2241H Magnets Out of Phase!!!

[toddalin]

Todd,

I'd tread carefully here and do some due-diligence home-work on magnets.

Some years back a bit of very interesting info surfaced ( over at the Altec Hostboard Forum ) that when charging magnets ( using the typical capacitor discharge type of charger ) ferrite magnets are charged when the machine is in an opposite zap-setting compared to when charging alnico magnets.

How this matters is if the technician forgets to change the setting for the type of magnet being charged, one will get ( as Todd & Barry have discovered ) a magnet with flipped poles.

Personally Todd, I would leave your 2241 as is, since additional info came to light within that thread that flipping the polarity back to standard wasn't an easy or sure fire thing ( in fact, in the case of this particular woofer it wasn't able to be restored to 100% charge - no matter how many times it was zapped > and the woofer eventually needed a whole new alnico magnet installed ).

Apparently, once a magnet is made a south-paw it resists being forced back into the right-handed world.

Thanks

[Mr. Widget]

On the topic of reversed magnetic polarity... I was having a few beers at a favorite watering hole with a colleague and we were lamenting the demise of JBL as a reputable brand to offer our clients. He told about a Synthesis theater he was setting up a few years ago. He was verifying speaker phase and found a SAM1 HF unit that was out of phase. It turned out it was the 435AL’s magnet. It was incorrectly charged. JBL’s QC certainly should have caught it.

I guess we should make sure all of our drivers are not only wired correctly, but were built to phase specs too!


Widget

[edgewound]

On the topic of reversed magnetic polarity... I was having a few beers at a favorite watering hole with a colleague and we were lamenting the demise of JBL as a reputable brand to offer our clients. He told about a Synthesis theater he was setting up a few years ago. He was verifying speaker phase and found a SAM1 HF unit that was out of phase. It turned out it was the 435AL’s magnet. It was incorrectly charged. JBL’s QC certainly should have caught it.

I guess we should make sure all of our drivers are not only wired correctly, but were built to phase specs too!


Widget

Magnets can be charged in either polarity. It's easy to check with a Gauss meter. It's easy for the recharger to either change the polarity of the magnetizer coil cables, or simply flip the magnet upside down if the cables are permanently connected. Not a big deal.

[Mr. Widget]

Magnets can be charged in either polarity. It's easy to check with a Gauss meter. It's easy for the recharger to either change the polarity of the magnetizer coil cables, or simply flip the magnet upside down if the cables are permanently connected. Not a big deal.

Not a big deal for you with the proper tools and skills, but a major problem for the rest of us!

Nice to know that it can be corrected fairly easily.

”Not a big deal” another reason why they shouldn’t leave the factory like that! Mr. Lansing would not have accepted such shoddy work.


Widget

[edgewound]

Not a big deal for you with the proper tools and skills, but a major problem for the rest of us!

Nice to know that it can be corrected fairly easily.

”Not a big deal” another reason why they shouldn’t leave the factory like that! Mr. Lansing would not have accepted such shoddy work.


Widget

You're right...please allow me to clarify. It IS a big deal when you've got two drivers of the same model and the magnets are reverse of each other.

The magnet polarity can be reversed/corrected, as long as the right equipment is accessible. I've had magnets recharged in the past, only to find out later when I was finishing the recone that they were charged in the wrong direction...which required a return trip to the magnetizer to have it corrected.

[grumpy]

Is there a reason you can’t just change the color of the driver’s terminals? Lol.
seriously... I’m still learning like everyone else.

[Mr. Widget]

Is there a reason you can’t just change the color of the driver’s terminals? Lol.
seriously... I’m still learning like everyone else.

Sure why not, or grab a Sharpie and write, "some asshat at the factory screwed this one up, reverse polarity".

To me the point is, when you are installing your $100,000 Synthesis theater and it doesn't sound right, you will need to grab a phase checker like a Cricket and test every driver in the installation... there may be 40 or more drivers in a larger theater. With the number of possible issues in larger projects, one would hope that a speaker's internal wiring is correct and the drivers were built properly!

In a DIY application, OK, so what, but in the real world of say a touring sound company with hundreds of speakers, this is something you shouldn't have to worry about.


Widget

[toddalin]

I was going to have the incorrect 2241H reshot to the correct polarity, and Speaker Repair Pros said they could do it for the usual recharge fee.

But word was that a repolarized magnet may not come up to quite the same spec as one done correctly in the first place, and it would be better just to leave it be and change the wiring, which I did at the woofer inside the cabinet so both are the same at the Speak-on connections.

Caca occurs, even though it shouldn't.

I got mine from a church use and I'm betting that they never got things to sound quite right, but were probably unaware of it.

When I couldn't get them to phase properly in my living room, it was obvious something was amiss and I figured that someone had internally mis-wired the cabinet. This is until I brought a compass in proximity and found the two 2241s were different when making magnetically attached grill cloths for the 2251H 10"s.

[edgewound]

Is there a reason you can’t just change the color of the driver’s terminals? Lol.
seriously... I’m still learning like everyone else.

The "newer" drivers with the plastic one-piece terminal block is pretty fixed in color...though reverse magnet polarity making red positive would be industry correct...though black is considered positive on the 2241.

An older driver with the HH Smith metal barrel terminals "could be" easily reversed....but it would still be "wrong" as far as history goes.

We don't like "wrong"...lol

[Robh3606]

If you know it's reversed why not just switch the leads around?? Why go through any potential headaches if you can avoid them?

Rob

[edgewound]

I was going to have the incorrect 2241H reshot to the correct polarity, and Speaker Repair Pros said they could do it for the usual recharge fee.

But word was that a repolarized magnet may not come up to quite the same spec as one done correctly in the first place, and it would be better just to leave it be and change the wiring, which I did at the woofer inside the cabinet so both are the same at the Speak-on connections.

Caca occurs, even though it shouldn't.

I got mine from a church use and I'm betting that they never got things to sound quite right, but were probably unaware of it.

When I couldn't get them to phase properly in my living room, it was obvious something was amiss and I figured that someone had internally mis-wired the cabinet. This is until I brought a compass in proximity and found the two 2241s were different when making magnetically attached grill cloths for the 2251H 10"s.

Did you check each woofer with a 9 volt battery? Always a good idea to make sure they move in the right direction.

Years ago, OCS recharged a couple AlNiCos for me after my Full Service Teardown/Cleaning/Recharge. We were busy talking and Eric didn't orient the charger cables right for the AlNiCo motor. I got back to my shop and noticed they were backwards with my gauss meter. I went back and he hit them again a couple times the other direction...all was well at the right charge flux density.

[toddalin]

Did you check each woofer with a 9 volt battery? Always a good idea to make sure they move in the right direction.

Years ago, OCS recharged a couple AlNiCos for me after my Full Service Teardown/Cleaning/Recharge. We were busy talking and Eric didn't orient the charger cables right for the AlNiCo motor. I got back to my shop and noticed they were backwards with my gauss meter. I went back and he hit them again a couple times the other direction...all was well at the right charge flux density.

1.5 volts suffices.

[grumpy]

Oh I get it... should be right, shouldn’t happen, should be exchanged if new, etc...
I was wondering if you, say... put it on a Klippel system, would there be any reason to expect a difference of any kind, at any level? I can’t think of any, unless you did some kind of dual driver box/arrangement that put the magnets in close proximity. Just thinking out loud. Carry on.

[edgewound]

1.5 volts suffices.

I keep a few discharged 9 volt batteries on hand for this. 9 volt is more of a form factor for ease of use. Typically they're around 4-6 volts...and won't harm anything. Not enough current capacity.

[edgewound]

Oh I get it... should be right, shouldn’t happen, should be exchanged if new, etc...
I was wondering if you, say... put it on a Klippel system, would there be any reason to expect a difference of any kind, at any level? I can’t think of any, unless you did some kind of dual driver box/arrangement that put the magnets in close proximity. Just thinking out loud. Carry on.

I think in this example, it's two 2241Hs in different cabinets of a stereo pair that were out of phase due to magnets with opposite polarity. And you're right, just simply reversing the leads on one will fix the issue functionally...But you already know that