Interested in opinions/ facts from owners or experienced listeners regarding new cones on old technology
Thanx
beek
Thanx
beek
metal cone dynamic drivers
- Thread starter beek
- Start date
Hi Bill,
YG certainly comes to mind. I'll be getting my Kipods in a couple of weeks and can provide input if anyone wishes.
They make their drivers out of solid blocks of aluminum (approx. weight before milling - 16 lbs.) using a very precise CNC machine.
Per YG, 99% of the block, which is recycled and reused, is milled out leaving only the cone.
What other speaker manufacturers are using metal cones?
GG
YG certainly comes to mind. I'll be getting my Kipods in a couple of weeks and can provide input if anyone wishes.
They make their drivers out of solid blocks of aluminum (approx. weight before milling - 16 lbs.) using a very precise CNC machine.
Per YG, 99% of the block, which is recycled and reused, is milled out leaving only the cone.
What other speaker manufacturers are using metal cones?
GG
Revel, vivid and several others that don't come to mind right now. I had a pair of joseph audio pulsar with the ubiquitous SEAS magnesium mid-woofer - Is was the finest sounding cone driver/standmount i've ever owned.
I think as far as cones go, aluminum is the most common. One driver designer I talked to said the resonant frequency of aluminum is such that it really doesn't ring. Another driver designer said that that is true but if not done right the opposite could happen and these could become dull. I'm guessing that he meant the cones were shaped (stamped or milled) in a way that they are too heavy for the rest of the driver. Magnesium said both have better potential than aluminum being lighter and stiff too but are harder to work with because these need to be coated. If I recall correctly, because magnesium oxidizes more easily.
I rather fancy magnesium. I've heard them on Esoterics and Fostex not to mention several others that use SEAS Excel based drivers. Fostex's MG midrange driver is a doozy. Other than their looks these very affordable range of Fostex MG loudspeakers are awesome. I don't know why nobody in the US has picked them up for distribution. These have got to be one of audio's best kept secrets. Outside Japan that is.
I rather fancy magnesium. I've heard them on Esoterics and Fostex not to mention several others that use SEAS Excel based drivers. Fostex's MG midrange driver is a doozy. Other than their looks these very affordable range of Fostex MG loudspeakers are awesome. I don't know why nobody in the US has picked them up for distribution. These have got to be one of audio's best kept secrets. Outside Japan that is.
AFAIK, YG is the only company milling the cones out of a solid block. The other guys use pressed aluminum. There's some marketing blurb on YG's website about this, with microscope comparisons.
alexandre
right. its milled to get the grain structure in a certain direction to improve stiffness, which cant be done stamping sheet metal - its an over the top way to do it and in part justifies the high cost. the Seas drivers are cast and then chemically treated to harden the surface the result is similar if less exotic.
Aluminum is quite easy to work with, honestly not much more difficult than MDF. When you can buy an 18" diameter, 10" wide set of rims for your car made with the same spin forged process for $1000, how much extra cost does it really justify in a relatively tiny driver cone?
The type of aluminum used is just as important if not more. A casting of 7075-T6 will be significantly stronger than a forging for 5052 for instance.
Titanium would be a far better choice. The cost isn't significantly more, it is also easily workable, and gives nearly twice the tensile strength of the best aluminum alloy at 1/2 the weight.
IIRC Wilson uses aluminium cones in their alexia bassdrivers , the last time I checked their Sophia model as well , scanspeak ?
I don't think Wilson uses any metal drivers for their mids/woofers. I believe they are all paper based.
For the alexia it says X material what ever that maybe .
Wilson Sophia 3 aluminium :
Those two upper drivers have themselves been upgraded. Where the Sophia Series 2 used a pulp-cone midrange driver—a nice enough thing in its own right—the new model comes with what's described as a "simplified" version of the pulp/composite cone driver used for current versions of the upmarket Alexandria and MAXX models, as well as the Sasha. Also, the Series 3 Sophia has the same inverted titanium-dome tweeter used in all the aforementioned models, all more expensive. That tweeter, made by Focal to Wilson's specifications, is said to be fitted with a newly developed device that inhibits rear-going waves from impinging on the dome and thus coloring its output. The Sophia's woofers, too, have been improved: Although the aluminum-cone drivers are of the same basic design, the magnets have been doubled up, for greater sensitivity and speed.
http://www.stereophile.com/content/wilson-audio-sophia-series-3-loudspeaker
Wilson Sophia 3 aluminium :
Those two upper drivers have themselves been upgraded. Where the Sophia Series 2 used a pulp-cone midrange driver—a nice enough thing in its own right—the new model comes with what's described as a "simplified" version of the pulp/composite cone driver used for current versions of the upmarket Alexandria and MAXX models, as well as the Sasha. Also, the Series 3 Sophia has the same inverted titanium-dome tweeter used in all the aforementioned models, all more expensive. That tweeter, made by Focal to Wilson's specifications, is said to be fitted with a newly developed device that inhibits rear-going waves from impinging on the dome and thus coloring its output. The Sophia's woofers, too, have been improved: Although the aluminum-cone drivers are of the same basic design, the magnets have been doubled up, for greater sensitivity and speed.
http://www.stereophile.com/content/wilson-audio-sophia-series-3-loudspeaker
I'm not so sure titanium would be considered easy to work with.
Grade 5 Titanium has a yield strength of about 827 MPa and a density of about 4.5 g/cc
Aluminum alloy like 6061 has a yield strength of about 276 MPa and a density of about 2.7 g/cc
That makes titanium about three times as strong but weighs 1.67 times as much as aluminum, so the weight strength gains are not so great.
For a speaker cone, the yield strength and modulus of elasticity is probably much more important than tensile strength. Grade 5 titanium has an elastic modulus 1.66 times that of 6061 aluminum alloy (113 vs 69) which would be important in reducing or preventing "breakup" at high volumes.
Gary, you are perfectly right with regards to the physics of the materials. However.....
Since f=ma (actually, f=dp/dt), for two drivers of the same strength, one made of aluminium would require amplifier power to the square of the mass difference to accelerate equally to the titanium cone. Since there are also energy losses in the crossover, the amplifier power would be even greater.
Also, because of the relative elastic modulus, with two drivers of the same strength, the titanium driver actually has a lower breakup mode than the aluminum. It rings at a lower frequency.
All important considerations when choosing between aluminum and titanium for driver material.
Perhaps something more complex than that - "Wilson Audio's proprietary X material, a mineral-filled resin compound now in its second generation of development. X material cannot be machined with conventional tools because of its hardness and density " - from the audiobeat site review of the Sasha. I am not a material expert but grade X paper phenolic is considered to be easy of machining. As far as I remember the price of X-material was reported to be around 10 times higher than simple MDF.
Sounds like FinnForm. A material from my past; used for very large super high quality concrete forms. Used for forms made for the concrete columns of the very tall Hancock Building built in Boston during the late 60s & early 70s.
zz.
ZZ,
FinnForm is not similar at all to Wilson X material - see the datasheet http://www.pdusa.com/products/finnform2.htm
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