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Discussion Starter · #1 ·
I posted in the Audyssey thread but there doesn’t seem to be many who have tried adding a sub-woofer to a center channel so I thought I would check with the DIY crowd.

http://www.avsforum.com/forum/90-re...hread-faq-post-51779-a-2486.html#post32436346

My thought is it it would just look like a single speaker to Audyssey. The CC now becomes a 4-way which granted is more complicated, but with an 18 db slope at 120 0r 150, integration should be pretty good and not much different than the front and right speakers that include 12” powered subwoofers.
Thanks.

I use an Onkyo PR-SC5508 and after running Audyssey MultEQ XT32 again after adding an 18” sub-woofer to my system, notice the center channel crossover is set at 150 Hz.

I am currently running a single sub-woofer and it is installed in the front of the room to the right of the center channel and while the dialog sounds fine now I can hear some CC content coming from the sub-woofer. I am concerned as I add additional sub-woofers farther from the center channel, the content below 150 Hz will throw off the sound stage.

I have an unused AuraSound NS10-513-4A 10” sub-woofer in a 1 cubic foot sealed enclosure I could add. I would put a crossover in the chain between the processor and the amplifiers, running 150 and up to the center channel and everything below to the 10” sub. I could still set the Onkyo crossover to small with 80 Hz and below to LFE. This would keep the center dialog, especially male voices, tied to the center channel. I also have a Scan-speak Revelator 23W 9” Sub w/9” Passive Radiator 23W in a 1 cubic foot enclosure I could re-purpose if needed.

I run an Infinity Compositions Prelude system. The Compositions Prelude Center Channel Model P-CC specifications:

Frequency Range: 80 -20,000 Hz, 120 – 20,000 Hx +/- 2 dB (-10 dB @ 80 Hz)

I have a couple options for crossovers including a Bryston 10B sub (RCA) and a Rane AC 22B (XLR). I was planning on using the Bryston for a 2.1 system but assume it is the higher quality crossover. I have balanced outputs and inputs on the Onkyo and Bryston amps so the Rane wouldn’t be a problem to configure either.

Thank you.
 

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Slightly confused by your post.

Where is the input to your 18" coming from? You make it sound like its coming from the center channel. Does the sub have a plate amp?

Subs generally should be crossed at or below 100hz, otherwise you get those male voices coming from your sub which can be weird.
 

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Your receiver needs to have a pre out for the center channel plus a 2ch amp with dsp (iNUKE?). Center on one channel and sub on the other, the dsp controls the bass management of the two.

Another option is to play around with the center channel placement unless you have a very tiny speaker then placement probably wont help.
 

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Below 150hz is non directional sound so i wouldn't worry about having the cross over at 150. The avr has detected that your center doesn't do below 150 so the 150hz cross is probably appropriate.
 

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If you don't want your front and right crossed at 150 and want them to play all content then set the front speakers to "large"
 

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I'd leave it at 150 them also try a manual setting at the next lowest cross ?120 ?100 and see if you like the center better.

A better upgrade than buying an inuke and extra sub just for the center channel might be just getting a center that can play down to 50 or 80hz and then set the cross over at that level.

I don't see why an inuke dsp or similar active crossover wouldn't work as long as you have a Centre channel preout.
 

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Discussion Starter · #8 ·
Slightly confused by your post.

Where is the input to your 18" coming from? You make it sound like its coming from the center channel. Does the sub have a plate amp?

Subs generally should be crossed at or below 100hz, otherwise you get those male voices coming from your sub which can be weird.

Where is the input to your 18" coming from? SUB 1

Does the sub have a plate amp? No, Crown CE-4000 bridged.

With the Center Channel crossed over at 150 Hz, my perception is some of the CC content under 150 could decouple the dialog as I add subs to the side and rear of the room. With a single sub near the CC it is currently not an issue.
 

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Well presumably it can't play past 150 although perhaps the calibration got it wrong or the center is in a wierd position that results in poor bass.
 

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Discussion Starter · #10 ·
Slightly confused by your post.

Where is the input to your 18" coming from? You make it sound like its coming from the center channel. Does the sub have a plate amp?

Subs generally should be crossed at or below 100hz, otherwise you get those male voices coming from your sub which can be weird.



The PR SC5508 is a pre-processor and has no amps. The only option is pre-outs to external amps which makes it very simple to put a crossover between the pre-processor and the separate amplifiers to power the center channel and sub driver, or what some might call a bass bin..
 

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Discussion Starter · #11 ·
Below 150hz is non directional sound so i wouldn't worry about having the cross over at 150. The avr has detected that your center doesn't do below 150 so the 150hz cross is probably appropriate.

I can hear voice coming from the LMS Ultra 5400 18" sub. It is not be noticeable from the listening position but I currently only have the single sub-woofer connected. My concern is when adding addition subs on side walls and behind my listening position, it may negatively affect the sound stage. Then again it might not.
 

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Did you try 1. different position of cc to see if you can get more bass extension? 2. Move subwoofer away from center channel then see if dialogue sounds split? 3. Try a bit lower crossover eg 120?
 

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Your idea of turning your center into another speaker with an "active" built in sub to match your fronts sounds solid but is a costly solution to a "problem" that may not actually exist.

I think i read that inuke is not good for amplifying main speakers compared to subs so might not be the best choice.
 

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Discussion Starter · #14 ·
If you don't want your front and right crossed at 150 and want them to play all content then set the front speakers to "large"
Audyssey has already set Front and Right at 40 Hz. They have 4-way crossovers with built in 12" powered subwoofers. Audyssey has set the CC at 150 Hz. Hence my earlier question: "The CC would become a similar 4-way which granted is more complicated, but with an 18 db slope at 120 0r 150, integration should be pretty good and not much different than the front and right speakers that include 12” powered subwoofers."
 

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Ahh i c. I have a pioneer which uses mcacc. the cross over only has a single hz setting for all channels and you can turn it on off for each individual speaker.
 

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Discussion Starter · #16 · (Edited)
Your idea of turning your center into another speaker with an "active" built in sub to match your fronts sounds solid but is a costly solution to a "problem" that may not actually exist.

I think i read that inuke is not good for amplifying main speakers compared to subs so might not be the best choice.

I already have the needed amplification, sub-woofer and crossover sitting around and not in use so there is no cost involved.


inuke? I don't have an inuke, actually have everything I would need; was just checking to see if anyone else has tried something similar. Surprised it is such a foreign concept.


Thanks everyone for the input. I appreciate it.
 

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You certainly could do it, I'm not sure you'll end up with anything noticeably better though then what you already use though.

Since you already have all the parts there's no reason not to play around with it.
 

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Ah cool. Sounds good. I don't see any potential holes with your plan as long as whatever is amping the centre is up to the task (ie does full freq well, not just bass). You'd also have the center going through 2x serial cross overs (once in prepro and another in the external active cross over) so I'm not sure if that results in any degradation.

I wish my avr had individual crossover settings as my fronts goto 35 and my center goes to 55.
 

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It's an odd concept because almost every center channel can at least do 100hz making this type of fix unnecessary.

Im surprised that can't do 100hz. Maybe your mic is in a null. I bet that would work just fine at 100hz. You could unplug all the other speakers and test only the center and see where it starts to struggle.
 
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