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PostPosted: Fri Feb 09, 2018 8:22 pm 
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Joined: Wed Sep 21, 2011 11:08 am
Posts: 41
Location: Toronto, ON, CA
Hi there,

I wanted to setup dual subs for my living room theater and currently I have a martin logan i think is dynamo 300 that came with this set for 5.1. martin logan mlt-1.

https://www.martinlogan.com/en/product/mlt1

my spare sub is klipsch

http://www.klipsch.ca/products/rpw-10-subwoofer.

i will be running from a y-connector rca.

will be mixing the two will cancel each other out? the placement will be one of the left and one on the right of the tv and they will be about almost 6' apart.

thanks all for the help.


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PostPosted: Fri Feb 09, 2018 8:49 pm 
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Joined: Thu Dec 07, 2017 4:22 pm
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Location: Grande Prairie, AB, CA
Mixing different subs in different locations can be problematic. Your biggest issues are going to be phase. Vented boxes by design are phase shifted by 90 degress at 12db/octave around the tuning frequency. Have two different subs with presumably different tuning frequencies can lead to odd cancellations or excessive reinforcement causing boominess or perceived "one note" bass. Often, engineers put 0 or 180 degree phase controls on a vented box, simply because it is a cheap and easy circuit. What they should do is offer variable phase 0-270 degrees at least, or even just switch settings for 90 or 270 degrees.

I have Martin Logan Vantage which is a vented 8" (rear, looks like a transmission line) and a Martin Logan Balanced Force 210 (sealed box, 180 degree opposed woofers) placed on a sidewall in front of the Vantages by 3 feet. My phase is set to 100 degrees, and I used anold car audio SPL test disc with pure tones 20-100 Hz in 1-Hz increment and an Audio Control SA-3055 RTA to set my sub up. I used a tone at the 35Hz roll-off frequency of the Vanatges to get the phase just right (used max SPL at test volume as a guide while adjusting variable phase knob). The sub has authority even at a 30 Hz high-pass, and completely disappears as it is blended with the Vantages. If I changed location of the sub, I would have to set it up all over again.

If I were you, I would stick to one sub, pick one.


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PostPosted: Sat Feb 10, 2018 7:50 am 
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Joined: Fri Feb 06, 2015 12:31 pm
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Location: Owen Sound, ON, CA
This is one of the most complete articles that I've read about adding a sub or subs to your system.
Gives you options depending how obsessive you want to be, very interesting.
www.soundoctor.com/whitepapers/subs.htm


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PostPosted: Sat Feb 10, 2018 8:39 pm 
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Joined: Wed Sep 21, 2011 11:08 am
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Location: Toronto, ON, CA
so there is no way i can mix this two for movie scene impacts?


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PostPosted: Sat Feb 10, 2018 9:17 pm 
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Joined: Thu Dec 07, 2017 4:22 pm
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Location: Grande Prairie, AB, CA
outfire wrote:
so there is no way i can mix this two for movie scene impacts?


Not saying that at all. It may work, or it may not. There is literally no reliable way to predict how they will interact in your specific application. Anyone who says they can is full of crap.

You can try it, and see how it works. Play with position, crossover points, phase and level. You might like it, or not.


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PostPosted: Sun Feb 11, 2018 11:34 am 
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You can also try plugging the ports on both and then playing with EQ. Two sealed boxes are always in phase. And the room extension addition my be enough, with an adjustable eq in play

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(Ken Hotte, of) Teo Audio


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PostPosted: Sun Feb 11, 2018 12:34 pm 
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Joined: Wed May 30, 2007 7:54 am
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Location: Vernon, BC, CA
outfire wrote:
so there is no way i can mix this two for movie scene impacts?


Yes you can, and with good results.

Despite what you (and others) may believe you want cancellation!

In room bass is full of peaks and valleys (nodes), and what you want, and what you get by mixing different subs in random location is extra room nodes that help to smooth out the frequency response.

As long as you can keep the subs xovers below 100Hz you wont be able to localize the bass.

Try it, you have nothing to lose and a whole lot to gain.

_I have been running (and measuring) multi sub setups for years to excellent results.


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PostPosted: Sun Feb 11, 2018 1:11 pm 
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Location: Ottawa, ON, CA
The phase argument doesn't hold a lot of water, once you realize that moving the sub a couple of feet away will also change it's phase, relative to the other speaker...

Multi sub setups are inherently more work to set up in the first place, but will almost always result in better sound once you find the ideal positioning. The first rule of thumb, is that symmetry is usually bad. You will probably find that having the two subs flanking the mains to the left and right isn't the best. The usual drill is to start with one sub, and walk around the rooms perimeter, and try and find where the bass sounds the weakest. That's where the second sub goes.... There are much more detailed instructions to be found if you do a little web searching.

Good luck! Dave


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PostPosted: Sat Apr 21, 2018 2:10 pm 
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Location: Mississauga, ON, CA
Use one sub, for movie impact instal bass shakers in the sofa. As noted by others 2 different vented subs are difficult to implement correctly, not impossible just difficult.

-- 21 Apr 2018 22:19 --

Jared Rachwalski wrote:
outfire wrote:
so there is no way i can mix this two for movie scene impacts?




As long as you can keep the subs xovers below 100Hz you wont be able to localize the bass.


.

That's popular myth. Most people including me can localize sounds well below 100 hz. Probably made up by subwoofer salesman, "you can put it anywhere..." lol


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