How to make a loudspeaker sandwich cone

Metal foil tweak applied to a small Bluetooth box.

One box with thin foil from the gold Smith.

The other one with household aluminium foil.

Sounds different: Clearly the driver with the thicker foil sounds more correct.

With added diy whizzer / double cone I apply smartfone app EQ with 1 and 2khz reduced by 7 decibels for linearization.

Added inside damping material and added bass reflex pipe. Original was no damping at all in the box and closed box design.

The box can be also EQed for close to floor and wall placement (reduced 250 and 150hz. For real corner placement the bass can be reduced even more.)



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Been following with interest and just purchased a big 2" roll of 0.06mm copper-foil one-sided tape. I guess I just have to try it on enough different drivers (that I wouldn't cry over) to form conclusions. Earlier I used "plast" automotive stretchy tape quite successfully on fiberglass honeycomb and resin-coated carbon fiber (very) hard cones. But on a "coated drum paper" cone the plast (applied only to the back) failed to eliminate high-frequency peak(s)/unevenness. These "hard" drum-paper drivers already have superlative clarity and dynamic articulation/realism.

Is metal foil better suited to softer cones like wool or PP?
Yes, definitely.

Paper and household aluminium foil together minimize resonances.

Its documented here in the thread with waterfall (burst decay) measurements.

One sided covering securely minimizes resonances.

Just make an A / B test with one speaker modified and the other unmodified. The balance knob on the preamp helps to switch fast left to right and back.

However better use glue like Pattex or Uhu and aluminium foil. I do not know if self adhesive foil glues well enough.
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I used the thin aluminum foil on pp (polypropylene) cones, too.

The "Anlegemilch" from Noris Blattgold Germany is on basis of Nitrocellulose, someone told me.

And it works well for PP cones, paper and wool cones, alike.

Copper foil will do like aluminum foil, technically there are only little differences.

It will have an alternative look.
Appreciate the info. When I landed in Beijing oh seventeen years ago I immediately concluded, China's #1 technology weakness was not chips etc but glue -- witness every tile-faced apartment or office building had (missing) patches. So I'd have to try ordering abroad and brave customs....
Concerning "Anlegemilch". (thin foil bonding)

For treating a whizzer cone like from Beyma 8 agn:

You first put one layer glue with the brush on the paper.

After short time you glue the thin aluminum from the gold smith with a fresh second layer of Anlegemilch glue.

This technique can be necessary on untreated paper absorbing fluids.
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Different than with working with thick(er) household aluminium foils with Uhu and Pattex on loudspeaker paper cones you apply the Anlegemilch glue only on the paper cone.

No glue is put on the thin foil from the gold smith - this foil is too fragile for applying glue on it.


One closer look at the treated paper surround of the cone. Two coats of Anlegemilch.


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Last edited:
Here an example for a quicker solution to putting household alufoil on a speaker cone. It's an eight inch driver with inverted dustcap.

You can cut the foil as one part. To reduce wrinkles you cut out 1/16 out of the circle.

The Fotos speak for themselves.



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Some Fotos with better light.

Already one sided with alu tinfoil there is a great stiffening effect. Will be added as bass for the Beyma 8agn speakers. Used for an outdoor Bluetooth speaker.

Current driven amp with Lm1875 will be used as amplification.


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@5th element

There are measurements to be found in this thread.
I did a lot of measurements. But have it archived somewhere. So not at hand.

Everyone can reproduce and test this foil tweak with own measurements with known conditions and equipment.

I have some measurements of already tweaked Fane Sovereign 15 300tc:

There are plenty measurements with waterfall of the big Fane in another thread of the original driver.

Saba Greencones before and after:

Measurements of a 10 inch fullrange after DSP

On what is to be expected from measurements
Third Bluetooth marble box about to be finished.

Alu-paper-alu sandwich cone.
Front of the cone is with aluminium household foil treated. Backside with thin foil from the gold smith.

Working with the thin foil is faster as the beaten aluminum delivered in books makes it easier to cut the foil in shapes.


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