Cone Treatment

[keantoken]

Hello all. I wasn't sure where this thread would fit, so I put it in the most general category.

A while back I treated some really harsh speakers with boiled linseed oil, which they really didn't deserve. Anyways, being the perfectionist I am, I agonized over the fact that there was no indication of whether the coating was even or not. Using spray wasn't encouraging; spray bottles don't spray oil very well.

Later on, when I started buying airsoft guns, I invented a new way to get a more even coat. I was at the time curious about putting gel like substances on speakers and watching the resonant patterns as I swept the frequency. Naturally, to waterproof the cone, it helped to apply a coating of linseed oil.

I experimented one day with putting BBs on top of the speaker and turning it on. The affect was disappointing, but I realized that this was a good way, a long as the speaker was level, to apply a fairly constant coating of oil, podge, whatever you use as long as it doesn't dry quickly.

The BBs I used were for airsoft guns. These BBs, if you get the decent ones, are polished and come in 3 different weights: .12g, .2g, and .25g.

This can be done with a signal generator/tone generator, but make sure it capable of driving the speaker. The method will only work for bass frequencies. For me it has worked best to use the driver's resonant frequency. To apply the oil, I hold a brush just above the cone where the BBs hit it.

The affect of spreading the treating substance around the cone is obvious, but I wonder if there are any affects on the cone surface itself. Is it possible this method could be used to quicken break-in? Of course the results would not be the same it seems...

I'm sure someone else has used a similar method to treat cones, and am interested in any thoughts. Attached is a picture of a small, crappy speaker being treated... For this one my signal generator wasn't loud enough, so as you see most of the oil is centered around the center.

- keantoken

[graaf]

perhaps a coating that is uneven is better?

because it breaks symmetry of the cone, modes become dispersed, more complicated but less pronounced
like in case of JVC's wooden and oblique cones

best,
graaf

[Globulator]

Doesn't linseed oil burst into flames rather easily on contact with cloth etc?

[keantoken]

Glob, you must be joking.

There is this widespread paranoia about linseed oil... In order to ignite it, you've got to leave a soaked rag someplace hot... IE, in the Texas sun, on top of a car or something that soaks up heat.

There is absolutely nothing wrong with putting it on speakers, as long as you aren't totally soaking something without wiping it off.

Nothing I have ever treated with linseed oil has ever blown up...

Too uneven a coating I think would cause uneven mass on the cone, cause it to wobble, etc. I suppose you can tilt the speaker to one side while coating, that should work swell.

Linseed oil should not be used on foam surrounds, it makes them shrink I think...

- keantoken

[Bill F.]

The affect of spreading the treating substance around the cone is obvious, but I wonder if there are any affects on the cone surface itself.

I guess there would be. Probably something like tiny hammer mill--makes a lot of tiny (invisible?) dings on the cone, loosens/weakens the fibers, etc.

Only before/after measurement could tell you whether it was damage or improvement.

[keantoken]

For fuzzy cones it would probably try to lay the fibers flat.

- keantoken