| 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.
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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.
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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
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Topic: Lab12 Reliability - Ripped 4 (Read 11448 times)