Thank you very much Pigiron for your extensive answer and Chris for your elaboration.
huh?... I'm totally confused... or stoned
I don't know if
you are. That certainly would add to the communication problem caused by my poor english and because I
am, both...
do I need some circuit to 'downconvert' to unballanced to go to the unballanced preamp?
yep...
Notice that the unbalanced plus signal (+) is going to the negative input on one opamp and the positive on the other... this is because a balanced cable carries two signals (hot and cold) 180 degrees out of phase... the advantage is, any noise injected into the cable (placing too near an electric motor for instance) will be canceled out by the preamp input circuit (which only outputs the differences between the two signals and the noise will supposedly be equal and in-phase on both wires).
clever system, thank's for explaining, slowly I understand just
how important ballanced really is.
An unbalanced line is simply a signal compared to ground (needing only two wires per mic)... and this is what an unbalanced preamp is expecting.
BUT... unless you're going fairly long distances or in an (electrically) noisy environment, I'd sure try to make my life easier without all this gorp... i.e. I'd try an experiment using an unbalanced extension cable before I embarked down this path... those circuits add capacitance, impedance, etc to your very low level signal path... and the opamp themselves induce a small amount of noise.
understood, thank's, my wish to convert to ballanced just for a cable run is done with.
in the case of the SP-CMC8, is it simply a matter of wiring, no circuit needed at all? - as it seems looking at the AT853 unmod thread, though the pics there are not available any more so I don't understand yet.
hmmm... confusion... if you're asking if the SP-CMC8's can go directly into an unbalanced preamp, then I think the answer is yes... most of the Sound Professional mics have a 1/8 inch TRS (Tip, Ring, Sleeve) connector attached to two microphones... hence unbalanced... one of the 3 TRS connections (can't remember the arrangement) will be left signal, one will be the right signal, and one is ground (the same ground is used on both mics).
'one 1/8 inch TRS connector attached to two microphones..hence unballanced'....again sounds if the are unballanced
only because of the wiring into a TRS plug.
Chris however says:
The mics your talking about are unbalanced mics they happen to be three wire mics meaning that the mics require a separate bias supply
3 wired but unballanced...well, I do not understand that.
And that is my confusion: Are they ballanced and can be made into fully ballanced simply by connecting each mic to a three pin connector? Or are they unballanced but can be more easily converted to ballanced than 2 wired mics? What is the significance of the three wires and do they help if I want longer cable runs?
Why I ask all these questions:
I want to separate the mics to be able to e.g. run split omnis and generally longer cable runs, and I was wondering how best to do that.
So better I simply ask:
Separating the CMCs to be able to run them separately with longer cable runs, which is the best solution?To unmod them? Would they need full phantom power then?
Or - the famous 3 wired battery box?
or...no worries, just put extension cables...
note: I mostly won't record very loud music but simply want to experiment with different mic configurations.