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Connecting Speakers to Computer + Subwoofer with Amp

 

New member
Username: Burahobbit

Post Number: 1
Registered: Oct-12
Hi guys, i hope this is the right place to post this, i've been digging through the internet for a few days and can't figure out exactly what i need. Maybe this should be in the speaker / subwoofer category but here goes..

So i'm buying:
Sony SS-B1000 5-1/4-Inch Bookshelf Speakers

https://www.amazon.com/Sony-SS-B1000-4-Inch-Bookshelf-Speakers/dp/B000OG88KY

and

Polk Audio PSW10 10-Inch Monitor Series Powered Subwoofer

https://www.amazon.com/Polk-Audio-10-Inch-Monitor-Subwoofer/dp/B0002KVQBA

The Sub is powered, but the speakers are not, i want to connect them up to my computer to play music, so i am assuming i need an amp to do that, but i am not sure how that works. Can i connect an amp to a powered sub?, and would the speakers plug into the sub or into the amp? help i'm so lost!
 

Gold Member
Username: Superjazzyjames

Post Number: 2042
Registered: Oct-10
The easiest way I know to do what you're planning to do is get a stereo 1/8" headphone plug to RCA jacks adapter. Plug the headphone plug into the audio out of your computer and plug a pair of interconnect cables into the RCA side, then run the interconnects to a receiver or integtrated amp. You can then "daisy chain" the sub and speakers by running speaker wire to the sub and then to the Sony speakers. IF your integrated amp or receiver can run 2 pairs of speakers in parallel, you can run wire from the speaker A terminals to the speakers and the B terminals to the sub. If the amp has a subwoofer/LFE output (RCA), you can run an interconnect to the sub INSTEAD OF speaker level if you so choose. Just DON'T connect both ways at the same time.
 

New member
Username: Burahobbit

Post Number: 2
Registered: Oct-12
Okay, i think i get what your saying, In the first scenario you mention, my computer would be connected to the amp which would connect to the sub which would connect to the speakers yes? I just want to make sure that i can hook a powered sub up to an amp without any risk.

One other thing for buying an amp: If the speakers have a 120 watt max input and 8 ohms impedence, do i need to get an amp that has those same numbers on it? Or if i get one that doesn't have as high wattage does that just affect the volume or the sound quality as well?
 

Gold Member
Username: Superjazzyjames

Post Number: 2044
Registered: Oct-10
Assuming that the subwoofer has speaker level connections, there is no risk there.

Don't worry about speaker power handling, even though the owner's manual will say otherwise. Speakers are blown by clipping and distortion, NOT too many or too few watts. I used to use a pair of Sony speakers like yours (book shelf rated at 120 watts each) with a 50 watt per channel receiver, no problem. One of my neighbors borrowed them and ran 200 watts through each speaker for over an hour, no problem! As long as the power is clean. Also, more watts do NOT equal better sound quality. Better made amps make for better sound.
 

New member
Username: Burahobbit

Post Number: 3
Registered: Oct-12
So you are saying to connect the amp to the subwoofer through speaker level connections not the rca line in connection? Or does it matter either way?
 

Gold Member
Username: Superjazzyjames

Post Number: 2046
Registered: Oct-10
If you run speaker wire from amp to sub, connect at the sub's speaker level. If you run RCA cable from the amp's sub/LFE output (assuming the amp has such an output) run it to the sub's RCA input. Speaker out to speaker level in OR RCA out to RCA in...and YES that DOES matter.
 

New member
Username: Burahobbit

Post Number: 4
Registered: Oct-12
Okay! Thank you very much, you have been very helpful!
 

New member
Username: Burahobbit

Post Number: 5
Registered: Oct-12
Wait, one last question, could i use a speaker wire to RCA converter like this:

http://www.buy.com/prod/rca-to-speaker-wire/211411505.html?listingId=46110585

or is that a bad thing to do to my speakers?
 

Gold Member
Username: Superjazzyjames

Post Number: 2047
Registered: Oct-10
Your link isn't posted properly, but if you run a speaker level output to the RCA input on the sub, you'll blow up the amp in the sub. If you run an RCA output on an integrated amp or receiver to a speaker level input, you won't get much sound out of your sub.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 17458
Registered: May-04
.

How you connect this system will depend on which receiver/amplifier you purchase or already own. To begin with, I see no reason to bother with an adapter for the run to the amplifier. Any modern computer should have a sound card installed with audio out jacks included. You can buy the correct cables for this connection at most electronics retailers, you'll just need to know the correct length of cable required.

Depending on the computer and the sound card provided, you might have just a stereo (two channel) output from the sound card. If the receiver/ampifier you purchase is a stereo (two channel) component, simply connect the outputs of the sound card to the inputs of the receiver. Use what is termed a "line level" input which would be AUX, CD, DVD, etc. Do not plug into anything labelled "phono in" on the receiver.

You do, however, have several options available to you at this point. You can use a 5.1 mutli-channel sound card which you can pick up from any electronics retailer and replace the existing sound card in the computer - if, that is, you do not already have a 5.1 card in your computer, many do. A 5.1 sound card will also have a "LFE" or subwoofer output jack and the division of frequencies between speakers and subwoofer will be accomplished by the computer's settings. You would still run the front Left/Right outputs to an amplifier but in this system the powered sub would be run directly from the computer's output jack. The amplifier's volume control would be bypassed (simply set it to 3 O'Clock and leave it there) and all volume changes would be accomplished through the computer's internal volume control. IMO this connection path makes the most sense if you are going to be working at the computer while listening.

There are also USB sound cards and USB driven amplifiers intended exactly for computer desktop systems. A few models will even provide an outboard DAC (digital to analog converter) which would equate to substantially higher quality sound than a cheapo sound card can manage. If you're watching videos or playing games on the computer, heading in this direction might be a valuable decision to make.

In large part answering your initial question comes down to how you want the system to operate and how much sound quality you can afford. Using a computer as your source player for CD,DVD, internet radio, downloaded music files, iPhone or Smart Phone, iPod or MP3 playback all involve various connection schemes which you can exploit to make a either more convenient system or a higher quality system or both if you select the right components.



If we go back to a simple two channel output from the computer's sound card, you should make your connections from the computer directly to the receiver/amplifier's line level input. Your next consideration would be whether you purchase an amplifier with it's own subwoofer output. Any AV or home theater receiver would have this connection included. Some two channel stereo receivers/amplifiers will have a sub out jack and some will not. A few stereo components will include twin "pre amp outputs" which would be somewhat similar to having a subwoofer out. The options for what to buy and how to connect it all together vary tremendously with each system and typically each system could be set up in more than one way to accomplish different goals for each listener.

So telling you exactly how to make the correct connection would depend on the amplifier you purchase and how you would prefer to have the system operate.

If the amplifier lacks the sub output, you have the decision to make as to exactly how you want the speaker/sub system to connect. A powered subwoofer has both line level and speaker level inputs. The simplest connection here is to run a single RCA to RCA interconnect from a receiver/amplifier that includes a LFE/sub output jack. Typically such a receiver/amplifier will then have provisions for setting the
"crossover" frequency which will direct high and low frequencies to the appropriate speaker/sub output. Your speakers would connect directly to the speaker outputs of this type of amplifier. This system set up would have the receiver/amplifier controlling the overall volume though the computer must be instructed to have its volume control now set to roughly full output.

The complication to this system set up would be purchasing a receiver that lacks a subwoofer output. This isn't a big deal but with the numerous options available to even the simplest system set up it can become confusing if you do not understand the basic signal flow of an audio system.



Rather than go through all the various configurations possible for such a system, I would suggest you give a quality retailer such as Audio Advisor a call. Ask for some basic technical assistance in setting up your system and selecting the best components for your needs. Their staff is well trained and can take the time to provide you with various options from which you can choose the most appropriate set up for your system.

Your Sony speakers are relatively easy to drive and won't require a high wattage amplifier. You'll need even less wattage if this is a system meant to play on a desktop while you work with the computer and you are sitting a few feet away from the speakers. Don't be surprised if the advisor suggests an amplifier with as little as 15 watts.

Determine your working budget and give Audio Advisors a call; http://www.audioadvisor.com/

Ask about this USB amplifier/DAC; http://www.audioadvisor.com/prodinfo.asp?number=NUICONIDO compared to a more simplified desktop amplifier only.

An alternative or "second opinion" retailer would be Parts Express; http://www.parts-express.com/?utm_source=google&utm_medium=cpc&utm_campaign=G-Brand-Main&utm_group=G-Brand-Main-Exact&utm_term=parts%20express




.
 

New member
Username: Burahobbit

Post Number: 6
Registered: Oct-12
Thanks for the detailed responses! i bought this amp:

Lepai LP-269FS 4 x 45 Watts Mini Amplifier
http://www.audiocircle.com/index.php?topic=102413.0

My plan is to attach my computer (via a stereo to RCA cord) to the amp, and then attach the bookshelf speakers with speaker wire from the amp and the sub with an RCA to RCA cord on the left side of the amp where it says output. Am i correct in assuming that would work?
 

Gold Member
Username: Superjazzyjames

Post Number: 2049
Registered: Oct-10
The jack says "subwoofer output" or "LFE output"? If not, you'll need to make sure the output is "variable" meaning its volume goes up and down with the volume control so that the sub level is always in sync with the speakers. Otherwise, you'll want to connect the sub via speaker level connections.
 

New member
Username: Burahobbit

Post Number: 7
Registered: Oct-12
If you look at the picture it just says output and the one next to it says input, however both of those are under/ surrounded by the little red box that says audio input. So i am just a bit confused as to if it really is an output rca jack or not.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 17461
Registered: May-04
.

The jacks labelled "output"are probably controlled by the unit's volume control. That's just a guess. I wouldn't buy anything I wasn't certain about unless I knew I could return the product. Why don't you try Parts Express if that's your price range and that's the sort of amp you want?
 

Gold Member
Username: Superjazzyjames

Post Number: 2050
Registered: Oct-10
Okay, I finally got a chance to look at it online. No mention of whether the output is variable or not. For $40, you're not risking a whole lot of money. However, I'd still find out about a return policy incase it doesn't work out.
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