1 Attachment(s)
LE15A, 5.5 cubic ft., port vs closed box
Quote:
Originally Posted by
speakerdave
The LE15A was initially presented by JBL as a sealed box driver. Does anyone have any experience with it in that type of enclosure? I've read quite a lot about disappointing bass from this driver in bass reflex enclosures, but no one seems to look at the more gradual roll off of low bass in a sealed box which results sometimes in actual greater extension. That coupled with careful use of room rise might get a good result with this driver in a livingroom sized space. Since this driver was first offered for either closed box or bass reflex, I should think it would be an option to try sealed. I would think also that the big magnet would be an advantage for that.
I think the real price of going sealed over bass reflex with that driver (and others) would be either remembering to stay within the decibel level it can produce safely that way (not a problem most of the time) or adding more cone area. The added cone area dictates a low crossover point for me. I find that even crossing over in the mid-hundreds there is definitely a sense of multiple sources that I don't care for (at my listening distance--10-12 feet). Even drivers side-by-side, following the most conservative view on when acoustic coupling occurs (acoustic centers a quarter wave length apart), pairs of 15 inch drivers must be crossed over at under 200 Hz.
David
Here you go - old fashioned data from a real oscillator (port tuned to 31-32 Hz):
"old fashioned" test gear
Nothing fancy, the response includes the room etc. Gear was an old HP 200 CD oscillator (recently refurbished) and the engineering standard, RadioShack sound level meter :blink: a couple feet back. Tried to stay close to minimize the room effects - not to engineering test standards - but surely shows the Helmholtz effect. Speakers are 30 years old! Owner is much older. MM