# Bookshelf speakers to computer sub?



## silkstone (Jul 12, 2014)

Hi guys,

I was wondering if the following was at all possible.

I have an old set of bookshelf speakers and an old computer sub (the kind that goes to small satellite speakers).

Would it be possible to connect the speakers to the sub or would I likely damage something?

Thx.


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## patrico (Jul 12, 2014)

hey,  so ya have a subwoofer plugged into the pc and ya wanna know if ya can plug the speakers into the sub, do I have that correct?


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## micropage7 (Jul 12, 2014)

no, just check and match the impedance


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## patrico (Jul 12, 2014)

yeah just make sure the sub isnt to strong so it wont fry the speakers


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## Kursah (Jul 12, 2014)

silkstone said:


> Hi guys,
> 
> I was wondering if the following was at all possible.
> 
> ...



I guess that depends on how you hook them up. My older Dayton 10" Powered Sub has Hi-Level inputs and outputs with a 250Hz crossover (iirc). Hi-level = amplified speaker inputs, which is handy if you have a unit that doesn't have a sub out or RCA outputs that you can donate to the sub's use. Not the best way to do things, it's at least possible to do it this way if necessary. I prefer to have a dedicated RCA to my sub and dedicated amplified outputs going to my bookshelfs. 

As other suggested, check the specs for output on the amp and impedance on the speakers. If you run lower ohm'd speakers to an amp used to running 8+ ohms, it'll increase power, distortion, heat and decrease the life of the unit as odds are it's super cheaply made and not very durable. But test it out, it could be a good temporary solution until you do something better.

That's where initially a cheaper Class-T amp came in. I split the speaker output from the sound card, one went to sub, other went to speaker amp. But that failed after 2 years or so...I replaced that with a refurb'd Denon AVR-1613...been amazed and content ever since. I run digital (with EQ) to my AVR too. Leaving analoge for my headphone amp I really haven't used anymore since the AVR's headphone output works so damn well too. I could never go back to PC speaker setups after this setup...it's really been a great 2.1 build.


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## Vario (Jul 12, 2014)

Measure the resistance of the satellites it came with then measure the resistance of the bookshelves.  If they are the same then you are fine.  If the bookshelves are higher impedence than they can be used as well, but they won't be very loud necessarily because when you increase the impedence/resistance you reduce the wattage.  Bookshelves are much more efficient than smaller speakers because they have a larger driver and cabinet so they usually require less wattage to drive the same level of sound pressure.

As a side note, its also a common misconception is that too much wattage will blow a speaker. In fact its usually the opposite.  If your speaker consumes more wattage than your amplifier can produce, the amplifier overheats and starts to clip, clipping off the top and bottom of the sinewave and creating a rectangular shaped waveform, this will cause the driver's motor to blow over time as well as killing your amplifier.

Running too low of a resistance will result in creating more wattage and more heat and this leads to clipping.

I run some 15-75 watt rated infinity bookshelves on an amplifier capable of producing as much as 1400 watts bridged (350 wpc @ 4 ohm). It gives me a lot of headroom.  Conservative gain and volume setting does not overdrive the speaker.

Another misconception is that larger speakers require more wattage.  This is not universally true because the size of the cone doesn't necessarily determine this, instead it is the size of the motor and the material of the cone.


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## silkstone (Jul 12, 2014)

Thx for the replies. I hooked it up and it works!


















I had to make my own connectors, the sub is RCA and the speakers take stripped wires.

I have no idea what the satellite speakers that go with my sub were rated at. They are hiding in the back of a closet somewhere. They are extremely crappy Chinese things and must be 10+ years old.

The bookshelf speakers though are 8 Ohm, 25-100 W.

I am noticing a little bit of clipping, but usually when I adjust the volume, or try to turn it louder. I live in an apartment, so I'm not wanting anything too loud anyway.

Should I ghetto mod the sub and slap a heat-sink in there somewhere?

Is there any chance that this could burn the house down?


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## Vario (Jul 12, 2014)

I'd just buy a cheap receiver from craigslist.


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## silkstone (Jul 12, 2014)

Vario said:


> I'd just buy a cheap receiver from craigslist.



I would but I live in Vietnam. The only stuff available locally is $50 and pretty much junk.

I have a assignment I should be writing, so I found this mini project to do to procrastinate on my real work


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