What kills a cone in a horn?
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
 25th March 2013, 12:25 PM #1 more10   diyAudio Member   Join Date: Feb 2011 Location: Solna What kills a cone in a horn? Hornresp now shows pressure on the cone (instead of pressure at S1). I am quite shure that the pressure by itself will not tear a cone. It must be a combination of pressure and the force that the current through the voice coil makes on the cone. Is there a simple way to calculate the sheer force on the cone? Mårten
 25th March 2013, 01:40 PM #2 AndrewT   diyAudio Member   Join Date: Jul 2004 Location: Scottish Borders Pressure and the acceleration times cone mass combined is what tears or collapses the cone. Both are directly related to VC current. __________________ regards Andrew T.
 25th March 2013, 03:48 PM #3 jbell   diyAudio Member   Join Date: Apr 2003 Location: . stupidity behind the mixer kill cones in horns... Stupid + Alcohol = 50% decline in cone strength. That's about as close to a formula as I've got.
 29th March 2013, 12:58 PM #4 VECTORDJ diyAudio Member   Join Date: Oct 2011 Help your local reconer. Take RMS power rating x 4, turn bass to 10, turn mixer slider to 10..........,then add : I have been a DJ for 15 years:,,,,,cone blow out. All things have a fail point. Please use a Crown 5000 on your Cerwin Vega folded horns at full blast. Send blown woofers to me for repair. Sorry it is just one of those days. VECTORDJ
JMFahey
diyAudio Member

Join Date: Mar 2009
Location: Buenos Aires - Argentina
Quote:
 Originally Posted by more10 Hornresp now shows pressure on the cone (instead of pressure at S1). I am quite shure that the pressure by itself will not tear a cone. It must be a combination of pressure and the force that the current through the voice coil makes on the cone. Is there a simple way to calculate the sheer force on the cone? Mårten
I make speakers and in the course of experiments or new product development *have* torn speaker cones.

In fact there is one *killer* sounding combination which I can't make any more because of guaranteed failure within a couple months.

After autopsy, rather than sheer pressure itself, I saw the following destructive mechanism:
Imagine a rectilinear cone pointing up, seen from one side.
When VC starts going "up", not all the cone goes up at the same instant, because:

a) cone is not rigid (none is).

b) the accelerating force is not applied over all the surface but only at the apex of the cone.
More properly at the "neck" that joins VC and cone.

c) the cone, besides being flexible, has mass, so "the center" starts moving up before "the edge".
Net result is that the cone flexes forward.
Now the applied voltage inverts, same happens but in the opposite direction.

Net result is that the cone is *vigorously* (and that's an understatement) flexed.

And not in an uniform way, since the center moves up and down at a different phase than the edge, and sound/movement takes a definite time to travel center to edge, there's a (literally) wave going back and forth.
Which depending on frequency has nodes and peaks at different distances from the VC.

If strong and sustained enough, this causes a weakening of the cone and eventual failure.
I'm not talking about sheer cone tearing but flexion caused fatigue.

In my experiments, it usually happens between 20% and 30% of the distance from "neck" to edge.
I have tried reinforcing the "danger area" by cutting a proper sized ring from other cone and gluing it there.
It works ... but it *kills* the sound

I guess that's why "big" efficient speakers tend to use large diameter VC (say, 100 mm) and curvilinear cones (JBL/EV/etc.)

 29th March 2013, 03:25 PM #6 tb46   diyAudio Member   Join Date: Jan 2006 Location: Texas Hi Y'all, This part of this thread: TH-18 Flat to 35hz! (Xoc1's design) especially Post #693, by Tom Danley may be of interest. Here is a neat pamphlet by Harman/Infinity on their C.M.M.D. cones: http://www.harmanaudio.com/all_about_audio/Cmmd.pdf John Sheerin posted an interesting reference here, Post #6: cone breakup Otherwise, you should be able to carefully tune just about any resonant mechanical system into self-destruct mode, particularly loudspeakers. All it takes is dilligence. :-) Regards, __________________ Oliver
weltersys
diyAudio Member

Join Date: Jan 2008
Location: Florida
Quote:
 Originally Posted by JMFahey I'm not talking about sheer cone tearing but flexion caused fatigue. I guess that's why "big" efficient speakers tend to use large diameter VC (say, 100 mm) and curvilinear cones (JBL/EV/etc.)
I have found curvilinear cones to be more subject to flexing induced failure than conical cones.
Curvilinear designs extend the upper response of cones because they allow some flexing.

 29th March 2013, 07:02 PM #8 PASC   diyAudio Member   Join Date: Dec 2004 Location: South Brazil Hi! Throat cone rate should be adequate with all kind of horns. What about failure limits: thermal and mechanical. Stay within limits wih good projects loudspeakers (good drivers) will be alive. My thougths. Regards, __________________ PASC
 29th March 2013, 07:06 PM #9 wg_ski   diyAudio Member   Join Date: Oct 2007 Curvilinear designs extend the upper response because they don't go to complete \$ when they do break up. They're on the light side to get that extended high end, and light cones die if you hit em too hard (as 4pyros has found out - the exact failure pattern that JMFahey described). Build one stout enough to withstand 1000 watts in a horn and it won't have good HF resonse, which defeats the purpose of the curvilinear cone. Good HF response isn't needed in a sub. You've just gotta use the right tool for the job. Back when more than 200 watts was a dream you could put an EVM15B in a horn with an 8 foot path and get away with it. Don't try it with a modern amp unless you want to support your local reconer.
 29th March 2013, 07:18 PM #10 Hentai   diyAudio Member   Join Date: Nov 2006 As JMFahey said it takes a while for the force to reach the outer edge of the cone. Now correct me if i'm wrong but the edge of the cone is where air load has the most influence, granted that in a horn's throat that resistance becomes much higher combined with the effect described by JMFahey you can visualize what cause the distruction of cone. A good cone loudspeaker for horn loading has high voicecoil diameter but smaller overall diameter, but it all depends on the horn design. Usually compression ratio for bass horns is small so not to create problems.

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Car Audio     diyAudio.com Articles     Music     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Aussie Amplifiers         CSS         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post bvan Multi-Way 30 27th November 2012 10:10 AM benpalmer Subwoofers 8 9th April 2012 01:10 PM mashaffer Multi-Way 2 14th October 2011 03:53 AM lieven Full Range 2 29th October 2010 07:15 PM EmergencyDpt Full Range 24 3rd April 2009 10:03 AM

 New To Site? Need Help?

All times are GMT. The time now is 04:02 PM.