Vibration Issue

only126db

4 Polk DX12's ported with 300 total watts <----:eek:

eloplayspolo

whats with u always posting this ****.

Kinetic

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only126db

eloplayspolo wrote: »

whats with u always posting this ****.

Um lets see....Polk Audio....Forum.....Uhhhh....

Showing what Polk subs are capable with very little wattage...

Maybe also to show others wondering about Polk audio that Polk audio has versatile equipment.......

Uh lets see, to piss u off....

Maybe you should worry about yourself and stay out of my posts....:rolleyes:

Poee7R

eloplayspolo wrote: »

whats with u always posting this ****.

What **** did he post?

He is posting a cab excursion video on a car audio forum.

I'm guessing you havent been around car audio boards for long?

Btw only126db, tape a pen/pencil to the roof of your car when you are going to record it, makes watching the excursion a bit easier when you have a point of focus that you can see on the white background.


Dave

Jstas

This was visited before. The original poster seems to think he knows more than Polk Audio Engineers and has told us all the Polk Audio's old DX series subs work better in a ported box. However, this is not true because the DX subs have high mass cones and ported enclosures do not offer enough dampening to control cone movement. This in turn will cause premature failure of the speaker.

The original poster thinks we are all nuts, even though Polk Audio engineers posted to this forum and backed up what was already said.

But hey, what do we know?

Meeks32

They may be designed for a sealed box but I dont think that the weight of the cone has anything to do with that. A tc sounds tc2k cone is two times the weight of the dx subs & they are made for ported enclosures.

eloplayspolo

Poee7R wrote: »

What **** did he post?

He is posting a cab excursion video on a car audio forum.

I'm guessing you havent been around car audio boards for long?

Btw only126db, tape a pen/pencil to the roof of your car when you are going to record it, makes watching the excursion a bit easier when you have a point of focus that you can see on the white background.


Dave

http://www.polkaudio.com/forums/showthread.php?t=68050

http://www.polkaudio.com/forums/showthread.php?t=67947

http://www.polkaudio.com/forums/showthread.php?t=66699

eloplayspolo

i feel no need to say anything other than what was said in a previous post by this author by Jstas.... and it goes like this

It's a video of a kid holding a camera pointed at a mirror that gets vibrated loose enough to droop. The subs don't "sound great" there is a ton of port noise and I'm just not impressed overall.

I know what "sounds good" really is and that's not it.

I posted the rolling eyes to avoid saying what I think and offending your "sensibilities". Since you had to post the childish challenge along with the mouthing off, I decided to oblige 'cause I'm a little bored at work and feeling punchy today. But don't worry, everyone else seems to have your back so I'm sure I'll be lambasted for my opinions as always.

I have a DX12 with 200 watts that was in the trunk of a Taurus. It worked great and sounded quite good for what it was. It was in a sealed box of approximately .85 cubic feet and had plenty of punch for music. I replaced with with an MM12 and 300 watts. Which was also quite effective and not recommended for a ported enclosure either.

If "sounds good" to you is just loud then DX12's are not the way I would go. I probably wouldn't use any Polk sub to go loud. Polk subs are clean and accurate and that's where they excel. If you want big boom, you're not going find it at Polk Audio.



Besides, you posted another thread where you question the work of the engineers that designed the sub just because you found favorable results with a setup that is not recommended. A Polk Audio Customer Service Representative with decades of experience in the car audio world told you that porting the enclosures for DX subs was not advisable and why it wasn't advisable. Then you went and did it anyway and you're looking for validation.

Your subs are on borrowed time at this point dude. They will break. It's not a matter of if but when. And honestly, since the sealed enclosure is not there to help limit the excursion of the woofer and aid in movement changes, your system impedance is probably sky rocketing at your tuning point and that over drives and will likely damage your amp too.

Have fun with it champ.

Jstas

Meeks32 wrote: »

They may be designed for a sealed box but I dont think that the weight of the cone has anything to do with that. A tc sounds tc2k cone is two times the weight of the dx subs & they are made for ported enclosures.

I'll bet you a tc2k has heftier surrounds, multiple and beefier spiders plus bigger magnets to handle more power to control those cones in a ported enclosure.

High cone mass has everything to do with it in this case. I have a DX12 and I would never think of putting it in a ported enclosure. It's not designed for it. In a sealed enclosure though, it's not crazy loud but it digs deep, into the low 20 Hz range with clarity.

You can argue with me all you want and tell me what you "think" but I will give you solid facts that anyone with a legitimate engineering degree will back up. If you are wrong, I will flat out tell you that you are wrong. Go get all your buddies to gang up on me like everyone else does, I'll tell all of them that they are wrong too and then I will furnish proof.

However, in this case, I don't have to because it's here in the forums already because we already had this discussion and it was determined that the original poster is, like you, wrong.

Jstas

One more thing. Do an experiment for me.

Grab a paddle ball and a rock about the same size as the paddle ball sets ball.

Start bouncing the paddle ball hard and count how many times or time how long it takes to snap the rubber band.

Once it is snapped, grab that rock and tie the rubber band around it so the rock don't fall off and see how many times you can bounce it before it breaks the band.

What the difference? Mass. The rubber ball has similar volume to the rock. However, it has much less density. That means it's mass is lower than the rock. Now, the rubber ball probably lasted much longer than the rock because the elasticity of the rubber band had enough potential energy stored in it to overcome the momentum of the ball at it's extreme limits of movement.

Problem though. When you over extend a rubber band, it loses elasticity and tends to snap. The rock, being heavier and therefore of a higher mass, takes much more energy to stop and change direction. The rubber band has to work harder. However, the rock may be too heavy to control with just the single rubber band and sooner or later, it will fail miserably.

Now you can make the rubber ball kill the fun pretty quickly by paddling it like a mad man. You're essentially over-powering the rubber band and that causes the whole apparatus to blow. Then again, you'd have to over-power the rubber band to get the rock to move sufficiently anyway.

Now what happens in a sealed enclosure is that the air pressure contained in the sealed space behind the woofer acts as a dampener. It enhances the spider and surrounds ability to control the speaker cone. However, heavier cones and control assemblies reduce sensitivity and require more power. Therefore the Sensitivity Rating drops. High mass cone speakers typically have low sensitivity ratings. But when that cone moves out of the box, it creates a low pressure pocket behind the cone which creates a level of suction which reduces the amount of electrical energy needed to change the direction of that cone. When the cone goes into the box, it creates a high pressure area by compressing the pocket of air behind it. This causes the pocket to push back on the cone and again, reduces the energy needed to change the direction, again.

In a ported enclosure, you lose that sealed pocket of air because the port lets it vent the pressure changes. So what you lose in accuracy and control, you make up for in the added pressure of the ports performance. It's a tradeoff. But due to that lack of control, we go back to the paddle ball and paddle rock.

Hopefully that illustrates why a high mass cone dictates a sealed enclosure in most cases unless it is specifically designed for a ported enclosure.

Meeks32

Yes, thank you for that lesson. I think we all understand the basic's of gravity here. Not starting an argument but you cant say that a sub is made for a certain box just because of the weight of the cone. I understand that the suspension might be weak but the moving mass of the dx series isnt really that "high mass" when compaired to other brands subs.

Jstas

I don't care about any other sub. The statements made are concerning a Polk Audio DX12. A DX12 does not have the surround or spider necessary to work properly and survive in a ported box. For a 300 watt sub, the DX12 has a high mass cone. Which is also the reason why it only has an 86 dB sensitivity rating. I don't care how many subs you can find that are different. They are not the issue. Those other subs were DESIGNED to be in a ported box. A DX12 was not. The others don't matter for the issue at hand. Is that too hard to understand?

And obviously you needed the lesson because you still haven't gotten it. Just because you can't wrap your mind around what's being discussed here and understand that no other sub matters, the DX12 is the one in question, it doesn't mean you aren't still wrong.

Have I been enough of a jerk yet to get you to shut up and abandon your silly argument? 'Cause I can keep going.

Meeks32

No need to keep going Mr "polk master", I think you have proven yourself to be a big enough **** bag for everyone.

Jstas

Meeks32 wrote: »

No need to keep going Mr "polk master", I think you have proven yourself to be a big enough **** bag for everyone.

It's got nothing to do with being a "Polk Master". You're wrong and you are grasping at straws to try and win something here. Otherwise you wouldn't be calling me a "**** bag". When you can come up with some evidence about a Polk Audio DX12, not any other subwoofer, working properly and reliably in a ported enclosure, I'll concede. I doubt you will ever find that info. As long as people like you and the original poster disseminate false info that could mislead someone, I will tell you that you are wrong and I will tell you why you are wrong in the same public forum that you chose to be wrong in. Could I be nicer about it? Maybe. But since you likely considered me a "**** bag" before you ever posted in this thread, I honestly don't give a damn about your feelings you ignorant little ****.

Have a nice day.

Meeks32

You're not hurting my feelings, I find your post's quite humorous. Sorry for getting your thread off topic only126db.

only126db

Here's some interesting stuff...

1) A trunk car has a lower frequency where gain starts and a lower resonant frequency(than my truck) so I'm sure it sounded alot diffewrent than my truck.

2) My Polk DB's (pre Momo series release) cones seperated from the spiders in sealed boxes with 300 rms to each after 2 months..... I have been running the two DX's for that long now and ........

3) There is no way you could hear port noise in my videos u r full of $h!t, the mic on that camera I used drops the db's so low port noise would not be detectable...:rolleyes:

4) The cone being too heavy for ported use would be true if I were running its full rms...Duh....

5) As for sounding good....In all reality unless someone posts a video with a high db mic you could never tell if it sounds good or not, unless the system doesn't go over 100db so come on be realistic here.

6) I know engineers too and they are all about "theory". I have been told all sorts of things by "engineers" about cancelation in multiple driver situations and woofer cone design and they really have shown no proof of any of the facts.I have seen/heard to the contrary pretty much all these "engineers have said. I use multiple mid/woofers and well hey it works, my sound stage is great, my imaging is great, the midbass is great (even though my little 2.5mm xmax drivers wont do much says an engineer)

7) So whenever one of you "engineers" "Polk Experts" Who are not confident enough in your own product to believe they work well, sound good and are capable of lasting in ported boxes decide to come out to the I.E. let me know we can set up a date and maybe you will feel better about the Products that you use/manufactuer/sell..

8) Oh and if I tear my subs up who cares...I paid for them...

9) To be continued.....

Ricardo

I need to stop by at the Car Audio forum more frequently....

Jstas

Ricardo wrote: »

I need to stop by at the Car Audio forum more frequently....

It starts hurtin' your brain after a while so be careful. Oh and English seems to be a second language on this side of the pool.

MikeC78

Redneck and unreadable.

demaples

ROFLMAO.. This thread is too funny. You guys have way too much time on your hands and my 2 cents worth on the video.... when I see or hear one of those things I think to myself, wonder how long it will take for that guy to go deaf and the best thing to do is shoot the radio with a .45.

MikeC78

I'd get some lettering for the back slider, "Instant Migraine".

Ricardo

Jstas wrote: »

Oh and English seems to be a second language on this side of the pool.

One more good reason to be here..I won't need to edit my posts when I see my typos.

eloplayspolo

this place - jstas its so much more enjoyable to read ur posts when ur aiming ur hate at others

only126db

One more for the noise polution police...:rolleyes:

eloplayspolo

congrats, your car vibrates and mine sounds good. let me show u a video of people sitting in my car with a smile on their face because they are in shock that it sounds that good.... enjoy that pencil.... im sure u can somewhere else to stick it

only126db

eloplayspolo wrote: »

congrats, your car vibrates and mine sounds good. let me show u a video of people sitting in my car with a smile on their face because they are in shock that it sounds that good.... enjoy that pencil.... im sure u can somewhere else to stick it

Well where's the vid....Or it didnt happen:rolleyes: