k brown
Well-known member
There's a mic array that I use often for classical recording that consists of two pairs of omnis - one closely spaced and the other very widely spaced. The system requires the two pairs to be mixed at equal levels (spare me the lectures about combing).
Since I have some mics that are inherently inverting (i.e.,Oktavas) and many that are non-inverting, it occured to me that if I connect the unbalanced output of the inverting mics to the (-) inputs of a preamp, and the unbal outs of the non-inverting mics to the (+) inputs of the pre, the two signals would be added together at equal gain (and non-inverted), rather than being subtracted from each other - thus saving a pair of preamps; the four-mic system can be done with a single 2-ch mic pre.
Initial tests at home, just talking into the mics shows no problem with this - noise isn't increased, the sound of the mics don't change any, etc., but is there a solid, engineering reason why this would be a problem - would headroom be affected, would this 'upset' the inputs in some way, etc.?
The mics are battery powered, or using 'outboard' phantom supplies, so mic pre phantom power is not an issue.
And, yes I understand that the noise-cancelling function of the balanced inputs is sacrificed, but I've run short (10-15') unbalanced lines to unbalanced preamps for 30 years with no problems, so not worried about that.
Since I have some mics that are inherently inverting (i.e.,Oktavas) and many that are non-inverting, it occured to me that if I connect the unbalanced output of the inverting mics to the (-) inputs of a preamp, and the unbal outs of the non-inverting mics to the (+) inputs of the pre, the two signals would be added together at equal gain (and non-inverted), rather than being subtracted from each other - thus saving a pair of preamps; the four-mic system can be done with a single 2-ch mic pre.
Initial tests at home, just talking into the mics shows no problem with this - noise isn't increased, the sound of the mics don't change any, etc., but is there a solid, engineering reason why this would be a problem - would headroom be affected, would this 'upset' the inputs in some way, etc.?
The mics are battery powered, or using 'outboard' phantom supplies, so mic pre phantom power is not an issue.
And, yes I understand that the noise-cancelling function of the balanced inputs is sacrificed, but I've run short (10-15') unbalanced lines to unbalanced preamps for 30 years with no problems, so not worried about that.
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