Discussing Cone Material

RedGTiVR6 · 08-07-2006, 12:23 PM

I was reading up on another forum and came across this post from a user over there. Great post discussing the differences in cone material.

With the individuals that regularly post on this board, I thought it might be a good discussion starter, so here's his post:

The original question that started it all:

Quote: Originally Posted by emperorjj1

In terms of sq what are the best materials to get for diff drivers. ive herd paper for subs, and silk for tweets. is that right? and what about midrange and midbass drivers? i know more then the material matters but im just wondering which is the best

Quote: Originally Posted by Anthony_B_Davis

If you can get your hands on a Focal Utopia Beryllium brochure, read it and it will explain the Optimization of Lightness, Rigidity, Damping and Velocity. You should read up on the Design of the W cone also.
http://www.focal.tm.fr/accueil_en.htm

The point is it’s not so match the material as it is the resulting properties.
You need to optimize the material based on the frequency range you want to reproduce.

For example a silk dome has great damping properties which reduce ringing of the cone at high frequencies, yet all great silk dome tweeters are treated resulting in improved rigidity.

Hiquphon tweeters are revealed as some of the greatest silk dome tweeters on the planet yet they all have some form of treatment. In fact, the primary difference between the 4 tweeters they offer is treatment, which has result in a different response between drivers that are nearly identical otherwise.
http://www.hiquphon.dk/

The same could be said for subwoofers, woofers and midranges.
For example most paper subwoofers are treated for sealing but this also develops rigidity. Mean while Image Dynamics’ original IDQ used a composite, similar to the Focal’s W-cone, and they developed the proper properties resulting in a great sounding subwoofer.

A paper cone woofer playing Midbass and Midrange needs treatment to perform better. See the SEAS Nextel cone ( http://www.seas.no/PDF%20data%20exce...LY001E0041.pdf ). The Nextel performs better than their plain paper cone for attack and distortion yet it does not have the attack or decay of the Magnesium cone. Because the Mg cone is stiffer it will go into resonance in the upper frequency range. A Paper or Damp Polymer Cone (DPC) will roll off the upper frequencies and require you to reduce the cone diameter and weight to play higher frequencies. The Mg cone just requires some tuning tricks and you can get an 8” Mg Driver to play MUCH higher than an 8” Paper or DPC cone while playing just as low.

All this dribble just to say the BASE material REALLY does not matter, it’s the resulting properties required for the task at hand that matters.

Anyone have any thoughts they would like to add to this?

ATXaccord05 · 08-07-2006, 01:57 PM

I agree, there are quite a few factors other than cone material that determine what the speaker will sound like. I've had way too many people tell me they want "good sound" and it all depends on what sound you're going for.

Abmolech · 08-08-2006, 12:52 AM

There has been a lot of "work" put into cone material. Suffice to say there are very little gains to be had in the material of the cone. A heavier cone material results in a lower Fs and a drop in efficiency. However on the plus side, it allows a smaller enclosure and lower frequency extension. Witness the "home audio" driver converted to car audio with the event of "doping" to allow them to run in a ultra violet environment. You may also notice them try to compensate for this with a drop in motor force (Bl) to try to maximise output. (That is from 8 ohms nominal impedance to 4 ohms).

The main problem with cones is resonance within the desired bandwidth, and of cause the harmonics developed over this band. Tests are reasonably conclusive that the choice of cone material contributes very little to dampening. Surprisingly the most important aspect of this is not the cone material but the choice of surround. One of the main differences between "fakes' and the real thing is this termination. If you observe the fake for all intense and purpose it is the 'real" thing. Same cone material, basket size and often a "superior" motor. They normally suck, because they miss the most important part of driver design the "surround termination".

The largest gains on cone material have come from superior manufacturing techniques that have allowed far more consistent results. Expect to see a wide range of materials being promoted to garner your attention, the gains in this area will be small.

We are "spoil-ed" for choice, discern a driver based on the best fit for the application. For me cone material choice is majoring in the minors. The real gains are in harmonic and transient response from a "correct" combination of suspension compliance and surround termination.

RedGTiVR6 · 08-08-2006, 08:18 AM

Abmolech - just curios - I notice that this is your first post. What got you to this site? This particular post?

Thanks for your input btw.

Abmolech · 08-08-2006, 10:20 AM

Yes, hobby horse of mine.

I was searching for crossover solutions for a complex setup. I was rather hoping for "pc'' crossover solution. So the only I far only found one external suitable solution (internal sound cards suck for induced noise).
If you note my join date, it was some time ago. At the present moment I am considering modding pro audio gear for this.

Cone material and termination is a facinating subject. To get you postulating about this, why do not drivers move both the apex and the cone edge in a ridge frame as one unit, that is, why have a surround at all?
Hint it is anti-nodes and nodes causing harmonics.

Specifications can tell you alot about a drivers performance but their primary usage is enclosure design. This is why listening tests still are valid for speakers.

RedGTiVR6 · 08-08-2006, 10:33 AM

Have you seen the thread discussing different software options for processing yet?

Abmolech · 08-08-2006, 03:12 PM

To be honest I haven't kept up with it.
This is one I was toying with.
http://www.thuneau.com/index.htm

I will check again.

My ideal would be "brick wall" crossovers that can handle 12 outputs.
I don't wish to drag this thread off topic.

I will use the search button.

OK doesn't seem to be much further ahead than my suggestion for a software crossover. If you could give me any other hints I would appreciate it.

durwood · 03-17-2007, 12:41 PM

Old thread but in case anyone comes looking here I wanted to add this. OT, but lightly related, thought I would include this here too.

Geometrical Stiffness of Loudspeaker Cones

Found on www.zaphaudio.com

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