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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => SR Forum Archives => LAB Subwoofer FUD Forum Archive => Topic started by: Marikili Oswin on July 08, 2004, 01:25:38 PM

Title: Lab12 Reliability - Ripped 4
Post by: Marikili Oswin on July 08, 2004, 01:25:38 PM

Guys,

I guess its time to discuss about the reliability factor of the Labsubs in the long run.

We got a pair of subs made in Nov 2003, added the second pair in June 2004.We did about 15 gigs with the first pair usually feeding it about 1200@4 Ohms.

Last weekend piled all four subs in the center and powered it with 2 Dynacord

Title: Re: Lab12 Reliability - Ripped 4
Post by: Bogdan Popescu on July 08, 2004, 01:54:06 PM

Looks real bad.

Eminence people should take a look at it.
I feel like something was wrong, maybe not setup, could be just a bad impulse from the amp...

Good luck

PS: I am just finishing number 5&6 this week

Title: Re: Lab12 Reliability - Ripped 4
Post by: Marikili Oswin on July 08, 2004, 02:21:52 PM

Bogdan P. wrote on Thu, 08 July 2004 23:24

Looks real bad. Eminence people should take a look at it. I feel like something was wrong, maybe not setup, could be just a bad impulse from the amp... Good luck PS: I am just finishing number 5&6 this week

Bogdan, If it was an impluse from the amp why didnt it affect the new sub on the other channel. I had connect one old and one new sub on each amp.

Oswin

Title: Re: Lab12 Reliability - Ripped 4
Post by: Tamas Tako on July 09, 2004, 04:44:37 AM

Hi,

I had the same problem with 8 pcs of LAB12 speakers and many others too...
The problem is coused by the bad sealing between the cone and the suspension.
there are two versions of the LAB12 (g2).
the earlier versions didn't had glue on the back side between the cone and the suspension, while the newer version has...
You should contact EMINENCE with the photos attached and send the serial nr to them too. (the ser. nr. is on the magent below the rubber thing)
I 'v got from eminence all the new recone kits for my old version speakers for free in few days.
Please try to contact Jerry McNut at eminence.

all the best,

Tako Tamas

Title: Re: Lab12 Reliability - Ripped 4
Post by: David Shan on July 09, 2004, 06:29:27 AM

Interesting Pics, I had 4x Kappa Pro in peavey DTH concert subs (we got the cabs unloaded) years ago all the edges cracked around the cone one by one.  

I put it down to not being able to withstand coming out the van in cold weather then being powered up. I also thought at first it was over excursion but we only put 1000w a side to them and nothing under 40hz with steep roll-of. To Be honest i never thought of eminence being all that reliable, but that was prob due to what happened with the concert subs. Have you guys considered what a lab sub would sound like if JBL/RCF etc were to make the special driver? My thoughts it would be tighter and more reliable?

Thanks

Title: Re: Lab12 Reliability - Ripped 4
Post by: Al Limberg on July 09, 2004, 09:10:12 AM

It strikes me as rather simplistic to blame the speaker manufacturer when you load a speaker in a box it wasn't designed for (or vice versa).
I too have lost a total of 2 Lab 12s over the last 2 years (out of 16).  One was inspected by Eminence and determined to be a factory defect (voice coil shorted at the point where it crosses from one side to the other as it's a dual layer v.c.) and the other questioned as perhaps over-powered but still replaced under warranty.  I have, since the second occurence, made it  my own policy to check the tightness of all module lid screws prior to each gig and also to now replace the lid caulking-sealant each spring and fall.  The combination of the energy created by the cab itself and the constant riding in a truck are enough to let machine screws come loose.  Loose screws and caulk trying to maintain a seal against the cone motion of the Lab is a battle that takes constant attention.

Al  
p.s.  I have also raised the HPF on my DSP to 35Hz/24db/Oct when using less than 4 in a block.

Title: Re: Lab12 Reliability - Ripped 4
Post by: Marikili Oswin on July 09, 2004, 10:01:00 AM

Al Limberg wrote on Fri, 09 July 2004 18:40

It strikes me as rather simplistic to blame the speaker manufacturer when you load a speaker in a box it wasn't designed for (or vice versa). I too have lost a total of 2 Lab 12s over the last 2 years (out of 16).  One was inspected by Eminence and determined to be a factory defect (voice coil shorted at the point where it crosses from one side to the other as it's a dual layer v.c.) and the other questioned as perhaps over-powered but still replaced under warranty.  I have, since the second occurence, made it  my own policy to check the tightness of all module lid screws prior to each gig and also to now replace the lid caulking-sealant each spring and fall.  The combination of the energy created by the cab itself and the constant riding in a truck are enough to let machine screws come loose.  Loose screws and caulk trying to maintain a seal against the cone motion of the Lab is a battle that takes constant attention. Al   p.s.  I have also raised the HPF on my DSP to 35Hz/24db/Oct when using less than 4 in a block.

Al

I guess you haven't read the post carefully. Here we are talking about the Lab12 in their own box it was designed for and driven as they  ment to be. This problem is faced with quite a few of the lab owners and we are trying to solve it. This problem is with the speaker or the box and I dont think it is with the screws and sealant.If you notice all the speakers show the same level of damage.

Is Eminence stepping in here??

OZ

Title: Re: Lab12 Reliability - Ripped 4
Post by: Too Tall (Curtis H. List) on July 09, 2004, 10:52:51 AM

Shane Gosling wrote on Fri, 09 July 2004 06:29

Interesting Pics, I had 4x Kappa Pro in peavey DTH concert subs (we got the cabs unloaded) years ago all the edges cracked around the cone one by one.   I put it down to not being able to withstand coming out the van in cold weather then being powered up. I also thought at first it was over excursion but we only put 1000w a side to them and nothing under 40hz with steep roll-of. To Be honest i never thought of eminence being all that reliable, but that was prob due to what happened with the concert subs. Have you guys considered what a lab sub would sound like if JBL/RCF etc were to make the special driver? My thoughts it would be tighter and more reliable? Thanks

In general I have to disagree.
Eminence has a "cheap" reputation from selling people millions of inexpensive drivers over the years. It does not mean they can't build as good a driver as anyone else.
   As to failure rates ALL the speaker manufacturers go through this. If I remember correctly the  "K" series for JBL was fragile. They sounded wonderful for the 2 minutes they worked and then self-destructed. Beyond that line they have had factory defect based failures in other lines.
   EV has gone through the same thing. I never kept track of RCF, but I would bet the same.
   There is nothing wrong with EV or JBL. This is something that happens when you make a large number of anything.
   The key is if they stand behind it and change the product if there is an inherent flaw.
   As for the statement that a JBL or RCF would sound "tighter" that is obvious brand loyalty with no basis in fact. They can only sound "tighter" if you find a better set of T/S values to put in the box that Tom Danley designed and good luck on that.

   All that being said there we should keep Eminence's feet to the fire on any factory defects.
   We should continue to communicate on any failures.
   And lastly we need to keep in mind that this design is NOT bullet-proof or magic and that we will break it on a regular basis if we don't learn its limits.
   These boxes are like a lot of other good sounding boxes. You can push them into dangerous output and they still sound good. It makes it impossible to tell by ear how much they can take.
Too Tall

Title: Re: Lab12 Reliability - Ripped 4
Post by: Mark Seaton on July 09, 2004, 01:11:36 PM

Oz wrote on Fri, 09 July 2004 09:01

Is Eminence stepping in here?? OZ

It appears this is an adhesive issue like Tako mentioned.  Eminence was closed for annual inventory, but they should be back in the office next week(I think).  Contact them and determine what the problem was, and include the serial numbers of the drivers.  Being that it was the older pair that failed, there is certainly a good possibility those older drivers might have been prone to the failure sooner.  You will have to talk to Eminence to find out.

I know that on our related, but different 12" used in a few of our products, including the B-DEAP-32, the large majority of any failures have come from gross over-excursion (at multiples intended/rated drive levels).  While the power applied was very high, coil burn has been quite rare.  Overall our drivers have been very reliable within intended useage.  

Title: Re: Lab12 Reliability - Ripped 4
Post by: Al Limberg on July 09, 2004, 02:26:49 PM

Sorry you missed that my post was obviously in response to Shane's post about using Emminence drivers in Peavey cabinets.
Al

Title: Re: Lab12 Reliability - Ripped 4
Post by: Geri O'Neil on July 09, 2004, 06:29:59 PM

Actually, it appears that YOU didn't read Al's post carefully, or at least missed the context. I'm pretty certain he was responding to the fellow that loaded the Kappa drivers into the Peavey cabinets and NOT your original post. From reading Al's posts over the years, I know he's pretty sharp. If I were you, I'd listen to him a little more carefully.

Respectfully,
Geri O

Title: Re: Lab12 Reliability - Ripped 4
Post by: thejesse on July 10, 2004, 08:36:50 PM

so we have allso lost 4 in this verry same manner dont know what to think and the cheapest recone kit ii can finde is 75 a piece ouch this is starting to get old   jesse bruce

Title: Re: Lab12 Reliability - Ripped 4
Post by: Tim Padrick on July 12, 2004, 12:39:32 AM

It seems to me that:

If the flex leads can be broken owing to over excusrion, it's a design flaw.

If the voice coil former can be damaged owing to hitting the back plate, it's a design flaw.

If the cone or surround can be damaged owing to the strength of the drive motor, it's a design flaw.

The only thing that should ever be capable of damage in a properly designed loudspeaker is the voice coil, owing to being driven beyond it's power rating.

Title: Re: Lab12 Reliability - Ripped 4
Post by: raj on July 12, 2004, 01:03:19 AM

I had heard of cloudburst but here I see cone burst

Title: Re: Lab12 Reliability - Ripped 4
Post by: Too Tall (Curtis H. List) on July 12, 2004, 11:12:21 AM

TimmyP wrote on Mon, 12 July 2004 00:39

It seems to me that: If the flex leads can be broken owing to over excusrion, it's a design flaw. If the voice coil former can be damaged owing to hitting the back plate, it's a design flaw. If the cone or surround can be damaged owing to the strength of the drive motor, it's a design flaw.

I disagree.
You could instead say that it is not idiot proof or totally bulletproof.
Your conditions above would seriously curtail the power of this motor and therefore its output capability.
   We want to use as powerful a motor as possible and leave as few restrictions as possible.
If we look at a race car you don't put in a tiny motor with a so little power that it can not hurt the drive train or blow itself up. We put in as powerful a motor as we can make (and still make sense for the purpose) and give the driver a RPM gauge letting him use the motor to its limit.
The limit here may be the strength of the glue, surround and cone material. That just means we need to use it within those limits, not replace the motor structure with something that has less power.

Where you are correct is that the surround and cone structure should fail before the leads run out of length and around the same time as you bottom out. It does seem that this is what is happening.
So far we have a problem with glue and that is been taken care of for the speakers coming off the line and is being covered by Eminence on a case by case basis for speakers in the field.

TimmyP wrote on Mon, 12 July 2004 00:39

The only thing that should ever be capable of damage in a properly designed loudspeaker is the voice coil, owing to being driven beyond it's power rating.

In a world where we have material with unlimited strength and durability this would be nice. Otherwise according to your guidelines if we have the best material available we should then cut down the motor strength till it can not hurt itself. Most of the Pro bass speakers out there are not designed that way. The products you see that are designed that way appear mostly in the home and MI market.
   "Yes, that's right, you can turn it all the way up to 10 and it won't break. Of course it sounds like garbage at 6, but it doesn't break." I've used enough gear like that through the years. It sounds like garbage at 25% of rated power and you only WISH it would blow up and put it out of your misery.
This design is a formula-1 race care, not a taxicab with a governor the driver can't get to.
For the LAB sub we need to determine its mechanical limits and properly filter and limit the input. This is less obvious with the LAB sub because it sounds good right up to the point where it starts to rip itself apart.
   As I said before we need to hold Eminence's feet to the fire on factory defects, which this glue issue seems to be, but this does not mean we can just turn it up till it breaks and call it their "design flaw".
   The tricky part here is what to do with failures that happen 1 year or two years down the road. Was it bad glue that fatigued or were we pushing it past its Xmax on a regular basis and it should have blown up the first night?

Respectfully,
Too Tall

Title: Re: Lab12 Reliability - Ripped 4
Post by: Graeme Goodacre [Centauri on July 13, 2004, 05:39:25 AM

Hi, haven't built any Labs myself yet, but had been looking at it.  My Hornresp simulation of the LabSub would seem to suggest that Xmax can be reached at 50Hz and 33Hz with an 800W input signal (400W per speaker). Depending on program material etc, I would think a 1200W amp would be capable of easily over-excurting the drivers.  Running things so much on the edge would HAVE to compromise long term reliability.

Maybe 800W should be the recommended maximum input for the Lab ?

Cheers
Graeme

Title: Re: Lab12 Reliability - Ripped 4
Post by: Tom Herr on July 13, 2004, 03:29:07 PM

800 Watts?  I have been hitting mine with 2400 watts per box for over a year now. No driver failures. To my knowledge non of the labhorns I have built have experienced driver failures. I do stress the importance of checking the access plates regularly. An air leak could shred a perfectly good set of drives.  I check mine just about everytime they roll out of the trailer. But I consider that part of system maintenance just like painting cabs, cases or cleaning connector ends, etc...   Just part of a days work.

Tom Herr

Title: Max Power
Post by: Brad Litz on July 13, 2004, 11:50:27 PM

I think most high spl users want to push the drivers past the one way linear travel (Xmax) 13mm to the two way max displacement (Xmech) of 44mm on peaks. The analysis I have done indicates that in 4 box groups they should handle 2400 watt peaks if high pass filtered -3db at 30 hz with a steep roll-off.

Mechanical fatgue is a very non-linear process. Easing off 1 or 2 dB can be the the difference between early failures or long life if you are operating near Xmech.

Title: Re: Max Power
Post by: Graeme Goodacre [Centauri on July 14, 2004, 06:53:49 AM

Brad Litz wrote on Wed, 14 July 2004 13:50

I think most high spl users want to push the drivers past the one way linear travel (Xmax) 13mm to the two way max displacement (Xmech) of 44mm on peaks.

I thought one of the original design parameters of the LasSub was to achieve the highest quality sound from a DIY box, and operating outside Xmax isn't really doing anything for quality of sound.  If I want higher spl, I add more boxes.....

Cheers

Title: Re: Max Power
Post by: Too Tall (Curtis H. List) on July 14, 2004, 09:42:56 AM

Centauri wrote on Wed, 14 July 2004 06:53

Brad Litz wrote on Wed, 14 July 2004 13:50 I think most high spl users want to push the drivers past the one way linear travel (Xmax) 13mm to the two way max displacement (Xmech) of 44mm on peaks. I thought one of the original design parameters of the LasSub was to achieve the highest quality sound from a DIY box, and operating outside Xmax isn't really doing anything for quality of sound.  If I want higher spl, I add more boxes..... Cheers

Ah yes, the difference between what we say and what we do.  
The box was designed to be used in blocks of four and my guess is more then half the time they are used as singles or pairs.
As to your comment on quality just about everyone would agree in theory while they push the volume higher and higher (as long as it sounds good and the amp they use doesn't show solid clip).
In the end many do not have the money to build headroom into their system and quality components at a decent price works for them too.
   Such is our business.