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View Full Version : Replace PR15 with LE15?



Donald
02-03-2004, 09:05 PM
The place that re-foamed my LE14 and PR15 in my L222 Disco said they could replace the PR15 with a LE15. How would this work? Would they be wired out of phase with the LE14 so the cones move like the LE14 and PR15 combo.

Any thoughts on how this might sound?

John
02-04-2004, 12:24 AM
:screwy: :screwy: :screwy: :screwy: :screwy: :screwy: :screwy:

grumpy
02-04-2004, 10:07 AM
This would -really- alter the intended design
in ways which you might not find helpful.

Wiring active bass drivers out of phase in the
same box (airspace), especially without redesigning
the crossover could actually result in both poorer
bass -and- damage to the drivers (over-extension
of the suspension). I can't really imagine a good
reason to do this (or that you would need more
bass than this system provides).

-grumpy :confused:

boputnam
02-04-2004, 10:24 AM
Originally posted by Donald
Would they be wired out of phase ...? That would result in phase cancellations, in-addition to the problems that Donald (and John... :rotfl: ) highlight. Two LF's being out of phase would (almost certainly) not increase the bass response.

GordonW
02-04-2004, 08:05 PM
Well...

This is all complete hand-waving speculation... but if anyone has ever examined Vandersteen speakers- he uses what he calls an "active acousic coupler"... which in short, is an "electrically-augmented" passive radiator.

Basically, it's a speaker with a voice coil, tuned by mass to act as a passive radiator, in the same cabinet and working with a normal smaller woofer. However, the voice coil of the "augmented PR" is driven ONLY at EXTREMELY LOW frequencies... where the PR is normally starting to roll off on its own. This not only augments the response below natural rolloff, it converts the bottom-end rolloff to a SECOND ORDER slope, rather than a 4th order... which, in theory, should improve the group delay response of the system.

Sounds almost too good to be true... and mind you, I expect that Richard Vandersteen has had many a night burning the midnight oil, figuring out how to make it work. But I can tell you, I've HEARD the results, they DO work...

Dunno how that would work with an LE15, tho... :spin: At the very least, it would have to be modified by mass loading... probably a very non-trivial technical process of figuring out how to do THAT right...

Regards,
Gordon.

grumpy
02-05-2004, 09:54 AM
This is all complete hand-waving speculation

Nice form. :wave:

Nestorovic, JBL, Vandersteen (other's I'm sure) have all dallied with active/passive LF systems. But adding an LE15 out of phase in an L222 in place of a PR15 without -some- level of system design such as that put into the commercial products (custom driver specs, system-specific crossover networks with separate outputs for each LF driver, etc...) -will- result in very predictable/undesirable results (no hand waving required).

4313B
02-05-2004, 10:15 AM
The place that re-foamed my LE14 and PR15 in my L222 Disco said they could replace the PR15 with a LE15.
Any thoughts on how this might sound? No.

I will say that if one is inclined to run amok doing intentionally stupid shit then they should probably hook up with the folks from Jackass.