Suggestions sought -- how to separate a horn and its driver(?)

mhardy6647

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So -- that whole story of the JBL 275 does have a backstory.
I want to lend the 275s to someone to try on a pair of Bill Martinelli's wooden horns.

The problem is -- those dump find 275s (which work beautifully -- they really do!) seem to be fused to their H5040 horns! :(

I pulled out the bolts and -- the horns wouldn't budge. I've tried getting a little vigorous with them, but they don't want to move. I did have the presence of mind to try both horn/driver combinations -- but the result was the same in both cases.

Now -- I am not sure whether there are (or were) gaskets between the drivers & horns.

In the perfect world, I'd like to salvage both the horns and the drivers (the combination actually does sound pretty good, even crossed over as low as 500 Hz). I chickened out at, e.g., drizzling WD-40 around the driver/horn interface, because I reckon that WD-40 wouldn't be a good thing to have oozing into the driver's throat :(

I am eagerly soliciting suggestions.
Thanks for your consideration.

DSC_0464 (2) by Mark Hardy, on Flickr
 
WD-40 might be a little hard on the paint, too. I'd probably try odorless mineral spirits instead, applied very carefully at the interface (I'll explain capillary action to you sometime ;) ). If it's a gasket or some sort of residue sticking the two surfaces together, that would probably unstick 'em.
 
WD-40 might be a little hard on the paint, too. I'd probably try odorless mineral spirits instead, applied very carefully at the interface (I'll explain capillary action to you sometime ;) ). If it's a gasket or some sort of residue sticking the two surfaces together, that would probably unstick 'em.

Do you think it would be a good idea to have the driver "on top" so IF anything penetrates it will get inside the horn, rather than the driver?
 
Do you think it would be a good idea to have the driver "on top" so IF anything penetrates it will get inside the horn, rather than the driver?
Sure. But I wouldn't douse them, either - a very small amount carefully applied, oughta be enough to wick in between the surfaces a bit without flooding the diaphragms.

I like mineral spirits because the stuff seems to evaporate quickly without leaving any residue, and it doesn't seem to damage most of the vintage paints out there, but use at your own risk. Mark might have even better solvents at his disposal, given his field of expertise.
 
I offer two options in order of recommendation (no implied guarantees):
1. Gently tap both parts with a hammer (use a towel to prevent damage to the surfaces), a new putty knife and hammer are essential for the next step; place the putty knife on the seam and give it gentle taps, work your way around the seam and it should pop off.
2. If the above does not work you can use a penetrating oil (some swear by cooking oil) use sparingly around the seam, a dropper is ideal to control amount used. Rotate regularly so it penetrates evenly. If you are worried about painted surfaces feel free to tape off such areas. After 15min wipe off excess oil, use the first or both parts of step 1 to separate the pieces.
 
Maybe I'm just a little paranoid but I'd avoid tapping on these with anything - one of the things that I've heard can effect alnico magnet charge (in addition to over-powering) is sharp impacts.
 
Whack it with a bigger hammer.
one of the local gurus - and I couldn't make this up - suggested a sledgehammer. He's in the "pro-JBL" camp, too :confused:

Bill, AlNiCo is certainly susceptible to demagnetization from a 'sharp blow' -- but I don't think tapping is anathema. Droppin' 'em on the floor (or, perhaps, even having them roll onto the floor...) is more of a concern, methinks.
 
If you're going to try a bit of tapping I'd go with a bit of dowel to go between the hammer and impact location. Common way to go about things with stuck bits in piano work.
 
I thought about putting a horse's head in with them to see if they got the hint...


That's a thought.

:)
Ok you have to tell us what ends up working. If only you lived down the street, I’d be right over, anxious to help get them apart (I’m a fixer by nature).
 
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