Planar & Ribbon Speaker Equations

[rockguitardude]

I've begun my first foray into planar / ribbon speaker design. I built a few simple prototypes but I'm looking to expand to a more sophisticated setup.

Does anyone know of a resource or know of some equations which govern frequency response of a ribbon or planar speaker?

I've noticed through reading that the width of the ribbon greatly affects the bass response but I'd love to find a way to actually calculate the -3dB point of the low end.

Any input would be greatly appreciated!

Thanks,
J

[applehorn]

Originally Posted by rockguitardude

I've begun my first foray into planar / ribbon speaker design. I built a few simple prototypes but I'm looking to expand to a more sophisticated setup.

Does anyone know of a resource or know of some equations which govern frequency response of a ribbon or planar speaker?

I've noticed through reading that the width of the ribbon greatly affects the bass response but I'd love to find a way to actually calculate the -3dB point of the low end.

Any input would be greatly appreciated!

Thanks,
J

Hi,

You wish to get hold of a copy of Ribbon Loudspeakers... by Justus Verhagen. This has plenty of theory.

BKAA65 - Ribbon Loudspeakers

Best wishes.

Iain.

[JAMESBOS]

Go to full range planars using neos, full of pictures and helpfull advice. I've built full range planars over the last 20 years.

[rockguitardude]

Thanks for the book recommendation! I saw it before but was worried it wouldn't be advanced enough. I can't wait to get it.

[rockguitardude]

Ack. They don't have anymore in stock and said they won't be getting them for months. Does anyone know of somewhere else to get this book? Internet searches have turned up nothing =(

[gootee]

Any book on The Calculus of Variations would cover the partial differential equation which describes the motion of a vibrating elastic membrane, and the solution of the equation.

Here's a free one, on line, found with a search on google.com for "calculus of variations membrane" (search results here: calculus of variations membrane - Google Search ):

Calculus of variations: with ... - Google Books

Here's another one:

Calculus of variations - Google Books

In the first one, they even solve for the eigenvalues and eigenfunctions of a rectangular membrane of uniform density, in Section 9-8, starting on page 160.

But it sure seems like setting up a finite elements model of the physical system and simulating it in software might be the best way to go. (Then later you could, for example, add magnets and conductors and a subset of Maxwell's Equations and apply signals and measure the simulated response, etc.)

Apparently there are even some Java applets on line that simulate vibrating rectangular membranes. I haven't looked at any of them but links to them are included in the google search results for "vibrating membrane simulation" ( vibrating membrane simulation - Google Search ). You can add the word "rectangular" to that search and try it again.

Cheers,

Tom

[applehorn]

Originally Posted by rockguitardude

Ack. They don't have anymore in stock and said they won't be getting them for months. Does anyone know of somewhere else to get this book? Internet searches have turned up nothing =(

Ok, I wonder if a new version is about to appear. In the meantime, how about having a look at some relevant USA Patents, which have appropriate information. Use International Classification H04R$ and use ribbon, planar etc for description. You can also use inventor names like: Levitsky, Bohlender, Graebener, de Haan. The link to the AES paper by Phil has a lot of useful information, about the Stage Accompany driver. I am sure that you will discover that the real secret, is the material technology. Do you have a magnetic modelling program? FEMM is worth checking out.

http://www.stageaccompany.com/downlo...es/aes8535.pdf

Iain.

[gootee]

Originally Posted by rockguitardude

Ack. They don't have anymore in stock and said they won't be getting them for months. Does anyone know of somewhere else to get this book? Internet searches have turned up nothing =(

(Ack. Apparently you didn't do a google search for the author's name.)

Maybe Dr. Verhagen has a copy he would sell you. Why not call or email him? Contact info: Purest Music: About Us

Also, I found a full download of that book, in RAR format: Ribbon loudspeakers Justus V. Verhagen » Full Rapidshare Hotfile Megaupload Megashare Downloads by LatestDL

Cheers,

Tom

[rockguitardude]

Originally Posted by gootee

(Ack. Apparently you didn't do a google search for the author's name.)

Maybe Dr. Verhagen has a copy he would sell you. Why not call or email him? Contact info: Purest Music: About Us

Also, I found a full download of that book, in RAR format: Ribbon loudspeakers Justus V. Verhagen » Full Rapidshare Hotfile Megaupload Megashare Downloads by LatestDL

Cheers,

Tom

I appreciate the effort but I hope you didn't click the link. It's definitely a virus.

Maybe I'll give the author a try as you suggest. It's worth a shot I suppose.

Luckily someone I know works for a library inter-loan program and may be able to get a hold of it to me. (Not sure why I didn't think of that to begin with).

Thanks for the google books link, it definitely seems like a worthwhile read. It's exciting getting back into this stuff.

Cheers,
J

[gootee]

No, I didn't click on the book-download link. If it had a virus, I'm very sorry about that!

Please let us know how you get on, with your efforts.

Regards,

Tom