CoastinHome
Well-Known Member
Greetings all,
I just received a late 50s Ampex-by-JBL 8 inch driver from a 621F integrated amp/speaker system which @Plimpington2 sent after helping him in repurposing the amplifiers for general use. These were used in the 620 and some of the later suitcase amplifiers as well.
On its way across the country the water-soluble packing peanuts compacted and shifted. The driver ended up floating somewhat freely in the packing material and had some pressure on the cone -- but that doesn’t seem to explain what I've got here.
The cone appears to be original.The cone isn’t damaged and the voice coil seems to move freely. The doped edges of the cone are in good shape.The spider is still attached to the cone and the frame.
Everything looks good except that with no signal the cone is in the last 10% or so of its normal range. The cone is nearly bottomed out as if it had a DC voltage on the coil.
I believe the restorative force is provided by the spider. Of course the spider is not on average flat.
For lack of time to make a path to its destination a couple of years ago I left a stereo console in the back of my station wagon (under a car cover) for three months during a heat wave which was hot enough to do some real damage to all four interior door panels (which held up fine for the 20 previous years). I would imagine that this level of heat over time could cause something like this -- but it didn’t.
Has anybody here ever had to take a heat gun to a spider in an attempt to restore the equilibrium point to the middle of the normal excursion? Any other suggestions?
Thanks… Hope everyone’s enjoying their holiday weekend!
I just received a late 50s Ampex-by-JBL 8 inch driver from a 621F integrated amp/speaker system which @Plimpington2 sent after helping him in repurposing the amplifiers for general use. These were used in the 620 and some of the later suitcase amplifiers as well.
On its way across the country the water-soluble packing peanuts compacted and shifted. The driver ended up floating somewhat freely in the packing material and had some pressure on the cone -- but that doesn’t seem to explain what I've got here.
The cone appears to be original.The cone isn’t damaged and the voice coil seems to move freely. The doped edges of the cone are in good shape.The spider is still attached to the cone and the frame.
Everything looks good except that with no signal the cone is in the last 10% or so of its normal range. The cone is nearly bottomed out as if it had a DC voltage on the coil.
I believe the restorative force is provided by the spider. Of course the spider is not on average flat.
For lack of time to make a path to its destination a couple of years ago I left a stereo console in the back of my station wagon (under a car cover) for three months during a heat wave which was hot enough to do some real damage to all four interior door panels (which held up fine for the 20 previous years). I would imagine that this level of heat over time could cause something like this -- but it didn’t.
Has anybody here ever had to take a heat gun to a spider in an attempt to restore the equilibrium point to the middle of the normal excursion? Any other suggestions?
Thanks… Hope everyone’s enjoying their holiday weekend!