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Author Topic: sub polarity  (Read 1446 times)

Kevin Conlon

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sub polarity
« on: January 02, 2017, 11:34:03 pm »

Some one here can settle this for me. When a speaker is mounted in a cabinet of horn or manifold design, where you see the magnet not the cone,  some people have said the speaker should move "in" with the battery test. Meaning reverse polarity. I have a hard time swallowing this. Are not subs built to push air and not try to suck it through the ports? I have heard this more than once. My old mtl2b EVs push air into the cab (the way i use them) ports do the work and it comes out the the rectangles as well as the center of the cab. I have more to ad to this but want some more info before i finish my question.  Thanks,      Kevin.
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Tim McCulloch

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Re: sub polarity
« Reply #1 on: January 02, 2017, 11:42:30 pm »

Some one here can settle this for me. When a speaker is mounted in a cabinet of horn or manifold design, where you see the magnet not the cone,  some people have said the speaker should move "in" with the battery test. Meaning reverse polarity. I have a hard time swallowing this. Are not subs built to push air and not try to suck it through the ports? I have heard this more than once. My old mtl2b EVs push air into the cab (the way i use them) ports do the work and it comes out the the rectangles as well as the center of the cab. I have more to ad to this but want some more info before i finish my question.  Thanks,      Kevin.

Waves go above and below the baseline so at some point in the waveform it will "suck" and then "blow" and repeat until the signal is no longer present.

Note that physical orientation of the driver may not be indicative of the acoustic output polarity.
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Len Zenith Jr

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Re: sub polarity
« Reply #2 on: January 02, 2017, 11:45:37 pm »

Are not subs built to push air and not try to suck it through the ports?

They do both, anywhere from 20 - 150 times per second. All your drivers do is vibrate the air back and forth at the frequency they are playing. The important part is to make sure that the phase of your subs line up with the phase of your tops over the x-over frequency over as much of the audience area as possible.
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Kevin Conlon

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Re: sub polarity
« Reply #3 on: January 03, 2017, 01:09:53 am »

Waves go above and below the baseline so at some point in the waveform it will "suck" and then "blow" and repeat until the signal is no longer present.

Note that physical orientation of the driver may not be indicative of the acoustic output polarity.
Is this something i need to test for? I have tested this to some degree, but it seems the speaker should push into the cab on a positivs pulse. i know it blows both ways but my real question is where should the pulse start + or -  ? I think if it works with the tops its good. My rest of the question is a friend i work with turned the speakers around in his ev subs to make them " front loaded ". This is my real question. Did his reversal change the way his cabs work? We will do some side by side comparison before we take these out for use, combing, etc. what did he change with the reverse oriantation?  Sorry if i am sounding dumb, i am tring to learn and you people are good at teaching.     Kevin
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Len Zenith Jr

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Re: sub polarity
« Reply #4 on: January 03, 2017, 01:22:37 am »

. i know it blows both ways but my real question is where should the pulse start + or -  ?
Some people will say that the initial vibration in the chest should be a positive (compression) pulse for maximum impact. I think that is all in their head at the air pressure changes from + to - so fast that the only ones who can hear the difference are the ones aware of the subs setting (placebo effect).

what did he change with the reverse oriantation?

The volume of the cabinet, the polarity too unless he reversed the hook up wires.
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Jeff Bankston

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Re: sub polarity
« Reply #5 on: January 03, 2017, 01:56:42 am »

If you have banana plugs just reverse on end and see it hear or feel any difference. A folded horn cabinet is still pushing the air toward you if thats what you have.
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Keith Broughton

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Re: sub polarity
« Reply #6 on: January 03, 2017, 07:23:48 am »

The idea that you will feel more "impact" when a speaker "pushes" air towards you is a bit misplaced.
As you can clearly feel, when you apply a battery to a driver and it moves, you don't feel any real pressure even though the driver might be moving quite a bit.
The "impact" you hear (feel) of is a group of waves propagated into the air over a specific time period with a fast rise time.
Positive or negative polarity will sound the same with a kick drum hit.
If you are keen to use a battery test, it is really only good to make sure the same type of speaker exhibits similar polarity so if you have a bunch of the same cabinet, you can confirm they are working together.
However, just because the drivers are all moving "forward" you cannot assume that means different types of cabinets will be working "in phase (polarity) in actual use.
The real issue with sub polarity in system integration, as indicated previously, is the get phase correlation at the crossover freq.
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Ivan Beaver

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Re: sub polarity
« Reply #7 on: January 03, 2017, 08:11:22 am »

Phase and polarity are very different things-although (sadly) they are misused and interchanged often within our industry.

What is correct for YOUR system?

It depends on the particular cabinets, the crossover points, delay times used etc.

The CORRECT answer is one that has the smoothest/flattest PHASE response around crossover.

So that could be IN or OUT of polarity.  Nobody knows without actually measuring YOUR system.

THERE IS NO correct answer that fits all situations.

But in terms of polarity, you have a 50/50 chance :)

And simply flipping the polarity and listening for the "loudest bass" DOES NOT mean it is correct.

It "could" be correct for the notes in the song you are listening to, but in a different song (in a different key) you may be cancellation at those notes.

MEASUREMENT (NOT RTA) is the best way to find the proper answer.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
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Keith Broughton

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Re: sub polarity
« Reply #8 on: January 03, 2017, 02:46:40 pm »



But in terms of polarity, you have a 50/50 chance :)


I'll take those odds Ivan  ;D ;D
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Paul G. OBrien

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Re: sub polarity
« Reply #9 on: January 03, 2017, 03:21:27 pm »

Is this something i need to test for? I think if it works with the tops its good.
Yes if it works it's generally good but optimizing time alignment between cabs or is something everybody should test for IMO.


My rest of the question is a friend i work with turned the speakers around in his ev subs to make them " front loaded ". This is my real question. Did his reversal change the way his cabs work?
No but it would change the frequency response some and combining these with identical cabs with conventionally mounted drivers would likely produce very poor results.
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