Help: Filling a Vitavox Multicell with cork granules

[laralpha]

I have bought what is supposedly two Vitavox CN123 10 cell horns.

They are damaged, so I have emptied them of their filling material which was cork granules (1-3 mm), cork nuggets (10 mm) and a little sawdust (and a cigarette butt). One horn had 11.8 kg and the other 6.3 kg of filling. Somebody must have tampered in the past. Also the horn had a lot of hollow sounding cavities.
The horns are at the local bodyshop which has fixed another horn for me in the past, but I need to find out how to fill them up again and with what.

I think the horn should end up weighing around 32 kg (the metal weight is around 14 kg) so I have to figure out how to get the filling a bit denser. I have considered using corkdust (0.2-0.5 mm) and a rubber hammer or vibrator of some sort.
But I would like to ask the forums experienced and savvy experts for advice.

 

[Buck_Rogers]

Try searching Amazon for "Rubber Granules" or "Rubber Mulch", Lots of options.

That should acoustically be better than Cork.

Just try not to over do the weight.

Good luck...

 

[BassKulcha]

The cigarette butt is actually very important, and—it's little known—menthol 100s tend to produce a "cooler" tone, in general ;-)

 

[asilker]

The cigarette butt is actually very important, and—it's little known—menthol 100s tend to produce a "cooler" tone, in general ;-)

*Kooler

(Not to be pedantic, but words mean things)

 

[Audionut]

Do you drink wine, and own a food processor?

 

[laralpha]

So, in the serious spirit of this thread I performed an experiment.

Fill 200 ml of corc granules in a jar.
Tap on the side with a rubber hammer for a while and watch the results:
1. The mixture is compressed (the red lines are before and after)
2. The bigger nuggets move to the top
3. The dust moves to the bottom.

 

[BassKulcha]

Do you drink wine, and own a food processor?

Now that's an interesting project (just how many bottles of wine and their corks would it take to fill up that horn cavity?) Time to get started!

 

[Topper]

Vermiculite?

 

[laralpha]

Now that's an interesting project (just how many bottles of wine and their corks would it take to fill up that horn cavity?) Time to get started!

I drink mostly beer. Maybe I should just fill it with shredded bottlecaps.

 

[laralpha]

Now to find out how it works in an model horn with narrow endings. I made a model of an ending in plastic, put in the cork and did the hammer tapping thing again.
Doesn't it look like some extra sawdust or corkdust and less nuggets is the way to go?

 

[J-ROB]

I like @Topper's vermiculite idea.

But I'd try to empty them out completely and listen to see if they really need any damping material inside at all, then pr9oceed with caution and listening evaluation.

At one time I had tar filled Altec (maybe Lansing), sand filled (Ballentyne?), and standard late Altec sheet metal 10 cells with auto undercoating spray on them. The ostensibly least damped sheet metal Altecs multicells sounded the best.

Vermiculite is light and irregular enough that here would be some space between points of contact with the metal, which is a mental image I like. It wouldn't totally kill the life of the horn.

 

[Buck_Rogers]

The problem with Vermiculite is ALL Vermiculite contains a small amount of Asbestos...

They are both contained in the same rock strata.

 

[Lucky Pierre]

Asbestos is only bad if it is friable

 

[J-ROB]

In that case, recommend to strongly resist the urge to snort vermiculite. 🐽

 

[Audionut]

I drink mostly beer. Maybe I should just fill it with shredded bottlecaps.

How about champagne?

 

[SparkleMotion]

There is a guy in my maker space that makes lamps out of cork. he takes cork granules, mixes them with a rubber-like adhesive (a/b silicone, I'd assume) and casts them in a mold. the 2-part silicone would add additional damping properties, while keeping the cork in place.

 

[laralpha]

So lots of premises:
Vermiculite is available in plant centers (and apparently asbestos free since 1993) but it is really good at absorbing water and I feel apprehensive about wet/damp stuff in my completely rust free horns.

Cork does not absorp water (hence the corks in champagnebottles).

The only reference I could find (on audioasylum) as to what VItavox did themselves, mentions sawdust. But there again is the water absorption problem.

Vitavox horns feels very dead when you knock on them. A bit like they're made out of massive soft plastic rather than metal.

The 10 cell Vitavox CN123 on the science museum in the UK weighs 40 kgs with 7 kg of driver and some mounting gear. So I think the original weight of the horn was between 31 and 33 kg.

My conclusion
There was cork in the horns and the cork felt old, so I will try that first. I will aim for the original weight by adding cork-dust to the cork granules and maybe remove some of the nuggets. Then we'll see.
I will try to play one of the horns without any filling first and compare to my stock 8-cells. I am a little worried about the horns mechanical strength without the filling though. It is made from very flimsy sheet metal.
Also it doesn't feel like the filled 8-cells are killing the life of the horn, even though they sound completely dead when you knock on them. But we'll put it to the test. The horns are empty after all...

 

[laralpha]

Further experiments
Added 150 ml sawdust and tapped.
Then added another 100 ml corkdust and tapped