Voice coil diaphragm speaker

[Ed Holland]

Funny how one search leads to another line of interest... I turned up this concept for driver design:

http://www.geocities.jp/adsshp/indexE.html

It looks like a lot of effort has gone in to R&D. Its an interesting idea, if a bit demanding in the magnet department.

Ed

[Ziggy]

Very interesting Ed.
A competitor to the PLANOT?

[Ed Holland]

Surely not....

Actually I was searching for ideas, prior examples etc, of cylindrical speakers - something away from the Walsh, or other designs with a conventional driver and an acoustic diffuser.

I have this notion, and it's only a notion, of something like a Magneplanar, except it is wrapped around a cylinder, and suitably dimensioned to overcome the directivity that my SMGa's panels exhibit.
I can already anticipate constructional difficulties in tensioning a diaphragm and applying voice wires in this geometry, but it might be possible.

It's also anticipated that the enclosed volume might be used (or not) as a means to modify the bass response, though I wonder what might be lost here, in comparison to the open baffle nature off the maggie panel. Either way, you'd still have a tranducer with the benign impedance curve and minimal amplifier interaction that is characteristic of the maggie.

Any thoughts?

Cheers,

Ed

[Ziggy]

Yeah, ........ I get your drift Ed.
I too am looking at different ways to reproduce music.

I have large 2 way AZZURA horns at home and even though it sounds magnificent, I somehow feel that not all the information recorded on C.D.'s is getting through.

I'm also suddenly(overnight) become sensitive to colorations and distortion(why I have changed from S.E.T's to MOSFET SOLID STATE).

The horns are probably adding coloration also but not as much as some others I have heard.

Seriously considering building a tall ribbon to go as low as possible without too much of a speed mismatch to the dynamic bass section(if that's at all possible). I don't wish to go down the ribbon bass panel or ESS route at present - too much hassle.

I'll keep researching. If you find anything let us know.

[Ziggy]

P.S...........used to own some TIMPANI's and MG11's .......loved em.........should have kept them except the W.A.F. came in on it !

[david yost]

Bart Locanthi at Pioneer in the early 70's used a pair of cylinders as tweeter and supertweeter in the HPM-200. The things were made from a piezo-electric film and were roughly 3" and 1 1/2" in diameter respectively. I have never seen or heard of this type of material being used for mid/low frequencies, but it would be interesting to try. Anthony Gallo currently uses a version of this tweeter in several of his designs.

Anybody know what this film is called or how to procure some?

David

[torroid88]

Unfortunately, it looks like a single-ended electrostat, meaning it will not have the balanced forces acting in it that will cancel even harmonics ... And will suffer from inverse square law non-linearity ...

[Calvin]

Hi,

since its motor structure relys on magnetic forces, it should be rather seen as a ´coiled ribbon speaker´, instead of a single-ended ESL.
But as toroid says it will be quite nonlinear because the coil is placed within the highly nonlinear strayfield of the magnets.

jauu
Calvin

ps. besides, the negative claims about ESLs on the website are false.

[PigletsDad]

Originally posted by david yost
Bart Locanthi at Pioneer in the early 70's used a pair of cylinders as tweeter and supertweeter in the HPM-200. The things were made from a piezo-electric film and were roughly 3" and 1 1/2" in diameter respectively. I have never seen or heard of this type of material being used for mid/low frequencies, but it would be interesting to try. Anthony Gallo currently uses a version of this tweeter in several of his designs.

Anybody know what this film is called or how to procure some?

David

I think they used a PVF (poly vinylidene fluoride) film, which is "poled" by applying a strong electric field while it is solidfying.

This is a vague memory of reading some description of the Pioneer technology 30 years ago or so.

[Ed Holland]

David:-

I noted the Gallo design already, designated CDT I believe. It seems to have a very good reputation. Tricky to DIY though, without access to the piezo film material and vacuum coating equipment.

torroid88
Good point about the non uniformity of the drive in the voice coil design, that could be a problem. It's a frequent criticism of some Magnepan designs, though I still love these speakers.

Ziggy:-

I got lucky, when I suggested the Maggies to "Mrs H" she went out and bought a second hand set from Craigslist as a birthday surprise, preferring them over conventional boxes! I'm a lucky man indeed. Then I got to learn how to rewire tired maggies.

On the subject of 360° dispersion I also recently saw this Elac driver:

http://www.elac.com/en/products/classic/4pi2tech.html

Interesting stuff.

Now I wish I had an unlimited supply of surplus magnets.