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Post by Jim D. on Jan 24, 2021 10:01:29 GMT -5
I just picked up a Fender chassis (removed from amp cabinet) after having it serviced. I removed the speaker connections so I could try a variety of speakers I have. I know, I should have used alligator clip cables and the speaker output jack.. This is a single speaker combo amp. I lost track of the speaker output polarity. Does this make a difference? If so, any way to test?
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Post by Jim D. on Jan 24, 2021 11:35:39 GMT -5
I should have asked what battery voltage is best to test polarity, but still wondering if it matters.
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Post by Seldom Seen on Jan 26, 2021 19:03:08 GMT -5
The polarity matters if you are playing with bandmates so it’s best to confirm polarity and get the white wire connected to the + terminal. A standard 9-volt battery provides the most movement but keep it brief. I’ve also seen D-cell batteries (1.5 V) used by soldering the wires to the battery terminals. This produces less movement but it’s also less dicey.
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pdf64
Wholenote
Posts: 558
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Post by pdf64 on Jan 26, 2021 19:15:58 GMT -5
The polarity matters if you are playing with bandmates... I’m not sure that’s factual / proven? Note that many amps have channels in opposing polarity. Absolute polarity in regard of an electric guitar system seems a somewhat nebulous, undefined concept. The only factual significance of speaker polarity is in the case of multi speaker cabs / arrays. For a single speaker, its connection polarity is immaterial, neither way around fundamentally correct / incorrect. Standard modern orientation is that a positive voltage on the +ve terminal results in the cone moving ‘out’, thereby resulting in an increase of pressure in front of the speaker.
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Post by Jim D. on Jan 27, 2021 9:37:58 GMT -5
Thanks guys. I can’t hear any difference either way. I could be wrong, but on a reverse wound Strat middle pup aren’t you effectively reversing the polarity through the amp signal?
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pdf64
Wholenote
Posts: 558
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Post by pdf64 on Jan 27, 2021 10:12:13 GMT -5
The ‘reverse wound reverse polarity’ middle pickup thing actually keeps the pickup’s signal output polarity the same as the other pickups - the old ‘multiply 2 negatives and the result is positive’ algebra process. What gets flipped is the hum, hence it gets cancelled out when the middle AND another pickup are selected.
But yeah, maybe some people are sensitive to signal polarity, anything is possible, but not me; I fitted a speaker polarity switch on the output of one of my amp builds, and can’t discern any difference either way, whether listening closely at home or cranking it out with the band.
Consider that if it was a thing, with it being so simple to flip polarity electronically, polarity flip pedals would be on everyone’s pedalboard.
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Post by Jim D. on Jan 27, 2021 15:46:39 GMT -5
One of the best closing comments ever! So true.
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Post by Seldom Seen on Jan 27, 2021 23:53:18 GMT -5
Tonto think speakers moving in opposing directions not good, but Tonto no expert.
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Post by Peegoo 🏁 on Jan 28, 2021 6:07:59 GMT -5
I’m not sure that’s factual / proven? Note that many amps have channels in opposing polarity. Absolute polarity in regard of an electric guitar system seems a somewhat nebulous, undefined concept. That is correct. Speaker polarity matching is important only when multiple speakers are driven by a single amp. Multiple amps in the same room don't need to be phase matched because reverberations within the room cause constructive and destructive phase interactions anyway. The only time it's important to get the speaker's phase "right" when hooking up a single-speaker combo amp is when it also has a jack for an extension speaker cab that doesn't defeat the onboard speaker. This ensures both speakers are in phase when using an extension cab.
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Post by Seldom Seen on Jan 28, 2021 7:44:07 GMT -5
So Tonto half right but still think it good idea to maintain polar consistency.
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Post by ninworks on Jan 29, 2021 5:29:37 GMT -5
I agree with Peegoo on the multiple speaker comment. Not that it matters but JBL speakers are always backwards compared to everyone else. The Black terminal is positive and the red one is negative. I don't know why they do that but it's always been that way. I have heard they have changed this practice in recent years but don't know that for certain. It's best to check them with a battery before wiring them.
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Post by ninworks on Jan 30, 2021 10:12:34 GMT -5
The polarity matters if you are playing with bandmates....... Not necessarily. Precise time alignment with speakers (polarity) comes into play when all the sound waves coming off all the instruments, or amplifier's speakers, are all at precisely the same frequencies and are precisely in line with each other, as if when they are in the same speaker cabinet. If the polarity of those 2 speakers are inverted then they can cancel each other out, theoretically. A guitar's fundamental frequency range is approximately from 80Hz to 1200Hz. It can go beyond 1200Hz with distortion but at those higher frequencies the wavelengths are so short that it's not as critical. For the sake of this example I'll say the center frequency range of a guitar is approximately 600Hz. The wavelength of a 600Hz sine wave is about 21 inches. If you take half of that length, 10-1/2 inches, that is the point where the polarity of that wave is inverted 180 degrees. That means all of the guitar amp speakers in the band would have to be a lot less than 10-1/2" of being precisely in line with each other for them to be time aligned with each other. That would be the only situation where speaker polarity could enter into the equation. There are not many band situations where that ever happens. Bands are set up in rooms where one amp is on one wall and another is set up on a wall 90 degrees from it on a different wall or in a corner. Amps are not usually lined up with the front of the drums and vocal monitors, when used, are at the front of the stage pointing backwards. When the added instruments such as bass, drums, vocal monitors etc. are all included in this audio stew the time alignment lines become severely blurred when considering the affect of speaker polarities in different amplifiers. If the amp's speakers are close-miked then, theoretically, it could be an issue but there is so much microphone bleed onstage that it doesn't usually enter into it. If you have a live sound engineer, who is running the band out front, and is any good, they will flip the polarity of any problematic phase problems between the instruments onstage to remedy any issues. A live band has so many different things entering into the sound propagation event coming off the stage and through a PA system, guitar amp speaker polarity choices are way down on the list if they are even on it. When recording in a studio, speaker alignment is still not much of an issue, if ever. Again, the recording engineer will address any phase inconsistencies and reverse them if they are problematic. All that being said, I still check my speaker polarity when wiring them up. It's more of an OCD thing than technical.
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Post by Seldom Seen on Jan 30, 2021 11:15:03 GMT -5
I still say “honor thy polarity”. If it didn’t matter it wouldn’t be marked.
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pdf64
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Post by pdf64 on Jan 30, 2021 13:14:08 GMT -5
I still say “honor thy polarity”. If it didn’t matter it wouldn’t be marked. No ones disagrees that it matters. But only when there’s an array, ie more than a single speaker (ie voicecoil) connected to the output of an amp.
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Post by Leftee on Jan 30, 2021 13:41:16 GMT -5
I think Peter Green hooked his up all wonky. Or something.
🤔
😂
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pdf64
Wholenote
Posts: 558
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Post by pdf64 on Jan 30, 2021 14:32:37 GMT -5
Precise time alignment with speakers (polarity) comes into play I’m a few decades past my comfort zone for debating or explaining the technicalities here, but as I understand it, whilst time, phase and frequency are all intimately tied together, polarity is a fundamentally unrelated characteristic. A big problem is the terminology, with even textbooks sometimes use ‘phase’ when what’s actually being referred to is polarity. I’ve not seen the inverse of that though, but nonetheless wonder if that’s caused a mix up resulting in the above? Other than on a random and momentary basis, independent signal sources such as the above can’t produce coherent signals, ie signals that share the exact same frequency and phase. Not even the tightest group in the world Rather it requires a mechanism that’s way beyond human capabilities, eg even two synthesisers would need to be linked and under the overall control of a phase locked loop That happens at low frequencies but even theoretically, above low mids, the cancellation effect pretty much evaporates. Somewhat analogous to combining pickups on a guitar that are opposing polarity.
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Post by LTB on Feb 17, 2021 2:50:33 GMT -5
Me thinks we are at the point where we are arguing for the sake of arguing now 😂😉
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Post by Peegoo 🏁 on Feb 21, 2021 22:06:10 GMT -5
The signal to a speaker is an AC waveform, which means the wires are interchangeable on a single speaker and the sound produced is identical when wired both ways.
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