mshilarious
Banned
Break out anything you want. The fact remains that the inputs and outputs he's using aren't matched to each other. Let's get the guy recording first, then if you want to prove how much you think you know about electronics, we can start another thread.
Nah, let's do it in this thread. You are confusing *level* with *impedance*. They are two totally separate things.
For your reference:
Mic, typical: -60dBV to -30dBV level, < 250 ohm output impedance
Line, typical: -10dBV to +2dBV level, < 600 ohm output impedance (often more like 100 ohm, so let's use that)
Instrument, -30dBV-ish, ~10K ohm output impedance -- this is highly dependent upon the instrument in question.
Now, for inputs, these are the typical impedance:
Mic: 1K
Line: 10K
Instrument: 1M
Because of that, some people who don't really understand what they are talking about think that plugging a mic or line output into an instrument input is an "impedance mismatch". It is not. Impedances want to be bridged (meaning load impedance should be much greater than source impedance); this is to prevent loss of signal (which is voltage). If we want to determine the signal loss, we can use this simple formula:
dBloss = 20 * log (Zload / (Zload + Zsource))
Here is a handy table for you to convert loads and sources, using my typical figures above:
Source Mic Line Instr
Mic -1.9dB -0.2dB -0.0dB
Line -0.8dB -0.1dB -0.0dB
Instr -20.8dB -6.0dB -0.1dB
So we can easily see that a) impedance mismatches *only* occur with high source impedances and low load impedances, as with the guitar into anything but an instrument input. It actually gets even worse for the guitar because its source impedance is complex, which means that the loss varies by frequency, so not only does the guitar lose most of its signal, its frequency response changes too. That's bad.
But none of that is happening with a low output impedance source like a mic amp. There could be issues of noise or headroom, but those are not caused by differences in impedance, they are caused by design decisions. For example, if you label an input "mic", probably the designer assumes that the signal level incoming is low, and they should apply an amount of minimum gain to said signal. If the incoming signal is actually hot, the gear will therefore clip. But there is no law of physics that says that a mic input must have minimum gain; it could be zero. It could have an input pad . . .
As for noise, if you have a line input, you might assume that the incoming signal is hot, so you might be happy with input noise that is 30dB worse than you could tolerate for a mic input. You might also assume that no gain is required, because the signal is supposed to be line level already. So when a poor soul plugs a mic directly into that input, the result is a quiet yet noisy signal, which they notice when they add gain at a subsequent stage. But there is no law of physics that says you can't design a very quiet line input with gain if required. It just isn't generally done due to cost and lack of need.
The next thing that happens is that poor soul will ask what happened, and somebody will say "impedance mismatch". But that's wrong, it's just a noisy input with no gain. How can there be an impedance mismatch when the source impedance of a typical mic and typical line output are ALMOST EXACTLY THE SAME!!!
There is no mismatch; there is just a level difference of up to 60dB. Level and impedance are not the same thing.
For the record, if he has the Behri output into an input labeled with a "mic/guitar" switch, the problem is the switch on mic probably has minimum gain, which is clipping the Cakewalk. Has nothing to do with impedance. I'd be willing to bet that switching to "guitar" would help matters, but you'd probably say that would make the "mismatch" worse, right? Read above again.
Any, yes, RCA inputs, likely much less gain, the correct answer. BUT NOT BECAUSE OF IMPEDANCE.
