Good morning, all.
Consider the following application: the mid-bass driver in a 2 way system, intended for near-field, moderate SPL duty, in a small to medium sized room. The mid-bass driver shall be 6 to 7 inches in diameter.
With all other things assumed equal (for the purposes of this discussion), what are the implications of cone materials available for such a driver? The single goal of this theoretical system is transparency.
Consider the following application: the mid-bass driver in a 2 way system, intended for near-field, moderate SPL duty, in a small to medium sized room. The mid-bass driver shall be 6 to 7 inches in diameter.
With all other things assumed equal (for the purposes of this discussion), what are the implications of cone materials available for such a driver? The single goal of this theoretical system is transparency.
To get the ball rolling, here are some of my novice thoughts!
Polypropylene
I must admit, I am a fan of Polypropylene drivers, and strangely enough I probably carry an emotional bias toward them. My first brand-new set of drivers were Radio Shack 8" woofers, with grey-metallic Polypropylene cones, foam surrounds, and black fabric dust caps. This was back in the early 90's. What an interesting new kind of driver! So I am tempted now, to go down that path again, though I suspect that technology has been somewhat left behind. That being said, enough of the subjective, on to the meat and potatoes.
Polypropylene possesses a high degree of self-dampening. Cone break-up can be near non-existent in a well-designed example. This simplifies the crossover, as I see it, as likely no break-up controlling notch filter will be needed. Also, there might be a chance of using a more shallow crossover slope than with a stiffer cone. With the right tweeter, a 2nd order design might be do-able, at least at low volumes (which is acceptable for this application).
On the down-side, intermodulation distortion would tend to be higher than with a comparable stiff-cone driver. Energy storage would likely be higher, which would degrade transient response, would it not? I've heard of time smear, though I do not understand its meaning entirely. I would suspect this has something to do with impulse response and the delay time it takes for the cone to come to rest.
Aluminum
Stiffer cones such as this (I love the Excel Mg drivers, but sadly my goose is out of golden eggs!) seem technically attractive though I have yet to work with one. Energy storage would likely be lower (would it not?) within the usable band that is, not around break-up. Transient response would likely improve over the soft cones. From what I've seen on the net, 2 way implementations of Al cones are usually of 4th order slope or greater, which could add to phase distortions in extreme cases. Could such a stiff metal cone sound natural? It seems like the trick is to cross over below the worst harmonic multiples of the main cone break-up, and employ a notch to kill the break-up itself. Does this type of cone stand to be the most revealing? That a Mg cone is good enough for Mr. Linkwitz is a strong precedent!
Paper
The oldest material seems to be making a stand once more. Scan-Speak has certainly made a case. There are so many variations for paper, however, that it's hard to consider as a single category. I would guess that a good hard paper cone has some of the damping properties of PP, with perhaps less energy storage, and less break-up vs. a metal cone.
Feel free to jump in and destroy my assumptions: it's the only way I'll learn! Be gentle though!
I think a good set of comparison drivers for this discussion are the Seas Prestige 18 cm units. They have very similar motors, they appear to have the same frame, with different cones. I'm sure there are other differences, but they are as close to a comparison set that I can find at the moment. That and I intend on using one of them in the end!
JF
Seas P18RNX/P mmm so pretty!
Seas L18RNX/P she's been a naughty woofer!
Seas CA18RNX classic, all business, very shiney!
Seas ER18RNX quite the looker, stiffer than the coated version?
Polypropylene
I must admit, I am a fan of Polypropylene drivers, and strangely enough I probably carry an emotional bias toward them. My first brand-new set of drivers were Radio Shack 8" woofers, with grey-metallic Polypropylene cones, foam surrounds, and black fabric dust caps. This was back in the early 90's. What an interesting new kind of driver! So I am tempted now, to go down that path again, though I suspect that technology has been somewhat left behind. That being said, enough of the subjective, on to the meat and potatoes.
Polypropylene possesses a high degree of self-dampening. Cone break-up can be near non-existent in a well-designed example. This simplifies the crossover, as I see it, as likely no break-up controlling notch filter will be needed. Also, there might be a chance of using a more shallow crossover slope than with a stiffer cone. With the right tweeter, a 2nd order design might be do-able, at least at low volumes (which is acceptable for this application).
On the down-side, intermodulation distortion would tend to be higher than with a comparable stiff-cone driver. Energy storage would likely be higher, which would degrade transient response, would it not? I've heard of time smear, though I do not understand its meaning entirely. I would suspect this has something to do with impulse response and the delay time it takes for the cone to come to rest.
Aluminum
Stiffer cones such as this (I love the Excel Mg drivers, but sadly my goose is out of golden eggs!) seem technically attractive though I have yet to work with one. Energy storage would likely be lower (would it not?) within the usable band that is, not around break-up. Transient response would likely improve over the soft cones. From what I've seen on the net, 2 way implementations of Al cones are usually of 4th order slope or greater, which could add to phase distortions in extreme cases. Could such a stiff metal cone sound natural? It seems like the trick is to cross over below the worst harmonic multiples of the main cone break-up, and employ a notch to kill the break-up itself. Does this type of cone stand to be the most revealing? That a Mg cone is good enough for Mr. Linkwitz is a strong precedent!
Paper
The oldest material seems to be making a stand once more. Scan-Speak has certainly made a case. There are so many variations for paper, however, that it's hard to consider as a single category. I would guess that a good hard paper cone has some of the damping properties of PP, with perhaps less energy storage, and less break-up vs. a metal cone.
Feel free to jump in and destroy my assumptions: it's the only way I'll learn! Be gentle though!
I think a good set of comparison drivers for this discussion are the Seas Prestige 18 cm units. They have very similar motors, they appear to have the same frame, with different cones. I'm sure there are other differences, but they are as close to a comparison set that I can find at the moment. That and I intend on using one of them in the end!
JF
Seas P18RNX/P mmm so pretty!
Seas L18RNX/P she's been a naughty woofer!
Seas CA18RNX classic, all business, very shiney!
Seas ER18RNX quite the looker, stiffer than the coated version?
Henkjan said:
Hi Henkjan,
I missed this as I was writing the second part to my post! I agree, from what I understand metal cone break-up can have sonic repercussions in fractional harmonic multiples. From browsing the net it looks like the 3rd harmonic is usually the last one you have to worry about, though crossing over before the 3rd harmonic of the main break-up might push the cross-over point very low. And a shallow slope like that of a 2nd order filter will likely still allow such a harmonic to be audible.
With that in mind, do you feel a LR4 slope, for example, is much worse in terms of altering the original signal than a LR2 implementation?
JF
J.R.Freeman said:
There really is no such thing - one must consider the entire design of the driver, especially the motor. Scan Speak uses paper, SEAS uses magnesium, and Usher uses a carbon fiber-paper matrix. All have advantages, all have issues, but all are among the best available without a clear "winner" - it then becomes personal preference and crossover design comes into play too.
If you are trying to decide on what driver(s) to buy, it is far more helpful to know if you have a particular design/project/budget etc. as a starting point.
Pistonic behaviour, so theorically the most stiff: diamond, followed by some rare metals (beryllium....), ceramics, aluminium, titanium... But the actual result does indeed depend on all the parts off the driver and how they interact...and how the driver is implemented...and on and on and on.J.R.Freeman said:
Higher self-dampening materials such as poly and treated paper will yield less gross coloration when run full range.
For example, this part would work well in a wide variety of applications;
http://www.seas.no/index.php?option=com_content&task=view&id=65&Itemid=89
However, a stiffer cone material such as a magnesium composite will typically have a more centralized break-up mode that creates recognizable coloration when run full-range.
In the same motor;
http://www.seas.no/index.php?option=com_content&task=view&id=63&Itemid=87
The extreme degree of non-linearity in the upper frequencies requires a much greater commitment on the builder to produce an accurate response. However, this extra effort would ultimately result in a cleaner midrange than the papered unit is capable of.
BTW, The second SEAS driver is a particularly magnificent part in the right hands. The breakup is not only beautifully centralized but well out of band.
For example, this part would work well in a wide variety of applications;
http://www.seas.no/index.php?option=com_content&task=view&id=65&Itemid=89
However, a stiffer cone material such as a magnesium composite will typically have a more centralized break-up mode that creates recognizable coloration when run full-range.
In the same motor;
http://www.seas.no/index.php?option=com_content&task=view&id=63&Itemid=87
The extreme degree of non-linearity in the upper frequencies requires a much greater commitment on the builder to produce an accurate response. However, this extra effort would ultimately result in a cleaner midrange than the papered unit is capable of.
BTW, The second SEAS driver is a particularly magnificent part in the right hands. The breakup is not only beautifully centralized but well out of band.
"What cone materials offer the least coloration, and are as true to the original signal in reproduction as possible?"
Good question. I am not sure there is a clear answer. It's possible to get good results in all materials that have been mentioned. It would seem to me that your best bet is not to bet on just the material. You really need to have a listen to the drivers you are thinking of using.
I have preferences but they are just that and are really not useful as yours may differ.
Rob
Good question. I am not sure there is a clear answer. It's possible to get good results in all materials that have been mentioned. It would seem to me that your best bet is not to bet on just the material. You really need to have a listen to the drivers you are thinking of using.
I have preferences but they are just that and are really not useful as yours may differ.
Rob
I'll give a precis of all the materials I have seen to stimulate further talk...
paper
plastics
metals
others...
The french I think have been more 'inventive' or experimental or curious I think the most due to audax and jm labs/focal.
carbon fibre
just looking the other day, from some cheap 'pro' monitors I found something called
aramid..interesting, I looked it up.
aramids are synthetic fibres, related to
kevlars, and another comes into this category
nomex.
which leads to audax's aerogel, mix of carbon and kevlar?
mission speakers commercially used a lot of audax and used most of the above plus
glass fibre
papers/pulps have all sorts of additives no doubt
plastics, well, tpx, another tp from audax I think
polypropylenes,
bextrene
( other common plastics, dunno why these haven't been tried, typical in capacitor dielectrics are polystyrene, polyester, nylons and relative duponts kapton, teflons)
metals...no doubt alloys, can be spun or pressed
aluminium, beryllium (yamaha ns....), magnesium (seas excel)
vifa used wood pulp, looks brownish on one, obviously paper related
used on avi pro 9 speakers in practise.
other pulps I have seen
fostex, banana!!
hemp, cannabis speakers.
probably a few others, too....
wow thats , quite a lot...
there are no doubt many many fillers
oh mission again, keraform. ceramics. muds?
whilst its a fascinating area, the best I have heard is a good paper cone,
carbons have been a big light/polite sounding to me
I liked the kevlars I have heard
not keen on metals
plastics...bit dull 'generally'? ymmv, not heard many.
oh, I have even seen wool as an additive touted in a chinese driver.
jamo used the w17 ex 002? in the concert 8, and I have the xover, its simply 3rd order electrical with no RLC, may? be a zobel
I would've suggested scanspeaks lovely paper cone, 8542 is it?
but having heard proacs studio 100 it was a bit laid back, and I don't think the xover had anything to do with that.
why not try vance dickasons studio monitor design?
in his loudspeaker cookbook no. 7
he used a scanspeak 8545k woofer in a 12 litre or so box, with the revelator tweeter, 2nd order on bass, 3rd on treble
should be about as good as is possible for a 2 way?
but yes I would be tempted too with that posh magnet seas excel listed above, with a posh seas or scanspeak tweeter
paper
plastics
metals
others...
The french I think have been more 'inventive' or experimental or curious I think the most due to audax and jm labs/focal.
carbon fibre
just looking the other day, from some cheap 'pro' monitors I found something called
aramid..interesting, I looked it up.
aramids are synthetic fibres, related to
kevlars, and another comes into this category
nomex.
which leads to audax's aerogel, mix of carbon and kevlar?
mission speakers commercially used a lot of audax and used most of the above plus
glass fibre
papers/pulps have all sorts of additives no doubt
plastics, well, tpx, another tp from audax I think
polypropylenes,
bextrene
( other common plastics, dunno why these haven't been tried, typical in capacitor dielectrics are polystyrene, polyester, nylons and relative duponts kapton, teflons)
metals...no doubt alloys, can be spun or pressed
aluminium, beryllium (yamaha ns....), magnesium (seas excel)
vifa used wood pulp, looks brownish on one, obviously paper related
used on avi pro 9 speakers in practise.
other pulps I have seen
fostex, banana!!
hemp, cannabis speakers.
probably a few others, too....
wow thats , quite a lot...
there are no doubt many many fillers
oh mission again, keraform. ceramics. muds?
whilst its a fascinating area, the best I have heard is a good paper cone,
carbons have been a big light/polite sounding to me
I liked the kevlars I have heard
not keen on metals
plastics...bit dull 'generally'? ymmv, not heard many.
oh, I have even seen wool as an additive touted in a chinese driver.
jamo used the w17 ex 002? in the concert 8, and I have the xover, its simply 3rd order electrical with no RLC, may? be a zobel
I would've suggested scanspeaks lovely paper cone, 8542 is it?
but having heard proacs studio 100 it was a bit laid back, and I don't think the xover had anything to do with that.
why not try vance dickasons studio monitor design?
in his loudspeaker cookbook no. 7
he used a scanspeak 8545k woofer in a 12 litre or so box, with the revelator tweeter, 2nd order on bass, 3rd on treble
should be about as good as is possible for a 2 way?
but yes I would be tempted too with that posh magnet seas excel listed above, with a posh seas or scanspeak tweeter
lt cdr data said:
most of the paper we use is made from wood pulp.
There are still no answers as to whether the hemp cones are made from manilla (as per the patent application) or from canabis (as they'd like you to believe). Note that manilla is a close relative to banana.
there are zilliona od potential receipes for paper
dave
Hi Cal isn't the smoking variety Cannabis Sativa??
Traditionally grown for its therapeutic powers with fibre being a very important secondary crop??
And I was under the impression that "Manilla" was a reference to the manufacturing source and type of twisted lay used in the original cable.
Interestingly there is a strong rumour that Levi jeans were made with Hemp sail cloth in the originals.
Traditionally grown for its therapeutic powers with fibre being a very important secondary crop??
And I was under the impression that "Manilla" was a reference to the manufacturing source and type of twisted lay used in the original cable.
Interestingly there is a strong rumour that Levi jeans were made with Hemp sail cloth in the originals.
Cal Weldon said:
Hemp is canabis sativa but with 0 or close to 0 drug content. After maling hemp illegal, the US govt started ading the term hemp to some 15 other plant varieties to signify them as replacements.
Ruderelis is a weed.
Moondog55 said:
Other way round. Primamrily a useful plant for making all sorts of cloth, rope, food... the other is a bonus. Modern horticulturalists has increased the drug content of drug varieties by at least 3 x since it became a huge agriculatural income source.
Not a rumour. Sail canvas s & rope were made with hemp.
dave
paper, for a cause
as seen on tv -
http://www.elephantdungpaper.com/
563
as seen on tv -
http://www.elephantdungpaper.com/
An externally hosted image should be here but it was not working when we last tested it.
563
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