Printer Friendly Forum Posts - Subs w/magnet out, Reverse Polarity?

thats only if u have multiple speakers with only like 1 facing in and 1 facing out that you have to reverse the polarity on the sub. If both are facing the same direction is shouldn't make a difference.

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02 Jeep Grand Cherokee

Monster System on its way.

Yes, the deck output reverse is the same as reverse polarity. And xtreamcc is very correct.

xtreamcc wrote:

If both are facing the same direction is shouldn't make a difference.

You still need to reverse the polarity in any situation where the sub is in reverse, , never rely on the deck to do the phase reversal, , what if you disconnect your battery and it resets, , then your subs blow?? You must reverse the wire's at the amp.

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2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

I thought that reversing polarity was only to correct phase issues. Hmm

it is, I'm not sure wtf ur talk'n bout here Alpine. I've hooked tonz of setups with 2 subs in reverse without reversing polarity on any of the subs w/o any bad effects. Plus I dont think u can blow a sub by just reversing the polarity cuz all ur doing is flowing electicity in a different direction. Please elaborate as to how a sub can be blow'n by reverseing polarity.

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"Shiny chrome when used in conjunction with bikini models is particularly effective in inducing brain deficit disorder"

02 Jeep Grand Cherokee

Monster System on its way.

Basically, when you hook up a sub normally mounted into a box, and wire it normally it sounds great, , the signals are amplified with the intention to fire outwards away from the sub, , but if you reverse the polarity and keep the sub normally mounted, , then the signal is sent to the back of the sub, , meaning the sub is fireing backwards, INTO the box. Usually the sub compresses the air outside of the box, , but if you have it wired wrong, you will have the pressure inside the box, ,the sub will struggle, and over heat. The bass will be noticeably quieter, ,and you will be able to hear a humming.

So basically it all comes down to what way the sub moves to make its frequencie, ,+ to+ the sub moves outwards, , + to - the sub moves inwards.

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2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

I was just having fun/experimenting while I am overhauling my trunk/system, so I mounted my 8000's upside down on my new enclosure to see what it sounded like. SO, I will switch the wires and adjust my phase output back to normal as suggested.

BTW, it sounds lovely that way.

>ALPINEGUY Wrote: Usually the sub compresses the air outside of the box, , but if you have it wired wrong, you will have >the pressure inside the box, ,the sub will struggle, and over heat.

I always thought that when a sub hit, it was moving inward, pressurizing the inside of box. So it's actually moving outward and pressurizing the outside air?

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Sound is AC, therefore the sub goes in and out. I still do not see your logic AlpineGuy.

Phase reversal by itself cannot "blow" a loudspeaker. It absolutely does not matter to the basic fucntion of a loudspeaker which terminal is "+" and which is "-" as the signal is, as indicated above, AC. They are only so-indicated for ease of connecting uniform phase in all speakers in a system. The logic that the loudspeaker somehow "fires" into out out of the enclosure is faulty.

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>>The logic that the loudspeaker somehow "fires" into out out of the enclosure is faulty.<<

So when a sub is hooked up and mounted normally, is if firing inwards into the enclosure or outwards?

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It is not "firing" in any particular direction. The cone moves backwards and forwards with equal intensity. The cone movement pressurizes and depressurizes both the airspace inside the listening environment and inside the enclosure. It uses the airspace inside the enclosure mainly to dampen cone movement. This keeps the speaker from overdriving and provides certain acoustic performance enhancements depending on the volume of air in the enclosure and whether is is sealed (relying exclusively on pressure wave transmission) or vented (adding the effect of soundwave transmission but reducing dampening and power handling.) But I digress: at a very basic level it does not matter which way your sub faces or which way the wiring is connected, except as it relates to the electrical and acoustic phase of the system. The speaker itself does not care.

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thats what I thought, I couldn't understand how mounting a sub inverted without using reverse polarity could possibly cause any negative effects what so ever without there being phase issues caused by one sub in and one sub out.

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"Shiny chrome when used in conjunction with bikini models is particularly effective in inducing brain deficit disorder"

02 Jeep Grand Cherokee

Monster System on its way.

We've never did any kind of reversing the the subs which the back was facing out of the box in any customers trunk, But from reading all of these posts.
So it does not matter which way you face your sub, the wiring is still the same. Using reverse polarity, only if there is a phase issue.

What I usually do is listen for a cpl hours with one polarity, then change polarity and listen to it again for a while. I then go with whatever sounds better.

In my case, it sounds better with the speaker wires hooked up in the normal fashion. These subs are just upside down right now for "fun". Just playing around with stuff until my new subs get here. If I had unlimited trunk space then I would build a box to mount them upside down, just because I think it looks cool. It does sound about the same though.

BTW, I saw a really nice plexiglass trunk enclosure that housed 1 13"JL7 up under the rear deck this weekend. Man that setup was nice! Must have had $$$ to burn. $30grand+ he said. It was definitely top notch SQ but hit some major SPL as well. Wish I would've had a camera. It was in a newer Brabus S500 FYI.

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BOOM, BOOM, BOOM BOOM....

94Legend, I remember a post you put up about a three-sub system with one sub in reverse. Remember it? That is a case wher you have to be certain that the inverted sub is connected in reverse of the other normally mounted subs. Other than that, one can switch the wires to the amp all he wants, and one should actually always try it out, too, to see which phase sounds best from inside the car. I just recently switched my sub amp to 180 using the switch, and it seems the bass is a little better that way.

And DYohn, please feel free to digress all you want. When you talk, I (among others) am getting an education! :)

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Huh, , whell, , i now know not to post after fiberglassing without a mask, wowa haha My post didn't make any sence at all, lol

Im just gona run 2 experiments by you and maybe you can tell me why they act the way they do.

#1 I put 2 woofers in a single chambered box, 1 woofer was connected + to +and - to -, and the other + to - and - to +, , the result was very little noise at all, ,but a whole lota movement, , when i hooked them both up properly the cone travel was greatly reduced, yet the volume was alot louder. So you telling me polarity has nothing to do with anything there?

#2 I put the same 2 woofers in a sealed box with 2 separated chambers, wired them normally + to +, - to - on both woofers and it was loud, , then i reversed the polarity on both woofers and played them again, the volume decreased by 1/4, and i could hear a humming.

All tests were done with my cda-9835, and 40 50 and a 60 hz test tone , mrp-t130, 2 8" fleemarket subs.

Experiment #1 is probably very whell cancelation because of lack of sound, but it dosn't explain the excessive movement when 1 sub was normal, and 1 was reverse polarity, but little movement when all is normal.

Experimant#2 i'll leave for your comments

im always game for learning, ,the more knowledge the better, if i am wrong, please correct me so i don't mislead anyone on this topic again.

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2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

My take on number 1: If you had two woofers firing the same in an enclosure that was the proper size for the two drivers, they would each compress air in the box when the cones moved inward, and the compression would dissipate while the cones moved outward. In this test you reversed one of the subs, and they shared the same enclosure. Now, only one sub is compressing inside while the other is moving outward. Result is little sound. The extra movement you saw is due to the lack of damping action on the subs and too much air space. The air space is twice what one sub would use, but with them firing at 180 degrees, only one sub is compressing the air at a time, while the other sub is decompressing. Flappy cones is the result. Proves that a great degree of cone movement does not necessarily result in loud sound, and in this case is caused by the improper air space in the box.

Test two indicated that the subs sounded better in one phase than the other. Which is what we want to do anyway when it comes to subwoofer frequencies: see which way sounds better. The hum you heard is an anomoly, it shouldn't be there. No answer for that.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

stevdart wrote:

In this test you reversed one of the subs, and they shared the same enclosure. Now, only one sub is compressing inside while the other is moving outward. Result is little sound. The extra movement you saw is due to the lack of damping action on the subs and too much air space. The air space is twice what one sub would use, but with them firing at 180 degrees, only one sub is compressing the air at a time, while the other sub is decompressing.

That the exact answer i was looking forward to hearing to prove my point the reverseing polarity does infact change the signal to the woofer. Obviously if polarity did not matter like was stated before, y would the woofers act differently?????

Is there something im missing, , or am i right?

Thank you Stevdart!

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2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

No, Alpine Guy, nobody is saying that reversing the wires makes no difference to the polarity. Of course it does. What makes a difference is the travel of the sound waves from the sub to our ears. Every environment is different, and just a change in placement of the enclosure will make a difference. How those sound waves react with the subs location and environment before they reach your ears in the driver's seat determines whether you want to switch polarity or not. The point is that, what DYohn so very well said, a speaker is moving in and out equally. So you can't damage them by reversing polarity.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Excellent, , its all clear now! Learn sumthin new everyday

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2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

stevdart wrote:

94Legend, I remember a post you put up about a three-sub system with one sub in reverse. Remember it? That is a case wher you have to be certain that the inverted sub is connected in reverse of the other normally mounted subs. Other than that, one can switch the wires to the amp all he wants, and one should actually always try it out, too, to see which phase sounds best from inside the car. I just recently switched my sub amp to 180 using the switch, and it seems the bass is a little better that way.
And DYohn, please feel free to digress all you want. When you talk, I (among others) am getting an education! :)

Hey thanks, This was very helpful, gave us the option to switch it around and experiment. Other wise we would have been 1 option less.

I would want to test it. but dont wanna flick with the customers car until i am certain of what i am doing. I'm gonna flick around with my subs,
Running two 12" DVC's i'm going to flip one around (inverted) and see how well the bass sounds. That way if i destroy my rear interior i wont get sued.

Hey Alpine guy, you are comparing apples to oranges (to use an old cliche.) You are talking about two woofers interacting with each other. I am talking about the electrical and physical behavior of any speaker system by itself.

In your example #1, stevdart is correct, you see lots of movement and little sound due to the worst case condition, 180 degree polarity difference with one speaker moving the other one. (A very common beginner's mistake with dual-driver systems, by the way.) In example #2, the reason the SPL apparently decreased when you reversed both connections has nothing to do with the physics of the woofers (unless they are defective.) It was most likely an anomoly - unless there is a passive crossover (or Zobel network) in the system.

Take any single woofer. Connect it positive to positive on the amp. Enclosure doesn't matter. Measure the SPL output. Now reverse the polarity. Measure the SPL output. It will be the same, only the phase of the soundwaves will be inverted. Speaker polarity is marked for convenience. Polarity only matters when comparing one speaker to another, as you proved in your example #1.

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Holy crap, all this for a simple answer. No polarity doesn't matter as long as both subs are moving the same direction at the same time. There are exceptions when tuning for SQ competitions but to most people will not really hear the difference, only an RTA can see the difference. Now if you have one sub mounted regular and one inverted then you must reverse the polarity at one of the speakers so that they move in the same direction at the same time. If the subs are mounted in the same manner, regular or inverted, then you only need the have them hooked up correctly.

Now I bet this will spark a hole different debate regarding phase alignment, where polarity will have an effect, and everything else.

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No debate, auex, because you said nothing that wasn't already said.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Alpine, u should invest in a respirator posted_image

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"Shiny chrome when used in conjunction with bikini models is particularly effective in inducing brain deficit disorder"

02 Jeep Grand Cherokee

Monster System on its way.

xtreamcc wrote:

Alpine, u should invest in a respirator

lol, just bought 1 tonight, , i was a lil more accurate this time when i was applying the fiberglass haha, , not so messy.

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2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

im putting two 8" subs into a single chamber tube enclosure with one sub faceing out of each end. they chamber will have about 1cf of air (each sub calls for .5cf) and the length of the tube will be roughly 4ft. since they will be facing away from eachother i assume that i need to wire them out of phase, but i was just wondering what would happen if i didnt considering the distance between the two subs?

thanks,
warren

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zane, they're sharing the same enclosure space, so you cannot wire them out of phase with each other. See the previous posts in this thread. It doesn't matter how long the tube is, it's still one air space.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

They should be both wired the same way since both subs are cone out (I am assuming). The only time they would need to be reversed from each other is when one cone is out, and the other is in.

ok thanks. i had read all of them but i was getting a little confused so i thought i would ask for clairification. i thought when two subs were facing eachother they had to be wired out of phase so i assumed the opposite would be ture if they were facing away from eachother as well. Thanks for the help. also, i know this is off topic, but i was thinking of making the tube out of .5" acrilyc. it is suposed to be extremly ridgid so i thought it would be sutible, any thoughts?

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I had Cheetos and wine for dinenr.

Put a seal in the center of that tube. Then you can experiment with phasing, which you will want to do considering the two will be pointed in opposite directions. For ease of wiring options, wire each sub separately to the amp. The tube should be very inflexible, given that it is small in diameter and round.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.