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Tejaus
11-16-2008, 09:37 AM
I recently sent a pair of 128H-1 woofers from my set of 4412LR's to be reconed to a JBL Authorized Service Center. I'm not going to mention names until this is all sorted out.

This center had quoted me bt email a price of 120.00 each to recone using geniune JBL kits or 85.00 with aftermarket kits. After they receive the speakers they call to inform me that they couldn't do them at that price and would have to get 155.00 each. Even though I thought that was wrong I agreed to the higher price. I received the speakers back yesterday and did a polarity check with an AA battery and found that one of them moves inward as it should and the other pushes outward. This is applying the positive battery to the red speaker terminal on both speakers. The speakers also have what looks to be dark grey "aquaplas" applied even though the original cones were just plain and uncoated grey paper. My thoughts are these are aftermarket cones that I got charged the OEM price for.

So before I call my credit card company to dispute the charges I want to make sure that there's not two different CR8128H-1 128H-1 recone kits. I know that the both the 4412LR and 4412ALR use the same components except the xover but JBL wired the 4412ALR to be consistent with the rest of the industry polarity schemes so I don't believe that could explain it.

Since I've never seen a 4412ALR I can only assume that color of the exterior input binding posts on the 4412ALR are oriented the same as on my 4412LR since the part number is the same on both spec sheets. It makes that they are and would now be in phase with everything else when you ran your positive speaker leg to the red terminal. Again I'm just trying to rule out any confusion with regards to polarity.


I've read the "Techical Notes Volume 1 Number 12c
Polarity Conventions of JBL Professional Transducers and Systems" .pdf
about the change over. My understanding of that paper is that JBL did not change the polarities of the legacy speakers still being manufactured.

Are there any part numbers that should be on the cones if they are geniune CR8128H-1 kits? These cones have large hand written numbers on them and some only partially legible stamped numbers that don't match between cones. Should the cones have any kind of treatment applied to them?

I'm going to have to call JBL Pro tomorrow to sort this out for sure but I would certainly appreciate if anyone can provide some insight today.

thanks

Serum
11-16-2008, 10:24 AM
The polarity is weird; didn't they simple switched the +/- binding posts? (though they don't need to be removed when reconing)

My 128H1 woofers have got a grey aquaplas cone, (much like the 2213H woofers, only black/greyish) the cones of my 128H1 woofers feel like sandpaper, not as smooth as normal paper. (though it might be the aquaplas causing this, i don't know what aquaplas exactly does/is to paper.

You are sure the woofers had original cones when you got them?

Allanvh5150
11-16-2008, 10:27 AM
Sounds pretty weird to me. I think that the 128H-1 cones had aquaplas on the back, but I could be wrong. Unless the kits are faulty, which I doubt, the only way that the speaker will be phased wrong is if the lead wires are soldered on crossed, very unlikely, or the voice coil has been assembled onto the cone buy the reconer and they have put it on upside down. They JBL kits come fully assembled as far as I know. Give the guys at JBL a call. I am sure they like to know of dubious practices from their certified agents. Or you could drop "Edgewound" a PM. :)

Tejaus
11-16-2008, 10:46 AM
When I first purchased the speakers one of the woofers had an aftermarket recone kit, the other was a factory cone. You could tell because the after market cone was out of phase from the true 128H-1. Same deal with the battery test, the oem cone would pull inward and the aftermarket would push out. Plus the oem was assembled cleaner around the spider/magnet joint. From the outside both cones were identical to each other. So when the oem woofer died I decided to get both of them reconed with true JBL parts so they would match. Now I get them back and they're still opposite of each other. Could it be possible that the magnets are out of phase with each other?

Tejaus
11-16-2008, 11:43 AM
http://i470.photobucket.com/albums/rr63/mntx/IMG_0383.jpghttp://i470.photobucket.com/albums/rr63/mntx/IMG_0394.jpghttp://i470.photobucket.com/albums/rr63/mntx/IMG_0395.jpghttp://i470.photobucket.com/albums/rr63/mntx/IMG_0393.jpghttp://i470.photobucket.com/albums/rr63/mntx/IMG_0396.jpg (http://i470.photobucket.com/albums/rr63/mntx/IMG_0383.jpg)

Serum
11-16-2008, 11:54 AM
Here are some pics of my original 128H-1;

The inverted polarity must have got something to do with the magnet.?

brutal
11-16-2008, 12:05 PM
Sounds like the shop sent you back what you sent in. Did you give them specific instructions?

Tejaus
11-16-2008, 12:59 PM
Mystery solved

I've determined that the magnet on one of the woofers is reversed. After looking closer at the frames I noticed some glue residue from the previous recone. This is the one that did the same th before and I attributed that to being what I thought was an aftermarket kit. I thought this was too much of a coincidence so I found a small magnet to test with.


If I place the magnet near the junction of the back plate and ceramic magnet on both speakers, one frame will attract and the other will repel so it's a factory defect. How's that for weird?

thanks for posting the pics of your 128H-1's. They do look the same as mine. I'll still give JBL a ring and ask about the magnets.

SMKSoundPro
11-16-2008, 01:55 PM
That is very ODD!

My 128 are white aquaplas, and let alone, a backwards charged magnet???

Send the whole kit and kaboodle to Momma JBL in Northridge and have them start over from scratch.

Remove the cones, Re-mag the baskets, Recone with the OEM kits!

It will cost a dime, and you will be the benefactor of it!

I re-foamed my 128's last week, and they are okay. I have to admit that I did not think of putting DC to a fresh recone. That was DAMN smart of you!!!

Scotty.

brutal
11-16-2008, 02:38 PM
That is very ODD!

My 128 are white aquaplas, and let alone, a backwards charged magnet???

Send the whole kit and kaboodle to Momma JBL in Northridge and have them start over from scratch.

Remove the cones, Re-mag the baskets, Recone with the OEM kits!

It will cost a dime, and you will be the benefactor of it!

I re-foamed my 128's last week, and they are okay. I have to admit that I did not think of putting DC to a fresh recone. That was DAMN smart of you!!!

Scotty.

128H are white. 128H-1 are black. Recone kits for 128H are NLA. If you send in for a recone, you're going to get black.

4313B
11-16-2008, 02:51 PM
It appears that the white coned 128H kits are currently in stock and the black coned 128H-1 kits are currently out of stock. It's always hit and miss with Consumer.

1audiohack
11-16-2008, 05:25 PM
I've determined that the magnet on one of the woofers is reversed.

That one is optimized for use in the southern hemisphere! :rotfl:You lucky devil you.

Oldmics
11-16-2008, 07:11 PM
We had a bunch of E.A.W. 18 speakers thru here recently that were polarity reversed due to the way they were magnetised from the factory.

We reconed them and they came back within a week destroyed.

Once I figured out the polarity problem we contacted the factory who admitted a few had gotten out reversed.

They were fair to us and the end user.

E.A.W.supplied new kits free of charge which we installed for free.We also changed the terminal color scheme to reflect a forward motion on (+) voltage applied to the red terminal.

Magnetic polarity is something we dont usually check when the speaker comes in for reconing,but I certainly do now check after reconing and before they go out the door.

Oldmics

SMKSoundPro
11-16-2008, 08:51 PM
Thanks Oldmics!

Smart, very smart!

I will too!

scotty.

boputnam
11-17-2008, 12:36 PM
...Now I get them back and they're still opposite of each other. Could it be possible that the magnets are out of phase with each other?:no:

I cannot tell from the (one) picture if that's an OEM kit. Regardless, if you want them to be the same and to OEM design, take the "outie" ( ;) ) and merely swap the leads connecting the voice coil to the connections on the basket. If the leads are too short, make a couple shunts to facilitate this.

Or, send 'em to our own edgewound, who can sort you out with OEM kits if they can be had.

grumpy
11-17-2008, 05:05 PM
If the terminals can be swapped, I'd do that instead of crossing the tinsel leads ... less likely to conjure up the magic smoke.
:)

boputnam
11-17-2008, 05:48 PM
If the terminals can be swapped, I'd do that instead of crossing the tinsel leads ... less likely to conjure up the magic smoke.That's funny. Good point. If the leads aren't sorta crossed now, the kit must've been made wrong. I'd do it and insulate the "tinsels", just so I never forgot. But that's just me...

Hey Dave - is your house and neigborhood OK? :hmm:

Robh3606
11-18-2008, 09:28 AM
Why do anything?? Just wire it out of phase so it's in phase with the other driver. Or just switch the terminal posts on the frame if you can. Don't mess with the tinsel leads unless you have too. It's working right??

Rob:)

grumpy
11-18-2008, 10:08 AM
Why do anything??If it were me, I'd eventually forget... and then be really unhappy with myself
when I eventually remembered. :D

(House & family are all fine, Bo ... Local law enforcement let us back into the neighborhood
late yesterday ... thanks for the thought, from you and others ... combined fire fighting forces
and wind calming really saved our behinds)

Robh3606
11-18-2008, 10:39 AM
Stick a note on the back of the driver. Your right though sooner or later you forget and wonder where the bass is when you get it wrong.

Rob:)