Slit cone principle??

[Elbert]

Hi!

I've noticed that Scanspeak has some drivers with what they call "slit cone" technology..

Does anybody know the theoretical principle behind this??

At first glance, it looks like some sort of diagonal irregularities have been introduced to the cone which I understand is meant to break up resonance modes..

The reason that I'm curious is because I have a pair of Access (focal) 6A 6" drivers with very light coated paper cones. Although they have a nice looking measurement plot, I do however suspect that they have a fair bit of resonances and distortion due to the very light cone.

Perhaps the slit cone principle, if understood, could be emulated, say in the form of bonding some strips of carbon-fiber yarn to the rear of the cone in a similar pattern?

I once read about a race car developed in the early sixties with glassfiber bodywork. The bodywork was prone to vibration and cracking, something which was eventually solved by epoxying in a grid of carbon-fiber yarn (hugely expensive back then) that took care of the vibrations and cracking of the bodywork. perhaps something similar can be hoped for with regards to cone resonances?

Also since Carbon fiber is very light, it is perhaps possible to do this without changing the moving mass to much?

I'm sure some of you goys have some thoughts on this and I'd love to hear them!

Best regards,

[woody]

You might look at the Enable threads. Briefly the enable process
uses a pattern of blocks painted on the cone to break up resonances.

[Elbert]

hey, that sounds interesting! I'll do a search for that right away!

[chrisb]

Originally posted by woody
You might look at the Enable threads. Briefly the enable process
uses a pattern of blocks painted on the cone to break up resonances.

"Briefly" , that's a bit of an oversimplification, and anyone trying to research the subject could easily get lost in the technical arcana and heated debate - but I am definitely a fan.

Depending on the driver, the "polka-dots" and gloss top-coat(s) might be only part of a full driver/cone treatment regimen, but I have yet to hear a driver that didn't sound remarkably more relaxed and natural after the process.

[Alex from Oz]

I agree with chrisb.
EnABL seems simple but there is a lot going on under the hood.

Elbert, have a look at the EnABL Listening impressions thread.
Then grab some duct tape and try it on your baffles/ports.

Cheers,

Alex

[dlr]

Originally posted by Elbert
Hi!

I've noticed that Scanspeak has some drivers with what they call "slit cone" technology..

Does anybody know the theoretical principle behind this??

At first glance, it looks like some sort of diagonal irregularities have been introduced to the cone which I understand is meant to break up resonance modes..

The reason that I'm curious is because I have a pair of Access (focal) 6A 6" drivers with very light coated paper cones. Although they have a nice looking measurement plot, I do however suspect that they have a fair bit of resonances and distortion due to the very light cone.

Perhaps the slit cone principle, if understood, could be emulated, say in the form of bonding some strips of carbon-fiber yarn to the rear of the cone in a similar pattern?

I once read about a race car developed in the early sixties with glassfiber bodywork. The bodywork was prone to vibration and cracking, something which was eventually solved by epoxying in a grid of carbon-fiber yarn (hugely expensive back then) that took care of the vibrations and cracking of the bodywork. perhaps something similar can be hoped for with regards to cone resonances?

Also since Carbon fiber is very light, it is perhaps possible to do this without changing the moving mass to much?

I'm sure some of you goys have some thoughts on this and I'd love to hear them!

Best regards,

You "suspect" resonance and distortion though they have a good measured response? All major resonances are reflected in the frequency response. If the response is relatively smooth, they do not have significant resonances. Distortion measurement requires a different set of measurements. Treating the driver can just as easily degrade the performance. Focal also has an excellent record of well-designed cones. The measurement I just saw on-line looks very good indeed, although it's 1/3 octave smoothed, it is not one that warrants a mod IMO.

The slits are a far more sophisticated and effective method of breaking up resonances than anything simply painted or glued onto the surface. It's also not going to be easy to DIY a true slit cone without risking damage and negative impacts. Surface treatments do not significantly alter the the mechanical impedance through the cone in most cases. The slits are both abrupt changes at wide ranging distances that are also highly damped with the sealing compound used. There's real research and science in their development.

Surface treatments are little more than added mass/damping. As with any treatment, there is no guarantee of improvement and most recommendations are made with no basis on evidence. If you want to take a risk with an already good driver, go right ahead and paint it, glue something onto it, whatever. Cheap drivers may be improved because, well, they're cheap. Good drivers are difficult to improve upon. Just keep in mind that few mods are reversible and most recommendations are made by those who cannot or will not provide any objective data to back up assertions.

Dave

[Elbert]

Dave, I stand corrected!

Thank you for your very sobering comments and recommendations!

I guess we all fall in to the trap of wishfull thinking every now and then when it comes to fantasising about sure-fire DIY fixes and improvements!

I'll take reassurance in what you say about the measurement curve and the general reputation of focal.

If they don't meet my excpectation despite a smooth measurement curve (and a whopping efficiency!), I'll simply have to upgrade with something better. (like the glassfiber cone Seas Excel units I can't find)

It is allso obvious that any such experimentation is in vain unless one has access to the right measurement equipment and a good batch of test specimens. I have neither..

[Alex from Oz]

Well, you could take dlr's word for it - although he has never seen or heard an EnABL'd driver or baffle or anything EnABL'd.
On the other hand, you could try it for yourself on a baffle using duct tape and then make a judgement.
BTW, you have all the test gear you need for this - they're called ears.

Cheers,

Alex

[Iain McNeill]

offensive posts deleted

Please don't resort to verbal harassing, let's keep the discussion on topic and factual.

<edit> last I checked this was slit cones, not Enable.

[john k...]

Originally posted by Iain McNeill
offensive posts deleted


Please don't resort to verbal harassing, let's keep the discussion on topic and factual.


<edit> last I checked this was slit cones, not Enable.

You have to be kidding. That was the point. This Enable nonsense has several threads of its own. The last thing needed is having this nonsense contaminate other threads on other subjects. Did you scan the rest of this topic and delete the 2nd, 4th, 5th, and 8th posts? 50%of the first 8 posts are about enable, not split cones.

Apparently injecting little humor is offensive? And, although embedded to the lyrics of Frank Zappa the post was factual.