Funky sub cone shapes?
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=36515
Printed Date: April 27, 2024 at 4:27 AM
Topic: Funky sub cone shapes?
Posted By: shaman
Subject: Funky sub cone shapes?
Date Posted: July 31, 2004 at 3:18 PM
Okay so everything I have ever used or installed in any audio system I (or any of my freinds) have built has been the typical round dish tpye sub. I have seen alot of different shapes in the last few years and was just curious if it is possible for a square (Kicker) or a pentagon (sony) shaped drivers (or any other funny shape for that matter) to produce sound correctly. I am under the impression that the parabolic/hyperbolic cone made of light rigid material is the best for optimal T/S parameters and minimal distortion. So then these funny shapes can't be that good, why do it? It would seem to me as an engineer to be a pretty stupid thing to do, but I don't build speakers for a living. I would tend to think that these shapes are more of a sales gimic than any thing. Whats the verdic on this stuff? Is there any technical or scientific reason to make subs like this, or is it just over-processed crunchy erbal cunsumer crap?
Replies:
Posted By: Steven Kephart
Date Posted: July 31, 2004 at 4:38 PM
What a great topic of discussion. I personally think it is more a sales gimic, especially with the pentagon and octagon drivers. Kicker released the square sub to offer more cone area for a given speaker "diameter". They rate them horrizontally rather than diagonally, so they have an advantage in competitions who decides class by speaker size. But I see it more as perspective. If you measure diagonally, then a round speaker of the same size will have the most cone area.  I can see some issues with possible noises in the surround from these wierd shapes. So this could effect the SQ of the driver without some creative engineering. I'm sure it would be an issue with higher frequency drivers if they utilized this design because cone modes can effect the frequency response. It may be an issue with these subs as well, but I haven't seen any testing on it. But you are right. A cone shaped driver has the most uniformly rigid cone structure for a given weight. Steven Kephart Adire Audio -------------
Posted By: dudek38
Date Posted: July 31, 2004 at 6:28 PM
whats wrong with a little variety? i think they produce the same levels as round subs. sony's look cheesy and definetely tried to copy kicker. you must admit, kicker made you look twice when you first saw them. and the solobarics sure are nice in tight applications.
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owner of
Motion Marine & Car Audio
the florida keys
Posted By: archemedes
Date Posted: July 31, 2004 at 8:01 PM
they are for people doing multi subs, and they look cool, how many chromed basket subs that sound like a bug hitting a windshield have you seen
Posted By: shaman
Date Posted: July 31, 2004 at 9:21 PM
mode shapes... now you got me thinking. The mode shapes of a round relatively uniform cone would be for the most part concentric. But a square cone cone would behave like a losely fixed plate. It would have torsional mode shapes about various axis and so forth, the pentagon would be a vibrational mess. This can't be good. I don't how much this would affect the sound, but I would venture it is noticeable. Not to mention the surround, a round surround is uniform throughout, but what happens at corners, it cross section enlarges so it would tend to be stiffer, etc. There is just alot of considerations for a non circular cone.
Posted By: Steven Kephart
Date Posted: July 31, 2004 at 9:54 PM
shaman wrote:
mode shapes... now you got me thinking. The mode shapes of a round relatively uniform cone would be for the most part concentric. But a square cone cone would behave like a losely fixed plate. It would have torsional mode shapes about various axis and so forth, the pentagon would be a vibrational mess. This can't be good. I don't how much this would affect the sound, but I would venture it is noticeable.
I'm of course guessing, but I have a feeling it isn't too much of an issue with subs. As I said, the advantage of a square driver would be from an SPL application, and someone else made a good point that they are easier to mount together (they fit tighter together). But from an SQ standpoint, there just isn't any need. Steven Kephart Adire Audio -------------
Posted By: DYohn
Date Posted: July 31, 2004 at 10:00 PM
I've only done some real informal testing for my own personal curiosity, but I agree with Steven. It doesn't seem to have much measurable effect in low bass frequencies as far as output. The main thing that makes me nervous about non-round subs is the undoubtedly strange forces being placed on their surround. There have to be some real non-uniform stresses in the corners that round speakers are not subject to. Some formal testing would be interesting. One obvious thing to point ut is that all the non-round speaker cones I know about are from low to mid-quality manufacturers and are designed for looks and SPL, not SQ. ------------- Support the12volt.com
Posted By: customsuburb
Date Posted: July 31, 2004 at 10:12 PM
DYohn] wrote:
p>One obvious thing to point ut is that all the non-round speaker cones I know about are from low to mid-quality manufacturers and are designed for looks and SPL, not SQ.
What about Xtants pentagon subs? Woudl you count them as mid-quality, because I have heard that have good SQ. -------------
Posted By: archemedes
Date Posted: July 31, 2004 at 11:27 PM
I would think the pentagon would have a better sq than a square though
Posted By: dpaton
Date Posted: August 01, 2004 at 9:48 AM
The biggest issue for the non-round subs is the nonlinearities formed by the "corners" in the surround. They're very different from the majority of it, and impart a fair amount of localized stress to the cone, making Steven's cone modes look really wierd. They;ll also have to be more heavily reinforced than a circular cone,since the "corners" will be more likely to crack and flex, likely making them heavier and giving them lower efficiency. A friend of mine did some FEA analyses on the Kicker square Solobarics when they first came out. Nothing really spectacular. The cones flexed and resonated in wierd ways compared to a circular cone, had higher distortion, and were more likely to fail. The circle is the best way to go for low distortion, strength, and efficiency. There's a reason it's so prevelant in nature. It's the Right Way (tm)
-dave ------------- This is not a sig. This is a duck. Quack.
Posted By: shaman
Date Posted: August 01, 2004 at 1:44 PM
Heres what I mean by the vibrational modes of a non circular plate for those non engineering types. I buy that it dosen't dramatically affect the sound for low fequency applications. Thanks for the imput. The "corner effect" of the surround definatly must affect the driver though. Look at the sony for a minute... 
Now if you divide the cone in half lef to right, the corners ballance each other out, but if you divide the cone horizontally, one half has more corner area than the other. I would think this would tweak the cone as it moves. This might create a rotational motion, the cone would rock back and forth a little as it moves. I am just speculating here...
Posted By: Steven Kephart
Date Posted: August 01, 2004 at 5:00 PM
Today I had lunch with Scott Atwell (CEO of Destijl) and Dan Wiggins (CEO of Adire Audio) and I asked them about this. As they said, the square sub is a great design for SPL because of the reasons given thus far. I asked them about the effect on SQ, and I was told it would be very minimal. The cone modes would be a little different, but shouldn't effect the sound any. And as for the surrounds, they wouldn't make any more noises than a standard round surround. As they said, our surrounds start to pucker and make noises under excursion as well, but the driver is producing so much output you never hear it. The same would be true with a square coned subwoofer. Now the Pentagon, Hexagon, and Octagon cones are complete marketing. You lose Sd (cone area) because of the part of the cone they cut off, but don't benifit from being able to mount them closer together. So they actually hurt performance rather than help. It is a marketing scheme. Man that was a great lunch. Nothing like sitting down at the Seattle harbor, just you and two great speaker engineers.  Steven Kephart Adire Audio -------------
Posted By: shaman
Date Posted: August 01, 2004 at 5:48 PM
Thanks Steven, that about put the nail in the coffin on this one.
Posted By: Ravendarat
Date Posted: August 01, 2004 at 9:49 PM
I think the questions about the surround were kinda interesting, because that very thing held the release of the Solo Baric off for aan entire year. They had the sub ready to go into production and then there R @ D department found they were blowing the corners out at high volumes. What they did then was play the sub at one frequency and then set up a strobe light that light up when the sub was at peak excursion and then went out when the sub pulled back. This made it so the techs could see what was happening to the surround. What they found was that their original surround, which WAS NOT RIBBED IN THE CORNERS, couldnt flex enough and was ripping clear off the cone. They found that by ribbing the surround they solved this problem and also all but completly eliminated the problem with noise produced by the surround. With that said, I cant believe nobody mentioned the triangular Bazooka subs, thats another great Idea (I wish you I could convey the amount of sarcasim in my voice as I typed that.
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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer
Posted By: shaman
Date Posted: August 02, 2004 at 11:04 AM
traigular, what where they smoking? yeah any corner of the surround whould have the stretch in two directions (normally and quasi-tangentially) vs the sides that only are stretched in a normal direction. That explains the ribbs in the Sony above too. But agian I would think that would make the corners more stiff than the rest of the surround.
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