Anybody seen this type of planar speaker?
 

also how would be the layout of the membrane where would be the conductive lines?

here's the add

SFI BIPOLE RIBBON TWEETER 4PC SETS EMIT-R ??

http://cgi.ebay.com/RIBBON-TWEETERS-...3A1%7C294%3A50

* BRAND: SFI - SAWAFUJI
* MODEL: SZ-2B
* OUTER DIAMETER: 1 1/2"
* CUTOUT DIAMETER: 1 1/2"
* SCREW SPACING: NONE
* OVERALL DEPTH: 7/16"
* MOUNTING DEPTH: 7/16"
* MAGNET DIAMETER: 1 1/2"
* COIL SIZE: PLANAR ELEMENT
* WEIGHT: .15 LBS
* IMPEDANCE: 8 OHMS
* POWER HANDLING: 50 WATTS

IF CROSSED OVER PROPERLY THE POWER HANDLING SHOULD

I'm also selling these and here's a link with
lots of information from Planet 10 on his t-line speaker
website...
http://www.t-linespeakers.org/drivers/ribbon.html

Steve @ Apex Jr.

I see the eBay guy poached my graphic... if i were you i'd buy them from Steve.

Even if there isn't a diyA discount, he is a known, good entity.

BTW i scored a set of Akai mini speakers that use these tweeters, Until the surrounds fell of the passive radiators they were my favorites in their class.

dave

Yeah, in the headphone world these are called "orthodynamic" drivers. A term coined (I believe) by Yamaha.

Over on Head-fi there is a long thread called "orthodynamic roundup" which talks all about this type of driver. I have personally built several headphones using this exact driver.

Essentially a planar magnetic driver these can sound quite good as headphone drivers, even though these particular units were originally designed for tweeter use.

Has anyone tried sacrificing one of these for it's front magnet to replace the rear magnet of another unit; effectively creating a dipole?

Yes.

No big difference.

dave

I don't know much about ribbons, but would it not at least make the motor structure more linear having the same magnetic force on both sides?

well it seems not verry usefull to do something with it exept making a headphone :). i was looking for neodym magnets and found rings and discs, so i rememberd some kind of driver using discs. but it looks it wont do any good replacing them with neodym.

I was mistaken, I thought the image you had posted was of the dipole version.
The seller used to (may still) have dipole versions with the perforated magnet on front
and back in 32 and 120 ohm.

I made several "frankenphones" with the dipole type but ultimately ended up preferring the production Fostex phones, which have the same type of driver.

All Magnepans I know have magnets on one side of the mylar, and voice coil wire on the other side.