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remagnetizing alnico speaker magnets for better speaker performance

bluesky said:
Very interesting. Now I know something about it. Hope this thread keeps going for awhile. Interesting.

Didn't know you had to take the magnet off of the speaker...disasembly and re-assembly.


I wonder how this would effect the sound quality of 40 year old alnico speakers??? As in...would it really be worth it to do this project, or just leave them alone, as is, in a speaker refirbrishment?
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Sky,

I didn't know it had to be removed either, I wonder why it's necessary?
Maybe RayW could help out here, he worked for the big "Em" for some time and probably has a better idea why they need to be removed.

The sound quality is what you might expect, it gets softer and doesn't react as quickly as a freshly remag'ed driver. It's actually quite common with Rock Musicians, as they use a lot of tube gear along with Alnico drivers (for the tone) and often overdrive their system during concerts (especially guitar players).
They get their Alnico speakers re-mag'd quite often, it's just the cost of doing business.

Best Regards,
TerryO
 
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Z!

Sam Cogley said:
How does one measure magnetic flux density, anyway?
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A simple impedance sweep will tell, if you can compare it to a known good one. A good one will have a huge rise at Fs, while the one with the weak magnet will only rise a little.

Running a Woofer Tester on it and comparing the results to published specs works too...
 
I could visualize a jig that could do boxed AlNiCo plugs assembled but the dust cap would have to come off to access the inner polepiece. The backside pole would be done magnetically thru the rear of the box or can if a SEAS style magnet. The big cup style magnets on JBL/Altec/ ect would likely need at least disassembly from the basket to do properly.
The rig would be handling some serious power.
 
TerryO said:
Sky, I didn't know it had to be removed either, I wonder why it's necessary? Maybe RayW could help out here, he worked for the big "Em" for some time and probably has a better idea why they need to be removed. The sound quality is what you might expect, it gets softer and doesn't react as quickly as a freshly remag'ed driver. It's actually quite common with Rock Musicians, as they use a lot of tube gear along with Alnico drivers (for the tone) and often overdrive their system during concerts (especially guitar players). They get their Alnico speakers re-mag'd quite often, it's just the cost of doing business.
Click to expand...

Understood!

Very interesting point made TerryO!

Musicians do, at least many, prefer alnico speakers for the sound quality. So they play real loud and need thier magnets re-magnitized/alligned magnetically all the time so to do this job you wouldn't need a speaker repair facility for stereo per-say. Maybe you could just go to a professional guitar/amplifier/speaker music store to get this done. Maybe even 'Guitar Center' could do it. ??? I'll check.

The way I see it is if you have your speakers out of the cabinets anyway...why not do it, sure couldn't hurt anything and it would only help.

Wonder how much this process would 'cost'? Can't cost 'that much' and the benifits may be outstanding, at least better for sure, at minimum up to spec.

The magnets that I would want serviced have been in a pair of 40 year old Sansui SP-2000s that, I don't believe, have ever been used (NOS - not a finger print on the cabinets). So maybe the speakers need a re-magnetism from 'not' being played loudly, but from loss of magnetism from 'inactivity' for so long??? They are stored in boxes in the closet. I do have 2 other speaker systems with alnico magnets that have bee played long and loud.

Seeing musicians do this all the time, this shouldn't be mission impossible to get this done. Someone should be able to do this locally wherever you are, is my thnking.

The SP-2000 magnets do 'hang out' so I believe it may be easy, unlike the magnets being in a speaker 'basket / cage' as mentioned above, like JBLs/Altecs.

Sam Cogley said:
How does one measure magnetic flux density, anyway?
Click to expand...

I have no idea for this is the first time I've investigated this situation of re-magnetising speakers.

4343 said:
A simple impedance sweep will tell, if you can compare it to a known good one. A good one will have a huge rise at Fs, while the one with the weak magnet will only rise a little. Running a Woofer Tester on it and comparing the results to published specs works too...
Click to expand...

Understood! Time to do some homework.

The benifits may be outstanding for sound quality! It makes sense to me, something that can be done that noticably works, a 'tune up' of sorts.

Thanks for all the feedback guys!! New uncharted speaker territory to me and for all of us who really love the 'sound of alnico magneted speakers'! To me, alnico magneted speakers just have the 'right correct live natural sound'.
 
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These guys have one, I have seen it work. :)
I forgot to ask how many amps it uses because it sure sounded like an awful lot when they turned it on. Only took a few seconds if that.
http://www.abrown.com/

Carl
 
would they just magnitize it as much as they can or is there a specific magnatism for different drivers??
if so how would they know howmuch to magnatize each driver???
 
bluesky said:
Didn't know you had to take the magnet off of the speaker...disasembly and re-assembly.
Click to expand...


No they don't. They just put the whole speaker in a "fixture" and hit it with a HUGE, instantaneous, magnetic charge.

I have professional JBLs with AlNiCo magnets (2205s reconed as 2235s). I had the magnets recharged by OCS and really couldn't hear a difference..., but then I had no way to do an INSTANTANEOUS A/B comparison.

When I found a dip in the midrange (actually mostly room acoustics), I had the magnets recharged again. On Woofer Tester 2 after the first recharge I had a BL of ~18.5. After the second recharge the BL went up to >22.5. Specs call for a BL of >20.

Once again, I still had no way to instantaneously A/B these and really couldn't tell if there was a difference. While I was at it, I also had the horn drivers and slot tweeters redone (L,C,R), again all at $25/pop. So at $225 you would think there would be an obvious difference..., wrong. Any sonic difference is very subtle.

A weak magnet will manifest itself more at the upper range of the speaker. A weaker magnet may allow for more (sloppy?) bass if the magnet cannot properly control the woofers movement at its extremes.
 
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aidynphoenix said:
would they just magnitize it as much as they can or is there a specific magnatism for different drivers??
if so how would they know howmuch to magnatize each driver???
Click to expand...


They simply BLAST the heck out of them and the magnet will come to its saturation point.
 
bluesky said:
Understood!

Maybe you could just go to a professional guitar/amplifier/speaker music store to get this done. Maybe even 'Guitar Center' could do it. ??? I'll check.

The way I see it is if you have your speakers out of the cabinets anyway...why not do it, sure couldn't hurt anything and it would only help.

Wonder how much this process would 'cost'? Can't cost 'that much' and the benifits may be outstanding, at least better for sure, at minimum up to spec.
Click to expand...

Orange County Speaker does them for $25 a pop.
 
I'm suprised to hear you couldn't hear 'any real' audio difference. Well, at least you know your at 'top performance' with remagnitized magnets. One less thing to think about.

$25 a pop sounds like a good investment. Not bad. That's a 'nice price' you can live with. Not really expensive. Cool. :thmbsp:

Question:
What do you think about magnets that have been in storage for 40 years? Do you think they could just lose their magnetic properties from just sitting around not being used??? :scratch2:
 
Question:
What do you think about magnets that have been in storage for 40 years? Do you think they could just lose their magnetic properties from just sitting around not being used???
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Time alone will probably have little effect on alnico V that has been properly alloyed, but certainly environmental conditions can take their toll on the magnetic circuit assembly over the course of 40 years, and some rare and extreme conditions could possibly affect the state of charge.

So, i think you have to re-word your question to say "proper storage" for a definitive "no" answer, or accept that the answer is going to depend on a few variables concerning both the quality/type of alnico and the storage conditions.
 
They simply BLAST the heck out of them and the magnet will come to its saturation point.
Click to expand...
NOT unless it has first been properly discharged.

There's more to re-charging a magnet than just having a gausser/de-gausser.:yes:
 
Ahhhhhh...so it's a type of 'gausser/de-gausser' remagnetizer machine. So the magnet needs to be discharged first before recharging?

Starting to learn about these magnets!
 
Ahhhhhh...so it's a type of 'gausser/de-gausser' remagnetizer machine. So the magnet needs to be discharged first before recharging?
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I'm far from an expert, and am aware that what is necessary for one particular driver might be something to avoid with another.

There is a lot of "depends on the driver" that comes into play. When it comes to re-charging older drivers, it's probably best to seek out speaker techs who are known for servicing your particular brand/type, those are the fellas who will know the intimate differences and details of those drivers.
 
bowtie427ss said:
I'm far from an expert, and am aware that what is necessary for one particular driver might be something to avoid with another.

There is a lot of "depends on the driver" that comes into play. When it comes to re-charging older drivers, it's probably best to seek out speaker techs who are known for servicing your particular brand/type, those are the fellas who will know the intimate differences and details of those drivers.
Click to expand...

That makes sense. Thanks!:thmbsp:
 
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