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Title: 2 mics (identical model/instrument), same input channel ??
Post by: Dean Wells on July 31, 2011, 01:45:06 AM
Hello all..
A school sound dude friend of mine asked me this.. Limited input channels avail to them:
One scenario might be backing vocals-2 or 3 mics on same strip, and let the singers "ride" their mics?
Scenario 2 is say double kick; same mic and placement in each drum. Obvious loss of individual control/eq etc, however, in a pinch, might it work to y both into one strip?

I guess I'm getting old-I simply can't remember if this is a go/no go. Feel I should know the answer to this one..

 Also what about twin condenser (phantom powered) on same input strip, say for remote, and fixed hi-hats,, or 2 overheads etc. ?

Thanks everyone !! Cheers !
Title: Re: 2 mics (identical model/instrument), same input channel ??
Post by: Mark Chrysostom on July 31, 2011, 01:51:59 AM
Hello all..
A school sound dude friend of mine asked me this.. Limited input channels avail to them:
One scenario might be backing vocals-2 or 3 mics on same strip, and let the singers "ride" their mics?
Scenario 2 is say double kick; same mic and placement in each drum. Obvious loss of individual control/eq etc, however, in a pinch, might it work to y both into one strip?

I guess I'm getting old-I simply can't remember if this is a go/no go. Feel I should know the answer to this one..

 Also what about twin condenser (phantom powered) on same input strip, say for remote, and fixed hi-hats,, or 2 overheads etc. ?

Thanks everyone !! Cheers !

I've done the double-kick thing before, in situations where channels or processing are limited. Seemed to work OK.

There are probably some very scientific reasons why this is a bad idea. You should probably avoid sharing vocals like that, but that's just me.
Title: Re: 2 mics (identical model/instrument), same input channel ??
Post by: Dave Dermont on July 31, 2011, 03:48:11 AM
Hello all..
A school sound dude friend of mine asked me this.. Limited input channels avail to them:
One scenario might be backing vocals-2 or 3 mics on same strip, and let the singers "ride" their mics?
Scenario 2 is say double kick; same mic and placement in each drum. Obvious loss of individual control/eq etc, however, in a pinch, might it work to y both into one strip?

I guess I'm getting old-I simply can't remember if this is a go/no go. Feel I should know the answer to this one..

 Also what about twin condenser (phantom powered) on same input strip, say for remote, and fixed hi-hats,, or 2 overheads etc. ?

Thanks everyone !! Cheers !

I've seen (heard) a guy do it with two tom-tom mics, and it seemed to work OK.

I've never felt comfortable with this, and have always found other solutions. It just doesn't seem right.
Title: Re: 2 mics (identical model/instrument), same input channel ??
Post by: g'bye, Dick Rees on July 31, 2011, 11:40:47 AM
Hello all..
A school sound dude friend of mine asked me this.. Limited input channels avail to them:
One scenario might be backing vocals-2 or 3 mics on same strip, and let the singers "ride" their mics?
Scenario 2 is say double kick; same mic and placement in each drum. Obvious loss of individual control/eq etc, however, in a pinch, might it work to y both into one strip?

I guess I'm getting old-I simply can't remember if this is a go/no go. Feel I should know the answer to this one..

 Also what about twin condenser (phantom powered) on same input strip, say for remote, and fixed hi-hats,, or 2 overheads etc. ?

Thanks everyone !! Cheers !

Dean....

I generally carry a 5-channel "mix pad" to use for a sub-mixer in a pinch.  You'll have to combine the mics somehow and if you shop well over time you can find one such unit for very little $$$.  I paid $50 for two older B******** 5 XLR mixers which have inserts on the first two channels and will provide phantom when using the "wall-wart".  If you don't have to use phantom it will run on a 9v battery all day.
Title: Re: 2 mics (identical model/instrument), same input channel ??
Post by: Dan Richardson on July 31, 2011, 01:32:46 PM
Hello all..
A school sound dude friend of mine asked me this.. Limited input channels avail to them:
One scenario might be backing vocals-2 or 3 mics on same strip, and let the singers "ride" their mics?
Scenario 2 is say double kick; same mic and placement in each drum. Obvious loss of individual control/eq etc, however, in a pinch, might it work to y both into one strip?

I guess I'm getting old-I simply can't remember if this is a go/no go. Feel I should know the answer to this one..

 Also what about twin condenser (phantom powered) on same input strip, say for remote, and fixed hi-hats,, or 2 overheads etc. ?

I've done all three, more than once. Got the job done.
Title: Re: 2 mics (identical model/instrument), same input channel ??
Post by: John Roberts {JR} on July 31, 2011, 02:00:38 PM
While obviously not optimal, yes for controlled circumstances you can parallel dynamic mics and they will sum with only modest amounts of signal degradation. In principle active phantom powered mics if they use internal build out resistances and have adequate power when phantom input is double loaded could sum too, but I am far less comfortable suggesting that as active devices driving into other active devices seems like it could release smoke if outputs do not anticipate such applications and provide protection. 
----
Back when I was in that business I defined a simple input expander accessory product that could sum a few dynamic mics together with rudimentary controls (relative level, pad, polariy, etc) running into and from the phantom power of a single mic input channel, but market research suggested this was not a very merchantable product. The price compression on mixers with more inputs for less dollars continues, making this even less attractive today than back then.

JR
Title: Re: 2 mics (identical model/instrument), same input channel ??
Post by: luis Markson on August 01, 2011, 01:34:06 AM
While obviously not optimal, yes for controlled circumstances you can parallel dynamic mics and they will sum with only modest amounts of signal degradation. In principle active phantom powered mics if they use internal build out resistances and have adequate power when phantom input is double loaded could sum too, but I am far less comfortable suggesting that as active devices driving into other active devices seems like it could release smoke if outputs do not anticipate such applications and provide protection. 
----
Back when I was in that business I defined a simple input expander accessory product that could sum a few dynamic mics together with rudimentary controls (relative level, pad, polariy, etc) running into and from the phantom power of a single mic input channel, but market research suggested this was not a very merchantable product. The price compression on mixers with more inputs for less dollars continues, making this even less attractive today than back then.

JR

Does this apply to mics and pres?

http://www.rane.com/note109.html
Title: Re: 2 mics (identical model/instrument), same input channel ??
Post by: Bob Leonard on August 01, 2011, 09:07:19 AM
While obviously not optimal, yes for controlled circumstances you can parallel dynamic mics and they will sum with only modest amounts of signal degradation. In principle active phantom powered mics if they use internal build out resistances and have adequate power when phantom input is double loaded could sum too, but I am far less comfortable suggesting that as active devices driving into other active devices seems like it could release smoke if outputs do not anticipate such applications and provide protection. 
----
Back when I was in that business I defined a simple input expander accessory product that could sum a few dynamic mics together with rudimentary controls (relative level, pad, polariy, etc) running into and from the phantom power of a single mic input channel, but market research suggested this was not a very merchantable product. The price compression on mixers with more inputs for less dollars continues, making this even less attractive today than back then.

JR

Does this apply to mics and pres?

http://www.rane.com/note109.html (http://www.rane.com/note109.html)

It does, and it has always been my experience that one signal will always attempt to outdrive the other. It's a matter of seperation, and as pointed out by Rane the point being the summed signal is not a controlled stereo signal to begin with. You have little or no control over the input signal levels of either device when simply summed.
Title: Re: 2 mics (identical model/instrument), same input channel ??
Post by: Tim McCulloch on August 01, 2011, 09:52:12 AM
Hello all..
A school sound dude friend of mine asked me this.. Limited input channels avail to them:
One scenario might be backing vocals-2 or 3 mics on same strip, and let the singers "ride" their mics?
Scenario 2 is say double kick; same mic and placement in each drum. Obvious loss of individual control/eq etc, however, in a pinch, might it work to y both into one strip?

I guess I'm getting old-I simply can't remember if this is a go/no go. Feel I should know the answer to this one..

 Also what about twin condenser (phantom powered) on same input strip, say for remote, and fixed hi-hats,, or 2 overheads etc. ?

Thanks everyone !! Cheers !

I have 'wyed' identical mics for orchestra pickup.  In the strings, I mic the first 2 stands individually and then wye together pairs of stands.  So in the first violins, the concert master and his/her stand partner get a mic & channel, ditto for the next stand.  After that each stand gets a mic and pairs of mics are wyed together.

I would not do this with sources that need individual control like drums or guitar rigs.

YMMV.
Title: Re: 2 mics (identical model/instrument), same input channel ??
Post by: John Roberts {JR} on August 01, 2011, 10:00:31 AM


Does this apply to mics and pres?

http://www.rane.com/note109.html

No. or a "yes but....".  Passive combining through resistors will add noise in series with the mics that we don't want or need.  Ok for combining line level outputs of gear, but not mic level inputs.

Simple parallel of same model mics, in very similar applications can work, but don't push your luck.

JR