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View Full Version : 4315 with two bassports ???



stefan_gsx
06-10-2012, 10:41 AM
Hi !

I´ve got my hands on a pair of 4315, in absolute mint cond. (of course I have to replace the surroundsbut got them from audiofriends in The Netherlands, superb quality.)

The speakers had not been used for 32 years ??? They was resting upstanding in original package in a cellar. All the factory packaged docs was inside,even the 5 year warranty label.


Now my question.

Why did JBL went from 2 bass ports to one, tried to find out some info on the net , but no success.

Regards ...

Stefan

Odd
06-10-2012, 11:28 AM
Do not know why they changed, but looks like it was manufactured with two ports in 1981 and later with one.

55964

55965

mech986
06-12-2012, 12:26 PM
Do not know why they changed, but looks like it was manufactured with two ports in 1981 and later with one.

55964

55965

Probably easier to tune (maybe slightly revised?) with one port, less likely for critters to crawl into, and allowed the woofer clamps to be arranged symmetrically.

subwoof
06-12-2012, 07:05 PM
these were introduced and sold in the short time ( like others ) during the big change from alnico to ferrite magnet structures. By changing the model numbers and baffle layout the various generations could be easily recognized. I have a set of 4315's in the study and had pairs of 4315A and 4315B over the years. there are arguable differences in the low freq between the alnico and ferrite models.

sub

Mike F
06-12-2012, 07:59 PM
The arrangement of the MA15 just looks wrong in the 2 port version me thinks.

ratitifb
06-18-2012, 12:44 PM
The arrangement of the MA15 just looks wrong in the 2 port version me thinks.not really wrong if you consider the vicinity of the 2 port holes vs the 2 MA15 fixing area at the bottom :dont-know:

Mike F
06-18-2012, 06:53 PM
not really wrong if you consider the vicinity of the 2 port holes vs the 2 MA15 fixing area at the bottom :dont-know:

True, but relocating the ports at say 9 and 3 o`clock relative to the woofer would make it a little more cosmetically appealing.
I`m sure there was a good reason for that arrangement.