damping coating substances for speakers' cones ?

[markbakk]

Well, musical instruments evolved by ear not by measurement.

Ever dived into the science of church bells through the ages? Even famous physicist and Nobelprize winner Lord Rayleigh tried to calculate the spectrum and since the eighties FEM computer simulations made bells with major timbre possible. Until then every church bell had a minor timbre.

 

[DevonHoward]

Mmmmm. That's very interesting - some science to follow up. Thankyou.

 

[planet10]

If you add a coating to a bass driver cone in a speaker system, you will increase its moving mass, thereby changing one of its Thiel Small parameters, and that might possibly upset the driver-enclosure alignment and change the sound quality in an unintended way.

In practise you have to add A LOT of coating material to significantly impact T/S parameters. It can be useful. I have used it with some vintage 12” (Philips & Foster) to move the F_s down.

If a minimal amount is added, then the change in T/S are less than natural factory unit to unit variation. n>5000 drivers done to back that up.

dave

 

[keantoken]

A 1db (~12%) difference over 6 octaves is similar in strength of effect to a 6db difference over 1 octave. So a small change in cone mass can affect the tonal balance significantly.

 

[pheonix358]

I read first and last page.

PVA glue does wonders on paper cones especially if you can get to both sides of the cone.

P

 

[keantoken]

Pics or it didn't happen.

 

[Boden]

Well, measurements in 5 db/Div or it id not happen..

 

[planet10]

I read first and last page.

PVA glue does wonders on paper cones especially if you can get to both sides of the cone.

Do be careful. Too much will kill top end response (not good in a FR)

And not all PVA is equal. I recommend something like modPodge which dries with more flexibility. I alos thin it a bit.

dave

 

[PeteMcK]

I've used a light coating of 'Rustoleum Leakseal', a flexible rubber coating, successfully on a couple of paper cone restorations.
In particular, a 4" mid came out sounding spectacular.
For aesthetics, I use leftover printer ink (from the craze years ago of re-filling cartridges) and a soft brush to get an even finish.

 

[PeteMcK]

re:'What's bad with Damer and shellacs on paper ?" - it stiffens up the cone and makes it prone to peaking, similar to an Alu cone