# Signal Conveter for subwoofer? Can this be done?



## ZeosPantera (Sep 12, 2009)

I am putting together a surround sound for a friend and have a dilemma. The center channel is suppose to be getting a support subwoofer which had to fit into a small area. So my friend ordered the smallest good sub he could find. The Yamaha Yst-FSW150. 











So, the sub comes in today (Left outside by UPS in a clearly labeled Yamaha box!) and low and behold the only thing on the back is a single RCA and a "System Connector" 3.5mm mono that is for the proprietary Yamaha Soundbar. I was expecting it to have the normal array of L/R rca and Speaker pass-through's.

As of right now the receiver he was planning to buy does not have any pre-outs. If he chooses another with a preout, problem solved. This thread can be deleted. If he doesn't then i need to know if this is possible?










Can some piece of hardware "?" (home-made or available to buy) allow me to intercept the powered speaker wires between the receiver and center speaker and get a weaker signal to give to this powered sub?

Worst case scenario: I will convince my friend to let me pull the entire power amp out of it, Seal the back and just install a simple sub-crossover. I'd just keep the Yamaha amp for future endeavors.


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## XEagleDriver (Apr 15, 2010)

ZeosPantera said:


> I am putting together a surround sound for a friend and have a dilemma. The *center channel is suppose to be getting a support subwoofer which had to fit into a small area*. . . .
> 
> So, the sub comes in today (Left outside by UPS in a clearly labeled Yamaha box!) and low and behold the only thing on the back is a single RCA and a "System Connector" 3.5mm mono that is for the proprietary Yamaha Soundbar. I was expecting it to have the normal array of L/R rca and Speaker pass-through's.
> 
> ...


Zeos,

1) When you say "center channel support sub-woofer" are you implying their is another sub-woofer in the system? 

- If so, I would not go down this path--replacing a bass-weak center channel speaker with a better one would be the preferred option.

- If not, just amplifying the low frequencies from only the center channel signal is not an optimal idea. It ignores too much content from the L/R mains nor include movie LFE signals.

2) Possible, well yes, in theory. I do not know of a commercial product for this. It could be a DIY electronic circuit design effort--although not recommended due to #1 above, and a potential impact on the center channel signal/sound.

3) Your "worst case" is also possible. But keep in mind, subs with speaker pass through handle both the L and R main speaker signals for a reason, just doing this for the center is not worth the cost/effort IMHO.

*Bottomline: By far, the best solution is getting a different AVR (like you already indicated) with a sub-woofer pre-amp output and the proper bass management tools.*

Cheers
XEagleDriver


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## ZeosPantera (Sep 12, 2009)

XEagleDriver said:


> Zeos,
> 
> 1) When you say "center channel support sub-woofer" are you implying their is another sub-woofer in the system?


There will be 2 subs total. The L/R are dual 5¼ so they will be fine. The .1 is a 12". The center is a smaller speaker (good quality for vocals mind you) it really can't get anything concerning mid-bass going on (which is an important area considering all that comes from the center with modern encoding). I want to add this sub to guarantee any 5.1 Barry White goes on correctly. I have done alot of experimenting with my own and other peoples setups for years. 3 subs would be my personal ideal setup. Preferably 2 passive Mid-bass for supporting high quality L/C/R monitors and whatever on God's earth you can afford for the .1 That or every channel should be a full tower speaker.


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## selden (Nov 15, 2009)

Using a separate sub for the center should be unnecessary. You do need to return the sub that was bought -- either get one that's more versatile, or do without. I suggest doing without.

All modern AVRs have bass management for all speaker channels, redirecting the frequencies below a specified crossover frequency to the subwoofer (most AVRs are designed with only a single subwoofer channel). Many, perhaps most, AVRs let you set a different crossover frequency for the different speaker channels, so if the center speaker needs a higher crossover frequency than the main speakers, that can be accommodated -- but check the AVR's specs to be sure.

Most modern AVRs include room equalization. Audyssey, for example, (included in Onkyo, Denon, Marantz and NAD equipment) can compensate for many (although not all) speaker defects, including the mismatch in timbre that you seem to be describing. However, I'd suggest replacing the center speaker by one that better matches the fronts. Correcting for speaker deficiencies after the fact is quite difficult.


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## Kal Rubinson (Aug 3, 2006)

1. The answer you want is that it can be done. You can buy a speaker-to-line level adapter to tap off a signal from the speaker wires running to your center channel speaker.

2. The answer you do not want is that it should not be done. The most significant reason is that you still will have no way to integrate the sub with the present center channel speaker. Who/what is doing the crossover and at what frequency?


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## ZeosPantera (Sep 12, 2009)

While I appreciate that most AVR's can push all the low end missing from the main channels down to the sub most likely tucked away in a corner and possibly even behind. Assuming you would be able to fix a lacking channels Mid-Bass (50-250hz) and still keep the sound direction intact is just silly. You either need full towers for every channel or if you have the cash, throw an 8 or 10" passive midbass, front firing, front ported under every channel. I may need to build a few.



Kal Rubinson said:


> Who/what is doing the crossover and at what frequency?


Thank you for the relpy. The Yamaha has a fixed crossover inside I tested it yesterday inputting full range signal from my cable box as a test and it sounds just about perfect for the frequencies I am looking for. Just touching the low end of normal speech.

The "speaker-to-line level adapter" does it have another name? All I am finding is the wall mount variety. http://www.abcconf.com/store/pc/viewPrd.asp?idproduct=24997


Just a quick addition. Has anyone here every watched a movie strait through with only one channel or pair of channels active or missing. I have. Did it for "Saving Private Ryan" From that experience I discovered just how important the center really is and not just for dialogue. It needs to be able to handle gunfire and explosions more-so then the left and right. The .1 goes on break for most of the movie. Granted this was with all channels set to large but then again I had large speakers on each channel. Try it sometime. See if adding a small sub to your center seems like a good idea.


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## Kal Rubinson (Aug 3, 2006)

Build one: http://www.epanorama.net/circuits/speaker_to_line.html

Or

http://www.ochomeaudio.com/p-136-adp-12-speaker-to-line-level-adapter.aspx
http://www.crutchfield.com/S-5J2GvpbLWAz/g_721/Line-Output-Converters.html

More at:


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## ZeosPantera (Sep 12, 2009)

Thank you VERY MUCH for the links. 

I would steer clear of crutchfield if your looking for the best price http://cgi.ebay.com/ws/eBayISAPI.dl...fdfcbfc&itemid=350344518272&ff4=263602_263622


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## Kal Rubinson (Aug 3, 2006)

ZeosPantera said:


> Thank you VERY MUCH for the links.
> 
> I would steer clear of crutchfield if your looking for the best price http://cgi.ebay.com/ws/eBayISAPI.dl...fdfcbfc&itemid=350344518272&ff4=263602_263622


True. OTOH, I understand that their sales, return and support policies are superior.


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## ZeosPantera (Sep 12, 2009)

Kal Rubinson said:


> True. OTOH, I understand that their sales, return and support policies are superior.


If it was a bigger ticket item the extra 8-10% on the price would probably be a good investment.


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