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[Josh Billings]

Hey Guys,

Curious if and how you guys have blown your LAB Subwoofers. Like under what conditions did they go? What kind of power? Heavy Limiting? Over Excursion? Air Leak? What kind of music? Etc...

I can chime in with one experience. I was feeding 2 LABs an RMX1850HD and i don't remember any clipping but the DJ was RIDING the system HARD...so who knows exactly what happened.

-Josh

[Marjan Milosevic]

I do know what exactly happened when mine was blown. No HP filter.
I did save them. The wire that goes from the cone towards the voice coil was burned at one small point. I just replaced around 1cm of the wire. All 4 drivers had the same problem.

[Jeremy Bridge]

I have built about 30 labs and have 18 in our rental inventory, we have gone through a fair ammount of drivers over the years.  We very rarely lose drivers on a typical club show, and never with a band / live setup.

Where we do loose drivers is large outdoor festivals and DJ events.  Specifically with electronic music.  

In the beginning when we first started building them it was air leaks.  The odd driver was over excurting, cones were tearing, spiders were seperating, voice coils were bottoming etc.  After the first couple boxes we had it down and that problem disapeared.

Since then it's almost always burnt voice coils, usually on events where the system runs for 16+ hours.  Our only real solution for this has been to try and do 1 large stack and cycle groups of subs out durring the non-headliner slots so they have a chance to cool down.

Lab's definatley aren't indestructable but after a bit of practice and knowing thier limits they are as reliable as any other sub.

Jeremy

[Ivan Beaver]

Jeremy Bridge wrote on Wed, 09 April 2008 11:56

Since then it's almost always burnt voice coils, usually on events where the system runs for 16+ hours.  Our only real solution for this has been to try and do 1 large stack and cycle groups of subs out durring the non-headliner slots so they have a chance to cool down. Jeremy

Why not just run all of them-each at a lower level?  I would think that would be better than running some at near full output for awhile and then swapping with others that were "fresh".

[Jeremy Bridge]

Ivan Beaver wrote on Wed, 09 April 2008 17:44

Why not just run all of them-each at a lower level?  I would think that would be better than running some at near full output for awhile and then swapping with others that were "fresh".

I am not sure it just seems to work better.  We've tried both ways.  Really I am sure it's just phycilogical because you turn it down...then turn a stack off, then cycle through them.  Instead of just turn it down.  When you have 6 stacks of 3 and you turn one off it doesn't really make a huge difference.

I think a problem with the LAB deisgn is that the heat transfer from the sealed chamber to the outside of the bos is not sufficient.  So the actual chamber temperature slowly increases over time.

We've thought about the cooling plug idea but honestly we've been too lazy to implement it.  lol

[Ivan Beaver]

At least the lab sub has some cooling to the outside world.  Most all horns (cone driven-without sealed drivers) have no cooling path to the outside world-except through the cone-which is very little.  The rear chambers are typically very small-which results in more heating of the driver

[Craig Hauber]

I know how hot the surface of a rack or roadcase can get on an outside show -especially up in the desert.  I'm sure at some point during these situations that heat is being added to the chamber from the outside because of the aluminum panel.

Any thought of a design where the motor structure is outside the chamber?  Such as having the magnet in the throat of the horn?

I was also curious if heat-pipe technology could work, conduct the heat out of the motor to a large heat-sink that doubles as the speaker's grille.

[Marjan Milosevic]

I only see a problem in horizontal stacking one on top of the other. This way the plates touch each other and the heat dont have where to go.

[Ivan Beaver]

YOu could place strips of wood (say 2x4) between the cabinets and that would allow for some airflow and would not affect the performance due to the large wavelengths involved.

Now stability of the whole thing from "sliding around" would be another issue.  If grooves were cut in the sides of the cabinets to accept the wood it would be more stable.

[Josh Billings]

Wouldn't these do a decent job too?

[Ivan Beaver]

The problem with rubber feet sticking out is that (especially large heavey cabinets like the labs) as they get moved and slid around the feet get knocked off-even with good quality feet and throught bolts into tnuts.

But yes that would work-as long as the feet were intact.  Not as much clearance as say a 2x4, but would be better than just laying aginst one another.

[Randy Pence]

Ivan Beaver wrote on Sun, 13 April 2008 16:40

YOu could place strips of wood (say 2x4) between the cabinets and that would allow for some airflow and would not affect the performance due to the large wavelengths involved. Now stability of the whole thing from "sliding around" would be another issue.  If grooves were cut in the sides of the cabinets to accept the wood it would be more stable.

how about wrapping the wood in non-skid rubber?  

[Ryan S Yorck]

Craig Hauber wrote on Sat, 12 April 2008 23:55

I know how hot the surface of a rack or roadcase can get on an outside show -especially up in the desert.  I'm sure at some point during these situations that heat is being added to the chamber from the outside because of the aluminum panel. Any thought of a design where the motor structure is outside the chamber?  Such as having the magnet in the throat of the horn? I was also curious if heat-pipe technology could work, conduct the heat out of the motor to a large heat-sink that doubles as the speaker's grille.

I think Pi speakers was making custom cooling plates for the LAB subs, as you described above.  

http://www.pispeakers.com/catalog/default.php/cPath/4?osCsid =mafhi5ggeti3s23nn9hjbie1t5

[Charlie Zureki]

Josh,
 Did you ever find out why your speakers were blown?

[larry gallant]

Air leaks blow LAB'S
No HP blows LAB'S
DJ's square wavin blows LABS
Check for air leaks with a Bick lighter around the access plate.
Using one or two a side,rate at 800 watts.
In a stack of 4,1600Watts is OK per cabinet due to increased efficency.
A Labgruppin Fp6400 works well on 4 Labs at1600per cabinet.
We do not blow Labs,only use them within their limits.
Larry

[jeffhtg (Jeff Kenney)]

larry gallant wrote on Wed, 23 April 2008 05:02

Air leaks blow LAB'S No HP blows LAB'S DJ's square wavin blows LABS Check for air leaks with a Bick lighter around the access plate. Using one or two a side,rate at 800 watts. In a stack of 4,1600Watts is OK per cabinet due to increased efficency. A Labgruppin Fp6400 works well on 4 Labs at1600per cabinet. We do not blow Labs,only use them within their limits. Larry

got any impedance graphs running your amps like that? That scares me running a $5000 amplifier so close to the red line.

[larry gallant]

Jeff,sorry for the long delay.I was not able to logon for some reason.It appears the impediance of one box is 2.5 ohms and 2 per side of an amp would be 1.25 ohms.This is not the case.The hornloading doubles the impediance to 2.5 ohms a safe load for a quality amp.We get 4 years out of a lab driver in a nightclub scene as the foam rubber gives out.Got no complaints the Lab sub is a bargoon.If you are paying 5 grand for a lab amp you should email me.
Larry

[Harry Sookraj]

never blown labs at indoor events, always  at the west indian carnivals. always vc burnout

[The Guy]

jeffhtg (Jeff Kenney) wrote on Mon, 03 November 2008 21:40

got any impedance graphs running your amps like that? That scares me running a $5000 amplifier so close to the red line.

Why the hell would that scare you?  Lab G amps are some of the best out there and can take all the abuse you can throw at them.  I'd be more worried about using an El-Cheapo amp to run 4 lab cabinets.  We've run 4 Labs per QSC PL9.0 for years with no issues whatsoever, including using them at 90 degree 16 hour EDM festivals.  In my experience, the LG stuff performs just as well.  

-J

And $5000 for a FP6400??  Find a new LabG supplier; you're overpaying big time.