Cone Material Discussion

I think there's more to it than just the cone material. I think it's more about the overall construction of the drivers. The cone material is, of course, very important, but there's more to the implementation. I will recommend looking at the Purifi drivers. They're so much better than everything else I've used in regards to low distortion and accurate reproduction of the signal. Nothing else I've used is even close and the measurements show that. I am working on my 3rd design with them right now. In my experience, they're unbeatable. I have only used the paper cone Purifi but the Aluminum looks to be even better in regards to low distortion and low end extension.
 
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What you want in a cone speaker is for the radiating area to shrink in a controlled manner

This is a particualrily important aspect of drivers use in 1-ways where you can’t (try) to filter out the ringing up top.

One ian trying to get ba well controlled transition form pistonic behaviour to chaotic behavior all the way up. Notice the use of “controlled” and “chaotic” in the same process, it is REALLY hard too do.

Things like cone shape, rings in the cone, even extra surround in the middle of the driver, different thicknesses thru the cone (Diatone 610) usally thinner at the edge), different come materials — there was an English FR (brand escapes me) with a metal inner part of the cone, and paper on the outside), varying cone coating thickness and or placement

I’m not s big fan poly but a favourite woofer was a poly cone, with a “weave” of some fiber. suppposedly carbon fibre, but i doubt it, the fibres were just layered over the cone. They vibrtated when the cone strated moving, and they had impressive ringing —a ring really, only 1. Once i locked down then fybres icer the cone with 3 deceasing iats of midPos=dge (a specific PVA that dries into a more flexible material lthan white glue) with great success.

sdx7wooferwithandwithouttre-gif.1073902


The big whoopmat the topmis flattened right out, making for much greater extension.

dave
 
Right, this is vital if you're wanting to use TL modes to extend the cone's upper operating BW.

With my 'ideal' hat on, drivers operating in pure piston modes over their used BW is actually my preference for multiways, if it can be achieved in the design context. But you need rigid drivers with very clean responses, decent motors etc., crossed with an eye to this (frequency / order & how you handle the stopband modes where relevant).
 
Yeah. I is my understanding that SB uses spark deposition to transform the top aluminum layer to aluminae, a ceramic composite.

"Spark deposition
An immersion-based process that uses an electric waveform to combine the aluminum with an acid-based electrolyte to create a ceramic oxide coating. This coating is resistant to corrosion and wear. "

Equivalent of Mark Audio MAOP process ?

People relate SB26ADC doesn' sound like the SB26CDC. So maybe not equivalent, although the observation could come from factory batches difference ot the front difusor that is not the same...
 
To discuss this sensibly, you first need to determine what you want a 'perfect' cone to do.

I'll start off by saying you DON'T want it to be a PERFECT PISTON. This was understood as far back as Kellog & Rice when they invented the moving coil speaker. Alas since then, there has been loadsa liquid BS about perfect pistons. hence da stupidly $$$ ceramic, metal (to some extent) bla bla materials touted as supa dupa but don't sound good.

Did you arrive on the same conclusion about dome and tweeter rang >2 K hz ? A prefered material here, or ...?
 
Did you arrive on the same conclusion about dome and tweeter rang >2 K hz ? A prefered material here, or ...?
The transition point is kR = 2. see any introductory text on Acoustics eg Beranek or Olson For a given size, it is the frequency above which a piston starts to beam and the radiation resistance is no longer 'simple'.

Below that, good sounding cones are sorta pistonic. Above that, the radiating area must shrink if the unit is not to beam excessively and the radiated power drop. Almost all cone units operate through this point which is why you don't want a perfect piston.

For very small units like dome trebles, you can operate only below kR = 2 so a perfect piston is OK. But the rigid materials will eventually breakup with a HUGE peak; sorta OK if this is at 50kHz.

We made some of the best hard dome trebles, using Aluminium, a diamond like ceramic from Sumitomo, Titanium (not quite as good as the very similar Aluminium dome) and also an experimental Beryllium dome ... cos Marketing wanted stuff hand carved from solid BS & Unobtainium by virgins.

But the favourite dome treble materials of my R&D Dept. were soft. Alas, the formulations we liked are no longer available.

That's not to say, you can't make good speaker systems using hard domes. We made and sold loads. But the second best selling speaker in Europe, one of my inventions 😊 , used a soft dome and was for a time, one of the 3 best small speakers you could buy.
 
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The 'woven' materials (carbon fibre, kevlar bla bla), because of their weave, don't have the required symmetry for nice controlled breakup. IM not so HO, they always sound blah compared to better materials.
Oh no, but woven cones look so neat! Is there any good news here?

https://sites.google.com/site/undefinition/updates/hivil6-4r
I've been thinking about using the HiVi L6-4R (or newer L6-8R) since Paul Carmody said nice things, in particular:
Second, the Frequency Response is very well-behaved. DIYers have lost the easy-to-work-with woofers like the Vifa P-series and Audax over the years, in favor of aluminum and inventive combinations of paper. The L6-4R behaves more like a classic poly cone, and is therefore super easy to work with. Just look at it. It's beautiful! No need for high-order filters here. Lots of room for experimentation, and it's not going to hiss at you like a metal cone if you screw it up.
 
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