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driver tweak to King BR box [message #22048] Wed, 31 December 2008 14:04 Go to next message
jim denton is currently offline  jim denton
Messages: 162
Registered: May 2009
Master
Many months ago Bob Brines told me I could remove the cast basket off my Lowther EX-2's to make them DX-2's seemed dangerous an after months of irration at how bad the King BR box sounded I did it--and boy was Bob spot on! Major improvement!! come to find from serious surfing that there are few designs with the EX 2--especially in the DIY world...now a new search for a DX-2 box to build! Jim

Re: driver tweak to King BR box [message #22049 is a reply to message #22048] Wed, 31 December 2008 15:22 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18787
Registered: January 2001
Illuminati (33rd Degree)

Not sure what you mean. To me, the basket is the frame. Can't very well remove that. Are you talking about a magnet cover or something?

What changes? Do the T/S specs change, perhaps by removing a vent plug or something?


Re: driver tweak to King BR box [message #22051 is a reply to message #22049] Thu, 01 January 2009 11:44 Go to previous messageGo to next message
Bob Brines is currently offline  Bob Brines
Messages: 186
Registered: May 2009
Location: Hot Springs Village, AR
Master
Wayne,

Here is the back of an EX4:

And here is the back of a DX3:

(Sorry about the scale, but that is all Lowther offers.)

Note that under the EXx cover is the complete, unmodified DXx frame, basket, whatever, including the binding posts.

As to T/S changes, I doubt that there is any change at the small signal level, but major changes at large signal. I have not measured these. The EXx cover severely damps the back wave. An EXx will not load a resonant cabinet, whereas a DXx works just fine in a MLTL.

If you buy a new EXx, you get the lemon squeezer phase plug. New Dxx comes with the bullet phase plug. I prefer the bullet, but YMMV. I would have brought my MLTL's loaded with DX3's to LSAF, but....

Bob



Re: driver tweak to King BR box [message #22054 is a reply to message #22051] Thu, 01 January 2009 12:23 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18787
Registered: January 2001
Illuminati (33rd Degree)

From the looks of it, the EX cover is pretty significant. I expect there may be some changes even at the small signal level. The volume of air behind the cone and the area of the openings forms a sort of chamber/throat relationship. This will affect the electro-mechanical parameters and it should be readily apparent in measurements. I would definitely measure T/S parameters after removing the cover to know what the modified driver does.


Re: driver tweak to King BR box [message #22055 is a reply to message #22054] Thu, 01 January 2009 12:35 Go to previous messageGo to next message
Bob Brines is currently offline  Bob Brines
Messages: 186
Registered: May 2009
Location: Hot Springs Village, AR
Master
You may be right about the small signal parameters. I took the backs off of my EX2's years ago and don't have a before/after comparison. As always, note that Lowther's published figures are pure fiction. My numbers agree with MJK's for the modified EX2>>DX2. Martin also has T/S numbers for many of the Lowther drivers.

Bob

Re: driver tweak to King BR box [message #22056 is a reply to message #22055] Fri, 02 January 2009 09:00 Go to previous message
Martin is currently offline  Martin
Messages: 220
Registered: May 2009
Master
I have always wondered if you could model the a Lowther EX driver as an undersized bass reflex system, which you then put into a larger resonant enclosure. The potential result could be similar to a double bass reflex system. If this were the case, and the designer mistakenly put the EX driver into a DX cabinet then it would not be too surprising that a non-optimal system was the result. Maybe there would be some advantage gained if the cover was modeled and the designer actually took it into account when designing the enclosure. I don't have any EX drivers so this is pure speculation.

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