Different cone "sound"

[subwoofery 0]

Hey guyz,

I know that different cones have differents advantages and drawbacks:

- strength

- lightness

- ease of use

But what I am wondering is what kind of "sound" (metallic, warm, etc...) do those have - subwoofer cones by the way.

For example, hemp, kevlar, aluminum, titanium, threated paper, and so on...

Thanks

Kelvin

[///M5 2,833]

Considering a subs whole goal in life is to accurately reproduce sound up to 40hz which is not a range your ear is very good at discerning, I might rethink the question and perhaps focus on the front stage with it instead. From a quality perspective it really won't make any difference in the sub range. I am not saying they won't sound different, but colorations are pretty minimal at those frequencies.

[DevilDriver 28]

For the most part, different sonic characteristics of a cone can be attributed to it's spectral decay times and frequency response (since the two are pretty heavily linked). But...very small differences in either are not particularly noticeable within a subwoofer's bandwidth. Distortion is considerably more important, but even then, a lot of the interpretation is very heavily room and enclosure dominated.

When it comes to mids and tweeters, it's a bit different story.

[subwoofery 0]

Humm... Interesting...

So people saying that for example the IDMAX has a warmer sound than let's say a TC3000 has nothing to do with the cone material?

[DevilDriver 28]

Not much, nope.

[subwoofery 0]

Thanks a lot. I can now stop looking at cone materials for sound.

[DevilDriver 28]

For subwoofers, that's pretty much the case.

Even for mids and tweets, looking at the cone material only accomplishes so much. As far as the end user is concerned, frequency response and CSD are big concerns (in my opinion) as well as various forms of distortion (IMD from inductance variation is a big concern in mids...again, my opinion). Cone material is a worthwhile consideration from an engineering standpoint when you're trying to match parts to a given target.

[sqguy 0]

Interesting. Well I am far from knowing all the reasons why but have run up on this with IB subs many times. Cheap poly subs sound really bad, and the noise is above the crossover point usually. I always figured it was a dampening thing and the cone had a resonance issue. Paper subs always sounded better, even real cheap ones. This was running up to about 50 to maybe 80Hz max on a crossover. Often I could run the same subs in a sealed or ported box and the noise was gone. It sounds like a popping tone in the VC even at normal volumes. Some subs one could tap the cone with a fingernail and that Hz was it. Today poly subs are better, but lately I have used few IB to tell. Have some Infinity ref 12s now and they also do this but it is very hard to pick it out, certain tones seem to trigger it and they don't do it when the crossover is down to about 35 where it really makes bottom. They are mounted into the seat which will normally cover that stuff up, but there is a vent area above the seat to them. I'd rather have paper but got a deal on them, and figured they would be good enough for the 420wrms I have into 4 of them without stress that makes it worse. Indeed they are only moving at most half travel with the amp near max output. Some of you would call these cheap subs, I call $20-50 a cheap sub.

Of course the problem is that IB will have more db at higher Hz just not as much as a sealed box. Even though you set the crossover at 50Hz while it slopes down the sub is ramping up and you still get some of the higher frequency. Some subs it does not seem to matter if you cross it real low anyway and they still make the noise. It is not rubbing and not topping out, it is almost like the VC is vibrating on the former with sharp inputs. That is the best I can explain anyway. A better sub is not going to do it usually but I still shy from poly when the driver is going to be in the same space as me (visible) and running IB. I would much rather have a paper based mid as well, but have heard plenty of other materials that sounded fine....just old school rules I guess. I swap until it sounds like I want.

[DevilDriver 28]

I knew when I posted it was too brief, so I will try to restate what I meant a bit more clearly.

This my approach:

1. Identify what we interpret unfavourably.

2. Identify how this can be objectively measured and duplicated, if necessary.

3. Identify the sonic tendencies of a particular cone material.

4. Compare these tendencies to what we identified in steps 1 and 2.

So step 1 is what we intepret unfavourably. There are so many factors here and this is something that people like Drs. Geddes, Lee, Klippel, O'Toole, etc. have been working on for years. For example, we all know that distortion is not a good thing...but certain levels of harmonic distortion with a reasonable magnitude (particularly in comparison to the fundamental frequency) are very acceptable, in some cases even interpreted positively. But it's so much more complex than that. For example, a little 2nd order harmonic distortion is no big deal (in my opinion) if you have significant InterModulation Distortion generated by heavy inductance variation...especially if this is occuring in a midrange. Any resonance or poor decay times (as seen in a Cumulative Spectral Decay plot) can make your detail disappear. I'm starting to blend parts 1 and 2 together here, but you get the idea.

For example, I agree that in many cases, a Poly coned midrange has a tendency to be a little hazy with less detail than, say, a metal-based cone. From a scientific standpoint, this can usually be attributed to two very measurable causes: 1. Decay times, 2. Lack of break-up. Honestly, I do like detail, but usually this detail can be attributed to a form of break-up, resonance, or a rough patch in frequency response from a form of distortion. In the midrange (in my opinion, the most critical part of any speaker system), these things can be very detrimental, although a steep slope or notch filter can go along way to controlling these artifacts.

But...I find this to be a much smaller issue in subwoofers...much smaller. Our ears are not very sensitive to small differences in SPL at low frequencies as described by various Equal-loudness contours (including Fletcher-Munson and Robinson-Dadson). In my opinion, these differences become even more minute with high SPL. As an example, the JL Audio W6V2 is routinely considered one of the best sounding subwoofers in the car audio market. It does employ a poly cone. Now it's only fair to mention that the W6V2 also has a "W Cone", which is basically JL Audio's approach at adding rigidity to the driver, which is very important for a subwoofer. If anything, this is just a good example of how a particular material might have various advantages or disadvantages, but the final result is controlled by a wide number of factors and the implementation of the material.

Paper is usually interpreted very favourably. It has a tendency for higher 2nd order harmonic distortion with low 3rd order via its damping capabilities. You can mix various materials quite easily with paper as well and increase rigidity as you please. Personally, I know that paper is an old material and many manufacturers are pushing to get the newest and greatest material onto their drivers...but I still love the abilites and flexibility (especially from a manufacturing standpoint) of a good paper driver.

But again, it's the implementation. The cone material can only account for so much if you have copious amounts of distortion generated from BL, Cms, and Le non-linearities. The material is only a small part of the final result...especially with subwoofers that are so unbelievably dominated by that filter we call an enclosure that falls right in our critical bandwidth and, even more so, the effects of the room or cabin that we put the speaker/enclosure into.

As far as IB goes, I would agree that certain effects are more noticeable. I, personally, find IB to be more revealing of a drivers performance because there is little no masking done by the enclosure. Also, you can typically reach your output limits without driving tons of power into the coil, and this is great (again, my opinion) for natural sound. I've made the analogy before, but its really easy to dump enough power into the coil to double Re, which doubles Qes, which doubles Qts, which drastically changes the enclosure the driver will work best in. This is perhaps the biggest advantage of an IB approach: you're almost forced to keep the power out of the coil or risk driving it to mechanical damage. Also, because you can so easily reach Xmax, you can also easily (and routinely) notice any distortion generated from BL and Cms non-linearity.

Rambling a bit, but my point is that yes, a material does have an effect on subwoofers, but one that can be easily accounted for during the design process and is swamped by various other effects, most notably any non-linearities of the driver.

[sqguy 0]

I must be weird, it always seems to be the sub stage I have problems with. Noise from the cone(s) themselves is just one of many issues. I prefer IB so maybe why I've seen it more as a problem, plus have often used cheaper subs since they got the job done. Great insight by the way, great post.

[ANeonRider 3]

Cones aren't making the noise, that is the suspension of the subwoofer that is making mechanical noise.

[sqguy 0]

Poor wording, I should have said from the sub drivers themselves. I think most of the issue is the response of the subs being off causing X music (or song even) to be more/less bass SPL than Y music depending on bass Hz played, and then the subs don't blend properly. Get tired of dialing the subs up/down/over all the time. What seems to help is to push the subs down in Hz as proper in SQ, but then the common deficiency of midbass shows up. Since I am not often spendy with drivers many of my better sounding systems used 6x9 for midbass (when I had room) paired with subs that had a smooth rolloff on the top side to back them up.

Issues with sub driver noise that were the worst seemed to be (or something causing) some kind of resonance in the cone thwarting a smooth rolloff into the midbass. Wanting to run some good power on the subs to support some SPL at 30Hz just makes it harder (with comparatively much more power on the subs they seem more sensitive to input change), though for me that is usually only 200-500wrms for subs. Rarely have room for a 30Hz box so run IB, and then you are down on the curve to hit 30 and have to kill SPL higher than that or EQ it...and I don't like a lot of EQ. That may be one reason I like 10" subs IB better, because they have more SPL above the crossover point. Then they blend better instead of rolling off faster....even though they are not as good at 30hz. Again if they have a driver noise issue, then it will come through even more with a higher Fs if you let them roll up under the mids like that. Hence my wanting to try 8s in my doors as an easy way out of this problem I always seem to get into. They should work much like 6x9 do for midbass.

[JimJ 11]

I've found that midbass is far more install-dependent than the drivers themselves. Cheap drivers can do amazing things when set up properly, but that's not something that happens automatically...

[mrray13 30]

here's a quick, no intelligent, bassheads view..

in subwoofers, i've never been able to tell the difference in sound between cone materials. meaning, without being at a clipping level, all subs sounded the same, no including transient response, ability to drop and output.

in midranges and midbass, teh same holds true.

only in tweeters can i tell a difference in materials used. and if under high power, IMO, textile based and metallic tweeters tend to resemble each other. i've heard silks as harsh as titaniums. but i've never heard ti's as warm as silks under lower power levels.

again, no scientific reasons or explainations, just a basshead's obsevations.

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[JimJ 11]

Kent, if you get the chance sometime, try running a metal midrange with a very shallow slope on the low pass...metal breakup nodes are pretty easy to hear if you have the crossover set wrong. Paper cones are a lot more tolerant of shallower transitions to the tweeter.

[sqguy 0]

I've found that midbass is far more install-dependent than the drivers themselves. Cheap drivers can do amazing things when set up properly, but that's not something that happens automatically...

Enclosure? Mine suck installed in doors with just some hole plugging and stock layer of foam on the door, but I'm just not going to attempt to make an enclosure in there if even possible. Next on list is dampening if I don't have some 8s/mid/tweets to try by then. 6x9s seem to make midbass in doors, but yeah I know most here hate them.

[vladd 26]

if you're happy with them, does it matter what everyone else thinks?

[///M5 2,833]

Issues with sub driver noise that were the worst seemed to be (or something causing) some kind of resonance in the cone thwarting a smooth rolloff into the midbass. Wanting to run some good power on the subs to support some SPL at 30Hz just makes it harder (with comparatively much more power on the subs they seem more sensitive to input change), though for me that is usually only 200-500wrms for subs. Rarely have room for a 30Hz box so run IB, and then you are down on the curve to hit 30 and have to kill SPL higher than that or EQ it...and I don't like a lot of EQ. That may be one reason I like 10" subs IB better, because they have more SPL above the crossover point. Then they blend better instead of rolling off faster....even though they are not as good at 30hz. Again if they have a driver noise issue, then it will come through even more with a higher Fs if you let them roll up under the mids like that. Hence my wanting to try 8s in my doors as an easy way out of this problem I always seem to get into. They should work much like 6x9 do for midbass.

Sounds like a tuning problem to me.

[mrray13 30]

Kent, if you get the chance sometime, try running a metal midrange with a very shallow slope on the low pass...metal breakup nodes are pretty easy to hear if you have the crossover set wrong. Paper cones are a lot more tolerant of shallower transitions to the tweeter.

i've got those alums from PE....i might try that. by shallow slope, your referring to say a 6db per octave cutoff vs a 24db octave one, correct?

just want to clarify, be being who i am and all, lol

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[///M5 2,833]

Either that or no slope at all, just need to get some energy into the region where the cone starts going wacky.

For instance, one of my favorite metal 7" drivers with a terribly active breakup mode.

http://www.madisound.com/catalog/PDF/seas/H1224.pdf

See the huge peak at 7kHz, it is up 12dB from nominal? Obviously in the case of this driver if you had a 6db slope at a frequency where your response was only down 6dB by the time you were at 7kHz the 12dB of boost would make the 7kHz response 6dB louder than the nominal response of the speaker. Then of course you see the valleys around the peaks which won't be excited that way and of course the harmonic peaks of the initial breakup. You can imagine what this might do to the frequency response...and of course there is another phenomena happening. The cone is going into "breakup" which literally means it isn't moving like a piston anymore, but bending in many locations as it tries to move in and out. This breakup will also have a natural tendency to color the sound leaving the response less than pleasant. Give it a listen, otherwise the next time I see you I will bring my RS180's which also breakup pretty bad so you can hear what it sounds like.

[sqguy 0]

if you're happy with them, does it matter what everyone else thinks?

Not at all, but only have only one good set of 6x9 here and I don't want to rip the tweeter out of them so I thought why not 8s. Prefer to have comps in front here, but I would guess that would work much better than 5x7 I have now. Might use 6x9 in rear however, after other things are figured out.

Edited November 1, 2007 by sqguyib

[sqguy 0]

Issues with sub driver noise that were the worst seemed to be (or something causing) some kind of resonance in the cone thwarting a smooth rolloff into the midbass.... Again if they have a driver noise issue, then it will come through even more with a higher Fs if you let them roll up under the mids like that. Hence my wanting to try 8s in my doors as an easy way out of this problem I always seem to get into.

Sounds like a tuning problem to me.

Not to many ways to tune IB subs. If you try aperiodic you lose the bottom and that is the #1 reason I run IB; to get the 30Hz, or 20 even. I want them to fly. Electronics might get rid of it, but then you end up at a crossover point you don't want so that is no good and sometimes you can't cross it out. Tuning ends up being...."find the right sub" and then you are golden.

[///M5 2,833]

Issues with sub driver noise that were the worst seemed to be (or something causing) some kind of resonance in the cone thwarting a smooth rolloff into the midbass.... Again if they have a driver noise issue, then it will come through even more with a higher Fs if you let them roll up under the mids like that. Hence my wanting to try 8s in my doors as an easy way out of this problem I always seem to get into.

Sounds like a tuning problem to me.

Not to many ways to tune IB subs. If you try aperiodic you lose the bottom and that is the #1 reason I run IB; to get the 30Hz, or 20 even. I want them to fly. Electronics might get rid of it, but then you end up at a crossover point you don't want so that is no good and sometimes you can't cross it out. Tuning ends up being...."find the right sub" and then you are golden.

So you are telling me that electronic filtering and mechanical filtering have greatly different results?

[mrray13 30]

Either that or no slope at all, just need to get some energy into the region where the cone starts going wacky.

For instance, one of my favorite metal 7" drivers with a terribly active breakup mode.

http://www.madisound.com/catalog/PDF/seas/H1224.pdf

See the huge peak at 7kHz, it is up 12dB from nominal? Obviously in the case of this driver if you had a 6db slope at a frequency where your response was only down 6dB by the time you were at 7kHz the 12dB of boost would make the 7kHz response 6dB louder than the nominal response of the speaker. Then of course you see the valleys around the peaks which won't be excited that way and of course the harmonic peaks of the initial breakup. You can imagine what this might do to the frequency response...and of course there is another phenomena happening. The cone is going into "breakup" which literally means it isn't moving like a piston anymore, but bending in many locations as it tries to move in and out. This breakup will also have a natural tendency to color the sound leaving the response less than pleasant. Give it a listen, otherwise the next time I see you I will bring my RS180's which also breakup pretty bad so you can hear what it sounds like.

sounds like a plan. i'll pm you some other questions so as not to hijack this thread.

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[Electrodynamic 2]

I knew when I posted it was too brief, so I will try to restate what I meant a bit more clearly.

This my approach:

1. Identify what we interpret unfavourably.

2. Identify how this can be objectively measured and duplicated, if necessary.

3. Identify the sonic tendencies of a particular cone material.

4. Compare these tendencies to what we identified in steps 1 and 2.

So step 1 is what we intepret unfavourably. There are so many factors here and this is something that people like Drs. Geddes, Lee, Klippel, O'Toole, etc. have been working on for years. For example, we all know that distortion is not a good thing...but certain levels of harmonic distortion with a reasonable magnitude (particularly in comparison to the fundamental frequency) are very acceptable, in some cases even interpreted positively. But it's so much more complex than that. For example, a little 2nd order harmonic distortion is no big deal (in my opinion) if you have significant InterModulation Distortion generated by heavy inductance variation...especially if this is occuring in a midrange. Any resonance or poor decay times (as seen in a Cumulative Spectral Decay plot) can make your detail disappear. I'm starting to blend parts 1 and 2 together here, but you get the idea.

For example, I agree that in many cases, a Poly coned midrange has a tendency to be a little hazy with less detail than, say, a metal-based cone. From a scientific standpoint, this can usually be attributed to two very measurable causes: 1. Decay times, 2. Lack of break-up. Honestly, I do like detail, but usually this detail can be attributed to a form of break-up, resonance, or a rough patch in frequency response from a form of distortion. In the midrange (in my opinion, the most critical part of any speaker system), these things can be very detrimental, although a steep slope or notch filter can go along way to controlling these artifacts.

But...I find this to be a much smaller issue in subwoofers...much smaller. Our ears are not very sensitive to small differences in SPL at low frequencies as described by various Equal-loudness contours (including Fletcher-Munson and Robinson-Dadson). In my opinion, these differences become even more minute with high SPL. As an example, the JL Audio W6V2 is routinely considered one of the best sounding subwoofers in the car audio market. It does employ a poly cone. Now it's only fair to mention that the W6V2 also has a "W Cone", which is basically JL Audio's approach at adding rigidity to the driver, which is very important for a subwoofer. If anything, this is just a good example of how a particular material might have various advantages or disadvantages, but the final result is controlled by a wide number of factors and the implementation of the material.

Paper is usually interpreted very favourably. It has a tendency for higher 2nd order harmonic distortion with low 3rd order via its damping capabilities. You can mix various materials quite easily with paper as well and increase rigidity as you please. Personally, I know that paper is an old material and many manufacturers are pushing to get the newest and greatest material onto their drivers...but I still love the abilites and flexibility (especially from a manufacturing standpoint) of a good paper driver.

But again, it's the implementation. The cone material can only account for so much if you have copious amounts of distortion generated from BL, Cms, and Le non-linearities. The material is only a small part of the final result...especially with subwoofers that are so unbelievably dominated by that filter we call an enclosure that falls right in our critical bandwidth and, even more so, the effects of the room or cabin that we put the speaker/enclosure into.

As far as IB goes, I would agree that certain effects are more noticeable. I, personally, find IB to be more revealing of a drivers performance because there is little no masking done by the enclosure. Also, you can typically reach your output limits without driving tons of power into the coil, and this is great (again, my opinion) for natural sound. I've made the analogy before, but its really easy to dump enough power into the coil to double Re, which doubles Qes, which doubles Qts, which drastically changes the enclosure the driver will work best in. This is perhaps the biggest advantage of an IB approach: you're almost forced to keep the power out of the coil or risk driving it to mechanical damage. Also, because you can so easily reach Xmax, you can also easily (and routinely) notice any distortion generated from BL and Cms non-linearity.

Rambling a bit, but my point is that yes, a material does have an effect on subwoofers, but one that can be easily accounted for during the design process and is swamped by various other effects, most notably any non-linearities of the driver.

Jesus Neil!! LOL! Very good post my man, very good post.

Just something to add to Neil's post -

When it comes to loudspeaker distortion in general (which it appears that a lot of people are finally starting to learn involves more than just the motor), the cone can add to differences in sound reproduction. If it makes it easier, imagine holding a 2'x2' piece of thin aluminum and striking it with a screw driver. Now imaging a 2'x2' piece of dense cardboard and striking it with a screw driver. Which one will resonate more and at what frequencies? I know that was a very bad example because it's going off the deep end as far as comparissons go, but you should get the idea. On a MUCH smaller scale, loudspeaker cone distortion is analyzed with similar goals in mind (to see what materials resonate at what frequencies, how much they resonate, from what areas of the cone do they resonate from, and how it all affects the sound that the speaker creates).

From our subwoofer testing, aluminum diphragms have a tendency to resonate at a frequency and level which the user can hear, whereas paper or poly doesn't. Aluminum's resonances tend to be much more severe than paper or poly. Even though they might be higher up the scale (3'rd order vs. 2'nd order), aluminum still resonates with the same, if not higher, peaks as paper in those registers. Technically, those harmonics can creep down into the subwoofers playback. Albeit at a very attenuated level...but it's still there. And those little "additions" can add to the sound your subwoofer plays back.

Having said that, there are some very neat poly's out now-a-days. Polk is using a "puffed" poly that is claimed to strengthen the cone by adding air to the poly mixture/forming process making it stronger without adding a considerable amount of weight. I like the idea of that cone a LOT...especially when it comes to a car audio mid/woofer (I'm referring to Polk's big-boy 6.5" component set).

Anyway, without digressing it all comes down to what you are willing to tolerate - from an enginerring standpoint and from the consumer standpoint. Take a marine speaker for example. Paper would not be a wise choice. Aluminum, poly, carbon fiber, fiberglass, etc should be used instead. It's a no-brainer really. But for car audio or home audio, it's really a choice. The battle is always the least amount of added distortion from the cone with the highest strength-to-weight ratio.

For us, it's paper. We thought the paper cones we used on the previous Mag's were good, but they're just pretty good compared to the new cone we're using.

But as Neil and Jim said, cone choice is MUCH more critical in midranges and tweeters than subwoofers. It's still important for subwoofers, but just not as important as a midrange/tweeter.