What Has Caused this Damage? |
Post Reply | Page 12> |
Author | ||
AJ113
Registered User Joined: 11 March 2016 Location: Hull UK Status: Offline Points: 123 |
Post Options
Thanks(0)
Posted: 21 October 2018 at 1:48pm |
|
This is a 450-watt Eighteen Sound 15 inch driver - it's not marked, but my super-sleuth detective skills have narrowed it down to a 15w700. It was in what seems to be a very-nicely built 6th order bandpass cabinet; as I understand it, made by Apart as a prototype. Obviously I gave it too much juice. I was running a 700-watt amp. It was live music so I figured it would be ok, but the kick drum was triggered and I had the bass guitar quite high up in the mix, I guess I pushed it over the edge. So my question is: the loudspeaker voicecoil is fried, obviously thermal overload, but I don't understand fully what has caused it. I have never seen a speaker looking like that before, just through excessive power being fed to it. Has the compression within the cabinet restricted the speaker's excursion and caused thermal overload, or has the excess power fried the voicecoil and the ripped cone is a result of that somehow? The reason I ask is because I want to replace the drivers (yes, I blew two :( ) but not necessarily with Eighteen Sounds, and I want to understand what has happened here so that I can pick suitable products. Edited by AJ113 - 21 October 2018 at 1:49pm |
||
valve head777
Old Croc Joined: 27 July 2012 Location: East Sussex Status: Offline Points: 1780 |
Post Options
Thanks(1)
|
|
Kick or excess bass ripped the cone allowing the voice coil to then move out of the magnetic gap causing it to burn? Cone must have ripped before the VC damage. How does the spider look? That's my 2p's worth...
|
||
Freedom of choice, choice of freedom.
|
||
Mircea Bartic
Old Croc Joined: 18 February 2005 Location: Romania Status: Offline Points: 2581 |
Post Options
Thanks(1)
|
|
high loading on the cone, cone too thin for the loads applied. Probably no highpass or incorect DSP settings.
also not a 15W700. suspension is different on that
Edited by Mircea Bartic - 21 October 2018 at 2:12pm |
||
general manager & head designer at nexus-acoustics research
http://www.facebook.com/nexus.acoustics.research Ex Nexus_3 |
||
ceharden
The 10,000 Points Club Joined: 05 June 2005 Location: Southampton Status: Offline Points: 11776 |
Post Options
Thanks(1)
|
|
As above, looks like the cone isn't designed to take the high loading you get in a bandpass.
A driver with a heavier, straight-sided cone might be a good place to start narrowing down your choices.
|
||
studio45
Old Croc Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3863 |
Post Options
Thanks(1)
|
|
The thing is, bandpass cabs are quite reliant on the driver parameters being just-so, to arrive at the correct tuning for the driver+cabinet system as a whole. So putting another driver in there might work, or it might not.
You may have just discovered why this was a prototype - did it actually go into production? Maybe Apart had this problem, and could not solve it other than by re-designing.
|
||
Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
|
||
AJ113
Registered User Joined: 11 March 2016 Location: Hull UK Status: Offline Points: 123 |
Post Options
Thanks(0)
|
|
Yes that makes sense, thank you. The spider looks fine to me.
|
||
AJ113
Registered User Joined: 11 March 2016 Location: Hull UK Status: Offline Points: 123 |
Post Options
Thanks(0)
|
|
|
||
AJ113
Registered User Joined: 11 March 2016 Location: Hull UK Status: Offline Points: 123 |
Post Options
Thanks(0)
|
|
Good point. As far as I know it never went into production. On the other hand I've used these boxes many times on hires and they've always been rock solid, so I think it's more likely to be user abuse.
|
||
AJ113
Registered User Joined: 11 March 2016 Location: Hull UK Status: Offline Points: 123 |
Post Options
Thanks(0)
|
|
...except the suspension! Very good point! Looks like the chaps at Apart have reconed it at some point.
Edited by AJ113 - 22 October 2018 at 8:02am |
||
AJ113
Registered User Joined: 11 March 2016 Location: Hull UK Status: Offline Points: 123 |
Post Options
Thanks(0)
|
|
Could anyone advise what characteristics and parameters I need to check for a loudspeaker to be suitable for a 6th order bandpass cab please?
|
||
odc04r
Old Croc Joined: 12 July 2006 Location: Sarfampton Status: Offline Points: 5483 |
Post Options
Thanks(1)
|
|
Tough stiff cone that does not flex easily, higher mms might be an indication.
|
||
studio45
Old Croc Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3863 |
Post Options
Thanks(1)
|
|
Can you measure the chamber volumes and port sizes? Because you need a driver suitable for *this* BP6 cabinet. They're not as forgiving as a reflex cabinet. If the driver parameters are not suitable the response will be less than optimal, possibly to the point of complete rubbishness. A strong cone is a good start, but the rest of the numbers need to be right too. If you can measure up the box, you can simulate various drivers in WinISD and arrive a a good solution.
|
||
Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
|
||
Post Reply | Page 12> |
Tweet |
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |