impedance matching?

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xacfoo

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If I buy a 4 ch behringer mixer, will i still need an impedance matching xformer? (guit/mic->mix->computer)
 
For +4dBu, use the main outs. For -10dBV, the tape outs.-Richie
 
I hesitate to mention it, but the immediately preceding post has nothing to do with impedance matching, or the question.

Mic -> mixer -- Shouldn't need to worry. I assume the Behringer mixer has inputs intended for low-impedance mics. They're probably female XLRs.

Guitar -> mixer -- This is a little harder to say. A more general question: do you intend to plug your guitar directly into the line inputs on the mixing board? This tends to produce a sound that is not what most people are looking for, for a number of reasons. If, on the the other hand, you mean you're going to plug the output from a Pod or something into the mixer's line inputs, you should be fine. If you're micing an amp, see the preceding paragraph.

Mixer -> computer -- This should be fine. The signal from your mixer's line outs should be happy so long as it goes into a higher impedance input. The line input on pretty much any reasonably modern piece of audio equipment should be fine.
 
Yo SJ, maybe I'm confused here, but the mixer has not only input impedence but also output impedence, and varying "line level" impedence, especially with cheap sound cards must be taken into account when setting up the signal chain. If he runs a +4 main out into a cheap soundcard's -10 line in, impedence incompatibility will result.-Richie
 
First of all, +4 and -10 are levels (of voltage), not impedances. Yes, those should be matched (or at least be compatible) or you'll either be overloading inputs or unnecessarily degrading the signal-to-noise ratio. Impedance isn't a measurement of voltage, but of how much current is drawn (or supplied) at a particular voltage.

Impedance-matching in almost all modern line-level audio gear isn't important, because power transfer isn't an issue, only "signal transfer" (in the form of voltage). Theoretically, you could have a problem if you run a high-impedance output into a lower-impedance input ... but -- if you have the specs at hand -- take a look at the stated output and input impedances on some gear. The input impedances are hundreds and thousands of times higher. Put another way: almost all line-level boxes are built so they don't require any significant current at their inputs, and are capable of supplying much more current at their outputs than any similar device is likely to want.
 
thanks for the help fellas... just gathering as much as i can before i spend dinero... its scarce round these parts, and I AM recording into a shit sound card.. but only for fun and "writing"
ill worry about all that fancy stuff when i get good
oh yea.. ive been lining in my guitar (amp line out to comp. line in) forever because ive had no mic... i wont go guitar straight to mixer Ill mic the amp from now on.. thanks
 
thanks for the help fellas... just gathering as much as i can before i spend dinero... its scarce round these parts, and I AM recording into a shit sound card.. but only for fun and "writing"
ill worry about all that fancy stuff when i get good
oh yea.. ive been lining in my guitar (amp line out to comp. line in) forever because ive had no mic... i wont go guitar straight to mixer Ill mic the amp from now on.. thanks
 
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