dismantling 802 alnico bad for magnet?

[joe3rp]

A local well respected altec/jbl guru claims that dismantling of 802 driver (or similardriver)with ALNICO magnets is bad for the magnet and may cause magnet damage or demagtization. Even if done with careful dismantling of the magnet plate (not the magnet pole and gap. I would like to do this in order to access the magnet area which may contain loose rusted pieces.

Is this correct?

Thanks

[dgwojo]

Yes, your local guru is absolutely correct, I've dismantled many of them to harvest parts, it does discharge them, they can be reassembled and Bill at GPA can recharge them, he's done dozens for me, Dave.

[scott fitlin]

Ditto! This is a job for GPA, NOT YOU! Even if you get the driver apart, you will never reassemble it correctly.

If you like the Altec sound, and value your vintage drivers, send it to Great Plains Audio, pay the money, let them do it and get a driver back that is functionally NEW!

Besides, Bills prices are quite reasonable, and he does expert work, and HE has the magnetizing machine, and proper parts you might need for that driver!

Penny Wise and Dollar Foolish = Someone that will have to buy another set of vintage drivers!

Believe this!

[thinking]

A couple of additional notes. First, if there is corrosion or rusting of the parts, the plating is probably compromised, and will have to be re-plated to ensure long life of the diaphragm. Any rust particles in the gap, besides causing distorted sound, act as an abrasive, and quickly wear through the winding, and render it useless. The cost of replating is usually prohibitive. Second, on reassembly it is necessary to realign the parts so that they are concentric, if not you'll never get the assembly to not rub. Third, yes, you lose around half the magnetic strength if you take it apart. Fourth, GPA is the place to go.