossover for each speaker in my Onkyo receiver set for 10Hz higher than those numbers.


The larger sub is a 15" JBL PSW D115, with 350 watts of power, and extension down to 25Hz (some report 20Hz, which would make sense considering the size, but I'm sure it depends on the room). The smaller sub is a 12" Pinnacle PS Sub 150, with 150 watts of power (200 peak) and extension down to 30Hz.


My thought is to use an inline high-pass 50Hz crossover for the smaller sub, but maybe then I'm not giving the large sub enough to do? I don't want to rely too heavily on the lesser of the two subs... but I want that nice, clean extension as much as possible.


What do you guys think?

 

[Mpray1983]

I would say don't even use the smaller sub. If you really want to then put your mains to 80hz. The only way to really find out what to put your subs at is by taking a measurement to see what they actually can do with room gain. Also if they are not in the same spot or same distance from the listening position then you are going to run into problems settings the sub's distance and delay/phase. I tried to do the same thing and it wasn't worth the effort. Its much easier to use identical sub's and even then you can run into problems. I have two identical sub's on either side of my tv. 1 sub is actually 180phase from the other because of it's relation to a few large openings. This can be a total PITA. Good luck.

 

[Mark Strube]

Well I currently have the two subs stacked in the same location and even though they're both receiving the same "full" LFE channel, I've noticed an improvement in the fullness of the bass in the room. The only downside is that the super-low extension isn't as obvious, I'm sure thanks to the smaller sub. Which is why I'm looking to limit what frequencies both subs take care of.

 

[Mpray1983]



Quote:
Originally Posted by Mark Strube /forum/post/0


Well I currently have the two subs stacked in the same location and even though they're both receiving the same "full" LFE channel, I've noticed an improvement in the fullness of the bass in the room. The only downside is that the super-low extension isn't as obvious, I'm sure thanks to the smaller sub. Which is why I'm looking to limit what frequencies both subs take care of.

You are going to have to compensate by boosting the lower frequencies. Basically adding in a house curve. For example...you raise 20hz by 6db and create a slope that will level off at 80hz. That probably isn't the exact #'s you need but same idea. Easiest way to boost the low end is with the DSP1124 by Behringer. boosting the low end can be accomplished by cutting the high end as well and turning up the gain on the amps. You need to take measurement sweeps to find out exactly where you are lacking. There is a program called REW that will do all this for you and it's free. Another thing to be concerned with is that most commercial subs have filters in them. For instance running audyssey could set 1 sub 15ft distance and the other at 25ft even though the your real listening position is 10ft away. Minidsp solves phase issues as well as eq. Matching two different SUbs is not easy.

 

[Mark Strube]

Hmm. But if I'm limiting the smaller sub so it only takes care of frequencies above 50Hz for example, and then the large sub takes care of everything under 50Hz, doesn't that bypass the need to adjust certain frequencies?

 

[Mpray1983]



Quote:
Originally Posted by Mark Strube /forum/post/0


Hmm. But if I'm limiting the smaller sub so it only takes care of frequencies above 50Hz for example, and then the large sub takes care of everything under 50Hz, doesn't that bypass the need to adjust certain frequencies?

What's the point of using two sub's then? Your still only having 1 playing at a time.

 

[craig john]

Mark,


You are attempting to use your smaller sub like a mid-bass-module. Hsu makes a product that does that. Go to their manual and read how it is set up:
http://www.hsuresearch.com/products/mbm-12mk2.html

Then you will need some sort of external crossover. The Behringer DCX2496 would be a good choice.
http://www.behringer.com/EN/Products/DCX2496.aspx

Then you'll want some type of measuring system to ensure you're doing things correctly. REW would be a good place to start:
http://www.hometheatershack.com/roomeq/


Good luck.


Craig

 

[Mpray1983]

I forgot all about the mbm...that's a great idea. Still involves buying the external crossover so might as well add the eq in as well.

 

[WhskyTangoFoxtrt]



Quote:
Originally Posted by Mpray1983 /forum/post/20809758


What's the point of using two sub's then? Your still only having 1 playing at a time.

See below.

Quote:
Originally Posted by craig john /forum/post/20809836


Mark,


You are attempting to use your smaller sub like a mid-bass-module. Hsu makes a product that does that. Go to their manual and read how it is set up:
http://www.hsuresearch.com/products/mbm-12mk2.html

Then you will need some sort of external crossover. The Behringer DCX2496 would be a good choice.
http://www.behringer.com/EN/Products/DCX2496.aspx

Then you'll want some type of measuring system to ensure you're doing things correctly. REW would be a good place to start:
http://www.hometheatershack.com/roomeq/


Good luck.


Craig

You might also consider the FMOD in-line crossover. If you use the 50 Hz high pass, you can pretty effectively create your own MBM.


Bonus: Cheap!


Enjoy