Why this shape

New to planar magnetic drivers and I am finding them very interesting, and since I am working on an loudspeaker which take advantage of dipole property's, planar magnetic drivers is kinda a necessity. But why the (mostly) rectangular shape, does it have a property favorable over round ?. Is say the vertical propagation of an elongated driver more desirable than its circular cuisine ?
If anyone has a take on this, come forward 🙂
 
1) Efficient use of materials and methods. Rectangles lend themselves to easy cutting, bending, etc. and produce less scrap.
2) Aesthetics - rectangles typically blend better visually in the average home.
3) Line source behavior allows for good horizontal dispersion while simultaneously employing large surface area. This also limits vertical dispersion which is often considered a benefit as well.
 
  • Like
Reactions: Oneminde
Line source behavior allows for good horizontal dispersion while simultaneously employing large surface area. This also limits vertical dispersion which is often considered a benefit as well.
The answer to this is going to depend on which dimensions, not wanting to be random. Also on preferences, not all prefer H and V to be opposite.. as well as the diagonal, which is the reason to give consideration to the idea of oval even if it is not chosen.
 
  • Like
Reactions: Oneminde
as well as the diagonal, which is the reason to give consideration to the idea of oval even if it is not chosen.
What I find interesting with the oval or elliptical shape is that it can be tailored made to meet a specific V and H dispersion pattern. Say you have a Line Source, here, the rectangular shape or "super" oval is perhaps better suited than for the Line Array / D'Appolito which uses dynamic drivers for the bass section, here, the overall pattern is probably leaning more towards round more so than "super", but could still have an overall oval shape.
 
Since you mention it yes, super-elliptical or oval. A design may go far enough to find the perfect shape but until then, this is just broad speaking.

Keele's better shaded array had drivers in the form of a spherical cap. He also talked about a shaded line array, and I think this was a better subject for discussing how the shading worked. However building the line array instead of the spherical cap, while considering one dimension and not another, doesn't make sense. If you choose to build a single driver wide line array then it should be because you have decided to have it exactly that width as well as height.
 
I have seen the Don Keele's type line source, which is the one you are referring to I guess ? .. but didn't pay much attention to it. Line Source and Line Array in terms of interest is new to me and the reason for this is simply not grasping the benefits of a narrow baffle before I heard some of YG Acoustics loudspeakers, ran into a few video's of Danny Richi / GR Research regarding Open Baffle dipole U-frame cabinet and reading some of the material provided by Music and Design / NaO loudspeakers as well as Martin King among others... and here we are 🙂

But that is besides the point of planar magnetic quasi ribbon driver... and yes, this is juts broadly speaking.
 
  • Like
Reactions: batteryman
A dipole with a diaphragm that extends to the edge can give you a large radiator without an extension baffle.
That is were I am heading, U-shaped Open Baffle Line Array/Source. I know the magic a narrow baffle can offer and can imagine how unloading the drivers, aka get them out of the f*** cabinet... LOL, will increase their performance, unload or reduce the room resonance.. and so forth.

Considering how long the classic loudspeaker has been on the market and even if you increase the driver performance, you are still battling the cabinet. Something have to change or give.

"In order to be better you have to be different, but the merely different isn't always better"
 
You should check out Radian which have been mentioned here on diya. The performance of their planars looks to be very good. I communicated with them today and the 10" version is common soon. I might start with them to have a reference for when I develop my own planars ... because ofc I will 🙂

https://www.diyaudio.com/community/threads/radian-audio-lm8k.337631/
Thanks. It is similar to the GSR 200mm unit I'm using. I need to reduce the output by about 6db with a L pad to better match the Aeons bass unit but pleased with the results so far.
 
How do you like their presentation compared to good dome tweeters ?
It's hard to compare because they are fitted into the Aeons in place of the electrostatic panels, hence why I wanted dipole drivers and to try and recreate the sound of the Aeons as much as possible. I also wanted just one driver to cover the range from 450hz to avoid interaction between mid and treble drivers.

I can't be more defintive as I have only done one and won't have the second working until tomorrow. There isn't a great mismatch apart from in level with the original worn out Aeon.

So far so good...


The only dome speakers I have are in TDL RTL3SE which of course are box speakers and sound like them too.
 

Attachments

  • mlrevamp.jpg
    mlrevamp.jpg
    102.9 KB · Views: 73
I think if the phase is the same for the mid and tweeters, there shouldn't be an issue, same thing for the material they are made of. If all is comparable besides their Sd, they should sound the same. The issue with pushing drivers beyond 4 octaves is non-linear distortion creeps in. So if your driver starts at 450Hz, then 1st oct is 450-900Hz, 2nd oct is 900-1800Hz, 3rd oct is 1800-3600Hz and the 4th oct is 3600-7200Hz... that is roughly it for the linear or pistonic region. That is ofc if the driver is capable of playing pistonic down to 450Hz.

One shouldn't be worried about using multiple drivers, just like one shouldn't worry about using enough components in the crossover.

Also, I hope you are considering mounting the driver flush with the baffle, looking at the image, you have too many edges on the front which will cause edge diffraction's. If you are only testing, please ignore comment 🙂