[Salkcin]

Hi,

I have 3x Phase Evolution Aliante 12" SI Ltd subwoofers laying around. 1 of them is perfectly fine, but unfortunately the surface is deteriorated/damaged on 2 of them, and I would like to fix them so I can take them of shelf and get at least 2 of them to play some music again. One if them got minor holes/dents here and there, and the other one is bad case with multiple holes in a straight line across the entire membrane.

I attached a pdf with info about the Aliante subwoofers. On page 3 it says "Exklusive flat aluminium and fibre-glass membrane, ten times stiffer than normal cardboard membranes" as one of the features. The membrane to my knowledge is made up of a honeycomb aluminimum frame, which is then coated/covered with fibre-glass.
The membrane of the Aliante subwoofers is 100% flat compared to other common woofers which are more of a cone-shape. I believe because of the thick and 100% flat surface it might actually be a DIY job to fix the holes in the membrane - its not a fragile thin membrane, but more like a solid dish. It's probably not possible without altering the T/S parameters, but hopefully the repair will have minimal impact to that.

The holes can easily be felt with by running a nail softly across the membrane, and a whistling/high pitch noise can be heard when blowing air across the holes, while blowing in places where the membrane is intact it makes no noise and just deflects the air. .

Here is some pictures of the membranes - first one is not to bad, but aluminium honeycomb frame shows deformation (previous owner probably beat the hell out of that sub - hurray for buying second hand):

Here is pictures of the second which is not in good shape:

So what do you think? Would it be possible to add some kind of layer on top of the membrane to fix the holes without altering the charasterics of the sound to much? and what kind of substance/materiale would be suitable for it (nailpolish, glas fiber repair kits for boats, other more special stuff?)

Please chip in with any ideas if this can be fixed.

Another drastic idea... these subs where handmade and can probably be taken apart and put together again. Since the membrane is a flat dish and simple design it would probably be possible to make an exact copy of the membrane without to many special engineering/manufactoring tools needed. Getting replacements membranes in an strong+lightweight material might be possible, and take a leap of faith they will stay play nicely. I'm willing to throw some money at this just for the fun of it, since these are legendary subs.

Best Regards
Nicklas

 

[SQ_Bronco]

Is it actually delaminated? You can check that with a small coin. Tap it across the face and see if the tone changes significantly. A delaminated section will be very audibly “dead” sounding.

If it’s not delaminated it’s probably fine—you can maybe add a little bit of resin to it to seal it up, but that doesn’t really look that bad.

a couple grams of resin really won’t change the T-s much. Maybe reduce the fs by 1-2 hz and lower sensitivity by a quarter db? You can check what effect it will have in winisd.

I’ve always wanted to try one of those subs… never found one at a reasonable price point. Good luck!

 

[OCD66]

Those holes are what is commonly referred to as "voids" in the composites world. When the drivers were new, those voids were probably not apparent, but had a very thin layer of resin bridging the gaps. Over time these thin areas broke away and created the gaps.

The honeycomb deformation is not from abuse. The inconsistency of the aluminum polygons are normal. They are formed and pulled apart. Honeycomb is used for strength, not perfect cosmetics.

The laminate was probably hand laid or possibly resin infusion. Definitely epoxy. Do not use polyester or any ester resin to repair.

Here's how I would fix it;
First, scuff the whole area with a grey scotchbrite pad by hand. A 25mm x 25mm piece will do. Only the laminate, stay off the surround.

https://www.3m.com/3M/en_US/p/d/b40071748/

This will probably reveal more voids, that's ok.

The transition from the surface into the voids needs to be "scuffed" for proper adhesion. This can be done with a jewelers file or a piece of sandpaper formed into a cone.

https://www.3m.com/3M/en_US/p/d/v100010908/

Once you have the area prepped, it's time to fill the holes. Most epoxies will work, but stay away from the 5 minute hardware store type.
You want a laminating resin.

Slowly dab the resin around the voids allowing it to slowly creep into the open area. Take your time, gravity will pull it down.

You want as few high spots as possible. If you get too much on the surface, a quick pull of a finger tip will get you back.

Once the voids are all filled, sand them carefully with your 320. Try to only hit the peaks. a 10mm x 10mm block should work good.

Now that everything is filled, it's time to make it look nice.
Mix up a batch of epoxy. Brush it on to the entire surface. You will do this while heating the area with a hair dryer.
The epoxy will go from a thick syrup state to almost water thin.
Work fast because the additional heat will not only decrease the viscosity, it will accelerate the curing.
Definitely do a test run on this part of the process.

At the end you should have a relatively smooth void free piston.

Good luck and post plenty of pics of the repair.

 

[OCD66]