# Need assistance connecting Active sub to PC



## yadav

Hi all. I have a powered sub (kenwood SW-305) which i would like to connect to my PC in conjunction with two 4" drivers. I have searched on the net for how to go about this, and came across this thread:

http://www.hometheatershack.com/for...ecting-pc-powered-sub-passive-speakers-3.html

which is confusing as that sub has different input plugs to mine and that user also had a different PC sound card set up. So here is what i have:

*Kenwood SW305 - Active subwoofer with 100w amplifier*
This has the following connections on the rear:

Line Input L & R [RCA]
From amplifier input [2 sets of speaker wire inputs]
To speakers output [2 sets of speaker wire outputs]


2x4" drivers + 3.5mm (1/8") to RCA splitter + cable

PC sound card supporting 6 channel audio.


So with all this stuff, what connections need to be made where? I am new to audio and the more i search the more confusing and varied answers i have found.

I have photos of all the stuff but can't post them here as links are blocked

Thanks for any help in advance.


----------



## Mike P.

Go here and post 4 more posts, then you can add you links.

http://www.hometheatershack.com/forums/testing/21659-post-padding-thread-167.html#post321692


----------



## yadav

Ok done. So here are links to the photos:


http://img251.imageshack.us/i/p1000012n.jpg/

http://img837.imageshack.us/i/p1000018t.jpg/

http://img121.imageshack.us/i/p1000016r.jpg/


----------



## Mike P.

You'll need a receiver and one of the sound card outputs will connect to a receiver input as shown in the diagram.


----------



## Slee_Stack

You only need a receiver or amp if you have to power your car speakers shown. You can also opt to buy some stereo computer speakers (self powered) for cheap and then use your 1/8" to RCA adapters to connect from the subwoofer jack(s) to the subwoofer.

You will need to configure your PC sound software/driver for 2.1 (mains + sub). Also, you may need to configure what jack does what. Each jack on the back of your PC normally outputs TWO signals (for two speakers). Some software allows you to assign specific signals to specific color jacks. Figure out the color, and then figure out which RCA is carrying the sub signal (ie. you may have center + sub output from the same color jack). In the end you may need a RCA splitter if you have to connect both subwoofer inputs. Many subs work just fine with only one RCA input hooked up.


----------



## drdoan

Welcome to the Shack. Have fun. Dennis


----------



## yadav

Slee_Stack said:


> You only need a receiver or amp if you have to power your car speakers shown. You can also opt to buy some stereo computer speakers (self powered) for cheap and then use your 1/8" to RCA adapters to connect from the subwoofer jack(s) to the subwoofer.
> 
> You will need to configure your PC sound software/driver for 2.1 (mains + sub). Also, you may need to configure what jack does what. Each jack on the back of your PC normally outputs TWO signals (for two speakers). Some software allows you to assign specific signals to specific color jacks. Figure out the color, and then figure out which RCA is carrying the sub signal (ie. you may have center + sub output from the same color jack). In the end you may need a RCA splitter if you have to connect both subwoofer inputs. Many subs work just fine with only one RCA input hooked up.


If that's the case, what are the Speaker Out terminals on the Subwoofer for. The specifications say it has a 100w RMS amplifier. Does this power only the subwoofer?


----------



## Mike P.

The speaker input and output connections are for speaker wire which is a high level connection. The jacks on your PC are low level connections and won't work with these. You can't connect your PC to the low level (RCA) jacks on the sub and run high level (speaker connections) to your 4" drivers. Make sense?


----------



## yadav

Mike P. said:


> The speaker input and output connections are for speaker wire which is a high level connection. The jacks on your PC are low level connections and won't work with these. You can't connect your PC to the low level (RCA) jacks on the sub and run high level (speaker connections) to your 4" drivers. Make sense?


Yes that does make sense.

So i basically need an amplifier to take low level (RCA) line in from the PC, which also has high level connectors to output to speakers?

I understand that but what i don't understand is whats the point of having the powered subwoofer. 

I have also got a sony Amplifier box which takes connections for passive speakers and a passive subwoofer. I'm not really figuring how the Kenwood powered sub would provide any advantage over using that setup considering i still need to use the same receiver/amplifier box in the end anyway.


----------



## Wayne A. Pflughaupt

yadav said:


> If that's the case, what are the Speaker Out terminals on the Subwoofer for.


You have to keep in mind that you’re trying to adapt a home audio sub to a computer. The speaker terminals on the subs have a purpose that’s specific to home audio. 

Normally the sub would be connected to the line-level RCA subwoofer output jack of an AM/FM stereo receiver. However, some receivers do not have a subwoofer output jack. So in that case you could run the speaker cables (that would normally go to the left and right speakers) to the subwoofer. Then, additional speaker cables would run from the “Speaker Out” terminals to the left and right speakers. 

The “Speaker In” and “Speaker Out” terminals are internally connected, so the left and right speakers are essentially connected directly to the receiver. The only function of sending the speaker cables through the sub is to provide a “tap” for an audio signal. 




> The specifications say it has a 100w RMS amplifier. Does this power only the subwoofer?


Yes, the sub’s internal amp powers ONLY the subwoofer. The receiver would power the speakers.




yadav said:


> So i basically need an amplifier to take low level (RCA) line in from the PC, which also has high level connectors to output to speakers?
> 
> I understand that but what i don't understand is whats the point of having the powered subwoofer.


If the sub wasn’t powered, you’d have to have a separate amplifier for it, too.

Basically what you need to do is (A) either get an amplifier of some kind for the Fusion speakers, or (B) get some computer speakers that are self powered, like the sub is.

Regards,
Wayne


----------



## yadav

The fusion speakers are staying as what they are going into has holes for 4" speakers.

Does anybody know if a plate subwoofer amplifier like so:

http://cgi.ebay.com.au/SUB-WOOFER-A...0939?pt=AU_Hi_Fi_Speakers&hash=item230baad72b


would be suitable to power the two fusion speakers? that seems to be the easiest way to find a 240V AC amplifier short of buying one made for 5.1 Channel home theatre systems.


----------



## Mike P.

That's a single channel sub amp, it won't work for what you want. At minimum you need a stereo amplifier.


----------



## Wayne A. Pflughaupt

On top of that, you don’t really expect to get a full-range signal from a subwoofer amp, do you? Its upper-end extension probably doesn’t get much above the crossover frequency. 

On top of that, you really don’t know what you’re getting with a subwoofer amp. For instance, they don’t usually offer any meaningful specs on THD, signal-to-noise ratio, broadband power or frequency response, etc. That stuff’s important for any amp you’d want to use for your main speakers.

I don’t know why you’re having such a problem finding an amp. I just searched “stereo amplifier” on eBay Australia, removing “car” from the search, and found no shortage of offerings for under $50.

Regards,
Wayne


----------

