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Discussion Starter #1
Hello,


I am thinking I might want more then 1 sub. I understand you can use a splitter to run the LFE output to a sub in the front of the room and one in the back.


Is there a benifit to run speaker level input to each sub? Maybe LFe to the big 12 or 15 and speaker level to 4 8" subs? One at each corner?


Anyone try this or have an opinion?
 

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I run 2 subs in my HT..and thats all you need IMO. Juist make sure you calibrate. I use a Y splitter by the way. :D
 

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Even if there was something like 7.2 source material, I'm not sure that a dedicated source for a 2nd LFE channel would really give you much over a single LFE split with a Y... Maybe if one was for motion related effects, that might prove interesting...
 

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The best method that I have personally experienced:

Requires Pre-amp/amplifier combo

Requires a sub that has pre-in with speaker out terminals. (we used a sunfire true signature)


Connect a front sub as normal


Take the rear surround outs from the pre-amp and connect them to right and left in on the sub amp.

Connect the rear surround speakers to the speaker out terminals of the subwoofer amp.


This made a huge difference. It added bass to rear output that wasn't there otherwise. We used U-571 to test with


Darren
 

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Quote:
Originally Posted by Darren Wadsworth
Take the rear surround outs from the pre-amp and connect them to right and left in on the sub amp.

Connect the rear surround speakers to the speaker out terminals of the subwoofer amp.


This made a huge difference. It added bass to rear output that wasn't there otherwise. We used U-571 to test with


Darren


Does this final output change the rear surround in a way that it increased the dB level? Or does it maintain the diffuse and low sound level as it was originally intended ?
 

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Quote:
Originally Posted by Darren Wadsworth
The best method that I have personally experienced:

Requires Pre-amp/amplifier combo

Requires a sub that has pre-in with speaker out terminals. (we used a sunfire true signature)


Connect a front sub as normal


Take the rear surround outs from the pre-amp and connect them to right and left in on the sub amp.

Connect the rear surround speakers to the speaker out terminals of the subwoofer amp.


This made a huge difference. It added bass to rear output that wasn't there otherwise. We used U-571 to test with


Darren
One step not mentioned is that the pre-amp settings for the surrounds would have to be set to 'Large' or the LF wouldn't be sent to the subwoofer/surround combination.


This is an intriguing suggestion Darren. I assumed that LF from ALL five channels gets sent to a sub when they are all set to 'Small'. I didn't know it was only the front three.


How many DVDs do you think have significant LF in the surround track?
 

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Quote:
Originally Posted by Darren Wadsworth
The best method that I have personally experienced:

Requires Pre-amp/amplifier combo

Requires a sub that has pre-in with speaker out terminals. (we used a sunfire true signature)


Connect a front sub as normal


Take the rear surround outs from the pre-amp and connect them to right and left in on the sub amp.

Connect the rear surround speakers to the speaker out terminals of the subwoofer amp.


This made a huge difference. It added bass to rear output that wasn't there otherwise. We used U-571 to test with


Darren
Wouldn't this only work for 6.1? How would you connect both rear speakers in a 7.1 set-up (and in PLIIx or Logic 7, their separate signals) to one sub?


John
 

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When my friend originally suggested that we try this out, I was under the impression that the rear surround stream does not contain the complete spectrum. However, I ventured to Dolby labs website and found out that the full range 20-20k hz is used there.


Tis true that I forget to mention that the pre speaker size must be set to "large". Sorry about that.




The sound level (db) will still be the same when setup properly (SPL).


Instead of having the mains sub deal with all of the bass (front and rear) it can concentrate on just the front. And the rear sub concentrate on just the rear bass.




Not sure. In U571 (the "depth-charged" chapter) some of the "ambient" explosions (behind the listener) were oinly heard from the surrounds, but were felt when the 2nd sub was installed.

 

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Discussion Starter #9

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Darren - I have a couple of questions as I'm trying to understand this a bit better.


The best method you mentioned, is that applicable because people don't have competent satelite speakers to reproduce low bass? Is subwoofer really needed or could you accomplish it differently? Lets say if somebody has a setup with competent 3 way speakers that can play really low would it be the same result by just setting all speakers to large? Would this work the same as separate sub for each channel? Or is the proposed setup better because you can place a separate subwoofer in a location that works with room modes which might not be the same as where the surrounds are placed?


What if you had definitive tech super towers? How do you deal with the fact that satellite location is not optimal location for subwoofers?

http://www.definitivetech.com/loudsp...owertower.html


Cheers,


Exipnos
 

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Hi Exipnos,


The method I described is not necessarily the "best method". It happens to be a setup that I have personally experienced.


Of course, the purpose of using a sub in a home theater is generally to help out the other speakers that are incapable of powerful bass. Even most mid level tower speakers can't reproduce the powerful bass that a decent 10" and larger separate sub can create.


The multiple sub theory is based on, the more subs you have, the less work that each sub has to do. One dedicated sub has to "help" 5 or more speakers with the potential of 5 or more different "effects" coming from each. Adding a sub just for the rear effects channels gives the mains sub a lot less work to do making it more efficient. When we tried out using 2 subs in this way, we could not only feel extra bass coming from the rear, but could also feel more "pressure" as there is now more speaker cone surface area to push the air in the room. (Read Bob Carvers white paper regarding the design of the Sunfire True subwoofers). My friend uses one for the mains sub.


You could use large speakers for every channel. The only problem with it is that the surround speakers should be at ear level or slightly above. Other than mounting towers to the wall (bass would not be as good), the treble and midrange drivers possibly may not be aligned with your ear level.


If the definitive techs do offer heavy bass and can be placed on the floor in a way that they can be used for surrounds, They would work great.


Look at it this way. You can get speakers with the sub built in (Def Tech) or use a preamp and have separate speakers and subs. I prefer having more flexibility. That's how I prefer it.


Having multiple subs would be difficult to setup.


Since the Dolby Digital stream utilizes the full frequency range of 20-20k hz, every channel has the potential to produce deep base.



Since low frequencies are non directional. It only matters that you place the subs where room modes would not have be a problem. It really doesn't matter where you put the subs for the satellites.


Darren


BTW, I would like to here those Def Tech speakers. I am going to try to find them at a local dealer.
 
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