Taperssection.com
Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: Tisbo on February 21, 2013, 05:37:03 PM
-
I know my SD MP-2 is a preamp, not a mixer. But with the M/S matrix engaged, each output is a mix of both inputs. Using mics that are NOT figure-8, can anyone foresee a problem using the M/S matrix to mix two inputs down to one output channel? As I understand it, the matrix reverses the no. 2 input's polarity in the second output, but trying different arrangements of two (non-figure-8) mics, I didn't hear any obvious signal cancellation. Just to be clear, I'm not trying to get a stereo effect: I'm only taking two inputs and mixing them down to a mono output, and it works! But does it matter which output channel I use to record? Are there other pitfalls I'm not aware of? Thanks for any observations and advice!
-
http://www.sounddevices.com/download/guides/mp2_en.pdf
-
"But does it matter which output channel I use to record?" No, not unless your using a figure 8, but change the inputs and you will hear a difference.
I have thought about running a mono sbd into input 1 of the V3 and just use my figure 8 onstage for input 2 and let the V3 decode it (or duo it post), but having 4 channels has made me forget about that.
Ya, It may be cool and work, but I don't see why you wouldn't just mix the 2 channels later and leave that weird phase reversal out of the mix.
-
Thanks, Jon. That makes sense.
Picklemic, for me the idea is 2 channel recorder with XLR inputs and decent pres. I'd plug one mic right into the recorder, then use my MP-2 to mix down two more mics into the deck's other input. Like having a 302, kinda sorta almost, and on the cheap. I'm not thinking music so much as, say, dialogue, where I could put two lavs (through the MP-2) into one channel and a boom mic directly into the other, but there must be musical situations that could use a 3-to-2 mixdown also, right? In short, just trying to get the most out of what I already have as I incrementally acquire better equipment.
-
M is L+R, that is a mix of the two inputs without inversion. S inverts the R channel, so don't use that.
Man I got confused on that statement. I think you meant L=M+S and the R=M-S . So ya, it will work just fine to mix the 2 and only use the left as an output into your recorder.
-
No, I meant M=L+R and S=L-R, but using math we can derive M + S = L + R + L - R = 2L and M - S = L + R - L + R = 2R.
Thus, an MS matrix will decode MS to LR or LR to MS. The electronics don't know or care which way you are trying to go. The labels on the unit might vary, but the function is the same.
<<<----- The personal text in my forum profile: M+S=L & M+(-S)=R so L+R=(M+S)+(M-S)=2M (mono sum)