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Author Topic: sub polarity  (Read 2270 times)

Ivan Beaver

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Re: sub polarity
« Reply #10 on: January 03, 2017, 04:09:15 pm »



 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.
Actually it DID change the performance-for the worse.

When the drivers were turned around, the internal cubic volume of the cabinet was less-so they would not go as low.

The difference between having them front loaded and flipped around is TWICE the air volume occupied by the driver.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

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Tim McCulloch

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Re: sub polarity
« Reply #11 on: January 03, 2017, 07:15:53 pm »

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

Do you have a pair of unmodified units to compare with?

Without a comparison there will be a very strong "confirmation bias" at work and a whole lot of denial about the Emperor's nakedness.

He didn't improve anything and almost certainly made it worse.  Ivan's response is spot on.  The change in air volume will fundamentally change the acoustic output of the loudspeaker.

{cynicism alert}
The confirmation will come when, while attempting to make them sound like they used to, he blows them up.... <very evil laugh> {/cynicism alert}

Tim "hey buddy, you want fries with that?" Mc
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"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Ivan Beaver

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Re: sub polarity
« Reply #12 on: January 03, 2017, 07:35:04 pm »

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? 
The problem is that many people "think" that just because they changed something that was DESIGNED A SPECIFIC WAY, that "somehow magically" it is "better".

In many cases changing it makes it worse-but since it is "custom modified", somehow that makes it "better".

There is a lot of effort that goes into the design.

There is a REASON the driver was mounted the way it was.  NOT just an accident waiting for somebody to "discover".

Or often it "may" get better in some aspect, but gets worse in others..

This is NOT saying that all things cannot be improved.  Very often they can.  But this comes from figuring out what the actual issue is, then addressing that issue.

In my opinion, to prove if the change works or not, is to have before and after measurement.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Kevin Conlon

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Re: sub polarity
« Reply #13 on: January 04, 2017, 08:39:11 pm »

Do you have a pair of unmodified units to compare with?

Without a comparison there will be a very strong "confirmation bias" at work and a whole lot of denial about the Emperor's nakedness.

He didn't improve anything and almost certainly made it worse.  Ivan's response is spot on.  The change in air volume will fundamentally change the acoustic output of the loudspeaker.

{cynicism alert}
The confirmation will come when, while attempting to make them sound like they used to, he blows them up.... <very evil laugh> {/cynicism alert}

Tim "hey buddy, you want fries with that?" Mc
  Yes he has 4. I think he won't have a problem Playing with them. Ivan is very right in changing the volume (how can you not take his advice). We have not used his gear and mine  together yet. We may need to in the spring as we could have 8 18's a side with both of our stuff. Thanks to all who helped.  About the confirmation, for some reason he is good at reconing speakers.   Thanks to all    Kevin
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Tim McCulloch

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Re: sub polarity
« Reply #14 on: January 04, 2017, 08:57:59 pm »

  Yes he has 4. I think he won't have a problem Playing with them. Ivan is very right in changing the volume (how can you not take his advice). We have not used his gear and mine  together yet. We may need to in the spring as we could have 8 18's a side with both of our stuff. Thanks to all who helped.  About the confirmation, for some reason he is good at reconing speakers.   Thanks to all    Kevin

That's good.  Not being sarcastic, because if you learn why something performed in a way that was not anticipated the cost putting in a cone kit or 2 is relatively cheap tuition at Yee Olde Skool of Harde Knox®.

It gets a bit silly if all you learn is "well, we won't do THAT again" over and over and over....

While it's generally pleasing to see folks explore their curiosity with experimentation I think that having some predicted, specific outcome to test for is important.  Does it go lower?  With how much output?  Does it get louder?  Where in the operational pass band does that happen?  Does it have superior or inferior power handling, etc?  A subjective "well, it sounds better to me" is another incident of new clothes for the Emperor.

I made a fair bit of sawdust back in the day (over 30 years ago).  Part of that was educational, part of that was perceived thrift, part based on enough dangerous "knowledge" about loudspeaker systems to blow up some transducers and amps.  The latter was regrettable at the time but provided valuable experience upon which to build.

Blowing up a few things is only about money or any damage to your reputation if it happens on a gig, rather than under test.  Experiment on.
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"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Kevin Conlon

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Re: sub polarity
« Reply #15 on: January 04, 2017, 09:04:42 pm »

The problem is that many people "think" that just because they changed something that was DESIGNED A SPECIFIC WAY, that "somehow magically" it is "better".

In many cases changing it makes it worse-but since it is "custom modified", somehow that makes it "better".

There is a lot of effort that goes into the design.

There is a REASON the driver was mounted the way it was.  NOT just an accident waiting for somebody to "discover".

Or often it "may" get better in some aspect, but gets worse in others..

This is NOT saying that all things cannot be improved.  Very often they can.  But this comes from figuring out what the actual issue is, then addressing that issue.

In my opinion, to prove if the change works or not, is to have before and after measurement.
I think somewhere somone told him to do it, but i don't know. I always bitch about Honda and Yamaha about over doing things. These guys should work on there stuff after it's been in the feild for 10 years. Tell the customer you have to remove the engine to do a valve adjustment and it will be 800.00 and try to tell them it's by design, some don't get it, some do. That speaker was put that way for a reason. I get that. Others say " it sounds better" it is mostly mental. I wish i had real gear to test with but i don't. To the motorcycle reference, these designers, most of the time know there shit and did it for a reason. The same reason you should buy a system that was made to work together by the people who know. One day i may have that but right now i am trying to make the best of what we have. Thank you    Kevin.
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Ivan Beaver

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Re: sub polarity
« Reply #16 on: January 04, 2017, 09:56:29 pm »


While it's generally pleasing to see folks explore their curiosity with experimentation I think that having some predicted, specific outcome to test for is important.  Does it go lower?  With how much output?  Does it get louder?  Where in the operational pass band does that happen?  Does it have superior or inferior power handling, etc?  A subjective "well, it sounds better to me" is another incident of new clothes for the Emperor.

I made a fair bit of sawdust back in the day (over 30 years ago).  Part of that was educational, part of that was perceived thrift, part based on enough dangerous "knowledge" about loudspeaker systems to blow up some transducers and amps.  The latter was regrettable at the time but provided valuable experience upon which to build.

Blowing up a few things is only about money or any damage to your reputation if it happens on a gig, rather than under test.  Experiment on.
One of the things that "should" be done is at least some simple basic measurements.

That way you can help to qualify the results.  If you don't, it is "simply opinion" and different people listen for different things.
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Craig Hauber

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Re: sub polarity
« Reply #17 on: January 04, 2017, 11:01:52 pm »

The problem is that many people "think" that just because they changed something that was DESIGNED A SPECIFIC WAY, that "somehow magically" it is "better".

In many cases changing it makes it worse-but since it is "custom modified", somehow that makes it "better".

There is a lot of effort that goes into the design.

There is a REASON the driver was mounted the way it was.  NOT just an accident waiting for somebody to "discover".

Or often it "may" get better in some aspect, but gets worse in others..

This is NOT saying that all things cannot be improved.  Very often they can.  But this comes from figuring out what the actual issue is, then addressing that issue.

In my opinion, to prove if the change works or not, is to have before and after measurement.
If they are that single-18 "subscoop" type cabinet (SH1810L, T18, or whatever other model numbers it was sold under) Then EV themselves sold front-loaded earlier versions before flipping the driver for later versions of the same box -they did change to a higher power driver, perhaps it was their way to accommodate that without re-tooling the box?
Anyways having the motor structure outside the box has got to benefit cooling and onset of power compression even if by just a little bit
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Craig Hauber
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Raul Suarez

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Re: sub polarity
« Reply #18 on: January 05, 2017, 05:21:26 pm »

It was Dr. Don that argued that the correct polarity for subs was positive voltage moves cone away from magnet.  His rational was that the attack was the loudest and that the Xtotal of a woofer was greater in an outward direction.  Moving toward the magnet could cause bottoming out.

Of course this rational does not question how much greater the first half cycle is than the second half cycle.  ;-)

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Raul Suarez
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Don T. Williams

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Re: sub polarity
« Reply #19 on: January 05, 2017, 06:03:16 pm »

It was Dr. Don that argued that the correct polarity for subs was positive voltage moves cone away from magnet.  His rational was that the attack was the loudest and that the Xtotal of a woofer was greater in an outward direction.  Moving toward the magnet could cause bottoming out.

This would assume that every subwoofer driver has unequal movement depending on the polarity of the input signal.  I believe most modern manufacturers try very hard to make their drivers linear, and thus lower in distortion.  They may not always achieve that goal.  I have also seen plenty of woofers where the voice coil jumped out of the gap moving forward.  They moved far past the Xmax.

This also assumes that the cone of the driver is the primary source of the audio output.  At some frequencies, the primary output from a vented box loudspeaker system will be from the loudspeaker enclosures' vent, with almost no cone movement.  For bandpass enclosures with both sides of the cone loaded by an enclosure with a vent, all audio comes from the vents.  There are a lot of different types of bandpass systems including these EV types.
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