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KentGriffith
08-27-2007, 08:07 PM
I own four JBL L-150's that use to belong to various band members of Lynyrd Skynyrd.

I love the sound of these speakers, but I am really getting sick and tired of having to replace the foam surrounds about every 6 or 7 years.

I have asked Central Florida Speaker if they could use cloth surrounds or even rubber surrounds and they say they can not find anything that will fit these speakers.

I know, I know, there are a lot of you out there wondering why in the world would I want to change the sound of these speakers? At low volumes I might agree with you, but I listen to these speakers cranked up and I am of the opinion that at loud volume levels you are not going to really notice what type of suspension is used up front. I don't think it will be that big of a difference.

I am just sick and tired of the $$$$ I have to spend to maintain 8 drivers every 6 or 7 years.

What can I do? I am hoping some of you here will have some helpful solutions to this problem.

I would really like for all of these speakers and passive radiators to have cloth surround that I never have to replace again!

Any and all suggestions appreciated! Thanks! KG


http://i40.photobucket.com/albums/e214/Cagey1/January232006002.jpg

DavidF
08-27-2007, 08:56 PM
I am surprised to hear that the surrounds are crapping out after only 6-7 years. Seems extraordinarly short time. Something in the air where you live, Kent?

DavidF

SEAWOLF97
08-28-2007, 01:07 AM
At low volumes I might agree with you, but I listen to these speakers cranked up and I am of the opinion that at loud volume levels you are not going to really notice what type of suspension is used up front. I don't think it will be that big of a difference.

I am just sick and tired of the $$$$ I have to spend to maintain 8 drivers every 6 or 7 years.

What can I do? I am hoping some of you here will have some helpful solutions to this problem.


I try not to change anything from factory specs. A person doesn't listen at high volume ALL THE TIME , AFAIK. Don't think you are going in the right direction to go to rubber or cloth. Most of us get 10-15 years on foams.

What can you do ?? Learn to do them yourself. It isn't really very hard to do. (The first is the hardest) . WORST CASE: 8 drivers X max of $10 ea. = $80 divided by 6 years is +- $13 a year to enjoy your system. Not really so expensive ? $13/year divided by 365 days = .035 cents a day for 8 or .000095 cents each driver per day. ( 1 cent every 3 days for 8 drivers)

Member BOputnam put up a great tutorial on how to refoam, do a search on this forum. Its actually very satisfying to "do it yourself". :D

KentGriffith
08-28-2007, 06:41 AM
I am surprised to hear that the surrounds are crapping out after only 6-7 years. Seems extraordinarly short time. Something in the air where you live, Kent?

DavidF


I live in central Florida where there is higher humidity and higher salt content in the air, not sure about chemical pollutions in the air though... the foam surrounds just don't seem to last as long around here. I may have understated the time, but still, I have had these speakers redone twice since the early 1990's when I acquired them.

And I have not been too happy with the work done on them either.

This time they put some kind of chemical on the foam surrounds that they say will increase the life expectancy of them.

One of the problems I have with how my speakers are refoamed these days is alignment of the cone.

I have never replaced a surround myself, but I would think the ideal way to do it would be to pull the dust caps and use some sort of a shim to make sure of a perfect alignment of the voice coil to the magnet structure.

It seems to me that the speaker repair company is taking short cuts by not pulling the dust caps and trying to replace the surrounds without any sort of shims and by just guessing at the alignment.

I can tap on one side of the speaker and hear it hitting inside. This crap pisses me off, but the speaker repair company just blows it off as normal and I don't think it is.

I know when I tap all sides of a new speaker it does not touch nor rub! But when I get them back from Central Florida Speaker, guess what? I tap on them and one certain side might hit internally. They did this to my old Altec Lansings I gave to my girlfriend.

I think from now on I will insist they remove dust caps and shim or else I will have to find another speaker repair company. I think they are just taking the easy way out and providing less quality to the customer by taking shortcuts. Just my opinion.

But why does most here not consider using another type of surround? WHY? The studio monitors have cloth surround and I hear no complaints. These speakers use very similar drivers, if not the same in certain applications, why not use something else?

And you are right... I do not always listen at high volumes, but at this point in the game, I am not looking forward to another round of surround replacements.

I would like to do them myself and maybe next time I will.

Thanks for the responses. I take it the general opinion is leave the speakers as they were made and just have fun doing the surrounds myself and quit my bitchin! Got it! Thanks!

KG

DavidF
08-28-2007, 09:55 AM
There are ways to center the cone electrically without removing the dust cap. That procedure is discussed in a thread on this site. I have used the technique personally with no problems. Also, remember that JBLs have close voice coil tolerances. If you push on one side of the cone you can easily rock the cone enough to make contact. The sure way is to use a test CD with a low frequency tone- 20 Hz for example- in free air to determine if there is any coil rubbing.

DavidF

macaroonie
08-28-2007, 12:15 PM
If you can find out what is the coating on the edge of the mid driver and then lay your hands on some and then lightly coat the inside and outside of your roll surrounds.............. well that might afford some protection.
Actually refoaming is a breeze and once you have done one then it is a walk in the park.
I can see where humidity and a salty atmosphere could accelerate the deterioration.

glen
08-31-2007, 01:15 PM
I know when I tap all sides of a new speaker it does not touch nor rub! But when I get them back from Central Florida Speaker, guess what? I tap on them and one certain side might hit internally.
KG

I like to thump speakers on the cone also, but that's applying pressure unevenly and can cause the voice coil to twist and rub in the gap in a way that would not happen if it were being symmetrically driven by the voice coil itself.

At the factory they test the speakers with a rather loud audio sweep starting at a low frequency sliding up to the high frequency covering the range of the driver while listening for rubbing/resonances/distortion.

Get a $20 audio signal generator off ebay or an audio test CD and you can run the same check at home. If there is any rubbing you will be able to hear it much more clearly with a pure test tone.

JBL 4645
08-31-2007, 07:22 PM
I am surprised to hear that the surrounds are crapping out after only 6-7 years. Seems extraordinarly short time. Something in the air where you live, Kent?

DavidF

Makes my skin crawl its does, when they start showing signs of holes or tearing in the foam after short usage:banghead: (edge ribbon surround) rules okay!
http://www.buswaredirect.com/tear-hair-out.jpg


I like to thump speakers on the cone also, but that's applying pressure unevenly and can cause the voice coil to twist and rub in the gap in a way that would not happen if it were being symmetrically driven by the voice coil itself.

At the factory they test the speakers with a rather loud audio sweep starting at a low frequency sliding up to the high frequency covering the range of the driver while listening for rubbing/resonances/distortion.

Get a $20 audio signal generator off ebay or an audio test CD and you can run the same check at home. If there is any rubbing you will be able to hear it much more clearly with a pure test tone.

You can use a simple and yet free sound tone generator like the (TrueRTA) just input the frequency and play it away.

http://www.trueaudio.com/rta_abt1.htm


I live in central Florida where there is higher humidity and higher salt content in the air, not sure about chemical pollutions in the air though... the foam surrounds just don't seem to last as long around here. I may have understated the time, but still, I have had these speakers redone twice since the early 1990's when I acquired them.

And I have not been too happy with the work done on them either.

This time they put some kind of chemical on the foam surrounds that they say will increase the life expectancy of them.

One of the problems I have with how my speakers are refoamed these days is alignment of the cone.

I have never replaced a surround myself, but I would think the ideal way to do it would be to pull the dust caps and use some sort of a shim to make sure of a perfect alignment of the voice coil to the magnet structure.

It seems to me that the speaker repair company is taking short cuts by not pulling the dust caps and trying to replace the surrounds without any sort of shims and by just guessing at the alignment.

I can tap on one side of the speaker and hear it hitting inside. This crap pisses me off, but the speaker repair company just blows it off as normal and I don't think it is.

I know when I tap all sides of a new speaker it does not touch nor rub! But when I get them back from Central Florida Speaker, guess what? I tap on them and one certain side might hit internally. They did this to my old Altec Lansings I gave to my girlfriend.

I think from now on I will insist they remove dust caps and shim or else I will have to find another speaker repair company. I think they are just taking the easy way out and providing less quality to the customer by taking shortcuts. Just my opinion.

But why does most here not consider using another type of surround? WHY? The studio monitors have cloth surround and I hear no complaints. These speakers use very similar drivers, if not the same in certain applications, why not use something else?

And you are right... I do not always listen at high volumes, but at this point in the game, I am not looking forward to another round of surround replacements.

I would like to do them myself and maybe next time I will.

Thanks for the responses. I take it the general opinion is leave the speakers as they were made and just have fun doing the surrounds myself and quit my bitchin! Got it! Thanks!

KG

That’s what I heard a few years back same deal down here in Bournemouth, being close to the beach within 2 miles. Salt of all the things we can’t see in the air slat is our number 1 public enemy!:biting::banghead:


I try not to change anything from factory specs. A person doesn't listen at high volume ALL THE TIME , AFAIK. Don't think you are going in the right direction to go to rubber or cloth. Most of us get 10-15 years on foams.

What can you do ?? Learn to do them yourself. It isn't really very hard to do. (The first is the hardest) . WORST CASE: 8 drivers X max of $10 ea. = $80 divided by 6 years is +- $13 a year to enjoy your system. Not really so expensive ? $13/year divided by 365 days = .035 cents a day for 8 or .000095 cents each driver per day. ( 1 cent every 3 days for 8 drivers)

Member BOputnam put up a great tutorial on how to refoam, do a search on this forum. Its actually very satisfying to "do it yourself". :D

I got roughly 12 years before I noticed one of the JBL Control 5 sounding a little odd back in the late of 2002:banghead: I brought them around early 1990.