balanced/unbalanced.

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flimtrick

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hello, could you give me some facts about this: I bought active monitors and they are connected to my soundcard´s balanced output. Ok, i can control the levels easily with my soundcard´s external mixer. The soundcard is Hoontech dsp2000 c-port. Now i´d like to be able to listen my cd and vinyl even then when the computer is shut down. Now i was thinking that i buy a behringer eurorack ub802 or something so that i could put my cd and vinyl player and the computer signal also to it. And then i could take the signal from the mixer´s main output to the speakers. But now if i take the balanced signal, take it to the mixer and then put it to the speakers from the unbalanced main output so will it hum??? Because i tried to connect my soundcard´s unbalanced output and i got this terrible hum. How can i solve this without buying a expensive mixer or something.

Ps: Is it possible to take the signal from stereo receiver´s output and put it to active monitors through the computer or mixer? I heard that there should be some kind of reducer between.....?

Thanks for any help.

Flim
 
here's the scoop

hi flimtrick

here's the scoop on bal/un-bal stuff.

A line level signal is fed out of your sound card/mixer (whatever). If the signal is un-balanced, it is usually fed thru a TR (Tip/Ring) connector (1/8" or 1/4"), which means is has 2 conductors, a hot (+) and a common/ground (-). This is the typical connector such as a guitar plug.

If the signal is balanced, it uses 3 conductors in the cable. There is a hot (+), a cold (-), and a shield/ground/common, fed via a TRS (tip/ring/sleeve) connector. What happens is the positive signal is fed via one wire, and an exact oppisite signal (180 out of phase) is fed via the cold. When the two signals are electronically recombined, it cancelles out any hum noise that gets in the signal. This type of cord is what is used on head phones.

(There are lots of refrences to this, if you want to read more)

If your sound card has "balanced" outputs ( i didn't research your particular card) it will have TWO separate line out's, one marked left, and one marked right. They will use a TRS (stereo) cord, and one will run to each monitor. This will be just like on the mixer you are looking at..... a left out, and a right out.

Now, if your sound card only has one little jack on the back, lableld "line out" it probably isn't (physically cant be....) a balanced output.

Balancing usually comes into play on longer cable runs. On most cords, probably under about 20' or so, you wont (shouldn't) have a problem.

In most circumstances, you can use an unbalanced feed out of and into a balanced connector without much of a problem. (there may be a slight level change, but it is something you can deal with.

Your idea of feeding your soundcard, stereo, cd player and what ever else into a mixer and then feeding the mix into the powered monitors will work fine.

Now, if you need to feed a "SPEAKER" level output (insted of a line level) into something, you need a converter placed inline to change the speaker level to line level.

hope this helps get you started
 
Thanks for the reply, but there is one thing i´m wondering. Why does my monitors hum when i connect my soundcard´s left&right output with 1/4 jack? I also thought that there shouldn´t be any problem with that because the distance is only like 2 meters....When i use xlr(my soundcard has xlr and jack output both) it does not hum, of course. And now my big question is if connect the signal from my soundcard´s balanced output to the mixer, and from mixer´s unbalanced output to the monitors will it hum?
 
Hi,
The humming sounds like something to do with EM interference. If these speaker runs are going near a monitor for example (which I'm guessing they will be) then EM interferrence will be a big issue.
Sounds like you have to use balanced TRS cables when near monitors? I read smething about speakers being magnetically sheilded but don't know much about this, may be worth reading up on.
Dave
 
Definately use balanced cables near CRT computer monitors whenever possible.
 
I'd like to add a (dumb) question to the balanced / unbalanced discussion.

Can all balanced cables be used interchangably? Same with unbalanced? In other words, will a mic cable function just fine as a patch cable, say from your mixer to your active monitors (provided both have XLR connections)?

Likewise, can an instrument cable i.e. an electric guitar cable be used in any application that calls for an unbalanced cable?

I ask this because a balanced patch cable costs more than a mic cable, an unbalanced patch cable costs more than an instrument cable.
Thanks for your replies
Doug

(I'm starting to notice that you can really spend a lot of money on this recording thing ;) )
 
A balanced cable is a balanced cable. The biggest difference is the connectors. It's the same with unbalanced cables.
Speaker cables are different because they are unshielded.
 
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