Some companies ship drivers with shorting wire twisted across the terminals , some don't.
Tapping the surface of 3/16" masonite covering a 15" woofer in a cabinet it's very easy to hear the difference between when shorted and when not. Deeper and looser when open, tighter and higher when shorted. So undamped and damped.
The question is, is it better to short them when shipping or not?
Thanks
Tapping the surface of 3/16" masonite covering a 15" woofer in a cabinet it's very easy to hear the difference between when shorted and when not. Deeper and looser when open, tighter and higher when shorted. So undamped and damped.
The question is, is it better to short them when shipping or not?
Thanks
Definitely cannot hurt. We talked about doing this back in the 70s.
But the powers that be thought the end user would not remove the short, and damage their amplifier.
But the powers that be thought the end user would not remove the short, and damage their amplifier.
Not something you think about every day. Normally it would restrict excursion but is it possible that it would result in greater excursion than when not shorted? I think it's possible under the right circumstances. I've encountered a similar situation tuning motorcycle suspensions, rebound and compression damping. While damping is not frequency dependent, too much damping can cause the vehicle to climb up on obstructions and have further to fall since it is slow to centre itself.
Not that I'm suggesting you shouldn't, I'm inclined to agree with Ray in general.. but I also can't help but wonder what would happen to the voice coil temperature if there was a resonance in transit?
Not that I'm suggesting you shouldn't, I'm inclined to agree with Ray in general.. but I also can't help but wonder what would happen to the voice coil temperature if there was a resonance in transit?
Is the intent to reduce driver excursion from shipping shocks? and therefore possible damage?
If so, I would have thought the kind of shock (assuming the correct axis) to cause over-excursion from handling, would have wrecked the frame well before then, if the driver has a ferrite magnet of reasonable size / weight.
If so, I would have thought the kind of shock (assuming the correct axis) to cause over-excursion from handling, would have wrecked the frame well before then, if the driver has a ferrite magnet of reasonable size / weight.
With no short, excursion is limited by the suspension. I cannot think of a shock that would bottom the coil without damaging the cabinet.
The magnet only comes into play when the coil is shorted. Granted, an aluminum vc form would certainly help with eddy dragging.
I used amplifier damping factor to limit cone excursion on stage when a hydrogen explosion pounded our chests. That and a sealed cabinet.
Not sure how the 12 inch would survive the 150 db pulse of the explosion without damping from the amp. With amp connected and on, I never had a problem.
John
The magnet only comes into play when the coil is shorted. Granted, an aluminum vc form would certainly help with eddy dragging.
I used amplifier damping factor to limit cone excursion on stage when a hydrogen explosion pounded our chests. That and a sealed cabinet.
Not sure how the 12 inch would survive the 150 db pulse of the explosion without damping from the amp. With amp connected and on, I never had a problem.
John
I usually ship FR drivers what no XOs. I always short the terminals.
If the driver gets a shock and moves the EMF generated resistes that movement, therfore decreasing potential issues with shipping damage.
A multiway with an XO might have somewhat different behaviour given what the XO does.
dave
If the driver gets a shock and moves the EMF generated resistes that movement, therfore decreasing potential issues with shipping damage.
A multiway with an XO might have somewhat different behaviour given what the XO does.
dave
UPS destroyed a pair of Monitor Audio speakers someone shipped me.
The basket of one of them was sheared off.... I mean, what kind of impact shears off the basket of a 5 inch woofer?
The cabinets were dented a bit too and the boxes were basket cases...
But the cone itself held on with its spider and the coil/magnet assembly were fine. I super glued the basket together and the speaker still worked ( but, don't worry, I replaced it)...
So, I wouldn't worry too much about shorting, or not, the terminals.... I think they are more important things to worry about.
The basket of one of them was sheared off.... I mean, what kind of impact shears off the basket of a 5 inch woofer?
The cabinets were dented a bit too and the boxes were basket cases...
But the cone itself held on with its spider and the coil/magnet assembly were fine. I super glued the basket together and the speaker still worked ( but, don't worry, I replaced it)...
So, I wouldn't worry too much about shorting, or not, the terminals.... I think they are more important things to worry about.
Thinking along lines similar to AllenB's motorcycle suspension analogy, At a certain frequency and force I can imagine it best to let the whole cone move softly and slowly (low Q). But I would think it best that damping at coil/spider is roughly the same as at surround so there's not much differential stress between the two ends in the event of a hard bump. Would that most likely be shorted or open?
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