Let's Try to Fix a MW6511 Damaged in Shipping...

gdb

What leads you to make such a bold statement so confidently ? What variables/constants are you citing that would prohibit the thing from "spec-ing" ? These MWs are not rocket engines, they were assembled haphazardly, they can be reassembled with as much or more care than than was originally devoted to them. IMO. I truly wonder just how much "spec" uniformity ever existed within the various iterations of these drivers. A little more attention might have been better paid to the adhesive "spec" aspect............:rolleyes:

Mystery

gdb wrote: »

What leads you to make such a bold statement so confidently ? What variables/constants are you citing that would prohibit the thing from "spec-ing" ? These MWs are not rocket engines, they were assembled haphazardly, they can be reassembled with as much or more care than than was originally devoted to them. IMO. I truly wonder just how much "spec" uniformity ever existed within the various iterations of these drivers. A little more attention might have been better paid to the adhesive "spec" aspect............:rolleyes:

+1
I'm interested to know that as well.
If it does really alter the spec, then it's not worth going all the trouble fixing them. :rolleyes:

Is it bent basket that changes spec or actual re-aligning of the voice coil/magnet?
If it really is voice coil/magnet realignment, then all speaker that go through repair service/refurb should alter specs to some extent. But if the spec altered doesn't affect much or if human ears can't notice difference, then it should be okay. Hmmm...

gdb

Unless one has "calibrated ears".....IMO.....if it sounds right, it is right.

Only ninnies and dipsticks buy gear based on the "specs" alone, as has been stated here many, many, many times previously !

Saftgeek

Through my lesser than calibrated ears it sounds stellarly freaking awesome!!! Specs are what I find on my shirt when I'm done eating salsa... Seriously, the voice coil is designed to allow electrical current to flow... That electrical current reacts with the magnetism to indice movement or throw... Unless I change the impedance, which in turn changes the amount of electrical current, how does it not sound to spec??? The old slipped magnet definitely affected the specs...

-Saftgeek

mesquitehead

I'd like to see how the "new" 6511 replacement currently sold by Polk Specs out against the old ones! Jesus Christ, the guy fixed the damn thing and he likes it...and should be damned proud he took the time and had the guts to dive in and make it happen. I just finished replacing the woofers in my LSi15's and doing the Dynamat on the frames and ports....and don't really know or care what the specs are but they sound pretty damned good to me...an that is all that matters round here!

Saftgeek

Mr. M

Your inbox is full. I'm trying to send you a PM. I'll call you tomorrow...

-Saftgeek

dorokusai

gdb wrote: »

What leads you to make such a bold statement so confidently ? What variables/constants are you citing that would prohibit the thing from "spec-ing" ? These MWs are not rocket engines, they were assembled haphazardly, they can be reassembled with as much or more care than than was originally devoted to them. IMO. I truly wonder just how much "spec" uniformity ever existed within the various iterations of these drivers. A little more attention might have been better paid to the adhesive "spec" aspect............:rolleyes:

Because we did the same thing at Polk and tested them....is that enough to make a general statement. Good lordd, sorry the opinion only matters if it's glowing and waving a flag. As I said, if that doesn't matter, inherently meaning if it sounds good who cares, then it doesn't matter. Where's the factual basis for your BOLD statement concerning the build and manufacture of these drivers? Have you seen the process, seen the factory, been involved in some behind the scenes testing no one is aware of? Certainly let me know since this would be intriguing.

This isn't the first time this has been done, first time its been successful or lack thereof. It's not a rocket that's for sure but it's also not easy to do this in the first place. The fact that Saftgeek took the time to keep trying is AWESOME but I wouldn't have wasted the time personally....its simply not worth it to me. Is that ok?

Mark

Mystery

dorokusai wrote: »

Because we did the same thing at Polk and tested them....is that enough to make a general statement. Good lordd, sorry the opinion only matters if it's glowing and waving a flag. As I said, if that doesn't matter, inherently meaning if it sounds good who cares, then it doesn't matter. Where's the factual basis for your BOLD statement concerning the build and manufacture of these drivers? Have you seen the process, seen the factory, been involved in some behind the scenes testing no one is aware of? Certainly let me know since this would be intriguing.

This isn't the first time this has been done, first time its been successful or lack thereof. It's not a rocket that's for sure but it's also not easy to do this in the first place. The fact that Saftgeek took the time to keep trying is AWESOME but I wouldn't have wasted the time personally....its simply not worth it to me. Is that ok?

Mark

Well my question was genuine as I also have a driver that's frozen and wanted to know if it really alters spec that prohibits the driver to sound as designed, it may not be worth.
As you mentioned, I've seen many threads here and at Audiokarma where many have fixed magnet shifts using the DIY jig.
$50 replacement may not be much but if the driver is fixable, why trash it unless it changes the speaker's original sound/spec?

audiocr381ve

dorokusai wrote: »

Because we did the same thing at Polk and tested them....is that enough to make a general statement. Good lordd, sorry the opinion only matters if it's glowing and waving a flag. As I said, if that doesn't matter, inherently meaning if it sounds good who cares, then it doesn't matter. Where's the factual basis for your BOLD statement concerning the build and manufacture of these drivers? Have you seen the process, seen the factory, been involved in some behind the scenes testing no one is aware of? Certainly let me know since this would be intriguing.

This isn't the first time this has been done, first time its been successful or lack thereof. It's not a rocket that's for sure but it's also not easy to do this in the first place. The fact that Saftgeek took the time to keep trying is AWESOME but I wouldn't have wasted the time personally....its simply not worth it to me. Is that ok?

Mark

Fighting words right there :P

pitdogg2

Mark,
when these drivers are built are the magnets magnetized after they are glued? Reason i ask is that i can see were flux or whatever can get eschewed when trying to reglue if not in the exact position as before the break.
just wondering.

dorokusai

Mystery wrote: »

Well my question was genuine as I also have a driver that's frozen and wanted to know if it really alters spec that prohibits the driver to sound as designed, it may not be worth.
As you mentioned, I've seen many threads here and at Audiokarma where many have fixed magnet shifts using the DIY jig.
$50 replacement may not be much but if the driver is fixable, why trash it unless it changes the speaker's original sound/spec?

I just don't....not sure how much more I can expound upon this singular decision. I have spare drivers, they're found on the internet and you can buy genuine replacements if you decide to go that route. If you want to fix yours, fantastic, good luck. I've been doing upgrades and repairs to SDA ETC since 2003.

Mark

dorokusai

pitdogg2 wrote: »

Mark,
when these drivers are built are the magnets magnetized after they are glued? Reason i ask is that i can see were flux or whatever can get eschewed when trying to reglue if not in the exact position as before the break.
just wondering.

I will ask this of the engineering dept. That's an excellent question.

Mark

gdb

dorokusai wrote: »

Because we did the same thing at Polk and tested them....is that enough to make a general statement. Good lordd, sorry the opinion only matters if it's glowing and waving a flag. As I said, if that doesn't matter, inherently meaning if it sounds good who cares, then it doesn't matter. Where's the factual basis for your BOLD statement concerning the build and manufacture of these drivers? Have you seen the process, seen the factory, been involved in some behind the scenes testing no one is aware of? Certainly let me know since this would be intriguing.

This isn't the first time this has been done, first time its been successful or lack thereof. It's not a rocket that's for sure but it's also not easy to do this in the first place. The fact that Saftgeek took the time to keep trying is AWESOME but I wouldn't have wasted the time personally....its simply not worth it to me. Is that ok?

Mark

Perhaps you/Polk did not exercise enough care to make certain that everything was aligned dead center. I'd love to know what the "specs/tolerances" were that were supposedly so exacting in the various runs of the 6.5" MWs, how much variance was permissable and...........how close the new batches come to the old generation ones.

gdb

audiocr381ve wrote: »

Fighting words right there :P

Nah....just snotty.

Saftgeek

eschew - definition
verb [transitive] very formal /esˈtʃu/
to avoid doing something, especially for moral reasons

I'm not exactly sure what you meant by the flux can get eschewed??? I'm pretty sure they couldn't magnetize them after they were glued on because the entire basket and the core would also become magnetised. When I took the speaker apart I could see where the glue was not uniform to either side. The glue was blobbed more on one side then the other. As far as the tolerance of the coil goes, it is much more critical to have the core centered than the magnet. there is a ton of room around the outside of the voice coil but very, very little on the inside.

I'm not an expert at anything... but I can tell you that this speaker sounds wonderful. I got my replacement driver in today and I put the box on the shelf in the garage. I now have a spare. I'm not putting the new one in, I'm leaving the old one in. Maybe it will become eschewed from the JB Weld and fly out and put my eye out... but I'll take the chance.

I am learning there are some very, very smart folks on this website. I love the banter back and forth. It's fun to witness the intellectual jousting about. I'm going to take my time before I actually offer myself to a real match. I want to make sure I've got somewhere to run!!!

Happy SDAing everyone. I'm not sure if that is a verb, but it should be...

-Saftgeek

gdb

Nice, enjoy.

11tsteve

askew?

pitdogg2

11tsteve wrote: »

askew?

yes and let me state spell check made me do it:redface:

Mark knew what i was talking about...

saftgeek,

Many companies do magnetize after the glue up and it does not affect the baskets. Only the part stuck into the field gets magnetized.

Saftgeek

Mr P -I did not know that. I would love to see the entire process. I'm one of those guys who stays home when I'm sick and actually watches the "How it's Made" marathon. Pencils... That was a pretty neat one. I never could figure out how they got the trees to grow around the little round pieces of graphite...

I actually like to have my vocabulary challenged and had never seen that word used in a sentence. I'm always on my teenagers to spell the words out. Stupid texting has all but ruined any kind of grammar and punctuation they've learned by the time they get to high school. U no wht I meen?

Thanks for the lesson. Let me know if Polk ever releases a video of their process. I'd love to see it. Of course today it is more than likely robotic and optically controlled whereby in the 1980's there were humans doing the work.

-Saftgeek

gimpod

Saftgeek wrote: »

Mr P -I did not know that. I would love to see the entire process. I'm one of those guys who stays home when I'm sick and actually watches the "How it's Made" marathon. Pencils... That was a pretty neat one. I never could figure out how they got the trees to grow around the little round pieces of graphite...

I actually like to have my vocabulary challenged and had never seen that word used in a sentence. I'm always on my teenagers to spell the words out. Stupid texting has all but ruined any kind of grammar and punctuation they've learned by the time they get to high school. U no wht I meen?

Thanks for the lesson. Let me know if Polk ever releases a video of their process. I'd love to see it. Of course today it is more than likely robotic and optically controlled whereby in the 1980's there were humans doing the work.

-Saftgeek

Funny you should mention "How it's Made", Ask and you'll receive not Polk but the basic process is most likely the same.

[video=youtube_share;izQHjVWfzDQ]http://youtu.be/izQHjVWfzDQ[/video]

Saftgeek

Mr G. Thank you! That was beyond interesting. What an amazing piece of science. I had no idea they magnatized the ferrite after construction. Not fighting the magnetic pull would make it easier to assemble. I didn't see where they clamped the iron when they glued it? I'm sure they would have to clamp them somehow. Pretty cool stuff. Again, thanks!

-Saftgeek

PolkieMan

Yea that was a great video.

Schurkey

I just did the magnet-pole piece re-centering on an MW6509.

I cut around the base of the dust cap from voice-coil wire around the long way to the other voice-coil wire, then lifted the dust cap up on the remaining fabric "hinge". If the dust cap is popped "backwards" it stays up nicely. This also assures that the dust cap will re-attach in the same position with minimal work.

Centering the magnet is fairly easy, and does not need the same precision that centering the pole piece requires. I daubed some Loctite 271 Red Threadlocker (3M equivalent) (About three or four drops) on the cleaned magnet, centered it "by eye" on the basket, and let the anaerobic adhesive set up. This happens fairly quickly; but I don't work fast, and several weeks passed before I got back to this project.

Used the same PVC coupling as pictured in the first post, however I marked the middle and ran it through the bandsaw. Less PVC in the way, easier to see "down inside" when working. This gives a PVC height of less than two inches.

This PVC coupling is intended to join two pieces of 3" PVC pipe; therefore the inside diameter is as big as the OUTSIDE diameter of 3" PVC pipe--close to but not quite 3 1/2 inches. It's also a bit larger than the magnet. I decided to first try attaching the PVC to the basket with three screws--and that worked just fine. My "Plan B" was to split the coupling by sawing a gap in it, then clamp it to the magnet using a large automotive hose clamp. This was not done as the screws worked just fine. The original poster used 1/4-20 screws in the coupling; and had some failures. I believe that those screws were a poor choice, the coupling is too thin to use coarse-thread screws. I drilled six holes with a 1/8" drill bit (a #29 would have been the "proper" bit, but 1/8" is easier to find for most folks.) Then I tapped the holes for 8-32 machine screws. Three holes are towards the "bottom" of the fixture, to secure the PVC to the basket. Three holes are higher up, to apply pressure to the pole-piece.

Next, I centered the half-a-coupling using the three bottom screws. This is not a critical adjustment. I got it close "by eye", snugged the screws, and then gave each screw a quarter-turn more. the coupling has some flex, there's no real point to cranking the screws down.

The pole piece has a wonderful little divot dead-center on the "top". I sunk a 7/16-20 bottoming tap into the hole, about two threads worth, and made sure that the tap handle was quite tight to the tap. This gives me a "handle" to install or remove the pole piece.


Some spare speaker wire and crimp-on terminals connected the voice coil to the Garage Stereo Receiver. I could engage the speaker and adjust the volume level from my workbench. Of course, there's no sound from the speaker while the voice-coil is locked-up by the misaligned pole piece.

I practiced centering the pole piece with the three upper screws in the PVC half-a-coupling. With all three screws snug, tightening one means loosening another. I looked through the partially-cut dust cap for guidance on which way the pole piece had to be shifted with the screws. When the speaker suddenly began to play music, I knew I was close. Some final touch-up with the aligning screws, and it sounded good. I chilled the receiver. Altogether, it took about two minutes before I had it so there was no rubbing noise or scratchy-feel when I pushed the cone with the receiver off. I loosened each upper screw about 1/2 turn, and used the tap and tap handle to yank the pole piece back off. It does not want to release from the magnet! The pole piece was given a final cleaning, the anaerobic adhesive was applied, and the tap and tap handle used to set the pole piece back in place. The magnetic field will try to push the pole piece out-of-position even with the handy tap and handle for leverage.






As typical, I think it took longer to get it aligned the second time. Again, as soon as it started to play music, I knew I was close. A little tweaking removed all trace of "scratchyness", and the anaerobic sealer was just beginning to set up. Perhaps two or three minutes of adjusting time.



I used 3M 08011 Weatherstrip Adhesive (black, not yellow) to re-attach the dust cap where it had been cut.
(Photo coming later.)

Mystery

Schurkey wrote: »

I just did the magnet-pole piece re-centering on an MW6509...

Excellent!
Thanks for photos.
I'll refer to them when I get around doing mine.

chefkungfu

You think that's bad... you should see what the inept postal workers did to my plate amp! I'll post some pics as soon as Art Martinez from Polk ships it back.
BTW,Saftgeek, I'm sorry you had that happen!
I just found this thread, and my blood boils everytime I hear a horror story due to inept workers!

PolkieMan wrote: »

Wow I saw the speaker frame, they beat the crap outta it! At first I was thinking that if you could straighten the frame maybe it would realign the magnet. But looks like it was worse than first thought. I don't know about the dustcover but superglue on a wooden toothpick might work

dan98svt

I'm sort of understanding the fixing thing, but I'm not quite there yet.
I have 5 "frozen" MWs. The baskets look fine. The drivers look fine. They just don't move. I am guessing that the magnet has shifted, meaning the adhesive has let go somewhere and that something moved causing the center pole piece to come into contact with the side of something (magnet? plate?) pinching the voice coil between them.
Is the center pole piece part of the back plate or is it glued and may have come loose? Did the magnet, which is sandwiched between the back plate and the front piece, come loose move towards the center pole piece? Did the back plate move? Did the front plate move?
What I'm trying find out is, does the magnet assembly need to be taken apart? Can't a jig be made with screws (bolts) going to the three parts of the magnet assembly and then just shift the parts by turning screw turns until the driver moves freely and then glue the magnet assembly when all works smoothly?

westmassguy

The front plate is either welded or mechanically fastened to the basket frame. The ceramic magnet is a separate piece. The back plate and poll piece is a single component. Theoretically you could make a jig that will have three different levels of alignment screws. The first would lock the jig to the basket frame and front plate. The second would be centered on the ceramic magnet, and the 3rd would have to catch the edge of the back plate.

Schurkey

dan98svt wrote: »

does the magnet assembly need to be taken apart?

Yes.

dan98svt wrote: »

Can't a jig be made with screws (bolts) going to the three parts of the magnet assembly and then just shift the parts by turning screw turns until the driver moves freely and then glue the magnet assembly when all works smoothly?

Unless you take the magnet and the pole piece off the frame, separate them, clean off the residue from the original glue, and add fresh glue to the proper places, you won't be successful.

pongshi

Amazing. I acquired a pair of SDA SRS speakers. One speaker had everything intact. The other had 7 frozen 6503s, so I am guessing someone must have dropped the speaker. I spent hours trying to fix these and finally ponied up the money for replacement. Hats off to you for a great job.