LE14A woes. VC toast ?

[LE15-Thumper]

http://audioheritage.org/vbulletin/a...tid=5255&stc=1

I was in the process of gettin this woofer ready for new foam and I noticed it was sticking near the mid point of travel. I un-did the spider and low and behold ! VC former has "bubbles" is this due to over heating or environmental issues ? Any fixes out there ?

[Steve Gonzales]

Hey LE15T,

I had the same problem with an LE14A in the last 2 weeks, although not as severe. My speaker tech at MB Sound was able to CAREFULLY cut out the bubbles and use a clear coating over the bare spots. He said the trick is to go VERY slowly and cut out the bubbles, if you cut into the voice coil, you're done.... He was able to fix mine and they have been put thru their paces with no problems. He used an EXACTO knife to "shave" bit by bit to get to flush.I think he might of used Nail Polish to coat the bare VC windings. You have a pretty bad one there though. What have you got to lose? Good luck. BTW, Mr Marlon Balan is a member of our Forum, you could PM him @ MBspeakerrepair and get the finer points explained. This man has done wonders for me. If you look at my thread entitled LE14H's back from the dead, you will see his work and all the cone drivers in my avatar were expertly done by Mr Balan too. Good luck and I hope you can salvage your driver(s) Steve G

[John]

That is over heating of the voice coil !!!

[John]

Or then again,I would think you should have some scorching on the paper former and there does not seem to be any signs of that yet???

[transducergeek]

I just thought of this, could a fan, perhaps of the type used to cool a Microprocessor, or other? be fitted to a woofer in such a way as to provide some effective air curculation to the voice coil? Thereby cooling and allowing a higher power level, or more sustained power with less probable overheating causing this type of damage? A swich should be included so during low volume listening, no fan noise is added. At higher levels the music will swamp any fan noise.. The first (?) forced air cooled woofer, anyone game to experiment? Anyone have any comment? Just wondering. Rolf Erickson.

[Steve Gonzales]

JBL had a few GTI series car audio subs that could be cooled this way. They had a small venturi in them that would allow for forced air cooling ( I'm not 100% on that). But you can see that GREAT MINDS THINK ALIKE, cool idea, no pun intended. Hey Thumper, I just thought of something. Is that LE14A an old Lans-aloy yellow surround? I have an idea that if it is, that when the Lans-aloy gets stiff, the voicecoil movement is limited (excursion) and it is not a typical case of abuse that is from just plain negligence but a more mysterious case where the voice coil is not black and burnt but the former is showing signs of over heating. I wonder if some of the site's BIG GUNS could give some feedback on that theory ?

[LE15-Thumper]

Hey Thumper, I just thought of something. Is that LE14A an old Lans-aloy yellow surround? I have an idea that if it is, that when the Lans-aloy gets stiff, the voicecoil movement is limited (excursion) and it is not a typical case of abuse that is from just plain negligence but a more mysterious case where the voice coil is not black and burnt but the former is showing signs of over heating. I wonder if some of the site's BIG GUNS could give some feedback on that theory ?

Thanks Steve, actually, I think it is one of the last Alnico LE14A's made. It came stock with foam surround. I believe it was pulled from a L222 disco.

I think the fan idea is plausible, but one problem comes to mind. Artificially created air movement in the cabinet might cause tuning and air pressure issues ?

[Steve Gonzales]

That blows THAT theory all to hell. Now it just sounds like there was a little TOO MUCH Disco in those Disco's

[LE15-Thumper]

Too much disco will "bubble" anyone or anything !

[4313B]

VC former has "bubbles"

Recone it and get rid of that old former. The new voice coil formers are superior. Don't forget to get that #&*@!#$ alnico magnet recharged while you're at it.

[LE15-Thumper]

PN # and cost of new cone kit ?
Re-gauss ? Who does it ? Can't I just use a car battery and really big screwdriver ?

[Earl K]

Hi

It's too bad you ended up with le14a(s) that have been abused .Perhaps that's a lesson for all prospective buyers to not buy used parts from the L222 "Disco" .

- You're likely in for a shock about how much this stuff costs to repair in Canada.

- If you have the patience you might as well try to remove those bubbles.

- If your patience runs out and if your wallet won't bear the cost of a recone then check out this fellows aftermarket voice-coils (out of California) as a possible solution. Here's the url for aftermarket voice-coils. Understand that this is not an endorsement of this sellers products. They may or may not work for you . It'll be a real crap shoot. I would contact this fellow and ask him how many coil-windings he makes for that .6" depth. If you can get the number of windings you'll then need to compare that number to how many JBL actually make for that particular .6" VC depth . ( I don't know that number myself but the info might be available.) The amount of windings in the gap will determine ( with the magnet strength ) the BL factor. Now the seller may just say that it's the same as JBL or that he doesn't know - then you're left with a quandry ( to Buy or Not to Buy ). If you decide to purchase, ask if he'll make up a coil(s) with a spider that has a stiffness that is one grade less than the 2225 type that he's using . That'll be more appropriate for the le14 .

- You can always ask your local reconer about after market voice-coils / maybe he'd have more accurate information. You might actually start there ( in Winnipeg ).. Whatever you do - I'd limit my repair budget for those old things to $100. Cdn ( but that's just me ) . Remember you can buy a new le14h-3 for less than $300 USD with some form of warranty. And that's list price .

[JBL Dog]

That is over heating of the voice coil !!!

I had the same problem with 2416H vc's in my SR4738's. JBL replaced them under warranty some 15 years ago. Regarding the LE14A's, aren't those kits obsolete?

This message comes from JBL Dog

[4313B]

It's too bad you ended up with le14a(s) that have been abused. Perhaps that's a lesson for all prospective buyers to not buy used parts from the L222 "Disco"

I've reconed more LE14A's out of L220/L222's than out of all the other LE14A-based systems combined!

Regarding the LE14A's, aren't those kits obsolete?

Yes, but someone might have some left. If they are that important and the totally superior LE14H-1 kit isn't desired, then I'd start calling every recone center on Harman's list looking for some C8RLE14A kits.

[Mike Caldwell]

Hello
As for fan cooled speakers and drivers...already been done!
A company based in Holland called Stage Accompany that builds pro PA speaker systems that use a high power ribbon driver had a model that used a fan to create a small airflow around the and through the driver to cool it.
Another company from here in the US called Community had a line of
cabinets called the "Air Force Series" that did the same thing only on the cone
drivers in their case.
Here's some links to their sites.
http://stage-accompany.com/new/
http://www.community.chester.pa.us/main/

As for the LE14 JBL had a pro cabinet far a short time that used 14 inch
woofers, I don't think though that any of the recone parts would be interchangable. There should be something about them if you dig on the JBL pro website.

Mike Caldwell