remagnetizing alnico drivers..

[toque-eh!]

can someone explain how i might be able to tell if my 15" alnico drivers might need remagnetizing? they are approx 40-45 years old.

and how does loss of magnetism change the sound/effeciency?

if they need remagnetizing, is there anywhere in the lower mainland of BC that does that kind of thing properly?

thanks!

[Alex Lancaster]

At the risk of being kicked out of here, I use a hacksaw blade broken in two, hold it about 3/4" from the gap, if it pulls sharply it´s OK, if it´s sluggish it´s bad; I will not buy test equipment for this and although my method is not precise, it has worked for me.

[paragon]

Hello,

What are your drivers ?
I doen`t think that they must be remagnitieced !
A loss in magnetic strange is (i think), that you get a
bump in the lower region, because the QTS wil raise.
It will change from 0.20 to 0.50 (may be) and enclosure
and (or) duct will not the rihgt for your driver.

Regards
Eckhard

[toque-eh!]

the drivers are 150-4c

my understanding is that long term proximity to other magnetic fields as well as excessive driving power can cause loss of magnetism in an alnico driver.. is that incorrect? i don't know too much about it.

they seem to sound a little different from each other, but don't have any signs of damage (voice coil rubbing etc.) one has noticably more sub 60Hz though. they are mounted in C40 lowboy horns.

[paragon]

Hi marc,

Yes, may be. Find someone who can measure
your drivers (frequency response).
This will help.

Regards
Eckhard