Polarity
- Thread starter drpat
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NewYorkDave
Well-known member
A positive voltage at the input results in a positive voltage at the output.
NewYorkDave
Well-known member
If you wanna be hardcore about it and include the transducers in the definition, sure.... :wink:
NewYorkDave
Well-known member
You need an asymmetrical acoustical waveform with significantly greater amplitude in one polarity--a clicker, if you like.
NewYorkDave
Well-known member
[quote author="mediatechnology"]
Sing "Ahh..." or "Eee" into a preamp monitored by a 'scope. It will always (OK 99.99% of the time) produce positive acoustic pressure in the near-field. [/quote]
Unless you use the Cookie Monster voice; that causes rarefaction in the near-field... and don't ever try it underwater! (Don't ask me how I know...).
:razz:
Sing "Ahh..." or "Eee" into a preamp monitored by a 'scope. It will always (OK 99.99% of the time) produce positive acoustic pressure in the near-field. [/quote]
Unless you use the Cookie Monster voice; that causes rarefaction in the near-field... and don't ever try it underwater! (Don't ask me how I know...).
:razz:
pstamler
Well-known member
There was a commercial polarity checker (don't remember the maker) that used a simple signal: three positive-going pulses followed by a negative-going pulse. The detector displayed the polarity on a pair of LEDs; if they flashed + + + - you knew the polarity was correct. An oscilloscope will also tell you.
Meanwhile, microphone polarity is defined as: a positive-going pressure on the diaphragm, from the front, produces a positive-going voltage on pin 2.
Peace,
Paul
Meanwhile, microphone polarity is defined as: a positive-going pressure on the diaphragm, from the front, produces a positive-going voltage on pin 2.
Peace,
Paul
[quote author="drpat"]OK, now that that's cleared up, let me try another question...
My question is, are there any circumstances where I would need to swap the polarity on the input xlr instead of the output xlr?[/quote]
If both the input and output are both balanced it doesn't matter unless you mix and match between balanced and unbalanced wiring.
Products like mixers that have multiple sends, with some unbalanced inserts, would need the balanced input polarity to be such that the unbalanced insert is correct absolute polarity should someone use that as an alternate output.
Absolute polarity while subtle is most audible on asymmetrical waveforms like vocals and some brass instruments.
JR
My question is, are there any circumstances where I would need to swap the polarity on the input xlr instead of the output xlr?[/quote]
If both the input and output are both balanced it doesn't matter unless you mix and match between balanced and unbalanced wiring.
Products like mixers that have multiple sends, with some unbalanced inserts, would need the balanced input polarity to be such that the unbalanced insert is correct absolute polarity should someone use that as an alternate output.
Absolute polarity while subtle is most audible on asymmetrical waveforms like vocals and some brass instruments.
JR
[quote author="mediatechnology"]
John I think in his scenario it might. Consider the same mic multed into two preamps, one inverting, one not, both brought into channel inputs. I can see how having some inverted, some not, would be a real PITA (even with the inputs not multed) in mic'ing a drum kit. He probably is constantly having to invert the polarity of some preamps for them to sound right particularly when they're used with the ones that don't.
[/quote]
If I understand correctly, a single mic feeding multiple outboard preamps, feeding channels of a mixer.
If the outboard preamps are balanced input and output, and a positive zig on either input pin 2 or 3 results in a similar positive zig on the same output pin, it doesn't matter. If it's XLR in to 1/4" out, or the input doesn't agree with the output, it matters.
I am not familiar with seeing many mics wrong. Even back 20 years ago when it was almost 50-50 between pin 3 and pin 2 hot, the mic guys seemed to have their sierra together (pin 2).
If I had an inventory of mics that varied in polarity, I'd be real tempted to rewire the mics. Note: It might be easier to check for polarity by comparing to a known (or determined) good reference mic when both are listening to a LF tone. They will either combine or subtract when summed in a mixer.
JR
John I think in his scenario it might. Consider the same mic multed into two preamps, one inverting, one not, both brought into channel inputs. I can see how having some inverted, some not, would be a real PITA (even with the inputs not multed) in mic'ing a drum kit. He probably is constantly having to invert the polarity of some preamps for them to sound right particularly when they're used with the ones that don't.
[/quote]
If I understand correctly, a single mic feeding multiple outboard preamps, feeding channels of a mixer.
If the outboard preamps are balanced input and output, and a positive zig on either input pin 2 or 3 results in a similar positive zig on the same output pin, it doesn't matter. If it's XLR in to 1/4" out, or the input doesn't agree with the output, it matters.
I am not familiar with seeing many mics wrong. Even back 20 years ago when it was almost 50-50 between pin 3 and pin 2 hot, the mic guys seemed to have their sierra together (pin 2).
If I had an inventory of mics that varied in polarity, I'd be real tempted to rewire the mics. Note: It might be easier to check for polarity by comparing to a known (or determined) good reference mic when both are listening to a LF tone. They will either combine or subtract when summed in a mixer.
JR
zig must zig and zag must zag...
ommmmmmm.
JR
ommmmmmm.
JR
G
Guest
Guest
Feedback between a mic and a woofer on very low frequencies is your friend...
