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Discussion Starter · #1 ·
My room is 20'x40' with Small speakers left and right that go down to 20Hz supported by a Contrabass crossed at 50Hz. I have Small Sides and Rears that go down to 60Hz.


I was wondering if it would be worthwhile to buy another sub like an ACI Maestro, place it at the rear of the room, set the Rears (and Sides?) to Large, buy an external crossover (and eq) to divide the now full-range Rear (and Side?) signal between the rear speakers and sub. [My Meridian 568 only supports one crossover for HT.] One problem would be that the rear sub would have to sit 12' behind the rear speakers, in the corner, and thus could not be easily time aligned.


I thought it might be interesting in such a large room to have the rear subwoofer frequencies originate at the rear of the room instead of the front. Thoughts??
 

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Bass below 80 Hz or so is not directional....if you want to add a subwoofer, don't bother to place it in the rear unless that is the best sounding place in the room
 

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I agree, get some room correction like a BFD and use it to flatten out your response curve first.
 

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One of the potential benefits of a rear sub is that your main sub will not have to handle the surround duties.

You'll have to set it up carefully to avoid large disparities between the rear channel and main LFE low frequency balance though.

ie:

This:
http://www.byrographics.com/media/lf1.jpg

Does not sound like this:
http://www.byrographics.com/media/lf2.jpg


There is also the possibility that cancellations can reduce the overall perceived bass output of your system.


Just set the surround channel to "large" (fullrange).

The surround signal is fed directly to the rear sub, then the surrounds are connected to the variable high-pass output of the sub.

This will allow you to control the crossover to surrounds, independent of the LCR channel settings.


BTW, although low-bass is "non-directional", subwoofers are still point sources, and some inexpensive subs actually put out a great deal of port and cabinet noise, which can cause localization effects and lower midrange coloration.

I'd be looking at one of the tiny "cube" style subs.

Sunfire is a perfect example.
http://www.vxm.com/primary_truesub.gif
 

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50hz is too low to cross "small" speakers. Bump that up to 80hz and forget about extra subs, especially when you have a Contra now. The only thing worth adding is another Contra :D
 

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Quote:
snickelfritz wrote: Just set the surround channel to "large" (fullrange).

The surround signal is fed directly to the rear sub, then the surrounds are connected to the variable high-pass output of the sub.
I use dual Hsu VTF3 subs for my LFE and also use dual JBL subs for my surrounds wired like snickelfritz described, with my Axiom QS8 surrounds. If you go this route make sure you calibrate the rear subs with an SPL meter and AVIA. Use the sub calibration on AVIA and you'll be able to blend the sub and surround so well that the surround and sub seem like one really tall speaker full range speaker instead of two seperate speakers.


My JBL subs have an adjustable high pass filter on the speaker level in/outs so I just set the surrounds to large, run the speaker wire to the subs speaker level in/out, and then run the wire up to the surround. Once you calibrate the surround and sub properly the sub just becomes an extension of the surround and works great and seems like you have full range speakers on the sides. You want the sub to pick up where the surround ends and not stand out and be distracting.
 

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Discussion Starter · #10 ·
The LR speakers go to 20Hz and are "set to" Small in the processor. Sorry for the confusion.
 

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Not tryinng to get off topic, but you did say that you wanted to hook up the real sub with only imput signel from the rear surrounds. Since surround speakers are typically small, do the studios really mix that many really low frequancies sounds in the surrounds? I don't know, but it would seam silly.


Would you happen to have an extra sub with speaker level inputs that you could hook up to the surrounds source (without the surronds) and see what comes out of the subwoofer?


I'm a daydreamer, with a little sub, who wish I could have one like yours, so take my advice for what it is (and look for good advice from Jeff-TheBland and Mark Seaton) but I think that if you are spending (and have already spent) that kind of $$$$, the second subwoofer should be put in a location where it smoothes out the FR of your current sub - not necessarly the rear of the room, and should be hooked up by splitting the LFE channel and if you like an external cross over.
 

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Quote:
Since surround speakers are typically small, do the studios really mix that many really low frequancies sounds in the surrounds? I don't know, but it would seam silly.
Surrounds are small speakers because most people don't have room or want tower speakers all over their room and also having the surrounds about 2 ft above ear level adds a more spacious effect.


Heres some links to six pages of movies that have bass below 50hz mixed into the surrounds. I have the rest of the article from Widescreen Review if anyone is interested. The article is from 2001 so there must be a LOT more movies by now with bass below 50hz mixed into the surrounds.

http://pages.cthome.net/lradden/ht/surroundbass1.jpg
http://pages.cthome.net/lradden/ht/surroundbass2.jpg
http://pages.cthome.net/lradden/ht/surroundbass3.jpg
http://pages.cthome.net/lradden/ht/surroundbass4.jpg
http://pages.cthome.net/lradden/ht/surroundbass5.jpg
http://pages.cthome.net/lradden/ht/surroundbass6.jpg


Just scroll over and check out the right most column of each page.


To enlarge the images just hover over the image and click the "sizing" block in the lower right corner.


There's plenty of bass in the surrounds and the Dolby specs call for all channels to be able produce a full range signal not just the fronts. Ive been using this kind of setup for years and as long as you have subs with speaker level in/out, can high pass around 80 Hz, and blend the surrounds and the subs properly it works great. It's really no different than having full range speakers as surrounds. While I use two Hsu VTF3 MKII subs for the LFE I like having a fuller sounding surround setup.


Legairre
 

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Run the LFE the way you have it and get another contra.You need some software to properly set they two up to integrate them right.Stack those babies and dial em' in.


Will you be renting that room out to indoor soccer teams.Wow, 40feet. Do you watch on the short wall or the wiiiide one? If you watch on the short wall that would give you room for about four tiers of seating :eek:


KG
 

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I have silver Triad in-wall surrounds and was wondering about adding an NHT in-wall sub to each surround. Anyone have knowledge or experience with these subs?


How do you add a sub to a surround?

Take Aim
 

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To Snickelfritz or Legairre:

Legairre mentioned Snickelfritz had a way of connecting a sub to a surround. Please repeat the idea or link. Thanks.

Take Aim
 

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takeaim,

This is how my surrounds and subs are connected. I run a seperate sub for each surround so just repeat the process.

NOTE: you need subs with adjustable high pass filters for this to work.


1) run a speaker wire from the amp or receiver's left surround channel to the sub's pos/neg speaker level input.


2) run a separate wire from sub's pos/neg speaker level output and connect the other end to the left surround speaker's pos/neg terminals


3) set the sub's crossover to whatever your surrounds roll off is or a little higher. This is the NOT the crossover on the pre amp or receiver, it's the crossover on the back or front of your sub.


4) Set the surround speakers to large in your receiver or pre-amp. By sendig a full range signal to the sub you'll be able to use the subs "high pass" crossover to control what stays in the sub and what goes to the surround speaker. Essentially what you're doing is turning a small surround speaker that only goes down to maybe 80Hz into a full range speaker by adding the sub.


4) Run AVIA subwoofer setup for the surround and adjust the subs volume(on the back or front of the sub not the pre amp or receiver).


As the AVIA sub test tone plays you'll get the freqs above the crossover coming from the surround and freqs below to the sub.


5) Calibrate the freq to the surround with an SPL meter to 85dB or whatever the rest of your sytem is calibrated to, and then as the sub plays the lower freq test tone calibrate the sub to 85dB as well by rasing or lowering the sub's volume control.


I run my surround subs a few dB hot, they just seem to blend better that way. Otherwise I can tell where the surround leaves off and the sub picks up. With the subs a few dB hot it seems like I have two 7ft tall surround speakers.


I hope this helped.


Legairre
 

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Discussion Starter · #17 ·
If you don't have a high pass on your sub, you could buy an external crossover to accomplish the same thing. Ranes are about $75 on ebay. Or you could buy a Behringer DCX2496 which not only has a crossover but parametric eq, delays, etc new for $225.
 

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Discussion Starter · #18 ·
Quote:
Originally Posted by kgveteran
Run the LFE the way you have it and get another contra.You need some software to properly set they two up to integrate them right.Stack those babies and dial em' in.
Well, one Contra scares me to death. Two would scare the neighbors to death. Would that be good or bad?

Quote:
Originally Posted by kgveteran
Will you be renting that room out to indoor soccer teams.Wow, 40feet. Do you watch on the short wall or the wiiiide one? If you watch on the short wall that would give you room for about four tiers of seating :eek: KG
The room is actually our living room, a "Great Room" that also has the kitchen and dining area. The big space is a lot of fun. I watch on the short wall (11'6" screen) with the Contra on the front wall.


I was curious as to what the effect would be of having another sub on the rear wall, 40' away, that would just produce LF from the rear speakers. It might create an interesting "rolling" effect due to the timing or it might be a disaster for the same reason. The Contra, Left and Right are all eq'd and time aligned with QSC DSP4s.
 
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