headphone splitter question

[dragonB]

Hi,
I run 2 sets of speakers from my Soundblaster Live Value with a little headphone jack splitter.(1 jack to 2) that I picked up at radioshack. It does it in stereo, and I have no problems there, but I seem to be losing loudness. Is there a better way to do this without loss of power? thanks, Brian

p.s. The setup is this..
1 room with TV out to TV, and ACS54 4speakers and sub for watching dvds or music.
Other room with the computer and another set of speakers for games, etc.
x10 connectors on both, so I can switch them on and off with a remote.
Lol, I also have 25ft extensions on mouse and keyboard to put in other room for DVD watching. http://www.sysopt.com/forum/smile.gif

[Bovon]

I think I am understanding you. Speakers, headphones, ect have what is known as impedence. The output of the sound card is so designed to 'match' a certain impedence. By connecting the two headphones together, you have changed the total impedence to just about one half of the impedence of one headphone.

There are two 'cheap' ways of doing this and help it out a bit. One would be to connect one side of each headphone leads together...in a sterio setup, there is probably three wires to the plug. One will be common...i.e...one of the wires will go to each side, and the other two will go seperately to each side, one left, and one right. For the two headphones, you could have both of the commons connected together, but the others need to be joined, one on one by a 0.1 to maybe 0.5 ceramic? capactor. Each 'live' audio wire from each headphone, needs to be tied back to the audio output from the card by one of these capactors. The capactors will pass audio, but will not affect the impedence of the circuit.

The other way would be to obtain an audio matching transformer...this transformer should have one input set of windings, and two output set of windings. The output from the sound card would go to the single input winding, and the headphones would connect to the output windings...one headphone for each winding.

The transformer should have a sterio type of winding...somebody at Radio Shack may be helpfull here, or someplace that sells electronic supplies.

There may be adaptors already made up with some type of isolation between the splitter outputs, that will allow a direct connection by two speakers or headphones...but I am not aware of any.

Also, when attaching two headphones, you are loading down the audio circuit more than if you had just used one...so, that will account for some loss in output.

[This message has been edited by Bovon (edited 04-22-2001).]

[dragonB]

thanks, I'll have to look for some type of transformer that you mentioned. http://www.sysopt.com/forum/smile.gif

[Graham]

Dragon,
Without some form of amplifier, there will always be a reduction in level. For example, if both sets of 'phones are identical, then each will have half the output power.
What Bovon says is true, matching the impedance will help, but in my experience, not much. If the output and 'phones are matched then you will get the maximum power available, but matching will not boost the power just use it 'efficiently'.
Some 'phones are low imp. (4-8ohm), some are high(ish) (~30 ohm), 'phone outputs are the same. So, you could have the situation, where putting two sets on in parallel will actually improve matching, but each set will still only get half the power.
Capacitors, and or matching transformers will not boost the power available (save for the possible increase in efficiency), but adding any components will create some loss.
What you have got is probably the best you can do without amplification, you might try good quality cables (less loss), and make sure the splitter in as near the soundcard as possible.

Do the mouse and kbd work ok on that length cables ??

G

[Roy]

Impedance matching is obsolete. It's really about power and voltage. Without an added amplifier, you can't get more of either. The best you can do is disconnect the load that's not being used.

[Bovon]

Hey Roy....at 70 years old...even I am obsolete! http://www.sysopt.com/forum/biggrin.gif

[Kuasimodem]

I built this handy little box and attached it to my desk, just under the keyboard. It has one male 1/8 inch cord running to my sound card, one jack on the back of the box for my speakers, and one jack on the front for my headphones. I wired it so that when you plug the headphones into the front jack, it disconnects the speakers. My next post will have the Radio Shack part numbers for the components that I used. Have to look them up...

[dragonB]

wow, Kuasi that sounds pretty cool. Might have to break out my soldering iron eh?

And to answer the other question, no the 25 ft extensions on the mouse and keyboard don't have any negative effect. I also thought it might, but to my pleasant surprise there isn't any "lag"

Brian

[alondra]

any card, or amp has only so much power available, more speakers, more load, less to each. I got tired of crawling behind my box to switch cables for speakers phones and mike, went to radio shack got cables with 1/8 sterio plugs and pack of jacks, less than a buck for two, cut off the plug on one end and soldered on the jack, mounted on a piece of metal by comp. now just plug in speaker or phones or mike when wanted, pot the jacks with silicone as the wires are real flimsey. works great do you need speakers in two rooms at the same time?

[This message has been edited by alondra (edited 04-25-2001).]

[Kuasimodem]

OK...

You need the following...(Radio Shack numbers)...
1--- 1/8" panel mount jack (open circuit) #274-246
1---1/8" panel mount jack (closed circuit) #910-0767
1---6 to 8 foot shielded cable with 1/8"stereo plug
1---small project box (about size of cigarette pack)
about 1 foot of wire, solid core prefered (it's easier to work with)
soldering iron, and solder
patience (I reversed the stereo the first time, had to do a little revision)

The second jack listed is the switching jack, it comes with pinout directions for source and destination, just follow them and you will have little difficulty. I used a plastic project box because it's really easy to drill the jack holes in each end of the case, along with the hole for the cord. For the cleanest look, drill the holes for the cord and the speaker jack in one end (back), and drill the headphone jack hole in the other end (front). I mounted mine with double-stick foam tape to the desk just below my keyboard drawer, it's handy, and the cord stays out of the way when I use the headphones.

Maybe I should market these things, but they are so easy to build...

[alondra]

Your box sounds great, my piddly R/S had no closed ckt jks or little boxes, hmm next stop frys http://www.sysopt.com/forum/smile.gif