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Phantom power with "Y" cable...?
Old 4 weeks ago
  #1
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MichaelK's Avatar
Phantom power with "Y" cable...?

Hi everyone --

I want to record a small vocal group in M/S stereo format. I plan to use a "Y" cable to split the side signal to two preamp channels, where I'll flip the polarity on one.

The "side" mic I plan to use is a phantom-powered multipattern LDC. My question is, should I activate phantom power on both preamp channels or only one?

Thanks!
Old 4 weeks ago
  #2
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bgood's Avatar
I’d probably use a standalone 48v phantom power supply for that... get a cheap Rolls or something similar for like $25
Old 4 weeks ago
  #3
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I would think it's one mic, one phantom source.
Generally it's ok to split sources (outputs), but not combine sources (outputs). Would phantom apply -as a 'source in this case? IDK, never had it come up.
Old 4 weeks ago
  #4
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Activate phantom power on one preamp.
But why not split the signal and flip polarity after the preamp (one)? Would be better impedance whise to.
Old 4 weeks ago
  #5
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MichaelK's Avatar
Quote:
Originally Posted by bgood View Post
I’d probably use a standalone 48v phantom power supply for that... get a cheap Rolls or something similar for like $25
Good solution. Thanks!
Old 4 weeks ago
  #6
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Quote:
Originally Posted by MichaelK View Post
Good solution. Thanks!
Why would that be needed?
Old 4 weeks ago
  #7
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Quote:
Originally Posted by MichaelK View Post
Good solution. Thanks!
Next question, should you activate phantom power on all, two of them or only one?
Your microphone needs phantom power.
It doesn't matter where it comes from.
Your pre amps don't "see" phantom power on the input.
Splitting a microphone to two inputs with an Y cable will give other (then phantom power) problems (impedance).
But all well, have fun.
Old 4 weeks ago
  #8
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Quote:
Originally Posted by BT64 View Post
Splitting a microphone to two inputs with an Y cable will give other (then phantom power) problems (impedance)
no it doesn't, gets done on most any stage daily, worldwide - maybe not ideal from a measuring point of view or if one is using a mic with a veeeery low output and long lines to the mic preamps, the latter of which is rarely the case these days, but otherwise, no problem! phantom power usually gets activated at the monitor desk (and of course only there)...
Old 4 weeks ago
  #9
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Aah, ok, yes it will work.
Depending on microphone and pre amps maybe even with no problem.
No need for transformer-based mic splitters.
Old 4 weeks ago
  #10
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Quote:
Originally Posted by BT64 View Post
Aah, ok, yes it will work.
Depending on microphone and pre amps maybe even with no problem.
No need for transformer-based mic splitters.
they are sometimes useful but not alway wanted: some broadcast engineers will not allow you to go through any active split or insist on getting the direct signal while foh and monitor have to go with the trafo splits - silly imo as the monitor mixer is way closer to what's happening on stage... - costs are another reason for using passive splits.
Old 4 weeks ago
  #11
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Brent Hahn's Avatar
 

Quote:
Originally Posted by MichaelK View Post
Hi everyone --

I want to record a small vocal group in M/S stereo format. I plan to use a "Y" cable to split the side signal to two preamp channels, where I'll flip the polarity on one.

The "side" mic I plan to use is a phantom-powered multipattern LDC. My question is, should I activate phantom power on both preamp channels or only one?

Thanks!
Hold on for a sec. Are you saying this "sides" mic doesn't have a fig. 8 pattern, but you plan on faking fig. 8 by recording it to two channels and then flipping polarity on one of them? At any rate, you only need to supply phantom from one place, but having them both on won't hurt anything. People inadvertently supply phantom from both legs of a splitter all the time and nothing ever blows up.

Last edited by Brent Hahn; 4 weeks ago at 04:37 PM..
Old 4 weeks ago
  #12
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as long as the multipattern ldc is set to fig8, i cannot see any problem... (besides setting the gains exactly the same on the two mic pres for the sides)
Old 4 weeks ago
  #13
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Wizzomixer's Avatar
For M/S recording you need two mics, a mono forward facing for the mid and a figure of eight facing left/right for the sides. You cannot get M/S from only a figure of eight. The left channel is centre plus the figure of eight, the right channel is centre minus the figure of eight.Record to a stereo track with centre on the left and figure of eight on the right, then decode the M/S with something like the free Hofa 4U meter fader and M/S pan where you can vary the stereo width to taste.
Also look here.
https://www.uaudio.com/blog/mid-side-mic-recording/
Attached Images
Phantom power with "Y" cable...?-ms_stereo.jpg 

Last edited by Wizzomixer; 4 weeks ago at 05:14 PM.. Reason: more info
Old 4 weeks ago
  #14
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Quote:
Originally Posted by Wizzomixer View Post
For M/S recording you need two mics, a mono forward facing for the mid and a figure of eight facing left/right for the sides...
Question is about the side mic.
Quote:
Originally Posted by MichaelK View Post
The "side" mic I plan to use is a....
Old 4 weeks ago
  #15
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Wizzomixer's Avatar
Whether it's about the side mic or not, and this is the "newbie" section, splitting a figure of eight and using two mic pres is a strange and convoluted way to get M/S decoding.
Old 4 weeks ago
  #16
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Agree.
Old 4 weeks ago
  #17
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Quote:
Originally Posted by Wizzomixer View Post
Whether it's about the side mic or not, and this is the "newbie" section, splitting a figure of eight and using two mic pres is a strange and convoluted way to get M/S decoding.
no, it isn't: not everyone has capabilities to decode m/s in another way - this is the most simple way to do it, at the cost if using another mic pre.

(another method with an analog desk would be to do it at line level, using the direct out or insert send on one channel, reverse polarity via a cable (assuming that the polarity flip only affects the mic in) and go into the insert return or line in of the next channel - depends on the desk though and chances to mess up things here are higher...)

no newbie thing, just straight forward analog signal flow!
Old 4 weeks ago
  #18
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Wizzomixer's Avatar
I'm no stranger to either analogue or digital signal flow. I've recorded in M/S and Double M/S since the early 1990s, and been in the recording industry since 1970.
Old 4 weeks ago
  #19
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Yet a other methode is to plug your (figure 8) mic into one pre amp and split the line output (and phase flip one).

No phantom power problem.
No extra pre needed (gain setting is easy).
No chance on impedance problems.
Just an idea and how I (and many others) have done it for years.
Old 4 weeks ago
  #20
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Brent Hahn's Avatar
 

Quote:
Originally Posted by MichaelK View Post
No
Figured as much, just asking.
Old 4 weeks ago
  #21
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MichaelK's Avatar
Quote:
Originally Posted by Wizzomixer View Post
Whether it's about the side mic or not, and this is the "newbie" section, splitting a figure of eight and using two mic pres is a strange and convoluted way to get M/S decoding.
Not at all. To track and monitor in real time the signal has to be split somewhere. I'm doing it before the preamps rather than after. Setting the same gain on both is easy because detented knobs. When I combine them to mono they completely cancel out.
Old 4 weeks ago
  #22
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MichaelK's Avatar
Quote:
Originally Posted by deedeeyeah View Post
no, it isn't: not everyone has capabilities to decode m/s in another way - this is the most simple way to do it, at the cost if using another mic pre.
Definitely the easiest way for me, with a polarity switch right on the preamp.
Old 4 weeks ago
  #23
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MichaelK's Avatar
Quote:
Originally Posted by Wayne View Post
Why would that be needed?
(responded w incorrect info a little while ago...)

It powers the mic on one cable before splitting the signal.
Old 4 weeks ago
  #24
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MichaelK's Avatar
Quote:
Originally Posted by BT64 View Post
Splitting a microphone to two inputs with an Y cable will give other (then phantom power) problems (impedance).
But all well, have fun.
Impedance on either side would be the same.
Old 4 weeks ago
  #25
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Quote:
Originally Posted by MichaelK View Post
Impedance on either side would be the same.
Correct.
For both pre's the impedance would be different from what the mic realy is.
Z total = 1/(1/Za+1/Zb)
And chances are you have a grond loop.
But seems you have found the solution, so that's good.
Old 4 weeks ago
  #26
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the way you intend using your gear, there is almost zero risk for ground loops unless you're using a weird way to power and set up the two pres for the side-mic (or your gear is faulty)...

regarding impedance mismatch: some pres allow to switch between different settings; sonically, i doubt you'd be hearing much of a difference though.

and regarding mic selection for the mid-mic: doesn't have to be cardioid, pretty much any mic with a somewhat directional pattern works.

m/s really is not that much of an elaborate setup, you seem to be ready to go.
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