[dB Cooper]

Was wondering why no home speakers I know of (with one exception: Boston Acoustics used to have some models doing this) ever used oval drivers? There would seem to be some advantages: Directivity could be controlled, breakup modes might be more 'spread out', and there might be other benefits. Aside from 'auto speaker stigma'. and maybe it is a little more costly to make an oval driver, why else has this type of driver never caught on? Are there. in fact, any real advantages (or disadvantages) of an oval over a circular shape? (And then there were those bizarre ear-shaped speakers Yamaha sold in the 70's....) Just curious...

[dB Cooper]

Not to immediately derail my own thread, but just for giggles, here's a pic of the Yamaha speaks I referred to,

[Phil A]

How about these?  http://www.safeandsoundhq.com/polk-audio-lsi-m705-floorstanding-speaker-(each).html

[guest60106]

KEF was one company that utilized oval drivers to their fullest extent.

[dB Cooper]

How about these?  http://www.safeandsoundhq.com/polk-audio-lsi-m705-floorstanding-speaker-(each).html

Well, those are a whole 'nother implementation of a moving coil driver- they have a central voice coil and a latticework frame behind the  panel to give it rigidity. They are not really 'cones' in the dictionary meaning of the word.  Interesting design though. Polk had them at Capitol Audiofest last year although they only played the monitors while I was there.

Harvylogan, I was unaware of the KEF oval drivers; thanks.

[G Georgopoulos]

dbcooper there is no difference whether oval or circular,the voice coil and suspension is the same only the cone is difference,hope this answers your question...

[JohnR]

Are there. in fact, any real advantages (or disadvantages) of an oval over a circular shape?

I suspect that there are no advantages to an oval driver, except in the case where the driver has to fit into a particular space.

I would assume that circular drivers are easier to specify and manufacture.

Only vaguely related: I wish that all drivers were made with a circular frame. As a DIYer without CNC capabilities, a round frame is one of my criteria for choosing a driver.  For the simple reason that round holes are a lot easier to cut and (especially) route than any other shape. That does count out some interesting options but... well, there are plenty of options anyway.

FWIW 

[dB Cooper]

Well, you know about things like cone breakup and standing waves, right? In a circular driver, the sound wave originates at the voice coil and travels to the edge of the cone where some of it is dissipated by the surround and some is reflected back. The frequencies those effects happen at are related to the distance traveled (cone size) and the speed of sound in the chosen cone material. Additionally, the cone is not perfectly rigid and intermodulation products resulting from cone flexing- again relating to the same factors- occur.

To relate this to my original question: In a circular driver, every point on the circumference of a circular driver is equidistant from the voice coil. So the cone resonances/breakup will be the same anywhere on the driver and strongest at a particular frequency. In an oval driver, both the distance to the edge of the cone and (as a result) the cone profile are different at different points on the driver and therefore the resonances and breakup artifacts should be more "spread out". Am I right? And I was just wondering if this is true and if so, so few manufacturers have sought to take advantage if it. Any speaker mfrs here want to sound off (pun intended)?

JohnR, I'm sure an oval driver is a little more expensive to build, but can it really be that much?

[jules]

... or, you could argue that the cone on the long axis will be less rigid than the it will be on the short axis leading to uneven reproduction of any given coil movements but, who knows  ?

jules

[*Scotty*]

As I understand it there are problems with the surround design and proper edge termination associated with woofers that are actually oval shaped.
The problem comes from uneven flexure in the surround that is a function of increasing excursion.
I could wrong however, maybe Danny Richie has some insights into oval loudspeaker design.
Scotty

[Vapor Audio]

I'd think it would be obvious that a circle is much stronger than any other shape.  Once cone breakup begins, it's happening in different ways at all frequencies above that point.  By making a less rigid cone, you're just guaranteeing that the point where it begins is lower in frequency. 

[JohnR]

In a circular driver, every point on the circumference of a circular driver is equidistant from the voice coil. So the cone resonances/breakup will be the same anywhere on the driver and strongest at a particular frequency. In an oval driver, both the distance to the edge of the cone and (as a result) the cone profile are different at different points on the driver and therefore the resonances and breakup artifacts should be more "spread out".

My understanding is that it doesn't matter what the shape is, there will be breakup modes. See this Chladni plate demo: http://www.youtube.com/watch?v=lRFysSAxWxI (turn the volume down before playing...!)

[dB Cooper]

I should probably have just put on some music rather than sitting around thinking about technical b***s***.... I think too much

[charmerci]

I should probably have just put on some music rather than sitting around thinking about technical b***s***.... I think too much

Aren't you listening to music while writing on the internet and thinking of all this stuff?

[stereocilia]

I wonder if the oval has any disadvantages over a racetrack shape.  Definitive makes some speakers with that design.  Linn did too.  Why not ovals?  I don't know maybe it fits the thin cabinet better? 
Definitive Mythoshttp://www.definitivetech.com/images/products/large/093207052699.jpg
Linn Keltik http://www.hifidatabase.com/static/gallery/6/6096-Linn_Keltik.jpg

[dB Cooper]

Aren't you listening to music while writing on the internet and thinking of all this stuff?

You would think, right?

[JohnR]

I should probably have just put on some music rather than sitting around thinking about technical b***s***.... I think too much

Not at all, it's worth thinking about!

If you have drivers lying about, try putting your finger gently on the edge of the cone at the back (near the surround). It's interesting a. how much it flexes and b. how different different cones are. Same kind of thing for surrounds. So I suspect that controlling breakup is much more about the cone and suspension material than the shape.