irb
pfm Member
Long post, sorry! I started a thread the other day in the classifieds, just incase anyone had a spare Bandor 100mm woofer lying around. Not likely, I know. But I also thought I'd post here as I'm considering a diy fix in the absence of a spare.
As I mentioned previously, I recently acquired a pair of Pentachord speakers with column bass units. Each bass unit has a pair of the Bandor 100mm woofers, mounted face to face in an isobaric configuration. I realised a little too late that there were problems - probably because I played them so quietly for the first few weeks. Anyway, having dismantled them, I found several problems - two of the four with blown leads, one with a rubbing voice coil. In fact the fourth one also had a rubbing voice coil, but I reckon it was just dirt, and I've managed to get it working fine now. (It's hardly surprising it had dirt in the gap, because the speaker it was in deposited a huge pile of brown dust on my carpet when I pulled the drivers out. I assume the dust had once been damping foam, but it was truly disgusting.)
I've resoldered one blown lead and it's fine, so that's 2 out of 4 working properly. I'm going to have a go at resoldering the other blown lead, although it's a bit trickier.
The one I'm most worried about, though, is the one with the persistent rubbing coil. I've established that if you press in on one side of the cone it is fine, but if you press elsewhere, including the centre, it rubs. So it's maybe just misaligned.
I'm in two minds whether to send it to a repairer or try fixing it myself. I've read about the acetone method, which involves removing the dust cap, shimming the coil to push it towards the position where it doesn't rub, and then putting a few drops of acetone on the spider, which apparently should soften the resins in the spider. Leaving it for 24 hours or so will allow the resins to reset, and hopefully the voice coil will be in a better alignment.
Any experience or thoughts?
And if I do have a go, should I cut the dust cap off or try dissolving the glue with a solvent? I've seen both methods recommended.
As I mentioned previously, I recently acquired a pair of Pentachord speakers with column bass units. Each bass unit has a pair of the Bandor 100mm woofers, mounted face to face in an isobaric configuration. I realised a little too late that there were problems - probably because I played them so quietly for the first few weeks. Anyway, having dismantled them, I found several problems - two of the four with blown leads, one with a rubbing voice coil. In fact the fourth one also had a rubbing voice coil, but I reckon it was just dirt, and I've managed to get it working fine now. (It's hardly surprising it had dirt in the gap, because the speaker it was in deposited a huge pile of brown dust on my carpet when I pulled the drivers out. I assume the dust had once been damping foam, but it was truly disgusting.)
I've resoldered one blown lead and it's fine, so that's 2 out of 4 working properly. I'm going to have a go at resoldering the other blown lead, although it's a bit trickier.
The one I'm most worried about, though, is the one with the persistent rubbing coil. I've established that if you press in on one side of the cone it is fine, but if you press elsewhere, including the centre, it rubs. So it's maybe just misaligned.
I'm in two minds whether to send it to a repairer or try fixing it myself. I've read about the acetone method, which involves removing the dust cap, shimming the coil to push it towards the position where it doesn't rub, and then putting a few drops of acetone on the spider, which apparently should soften the resins in the spider. Leaving it for 24 hours or so will allow the resins to reset, and hopefully the voice coil will be in a better alignment.
Any experience or thoughts?
And if I do have a go, should I cut the dust cap off or try dissolving the glue with a solvent? I've seen both methods recommended.