i have a question about +4/-10 bB inputs. I understand, on my adat anyway, that the +4 inputs are balanced which is good for various reasons. What I dont understand is that to get a decent level when using the +4 inputs ( as opposed to the -10 inputs) I have to pump the mic pres more than when I use the the -10 inputs.
Doesnt this just add more mic pre noise to the final signal.
I have said it before and ill say it again, but im sure on this issue im missing somethin really basic.
Im very new to using +4 inputs but so far have found that when pumping the pres this much im raising that low mic crackling noise floor to an audible level.
I go mic to mackie vlz to adat.
Thx all. A
I had a roadie from a VERY famous rock band call me one time complaining that he couldn’t get a good level out of an audio processor I designed. I went down to the rehersal studio to see what was wrong. He had his electric guitar plugged directly into the +4 input. I asked why he was using the +4 input and he said, “well, +4 is the professional level and we’re professionals!” Ahhhhhhhhh!!!
Anyhow, the right answer in your case is simple - what sounds better? If you need to drive the pres very hard to get a decent signal on a +4 input that’s probably not the right choice. Besides the level difference, +4dBm inputs are usually low impedance (600ohms) whereas -10dBV is usually high impedance (10K or more). Your preamp may not be designed to drive low impedance loads.
Finally, the benefits of a +4dBm balanced input are really only significant in electromagnetically noisy environments (such as from theater light dimmers, radio interference, etc.) and over long cable runs. In a typical home studio there is not much to be gained. Use -10 if that works best.
Good post, slowfingers.
BTW, +4 isn’t always balanced and -10 isn’t always unbalanced. If you have switchable inputs, chances are that both +4 and -10 are balanced, and you can plug an unbalanced signal in regardless and it will work fine. The reverse isn’t necessarily true: you can’t plug a balanced output into an unbalanced input unless the specs for the input say you can – it takes a 3-conductor jack to make it work and the gear may or may not have it.
Also, fyi: the difference in signal level between +4dBu and -10dBV is roughly 12dB. Not 14dB like you might expect, because dBu and dBV have different reference standards (0.775V vs 1V, or something like that). Anyway, the 12dB difference means that the voltage level has to be 4 times higher on +4 to achieve the same signal level as for -10, downstream of that input.
Thx for replying everyone.
I am shocked to find out that there are quieter preamps than the ones in my Mackie.