Hello All,

I am just curious to know what can cause a woofers suspension to weaken? As stated in the thread title this is in reference to a Havoc 12" that I have had for a little over a year. I have never overpowered the sub and have always set the gains properly with an O-scope, and after doing so I have always turned the sub output on my deck way down into the negatives to get it to blend properly with my components. The amps I have used on the sub are the Sundown SAE-1000D, SAE-1200D, and most recently the SAZ-1500D. The box I have been using is two cubic feet tuned to 32Hz. This is a box I had built by Fisher customs here on the forums.

I am currently in the process of changing up my system and in doing so I removed the sub and noticed that I can easily push down on the cone. And when pushing around the edge of the cone near the surround I hear a little scraping noise, almost as if the coil is scraping against the motor as it moves up and down. The sub still plays fine, everything on the sub looks fine, and nothing smells odd. However, these issues are of concern to me just in case I ever decide to sale the sub. I don't want someone thinking I sold them an abused piece of equipment.

Thanks in advance for any input.

P.S.

I am the original owner of the sub.

And when pushing around the edge of the cone near the surround I hear a little scraping noise, almost as if the coil is scraping against the motor as it moves up and down

when you check for coil rub, you should push straight down, preferably on the center of the cone.

pushing on the outer edge, or unevenly on the cone can cause the coil to rub on a perfectly good sub. the only thing locating the coil in the motor is the spiders and the surround, neither of which is a solid mount. the coil "floats" and goes where it is pushed.

Edited August 28, 201015 yr by ScottXGTR

Spider assemblies tend to loosen over time. I would not worry unless there is noticable sag on the spider.

And when pushing around the edge of the cone near the surround I hear a little scraping noise, almost as if the coil is scraping against the motor as it moves up and down

when you check for coil rub, you should push straight down, preferably on the center of the cone.

pushing on the outer edge, or unevenly on the cone can cause the coil to rub on a perfectly good sub. the only thing locating the coil in the motor is the spiders and the surround, neither of which is a solid mount. the coil "floats" and goes where it is pushed.

I checked out the coil rub again and I agree with your logic..............it only occurs when pushing around the edges, and does NOT happen when pushing in the center of the cone. So just to verify, its nothing to be particularly worried about?

Spider assemblies tend to loosen over time. I would not worry unless there is noticable sag on the spider.

No, there is not a noticeable sag. However, what causes them to loosen up over time? I just always thought that the cone was supposed to be "stiff"

Edited August 28, 201015 yr by SilkySmoove

Movement causes it to loosen, and it is true with EVERY spider back, that is why Fs if the woofer lowers after break in.

I checked out the coil rub again and I agree with your logic..............it only occurs when pushing around the edges, and does NOT happen when pushing in the center of the cone. So just to verify, its nothing to be particularly worried about?

it is operating as intended. the coil and motor are aligned properly, and when YOU push on the outside of the cone, YOU misalign the coil and cause the rubbing.

Spider assemblies tend to loosen over time. I would not worry unless there is noticable sag on the spider.

No, there is not a noticeable sag. However, what causes them to loosen up over time? I just always thought that the cone was supposed to be "stiff"

the cone is supposed to be stiff. the spider however is not. the spider of a subwoofer is like the suspension of a car. its job is to suspend the coil. and the material the spider is made of breaks in much like a pair of jeans that have been worn for a couple months. again, not a negative in any way, shape, or form.

find a good article on the parts of a subwoofer with a cross section and youll have a better understanding.

This may give a better understanding, pretty simple design

All,

Thanks for the useful feedback! It looks like I will be doing some research on speaker construction to get a better understanding of their operation.

Regardless..if you have stress marks around your surround you probably have popped holes/rips in the spiders radially at 12,3,6,9 oclock..

You didn't have your subsonic filter set right to roll things off properly...the screen printing on those amplifiers is a crap shoot at best because the variance in the potentiometers that they use can be as high as 20%..regardless of what anybody wants to say.

The only way to set it properly is by verifying where the filter rolls off with a tone burst track on a bass CD...