Cone material

[Aaron Clinton 2,372]

I thought this would be interesting since different materials have been a hot topic recently.

As in:

Non-pressed paper, pressed paper, pulp, plastic, wood fiber, IMPP, carbon fiber, Aluminum, Titanium, woven fiber, poly, etc...

which material would be the best to use in what application etc....

[JimJ 11]

For subwoofers, as long as the cone can physically take the stresses it's under I don't see the difference. Problem is making a metal cone that withstands that kind of abuse. On speakers like the Rainbow Vanadium that doesn't have the mechanical travel to stress the cone, it's fine...but those TC drivers show what happens when you have a flexing cone subjected to that kind of strain.

Metal cone midbasses have some pretty nasty breakup nodes if you don't cross them over low enough. (might be a good place for Sean's cool laser vids ) If you want to do an 8" two way with a standard dome tweet, any sort of metal is pretty much out of the question.

oh...and banana cones kick ass

[///M5 2,833]

IMO you always want the lightest, stiffest cone you can use for an application. Of course, this means that it has to be strong enough to take the abuse the motor can put out on it and also not have any breakups than completely ruin the response in the frequency range you want to use them.

[audio-neon 34]

for some reason i am in love with pressed paper cones in mid-bass's, it sounds good, it is highly efficient, and relatively strong weight to strength ratio.

Of course i am biased by my favorite set of components which are Hertz Space k8l components.

[vladd 26]

seas has shown that with proper cone shape the break up node on metal cone drivers can be pushed up to at least 7khz (L18).

[///M5 2,833]

seas has shown that with proper cone shape the break up node on metal cone drivers can be pushed up to at least 7khz (L18).

but it is 10db up and then has nasty harmonics at 8k, 98k, 10k and 11k which aren't as easy to deal with as the single peak of the mag cones.

[DevilDriver 28]

The speaker cone is one of those wonderful engineering challenges where hundreds of materials are tried in an effort to achieve the perfect result, which has been known for quite some time.

For the most part, the ultimate goal is something light, stiff, and porous. Light is good for efficiency, stiff is good for keeping modes to a minimum, and porous is good for providing damping (again, keeps modes to a minimum). Any modes would ideally be absorbed by the cone's inherent damping it provides. It has been quite challenging to find a single material that is capable of meeting our desires, so this has lead to a large number of composite cones being designed. I'll try to mention the differences between some for just a moment.

Paper - Paper can be a very good material. It's stiffness to mass ratio is very appealing and can provide adequate damping. Due to the nature of paper, it is very easy to adjust the number of fibers or strands to increase weight (good for lowing Fs) or decreasing mass (good for increasing efficiency). It can be a very flexible product. At the same time, paper that goes untreated is not particularly durable, which you likely noticed when you were 3 years old. Popular treatments include adding a layer of carbon fiber treatment over the paper cone or coating the paper cone with glass microspheres. The latter is known as "PolyGlass", which you have probably seen on some Focal drivers (I believe it is a Focal proprietary technology). Paper (and it's various treatments) also makes for a highly affordable cone.

Polypropylene - PP is a good alternative to paper and is growing increasingly popular. PP has a natural stiffness to mass ratio that is often lower than desired, so it is not uncommon that it is reinforced with various fillers to raise this ratio; fillers include kevlar, carbon fiber, talc, mica, and acrylic. PP is also pretty affordable and has good internal damping.

Aluminum - Decent stiffness to mass ratio (fairly light material with good efficiency), but the big issue with aluminum has already been mentioned: nasty resonance due to a lack of internal damping. This creates noticeable breakup modes in most midranges or tweeters. It's still a common material to use in subwoofers, as any resonance will come outside of the typical passband. An issue experienced by a certain OEM was that, like all metals, aluminum can fatigue, which will can cause big issues in high excursion where the cone meets the surround.

Magnesium - Very similar to aluminum. Magnesium is even lighter and has even less internal damping, leading to the same issues with resonance and breakup modes. It's worth mentioning that both magnesium and aluminum can receive a thin rubber treatment to help increase damping.

Kevlar - Kevlar is extremely stiff and common in body armor; it presents a very appreciable stiffness to mass ratio. However, it also lacks damping and can experience noticeable resonance. For these positive and negative aspects, kevlar is more common in composite cones rather than being the primary material used.

Carbon Fiber - Much like kevlar, carbon fiber is more popular in composite cones or as a paper coating. It displays a good stiffness to mass ratio with better internal damping than kevlar. Carbon fiber is very flexible in how it can be applied, so it makes for a great material in a composite cone during the engineering process. It's use as a primary material in cones hasn't really taken off at this point.

Hemp - Hemp is a relative new-comer to the cone material world. There isn't much experience to be had regarding hemp cones, although they are used exclusively by Hemp Acoustics and are growing increasingly popular. Hemp has a good stiffness to mass ratio and demonstrates good upper frequency and low frequency damping. It is also a versatile material and has been used in composite cones in the past.

All other cones are usually based off of these primary materials. Some are a combination of the above, while others take the above and add treatments. There are a couple others I have never come across, but know exist, including diamond cones (yes, they're out there) and various pulp based materials (including banana). Hope that helps a bit.

[Aaron Clinton 2,372]

Nice job neil.

[///M5 2,833]

Magnesium - Very similar to aluminum. Magnesium is even lighter and has even less internal damping, leading to the same issues with resonance and breakup modes. It's worth mentioning that both magnesium and aluminum can receive a thin rubber treatment to help increase damping.

I am assuming that magnesium is stiffer since mag cones tend to exhibit breakups that are much more defined than aluminum. The aluminum typically have lots of resonant peaks, ring tones/harmonics that are closely spaced at breakup making them a bit more difficult to implement into a crossover design. A quick peak at the L18/RS180 vs W18 frequency response graphs will outline what I mean.

To answer Denim's original question of which would be my preferred cone for each application, I personally lean towards aluminum subs (not into high SPL so they have never been a problem for me), paper cones for midbass, magnesium cone for midrange (wonder what driver... ), and silk for tweeters. Of course that is my generic choice at the moment and those of you that know me understand I listen to detailed music and only care about SQ. Most of the choices are based on price performance and what I'd buy for that reason.

[Godsmack 360]

One thing man

Hemp is also used by kronic audio.

J

[Aaron Clinton 2,372]

For mid's I seem to prefer woven fiber or paper. Not been a fan of the aluminums for mids. For subs, I have mixed feelings; I love the sound and clarity of my old TC7 Eclipses', but I do also like the sound of the paper cone (ie. MAG / Q / ICON / MJ-18).

[ngsm13 1]

I'm a fan of pulp cone woofers, poly mids, and silk or textile tweets.

nG

[visitor 3]

Devildriver- that is for sure a nice write up! One material that i didnt see your thoughts on that i would be interested to know- Titanium.. everyone knows of TC's problems with the aluminum one piece cone- fair enough. but with the apparent lack of failures of the TI cone- it really seems to be a viable option as far as cones go... So- anyone, really- what are your feelings on the TI cones?

[JimJ 11]

They'll fail under stress in the same way aluminum will

[Lord Baccus 1]

i was speaking with :John @ Pierce Audio : and we were discussing the same thing , i asked him if he could build a sub using the WMD motor & using the new cone for the MOAB, and so im getting 2 of em custom built & shipped this week...

honeycomb w/ Kavlar coating cone, motor needs less power to get up & going

not as power hungry... http://pierceaudioproducts.com/forum/index.php?topic=3.0

Edited May 31, 2007 by Lord Baccus

[Typo_Knig 0]

Devildriver- that is for sure a nice write up! One material that i didnt see your thoughts on that i would be interested to know- Titanium.. everyone knows of TC's problems with the aluminum one piece cone- fair enough. but with the apparent lack of failures of the TI cone- it really seems to be a viable option as far as cones go... So- anyone, really- what are your feelings on the TI cones?

Titanium alloys fall somewhere in between aluminum and steel alloys as far as weight and stiffness. TC is experiencing a lower failure rate with Ti cones mainly because it an extrememly faftique resistant metal. It has a very high modulus of elasticity and strong memory making it an ideal material for springs. It has a more than acceptable strength to weight ratio and is corrosion resistant, this is why aerospace industries like it so. When compared to aluminum, Ti's stength to weight ratio and modulus of elasticity make it a more ideal material for a subwoofer cone than aluminum. Because it is stronger than aluminum, a thinner cone can be made. Cost in material, tooling and manufacturablity are the things holding it back.

Coming from a bicycle frame building background, I have seen frames made from Ti, steel and Al alloys. The ones that are on the road the longest are the ones made from Ti.

Edited May 31, 2007 by You Ham-fisted Cluck!

[Aaron Clinton 2,372]

Sweet looking sub.

[Lord Baccus 1]

Sweet looking sub.

you mean the Pap Wmd/Moab Hybrid

coils take more power with less motor / less power hungry... i just asked if it could be done and BAM he did it

[Aaron Clinton 2,372]

T/S or specs on that thing?

[Lord Baccus 1]

T/S or specs on that thing?

We now have available a SPL package option for the WMD 15's. They feature a glass/cabon fiber honeycomb cone with a tall high excursion foam surround. The lighter honeycomb cones increases effeincy by 3 db over the standard WMD pressed paper cone and add 14 sqaure inches of cone area by incorperating the tall surround.

T/S parameters:

REVC: 4 ohms

FS: 34hz

QES: .97

QMS: 7.2

QTS: .86

VAS: 3.6

BL: 14

MMS: 241g

Sens:91db@2.83v

[audio-neon 34]

They'll fail under stress in the same way aluminum will

I have never heard of cone related failures with the titanium cones, and the issue with the aluminum cones from TC sounds has been dealt with and fixed.

[audio-neon 34]

They'll fail under stress in the same way aluminum will

The only issue I have had with aluminum was the plastic dustcap coming off every once in a while on my diamond d1's.

Edited May 31, 2007 by audio-neon

[JimJ 11]

They'll fail under stress in the same way aluminum will

I have never heard of cone related failures with the titanium cones, and the issue with the aluminum cones from TC sounds has been dealt with and fixed.

Seen it with my own eyes...they're not immune to the problem. More resistant than the aluminum cones? Sure.

And that Pierce Audio driver is nice looking, but the WMD we tested before was a turd. Really didn't do anything notable, subjectively or objectively...

[JimJ 11]

T/S or specs on that thing?

We now have available a SPL package option for the WMD 15's. They feature a glass/cabon fiber honeycomb cone with a tall high excursion foam surround. The lighter honeycomb cones increases effeincy by 3 db over the standard WMD pressed paper cone and add 14 sqaure inches of cone area by incorperating the tall surround.

T/S parameters:

REVC: 4 ohms

FS: 34hz

QES: .97

QMS: 7.2

QTS: .86

VAS: 3.6

BL: 14

MMS: 241g

Sens:91db@2.83v

If those specs are right, that'd be one hell of a candidate for open baffle, if inductance is low enough...almost as underdamped as the RL-s is.

[Lord Baccus 1]

They'll fail under stress in the same way aluminum will

I have never heard of cone related failures with the titanium cones, and the issue with the aluminum cones from TC sounds has been dealt with and fixed.

Seen it with my own eyes...they're not immune to the problem. More resistant than the aluminum cones? Sure.

And that Pierce Audio driver is nice looking, but the WMD we tested before was a turd. Really didn't do anything notable, subjectively or objectively...

i think it deserves another test as it looks like something touched the coil and made a burn mark

i have seen coilsfail & they turn black all aver ! i saw the video and i saw the spark from the probe touch the coil.

please re-test the PAP and give a fair review.

i have 2 MOABs 15" and i tortured 1 @ 2ohm with my Massive P3000.1 for 2 weeks and it did fine and sounded great, got Hella Low & Loud

Edited June 3, 2007 by Lord Baccus