Custom JBL/Altec Build - LE15A Woofers "Frozen"

The picture I get in mind is that the ride back to your place jostled some debris into the voice coil gap. But it does not make sense in thinking where the debris came from or got into the gap??

That could be it. Sometimes there’s foam damping material in there.
 
Was the voice coil of each woofer making a scraping noise or was it that the cone ( almost ) didn't move without the scraping noise ?
 
Just a hunch, and hard to believe it could happen to both woofer simultaneously -
but maybe the magnets dislodged and have pinched the voice-coil on the woofers ...
Happens sometime when shipping speakers -
 
Just a hunch, and hard to believe it could happen to both woofer simultaneously -
but maybe the magnets dislodged and have pinched the voice-coil on the woofers ...
Happens sometime when shipping speakers -

When I read the first post, this was the very first thing that came to my mind.

I would refrain from forcing them to work. It is possible, if it is a shifted magnet situation, that if they are dealt with carefully, the cones and voice coils can be saved. The surrounds, spiders and dust caps will have to be replaced, as the cone assemblies will have to be removed from the woofers, the magnets pulled off, cleaned, shimmed and re-glued, and the cones reinstalled with new spiders, surrounds and dust caps.

I've done this procedure before- and I have seen the results when people forced the speakers to move once the magnets had shifted. Very quickly, the insulating lacquer is rubbed through to bare metal, on the outside of the coil windings- when this happens, you might as well assume that the coil windings are shorting against each other. Once that happens, a total recone (and there are no factory kits available for these, PERIOD, so it would have to be an aftermarket kit) is the only solution.

As of now, it MAY be still possible to save these- but not if they're beat on to try and force them to work, as they are.

Regards,
Gordon.
 
Re-cone would be the best permanent option. To see if the problem is debris in the gap do the following. Remove woofers. Place face down with spacers to allow no contact of surround to table. Play test tones. Debris may dislodge .Keeping driver face down remove dust cap and see what the debris was. Re cone would be the best option.
 
When I read the first post, this was the very first thing that came to my mind.

I would refrain from forcing them to work. It is possible, if it is a shifted magnet situation, that if they are dealt with carefully, the cones and voice coils can be saved. The surrounds, spiders and dust caps will have to be replaced, as the cone assemblies will have to be removed from the woofers, the magnets pulled off, cleaned, shimmed and re-glued, and the cones reinstalled with new spiders, surrounds and dust caps.

I've done this procedure before- and I have seen the results when people forced the speakers to move once the magnets had shifted. Very quickly, the insulating lacquer is rubbed through to bare metal, on the outside of the coil windings- when this happens, you might as well assume that the coil windings are shorting against each other. Once that happens, a total recone (and there are no factory kits available for these, PERIOD, so it would have to be an aftermarket kit) is the only solution.

As of now, it MAY be still possible to save these- but not if they're beat on to try and force them to work, as they are.

Regards,
Gordon.
Hey Guys
So, I learned a lot today but I'm still one woofer down. The woofer that was broken free last night is working very well as is that entire speaker.

I did not mess with the more stubborn woofer this morning as I now have bigger problems at hand. I believe powering the speakers before I was aware many of the shotty XO connections had snapped during transit caused issues with the caps within... I also believe that this was what caused both woofers to freeze up, but someone can educate me if that is a faulty conclusion.

Anyway, I attempted to power another 8ohm woofer with the speaker that is not entirely setup and working, and I got zilch...

I set the bias on my pwr amp and ran a constant 60Hz tone generator video off Youtube through my pre with the volume at 12 o'clock. I hooked up my meter to the wires for the woofer on the working speaker and got a reading of about 100mv. The non-working speaker read 50mv.

This was just me screwing around and I'm sure there is a more traditional way to test the XO to ensure all is good, but it let me know I have some more work to do before messing with that stuck-ish woofer. Also these XOs are like lamp cord rats nests...

I checked all my connections and compared the XO in the working speaker to the non working. All looked good but it is definitely hard to tell considering the crazy job this guy did wiring everything up by hand. I'm assuming the caps are bad somewhere.

The mids and tweeters work fine in both speakers - it's just the woofer that is not being powered properly in the one speaker.

I guess I can put new caps in and see if that does the trick unless someone else has a better idea of where to start.

Also, I'm all ears if anyone has suggestions for an original JBL/Altec XO network that I can buy given the drivers I'm working with here.
Thanks in advance for your thoughts guys.
 
A direct short in between the stuck woofer's terminals would render the cone stiffer, could it be?, faulty re-wiring?...
 
If the voice coil was frozen in the gap by any means, it would most certainly make all manner of unpleasant noise in the process of breaking free from outside motive force.

When you physically move a cone with your hands, if the voice coil or it's former makes any contact with any part of the magnetic gap (pole piece or front plate) it will make noise, loud enough and abnormal enough that there will be no mistaking it for anything else.

Since you have made zero mention of any scraping or grinding noise, i am very doubtful that the voice coils were seized.

I suspect the following:

a) rock hard lansalloy surrounds, get rid of them, there are proper foam replacements. If you DOT3 treated the surrounds, the cones will need to be cleaned well. DOT3 is a glycol/ether compound, it also has bromine in it, no "oil". If you treated them with some kind of oil, it may penetrate the cone material deeply enough over time that it will be near impossible to get an adhesive to bond for re-foaming.

b) you auditioned them in a very different acoustic environment than you have them in now. Not having heard them when they were fresh and properly operational, you had no reference to judge how they should sound when you auditioned them, the bass was probably constrained and lacking, but the acoustic environment made that less than obvious from your point of reference.

c) the ride home likely disturbed the internal wiring, and this should be sorted out. It's doubtful you have passed enough signal for enough duration to damage any crossover components, it may still be wise to inspect/test.

Bowtie,
Again, I'm talking about working (wonderfully) when auditioned, and NOT working (at all) once I got home (zilch, kaput, nada). The surrounds made and make no difference in my case.

This whole time I thought the brake fluid method was meant to be applied in tiny drops to the voicecoil. Brushing the surrounds with oil would not have done anything to free the woofer that is now working, though I may consider doing that once I get both speakers running and before I put an order in with Simply Speakers.
 
A direct short in between the stuck woofer's terminals would render the cone stiffer, could it be?, faulty re-wiring?...
Do you mean I hooked them up out of phase? I have tried other 8ohm woofers with these speakers and they get no response either. Unfortunately, the original creator used lampcord that he would split and tie one lead in a knot to indicate a negative wire. This is evident in almost all of his wiring, but there are some lamp cords that are just ran to and from the XO with no indication of positive/negative.

I've ran them all back to their source and compared each XO to ensure they are the same. I've marked them since. It took a couple hours and a 2nd set of eyes, and we agree it is hooked up correctly.

I still believe that when the solder joints broke unbeknownst to me and I powered the speakers up, that some caps failed, but if anyone can guide me towards a suitable JBL/Altec XO like the two I linked below, it would be greatly appreciated.

https://www.ebay.com/itm/Altec-Lans...304606?hash=item4d6e6092de:g:YLcAAOSwk-1aJcRe

https://www.ebay.com/itm/Altec-9849...122133?hash=item44190df895:g:~4UAAOSw10hao-ma
 
I think I found the problem - a bad cap had burst... This little guy was attached to a few others that were bundled in tape and connected to one of the two giant "bass coils". I suppose that would make sense why I was only getting half power to the woofer... Still looking for a canned XO if anyone has suggestions, though.

bad cap.jpg
 
Did you ever watched '' supernatural '' episodes ?

Geez, does this one episode of yours is, well, supernatural.

Still can't get it. But I honor your perseverance in all ways.

Sorry to come up with no clues.
 
So, both caps had to blow in both cabinets to get both woofers to work incorrectly.
 
Did you ever watched '' supernatural '' episodes ?

Geez, does this one episode of yours is, well, supernatural.

Still can't get it. But I honor your perseverance in all ways.

Sorry to come up with no clues.
So, both caps had to blow in both cabinets to get both woofers to work incorrectly.
Thanks Sax, I know these speakers will be worth it given the performance of the one I have going.

The caps in the working speaker are "good" (working at least). As for the woofer, I seriously just massaged it's frozen cone in and out with force and then broke it free with a high powered frequency test straight form my amp. Some soldered points broke in the XO on that cab too but I had repaired those last week.

It just had to be the shock of moving them. I hauled these speakers myself and they probably weigh 150lbs each. I may have put them down a little hard with my handcart once I got them in the garage, causing the connections to break and the woofers to each be "jolted". What internal effect that had on the woofer I cannot say as I don't know much about driver construction, but this is the most likely conclusion as they had worked fine before I picked them up.

I've got other problems as these freakin' 100uf 20v (20%) caps are $10 each online...
 
bad cap.jpg
Does anyone have advice on replacing these caps?
Values are:
2X 100uF 20v (20%)
2X 15Uf 20v (10%)
I've never seen caps daisy-chained like this together, so I'm wondering if a single capacitor could replace these 4 in the pic.
 
Your request for a canned crossover: if the working speaker sounds great, the original designer may have known what he was doing. Can you try working out a simple schematic with the value of each component listed? I hope the values of the inductors (the coils) are written on them somewhere.

We can easily give you suggestions on off the shelf crossovers, if you are sure that's what you want. What are the impedances of each driver? If you don't know, just use your multimeter and measure the resistance (ohms) across the terminals on each speaker/driver.

If you want to repair the current crossovers, you should replace all the capacitors as the blown one is indicative of the condition of the rest of them. And one cap can replace the others if the total value is available.

https://www.kitronik.co.uk/blog/how-to-calculate-capacitors-in-series-and-parallel/

GeeDeeEmm
 
Your request for a canned crossover: if the working speaker sounds great, the original designer may have known what he was doing. Can you try working out a simple schematic with the value of each component listed? I hope the values of the inductors (the coils) are written on them somewhere.

We can easily give you suggestions on off the shelf crossovers, if you are sure that's what you want. What are the impedances of each driver? If you don't know, just use your multimeter and measure the resistance (ohms) across the terminals on each speaker/driver.

If you want to repair the current crossovers, you should replace all the capacitors as the blown one is indicative of the condition of the rest of them. And one cap can replace the others if the total value is available.

https://www.kitronik.co.uk/blog/how-to-calculate-capacitors-in-series-and-parallel/

GeeDeeEmm

GD
Thank for your help. I don't think I can make a schematic as everything is jumbled up. Using the link you sent I'm trying to figure out the combined value of the cap arrangement that I intend to replace, but I am pretty confused..

. The cap values are:
2X 100uF 20V connected to 2X 15uF 20V
They are all connected to each other and form a bridge to the two inductors

Here's the pic again:
bad cap.jpg

Given that arrangement I am not sure if they are considered parallel or in a series.
I get 230uF in parallel and 6.52F if they are in a series...

Also, here are pics of the inductors with values written on top:

coil.jpg
Coil2.jpg

Here are the impedances for the drivers:
15" JBL LE15A woofers (8ohm)
JBL 075 tweeters (16ohm)
Altec 802D Mids (16ohm)
 
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