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View Full Version : 15s facing down ?



Tom Loizeaux
06-16-2006, 05:58 AM
Quote: "This equipment has been sealed behind massive doors for almost thirty years... The JBL K140 woofers look like they just came out of the factory cartons... The speakers were in custom made enclosures where the woofers faced straight down..."

Doesn't facing down for 30 years raise the question of whether these 15s suffer from cone sag?

Just wondering.

Tom

johnaec
06-16-2006, 07:05 AM
I'd be very suspicious of this. I looked at a used 2226H that had been this way for only a couple years and it had significant sag.

John

frank23
06-17-2006, 01:09 AM
Doesn't facing down for 30 years raise the question of whether these 15s suffer from cone sag?

Very probably and there is nothing but a recone to fix it, I think. It had happened to a pair of 2231H I once bought that had been stored horizontally and I had to have them reconed to 2235 before I could use them.

Frank

garyl
06-17-2006, 03:46 AM
I have never dealt with the facing down orientation and sag problem but I can say just about any orientation after many years can cause some sag or other problems.
With my 19s, I found the black tar on the surrounds wanted to flow down the cone face or pool at the bottom. What I do is flip the position of the woofs every few years to keep them from setting up in any one position.

I would think, but don't know, the magnet should hold the cone in place while not in use both centered and from sagging in either direction?

Gary

johnaec
06-17-2006, 08:24 AM
I would think, but don't know, the magnet should hold the cone in place while not in use both centered and from sagging in either direction?Nope. The magnet has absolutely no effect on the coil when it's not energized. The coil is only magnetic when electrons, (amp power), are flowing throught it. Gravity will definitely pull the cone assembly down when at unpowered rest.

John

Mr. Widget
06-17-2006, 10:54 AM
Sagging woofers... it'll happen to some woofers even when properly mounted in their cabinets on a vertical baffle... I have seen 2230s with their heavily aquaplas coated cones sagging in their 4350 enclosures... many of us rotate our woofers periodically to prevent this. Stored woofers should always be kept on their sides and even then if they will be stored for a very long time you should rotate the box every year or two.


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duaneage
06-19-2006, 10:24 PM
Heat from an attic will make it worse. Some drivers from some manufacturers are not recommended for downfiring since the cone can leave the gap too much.

remusr
06-20-2006, 06:05 PM
Anyone know how JBL stores inventory? I have been told they sit them horizontal, magnet down but to read the writing on my JBL boxes would suggest magnet up. I store mine horizontal magnet up but they are flat-faced down on styro or cardboard. Since the surround is flush with the exterior gasket on most of 'em the surround is actually touching down and helps support the cone weight. Don't know if this is all good as it could flatten the surround but I have a 2235 woof that sat for years and showed some surround flattening that disappeared after a month or so of use. Sounds good too.
My guess is best way to store is probably sideways just like they'd be mounted and rotate them every year or so. But they don't fit my shelves that way, esp the 18's.

Mr. Widget
06-20-2006, 07:14 PM
Anyone know how JBL stores inventory?...
My guess is best way to store is probably sideways just like they'd be mounted and rotate them every year or so. But they don't fit my shelves that way, esp the 18's.I think in line with the current just-in-time manufacturing principles they no longer produce a pile of drivers and leave them on the shelf until they are ready to be installed in cabinets.

If you can not store yours on edge, I'd suggest you should flip them over every few months. It is a pain, but it is also a pain to have to spring for a recone job.


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