123A surrounds last forever?

[Mitch Noble]

I've been checking out the different threads about surround rot and replacement.

I had to replace the surrounds on some L46's that a friend gave me, but the 123A's in my L100's still look fine after all these years. I see that they are made of different stuff, but how long do the surrounds last? I hope forever. I really love those speaks!

Is there any tips to keeping the speakers in good shape? I turn them upside down around christmas time every year because a friend told me if you leave them in the same orientation all of the time the speakers would sag. Is that true?

I'm glad to find a forum full of JBL lovers. I've had that set of L100's since my brother sold them to me in 1981 after he found a set of L200's that he liked better.

His L200's are long gone, but I will have those L100's as long as I have a house to put them in.

[rek50]

Forever??? According to the "Nelson" banished to the basement, by Ozzie and Harriet, "Nothing lasts forever, 'cept old Fords and a natural stone"....:)

[Zilch]

How long do the surrounds last? I hope forever.Alas, they will outlast all of us here....

[Think "Tar Pit." :p]

[Mr. Widget]

The surrounds will certainly last a very long time especially if the woofers are rotated periodically. If played hard regularly the spiders will not last as long.


Has anyone studied the deterioration of spiders in general? Gordon? Lancer?


Widget

[Titanium Dome]

Alas, they will outlast all of us here....

[Think "Tar Pit." :p]

I'd rather not. ;)

But the darn things are long-lasting, and JBL felt pretty sure about quality.

From my L100 warranty card:


Moreover, because we believe a fine louspeaker, like a fine musical instrument, should never wear out, we will repair any JBL transducer free of charge without time limitation if factory inspection discloses evidence of an original factory defect.

That's why years after the two year warranty ran out, JBL fixed the woofer free for me, no questions asked, when their inspector discovered a flaw. :applaud:

[Don McRitchie]

The doped pleated surrounds are not indestructable. There are three main issues to watch out for - dust, heat and humidity. Dust can attach to the doped surrounds, drawing it out and drying the compound. Heat and humidity can cause the dope to lose its viscosity and migrate out of the surround and into the cone material. It's relatively rare for these conditions to develop, but I have seen it happen.

[boputnam]

... I will have those L100's as long as I have a house to put them in.Well, not that I have any ill regard for your house, per se, but you might try a pair of 4312's, just as a comparison...

And, to moot the pleated surrounds question, drop a pair of 128H's in them 4312's, and really light-up the ears!

Lastly, a plot from a very old thread to consider the merits of the 128H

:slink:

[GordonW]

The surrounds will certainly last a very long time especially if the woofers are rotated periodically. If played hard regularly the spiders will not last as long.


Has anyone studied the deterioration of spiders in general? Gordon? Lancer?


Widget

Depends on the material. I've seen spiders on some older speakers just seem to rot, and rip at the lightest load... but I've never seen this happen to a JBL speaker, that I can remember...

If the speaker is mounted in a cabinet where it's shielded from direct sunlight (UV and the like), and from excess dust or contaminating elements, they seem to last pretty much indefinitely, in most JBL stuff I've seen. It is, as was mentioned above, hard use/abuse that "stretches" them, and causes them to need to be replaced...

Regards,
Gordon.

[edgewound]

Nothing flexible or elastic lasts forever. Not even doped cloth surrounds. Yes...they last alot longer...but the thing that really wears them out is playing music through them. The mechanical fulcrum points at the spider and surround will simply breakdown from the repetitive motion of moving back and forth. The louder it's played the faster it wears out. Speakers that have been around for 40-50 years and are still playing probably belonged to your or someone else's grandparents and were never turned up beyond background music listening.


The problem with foam surrounds is that they simply rot...oxidize. And in high humidity climates they get eaten by fungus and mold...ever seen the little powdery spots on a foam surround?....it's fungus. I've seen it alot from speakers that were brought home from the Philippines. The other problem with foam surrounds is they sound the best for hifi/studio monitoring use...or should I say don't sound at all...higher internal damping from the little air pockets inside the foam...and the woofers can extend lower in frequency due to higher compliance. Even butyl surrounds crack over time, and Santoprene has a lower compliance(stiffer) than foam.