Remagnetizing drivers

Hi again.

Thanks to all for the A8 replies-I'm going to build those after all- with the slit port and extra internal bracing as per the 1966 design.

To the matter at hand:

Can remagnetizing be done without reconing? I inquired at Santon Audio in the greater Toronto area (?markham) who said reconing would be a necessity. As the cones are good I'd rather not replace the originals. I know GPA does it but I live in Ontario Canada and shudder at the shipping cost.

TIA
Jon Archibald
Peterborough County, Ontario, Canada

BTW I love this website, and have desired Altec pro speakers since I was a pre-teen.

This is just a guess, but I went through the Advent factory once, about 1971. I seem to recall the full assembly being finished, then through their magnetizing coil. Maybe someone with a more recent exposure can confirm this. I really can't see why not a finished assembly couldn't be remagnetized.

Remagnetizing can certainly be done Without reconing. I understand Beyma drivers are assemled and magged after. Also have had several speakers remagged.

I would suspect that reconer is just trying to pick up some extra profit.

Woofers can definitely be remagged without reconing them.

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- This sort of "instant" magnetizer will "blow" the aluminum cone basket right out of the charging cradle ( loop ) if left attached to the magnet.

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<font size="2" face="Verdana, Helvetica, sans-serif">I'm not doubting your word, just wanting more info. Aluminum is non-magnetic. What you are saying doesn't make sense so far.

- Bob Santon is not pulling your leg regarding remagging & reconing ( at least with his available contacts ).
- The type of remagnetizer that he has access to, is one that delivers a huge, instantaneous charge pulse .
- This sort of "instant" magnetizer will "blow" the aluminum cone basket right out of the charging cradle ( loop ) if left attached to the magnet.

- You need to find a remagnetizer that charges up the magnet in ever increasing incremental stages. This type of magnetizer can charge a fully built ( cone intact ) speaker .
- In Canada, try calling Belisle Acoustics ( Montreal ) at 450 691-2584 ( this may be an old number / check their website for an update ). Ask them about recharging magnets and their necessary protocols ( ie; disassembly / magnetize / reassembly ?? or other ??? ) . They make their own woofers for their line of M.I. speakers .

- They do have a website. Search for " Transparence Speakers ". Try this url ; http://www.tr.ca/2006/english/services.htm for a list of their available speaker services.
- Their site requires the "Flash" plugin.

regards

Yeah, someone's chain's being jerked, GPA's rig is a HV capacative-discharge, "instantaneaous" magnetizer, and they charge fully-assembled drivers all day long in a few seconds for each. The rig does make a dandy 'thump' when discharged, but the operator just bends over the fixture and holds the driver in place with his body. They do have to make sure there are no loose razor blades, paper clips, etc. in the immediate vicinity.....It takes far longer to unpack and repack the driver for shipping than anything else. All AlNiCo drivers they recone get the treatment as SOP, included in the recone price, or they get $15 for a remag-only (last I had done, check for current pricing). In case anyone is concerned about shipping damage, they should only be concerned with doing a good job in packing to send stuff TO GPA, for it WILL be properly packed for the return trip.

For the diehard DIYer, you can buy a new magnetizer and fixture for about $6K and change....

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They do have to make sure there are no loose razor blades, paper clips, etc. in the immediate vicinity.....

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<font size="2" face="Verdana, Helvetica, sans-serif">Wonder what that thing would do to the insides of a wristwatch.

Just an aside, never seen a machine that charged in increments. Have only seen a few, but they've all been magnetic blasters. Did a tour of the Beyma factory in Spain, their machine is that type.

Hi,

That's what I heard to. They do it at the end of the assembly line. What about Duplex speakers?
There is no harm to the Hf driver there either I guess!

For your protection remove your Rolex or chain or stay away from the zaper .

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There is no harm to the Hf driver there either I guess!

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<font size="2" face="Verdana, Helvetica, sans-serif">You're correct Convergence. I know of at least 3 manufacturers who charge HF mags after assembly.

For what it's worth, it is my understanding that alnico magnet structures have to be magnitized after assembly, not before. GPA informs me that if you dissassemble the structure it will lose fully half of it's strength.

I guess I should note though, that the magnet structure could be charged either before or after the installation of the basket and cone, without the strength being affected.

I'm unsure of the etiquette of adding to a 5-year-old post so hear goes:
For any fellow Canucks in need of speaker remagnetizing there's a place in Vancouver that did a swell job on a pair of Tannoy HPD-385's with a 6db difference between drivers due to that problem. They can do it on assembled drivers according to their blurb. Here's the link:
Vancouver Audio Speaker Clinic - Magnet recharging
Best regards all,
Jon Archibald

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Originally Posted by aeyb701

I'm unsure of the etiquette of adding to a 5-year-old post so hear goes:
For any fellow Canucks in need of speaker remagnetizing there's a place in Vancouver that did a swell job on a pair of Tannoy HPD-385's with a 6db difference between drivers due to that problem. They can do it on assembled drivers according to their blurb. Here's the link:
Vancouver Audio Speaker Clinic - Magnet recharging
Best regards all,
Jon Archibald

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Vancouver Audio Speaker Clinic - Magnet recharging

I will always use GPA for any repair work of my Altec drivers but thanks very much for posting this link--some really interesting info there. I recommend everyone here check it out (and let us know if any of the info isn't accurate). Here are a few things that caught my eye right off the bat:
"Disassembly If an Alnico magnet structure is opened, such as to re-centre a shifted pole-piece, repair a broken throat, or remove a bug-screen, the magnetic field collapses instantly. While this type of damage is not common, ill-advised repairs create very unwelcome problems."

Wow, am I glad I never removed the bug screens from my 802-8G's!!!

"Pulse loss Most Alnico compression drivers (JBL LE85, LE175, 375, 2410, 2420, 2440, 2441, Altec 288, 290, 802, 804, 806, 808, Emilar EA-175, TAD 2001, 4001, Goto Unit, etc) have tall magnets, short voice coils, and modest power inputs, so do not suffer degaussing. Those compression drivers with low aspect ratio magnets, especially if used <500Hz (Vitavox S2, University ID series, Klipsch K-55-V, Electrovoice 1823M etc) can suffer flux loss, and will benefit from remagnetization. "

I think my 802's and 902's are safe.....

"Pulse loss For example: Low frequency drivers with 4-inch voice coils (JBL D120, D130, D140, LE15, 2205, 2215, 2231, Gauss, or TAD drivers) can lose 2~3dB, becoming 'dull' or 'slow' sounding, unless they have been grossly abused, in which case they more and sound dreadful. Drivers with short Alnico slugs and 3-inch voice coils, (JBL 2213, 123A, etc) are effected more severely, so typically show 3dB sensitivity loss, while small alnico woofers (JBL 116A, 125A, 127A etc) are commonly 4dB down after quite modest use. Conversely, speakers with higher coercivity ( taller Alnico slugs) and short voice coils, such as Tannoy dual concentrics, Altec and EV woofers, rarely suffer unless they have been badly abused."

Gotta love Altec (alnico) woofers!

What's badly abused? Can't I just add 30 or so computer magnetic drive super magnates and increase the "back to the future" flux capacitorism? I assume they will self align?

Just wire a small flux capacitor across the terminals of your Alnico unit. Should it be abused it will automatically travel back in time and restore itself to new.

Aluminium(or other electrical conductor) in a changing magnetic field:

Eddy current - Wikipedia, the free encyclopedia

Certainly a magnetic field can induce a current in any conductor.

It just plain period end of story ain't gonna blow the frame out of the charger though. And frankly, the induced current can be ignored in this case.

You've suggested a great name for a band ....is the world ready For Eddy Current and The Generators?