JBL L150a - to re-cone or not to re-cone? That is the question.

[calderdoran]

Hello -

I just purchased a pair of JBL L150a's and all four "woofers" are totally shot and need reconing, also one of the midranges speakers is slightly dented - I am not sure of the cost to recone/refurbish these speakers - Is it worth it? I plan on selling at some point (perhaps) but do not want to put too much $$$$ into them if there will be no return - To part out or not to part out??????

Thanks for your help and advise.

DAVE

[rdgrimes]

http://www.speakerrepair.com/ocsrepairprice.html

128H: $248 original, $148 aftermarket, each.

PR300: $118. These are listed as a 15", which may be a typo.

These prices are an example of why many folks opt for buying used drivers.

[Allanvh5150]

When you say all four woofers are shot, the L150 only has one per cabinet. If you are only talking about the foam surrounds, these can be repaired for a few dollars each.

Allan.

[hjames]

When you say all four woofers are shot, the L150 only has one per cabinet.
If you are only talking about the foam surrounds, these can be repaired for a few dollars each.
Allan.

If I recall, there is one woofer and one matching passive radiator (PR) per cabinet.
If the surrounds are shot on all 4, he'd need 4 surrounds for all the "woofers"

Then again, he did say "... all four "woofers" are totally shot and need reconing"

... there is this thread ....

http://www.audioheritage.org/vbulletin/showthread.php?26346-Still-Looking-for-jbl-pr300-s-So-how-do-you-make-a-passive-radiator

52437

[Allanvh5150]

If I recall, there is one woofer and one matching passive radiator (PR) per cabinet.
If the surrounds are shot on all 4, he'd need 4 surrounds for all the "woofers"

:blink:

[SEAWOLF97]

I too was wondering is he is talking abt foam surrounds or cones....a quick and easy test with unknown speakers and bad surrounds is to lay them on their backs, firing straight up , so that gravity doesnt induce misalignment and play them (at low volume and not very long)

a passive radiator could also be called a passive woofer , so active + passives = 4
(since you seem confused)


:blink:

[Allanvh5150]

A woofer would tend to go WOOF. A passive radiator would tend to say "REALLY". :)

[calderdoran]

Yes -

I am mistaken - What I mean is that the foam Surrounds on the bottom two "speakers" are shot - Meaning the large white cone on top and the large black cone on the bottom - Would it be worth it to just replace the foam surrounds and could I do it myself? Hey - thanks to all for helping me to understand more about what I am looking at - I picked up this pair at a "junk" shop for $25.00. I will take photos so that you can get a better idea of what I am talking about.

Thanks - Again -

DAVE

[calderdoran]

Here are the images -
Yes it looks to be just the foam surrounds - where can I get those parts and is it relatively easy to fix? Any help or explanations or advise would be greatly appreciated.

DAVE


52460

52461

52462

52463

[SEAWOLF97]

dont let that loose foam from the surround fall out on the rug ...if it gets ground in by a foot, the stain will never come out .....


ask me how I know..:(

[rdgrimes]

If those woofers have been operated in that condition, or even left to sit for years like that, there can be damage to the voice coil and/or spider. That said, it doesn't hurt to re-foam and try it. Obviously the passive radiators will be fine. Please note that there are a couple different variations of the 128H, and they technically should use different surrounds. They are also not the easiest model to "learn" on. For those reasons I'd suggest sending them off for the re-foam. You can learn on the passive radiators if you want to save some $.

Orange Co Speaker (http://www.speakerrepair.com/) is often recommended, I've used them with great success. Local member "edgewound" is an expert and is also highly recommended.

[Lee in Montreal]

A woofer would tend to go WOOF. A passive radiator would tend to say "REALLY". :)

Great one!!! :D:D:D

BTW To check if the coil hasn't rubbed too much and worn thru the varnish, you could lay the woofer on its back and connect a Ohm meter. Move the cone around and see if the Ohm reading changes. If it does, I suspect that the varnish has eroded in some areas of the coil and shorting.

[4343]

Great one!!! :D:D:D

BTW To check if the coil hasn't rubbed too much and worn thru the varnish, you could lay the woofer on its back and connect a Ohm meter. Move the cone around and see if the Ohm reading changes. If it does, I suspect that the varnish has eroded in some areas of the coil and shorting.
Good idea, but most ohmmeters don't like having the voltage generated by moving the voice coil in the magnetic field applied to them, and will respond by jumping around (in the case of an analog meter) or counting up and down around the correct reading.

[Allanvh5150]

For all it is worth, put new foam surrounds on them and see how they go. I have done many in this condition and have not yet come up with a dud. Crank em up and see how they go. Nothing to loose here and if they go OK you will have a damn fine set of speakers for under $100!!!!. Check the voice coils first of course.

Allan.

[calderdoran]

.....Nothing to loose here and if they go OK you will have a damn fine set of speakers for under $100!!!!. Check the voice coils first of course.

Allan.

Hello All -

and thanks for all the info - One question - What do I need (tool wise) and how do I check the voice coils?

Thanks -

DAVE

[Allanvh5150]

Hello All -

and thanks for all the info - One question - What do I need (tool wise) and how do I check the voice coils?

Thanks -

DAVE

Hi Dave,
If you have a multi meter, set it to low ohms and check the voice coil is a closed circuit, usualy about 5 ohms. If you do not have one, get a small battery and briefly connect it to the speaker. The cone should move forward or back. Do not leave the battery connected!

If the cone moves, the voice coil is probably ok. Lay the speaker on its back to do this test. Also, try to move the cone with your fingers to check for rubbing. If there is nothing that is extreamly obvious, I would go with a refoam. As I said, you have nothing to loose.

Allan.

[DavidF]

dont let that loose foam from the surround fall out on the rug ...if it gets ground in by a foot, the stain will never come out .....


ask me how I know..:(

Didn't know about that! Thanks.

[DavidF]

Hello -

I just purchased a pair of JBL L150a's and all four "woofers" are totally shot and need reconing, also one of the midranges speakers is slightly dented - I am not sure of the cost to recone/refurbish these speakers - Is it worth it? I plan on selling at some point (perhaps) but do not want to put too much $$$$ into them if there will be no return - To part out or not to part out??????

Thanks for your help and advise.

DAVE


The adage around here used to be always go with a JBL recone kit. This, by default, also meant that it would to be installed in a JBL certified shop since they only could get the part. That would return the full moving system of the driver to proper spec. Though the spirit of that adage still is valid the escalating price of JBL kits (about $500 per pair I think for the 128H) and the lack of parts for the passive radiator makes a tough nut to justify the cost. Especially if the intention is to flip these. Not likely you will get your out-of-pocket back unless all the drivers are in top shape. The tweeter dome might be flaking a bit. The mids look OK other than the domes but those exact replacement parts are hard to find these days.

If the cabinets are in good order and you know you will want to keep them and use them, then I say spend the dough and get the woofers reconed. The passives will have to be repaired with new surrounds. If not, try to get a good resurround job for both and leave the expensive recone work up to anyone who wants to buy and restore them.

[calderdoran]

Well -

I got all the info I needed today from Rick Cobb and I plan on doing the refoam myself....
I understand David F's comments but the $$$ needed is not in my cards and I plan on living with these for a while.

Now my "don't know what I am doing point" - I am curious to know the proper way to detach the drivers from the cabinet - is it from the front or the rear...... I know this is a amateur question but I don't know the answer -

Thanks folks -

DAVE

[Triumph Don]

Remove the 4 screws on the front of the woofer[s]. Remove them from the cabs. Install the Rick Cobb foam kits, as per instructions [clean up and removal of the old stuff IS the worst part]. Reinstall, enjoy the music, or light sand 'em and oil with Watco Danish Oil take some nice pictures and flip 'em!

[DavidF]

Well -

I got all the info I needed today from Rick Cobb and I plan on doing the refoam myself....
I understand David F's comments but the $$$ needed is not in my cards and I plan on living with these for a while.

Now my "don't know what I am doing point" - I am curious to know the proper way to detach the drivers from the cabinet - is it from the front or the rear...... I know this is a amateur question but I don't know the answer -

Thanks folks -

DAVE

Good chance that they will need some encouragement to free up from the baffle. The original gasket is a thin rubber piece that seemed to get into the paint on the baffle and become stuck. Some have used a block of wood and light touch of a hammer to shock the pieces a bit. I use two-handed finger pressure and hold on for a while until it finally gives. In some hard cases I used some leverage with a pointed wood block under the woofer frame. I put some hard cardboard underneath to protect the paint. Always go nice and easy.

[calderdoran]

OK -

With encouragement - I was able to remove the speakers - yes they were "stuck" to the paint. I appreciate the help I am getting on this - Now one more question? How to disconnect the wires from the speaker. I am sure this is easy but how do I properly remove the wires ? Are the connections threaded? Do I Pull? Hmmmmmm?

Thanks-

DAVE

[hjames]

OK -

With encouragement - I was able to remove the speakers - yes they were "stuck" to the paint. I appreciate the help I am getting on this - Now one more question? How to disconnect the wires from the speaker. I am sure this is easy but how do I properly remove the wires ? Are the connections threaded? Do I Pull? Hmmmmmm?

Thanks-

DAVE

Are they red & black push buttons button-post connections? Push to release the wire?
I gather they are not spade lugs and matching connectors ...

[DavidF]

OK -

With encouragement - I was able to remove the speakers - yes they were "stuck" to the paint. I appreciate the help I am getting on this - Now one more question? How to disconnect the wires from the speaker. I am sure this is easy but how do I properly remove the wires ? Are the connections threaded? Do I Pull? Hmmmmmm?

Thanks-

DAVE
The connectors a telescoping tubes. They are spring loaded to crimp the wire. Pressing down lines up holes in the tubes. So just press firmly and pull out the wire. Not sure about the passive connectors but likely the same.

[calderdoran]

I will be the :D PUSHER man :D when I get home from work.

Thanks

DAVE

[BMWCCA]

Not sure about the passive connectors but likely the same.I hope you're kidding! :wtf:

[hjames]

So just press firmly and pull out the wire. Not sure about the passive connectors but likely the same. ;)

:D Brilliant!!

[calderdoran]

It's all tongue in cheek but listen to this - I will fix my speakers.

Thanks people

DAVE

http://www.youtube.com/watch?v=dJ0jjA6HA4k

[DavidF]

I hope you're kidding! :wtf:

Ha!~ No I was not kidding, ashamed to say. Mind fart. No dinner for me, straight to my room.

[calderdoran]

Well -

1 de-foamed and 3 to go -
Do I have to get all of the sticky glue? off of the cone backside and the basket? If I use acetone to do so, will it take off the paint on the basket and will it damage the cone?

Thanks - in advance

DAVE - :confused:

[rdgrimes]

Well -

1 de-foamed and 3 to go -
Do I have to get all of the sticky glue? off of the cone backside and the basket? If I use acetone to do so, will it take off the paint on the basket and will it damage the cone?

Thanks - in advance

DAVE - :confused:
Just the foam itself needs to come off. Usually a finger rubbing the cone surface will remove it all. Use no solvents on the cone! To clean the basket, most anything can be used, and usually a sharp blade is all that's needed. If the baked-on varnish refuses to scrape off, just leave it. On some of them it pops right off with a blade, on others it stays put.

[Allanvh5150]

What he said!

Allan.

[calderdoran]

Well I picked up a Fluke 77 multimeter ( $4.00 GS) today so I suppose can test the voice coil - if I knew how. The OHM symbol is the upside down U but Where to I touch the probes and what should my reading be.... If the reading is not desirable what next?

Thanks - DAVE

[calderdoran]

Figured it out - tested the voice coils and got 5.9 ohms on each - I believe that means they are good.......no?

DAVE

[DavidF]

Figured it out - tested the voice coils and got 5.9 ohms on each - I believe that means they are good.......no?

DAVE
It's a good sign, yes. The coils could still be out of tolerence or someway binding but that's difficult to gauge until the surrounds are installed. Still the coils are intact and that is encouraging.

The 5.9 ohms may be a little high. Are you using a digital multi meter?You may need to factor the internal resistance. If so set the range to 2 (or 200 if there is no "2"). Touch the probe leads together. This may read something less than one ohm. Subtract this amount from what you read from the coils. In other words if you read 0.6 ohms from touching the probes the resistance of the coil is then 5.9 less the 0.6 or 5.3.

[Allanvh5150]

Now that you know there is no dead short on the voice coil, lay the speaker on its back and hook up some signal to it. Just play it at very low volume. If all is good, go ahead with the surrounds.

Allan.