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Author Topic: +/- (hot / cold) connections. Does it matter?  (Read 6667 times)

John Roberts {JR}

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Re: +/- (hot / cold) connections. Does it matter?
« Reply #30 on: September 24, 2014, 04:42:17 pm »

How did I not see that on the sheet?  Thanks.
So is Yorkville using the term correctly when they say, "Balancing code is; Tip= (+) 0 phase, Ring= (-) 180 phase, and Sleeve=Ground."?

No they are not technically correct, but when writing owner's manuals for beginning customers, it is more important to be understood than absolutely technically correct, so I will give them a little leeway.

Most customers will probably understand what they mean using that somewhat incorrect terminology. I have had to deal with this before supporting Peavey customers, while I strive to be both correct and understood (I would have said polarity).

 JR
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Jonathan Johnson

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Re: +/- (hot / cold) connections. Does it matter?
« Reply #31 on: September 24, 2014, 06:22:19 pm »

So is Yorkville using the term correctly when they say, "Balancing code is; Tip= (+) 0 phase, Ring= (-) 180 phase, and Sleeve=Ground."?

Well, no. That terminology would imply that the ring is one-half cycle delayed behind the tip, for some unknown frequency they aren't telling us about. :-)

In a true balanced signal on a TRS plug, the ring voltage is only the inverse of the tip. The signal is not referenced to the sleeve/ground, though in a pseudo-balanced system it may be. Referring to the tip and the ring as + and - is a bit misleading, because that really depends on which portion of the cycle of the waveform you are observing. At some point in the waveform, the tip will actually experience negative voltage (-) and the ring will have a positive voltage (+).

When we say that the tip is +, what we really mean is that when a positive voltage is applied to the tip, the speaker cone moves outward. This is industry standard.

For a microphone, the movement of the diaphragm is the inverse of the speaker. When the microphone diaphragm is moving inward (away from the acoustic source), a positive voltage is applied to the "hot" line (+) and a negative voltage is applied to the "cold" line (-).

It's a bit easier to imagine if you imagine everything in a row, facing from left to right:

Lead singer -> microphone -> mixer/processors/amplifier -> loudspeaker -> ear

When the singer exerts positive pressure on the microphone, the diaphragm of the microphone moves to the right, generating a positive voltage on the "hot" signal line (tip, if 1/4" TRS or TS; pin 2 if XLR) and a negative voltage on the "cold" signal line (ring if 1/4" TRS; sleeve if 1/4" TS; pin 3 if XLR). Through the various mixing, processing, and amplification stages, this positive voltage on the "hot" side is maintained. The amplifier generates a positive voltage on the + (tip, if 1/4") speaker line, and a negative voltage on the - (sleeve, if 1/4") speaker line, causing the speaker cone to move to the right. Ignoring acoustic delay, this will result in the listener's eardrum also moving to the right (inward).

In other words, INPUT transducers move INWARD (in response to atmospheric compression) to generate a positive voltage on the + line, and OUTPUT transducers move OUTWARD in response to a positive voltage on the + line (to create atmospheric compression).

Vocabulary term: the opposite of compression is rarefaction. The root of rarefaction is rarefy. Atmospheric rarefaction corresponds to a negative voltage on the + line. In a waveform, that portion above the "0" line represents compression; that portion below the waveform represents rarefaction. (Not referring to dynamic compression, for which the opposite is dynamic expansion.)

(By the way, vocal cords are output transducers and eardrums are input transducers.)
« Last Edit: September 24, 2014, 06:27:56 pm by Jonathan Johnson »
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Josh Millward

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Re: +/- (hot / cold) connections. Does it matter?
« Reply #32 on: September 25, 2014, 01:07:31 pm »

So is Yorkville using the term correctly when they say, "Balancing code is; Tip= (+) 0 phase, Ring= (-) 180 phase, and Sleeve=Ground."?
As others have said, that is not really correct at all.

The most correct way I have ever seen something like this expressed is by saying that the tip (+) is the non-inverting input and the ring (-) is the inverting input and the sleeve is ground.
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Josh Millward
Danley Sound Labs

Mark Cadwallader

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Re: +/- (hot / cold) connections. Does it matter?
« Reply #33 on: September 25, 2014, 01:27:01 pm »

I find this to be a facinating discussion. It reminds me of the explanation and analysis of how a bicycle (motorcycle, or other single track vehicle) turns and maintains direction. Not necessary intuitive, but perfectly logical. Mark C.
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