Multi sound-cards to single speakers

Hi there all,

I want to know if there's a way I can connect 3 sound cards (on three
separate PC's) to a single set of speakers.

I know this can be done by using an expensive KVM switch that handles sound,
but I already use a cheapie KVM that works well for me and I don't really
want to go and buy another one.

Thanks,
Chris.

 

Yes, of course, just buy a Y-shaped audio cable that can do this for you.
Inside will be a transistor that combines the signals.

Cheers,
Nicholas Sherlock

 

A Y shaped cable will only give you 2 inputs into 1 output.
A transistor is not used for combining signals, that will be
done (if you are lucky) by resistors.
However, most Y leads seem to not even bother with resistors.

Using a many-into-one cable will combine the outputs from all
the PC soundcards all of the time. You may not want this.

Seeing as you mentioned using a KVM switch, you might be best
to get an audio switching box (such as sold by Dick Smith).
These allow you to manually select which input goes to the
output.

Murray.

 

Switch them with an audio switch box, from Jaycar or Dick
Smiths, $50
http://www.dse.co.nz/cgi-bin/dse.storefront/3fb5a1170f9822d62740c0a87f990740/Product/View/C2505

 

Are these amplified speakers..?

If not its a BIG NO..

Then you will need a 3 Way Audio Mixer, and then it will depend on the Input
resistance of the amplified speakers, some are set for 8 ohms, so then again
its a BIG NO..

 

If he does want to have the six signals on all the time he could passively
combine the three lefts with ~4k7 series resistors to the input of
one powered speaker and the rights the same to the other input.
There will be an insertion loss but there's plenty of gain on powered PC
speakers.

 

Useless if the powered spwkers have a 8 ohm input, and yes they do as I have
some..

 

It will work even better, nice low impedance at the summing point, all the
resistors are doing is stopping the sound card outputs from loading each
other. An even better solution is to use a dual op amp as a virtual earth
mixer.
http://www.all-electric.com/schematic/simp_mix.htm
There are plenty of project boards that will do the trick, but the passive
combiner is the cheapest.

 

And will not work..

 

Useless if the powered spwkers have a 8 ohm input, and yes they do as I have

Err, 47kohm will drop about... well more then 40dB on the origional signal into
8 ohms.

It may "work" but it depends on how far you want to stretch the definition of work.

Best not to use no resistors as most computers have no true line out instead
going for something with a relativly low impedance aimed at driving headphones
to an ok volume. Wouldnt be happy fighting against an ouput from another
motherboard.

Perhaps locate a bedroom dj that has given up and offer them some beer for there
mixer?

 

4k7 is what I said, but you have been reading the thread haven't you ?
There are plenty of op amp project preamps available from dse and jaycar
to make a virtual earth summing amp easily.
Wait on, thats just what I wrote above with a link to schematics.
But if he has a second hand DJ mixer well golly ! all he needs is one with
three stereo channels and blah blah blah blah blah lets have a big roger
sheephard pissing match about nothing.

 

Seems from you comments that you have never ever developed any thing at all,
my developments ever got in the Dom news paper, and is a few Data Bank
magazines, I can post the Facts here if you like.

were are yours..?

And will these Amps will drive into 8 ohms, I don't think so.

Gee I do think you need to take a Basic course in Electronics..


If you can't post FACTS, do not post at all, in only confuses the recipient..