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NS-1000M woofers

B

borealis

New Member
Hi, Just wondering about alignment for the metal plates on the back of the woofer magnets. I added a red arrow in the photo to point at the part of the assembly I’m asking about. They are not centered on the back of the magnets. I’m going to guess they are dust caps for the back of the assembly, but I’m not familiar with the build or design. The fact that they are ~1/4 inch out of center doesn’t seem to be affecting performance.

Everything else looks good, magnets are centered on the baskets, the glue is intact and not failing, the cones are moving freely and playing OK. I was going to add a bead of epoxy between the magnet and basket to avoid the magnet shift I’ve read about, but I don’t see any need as the glue seems to holding up just fine.

Thanks for any assistance


woofer (Medium).jpg
 
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Sounds like they are working fine but I would add the epoxy just to be safe. They're getting up there in age and could fail. Could save you a huge headache down the road.
I have these speakers also and need to do it.
 
OK Thanks. Yes, I couldn't see or hear anything wrong with the woofers other than that offset of the back plate on both. I was planning to add the epoxy, but it all looked OK so I left it as is. Maybe I'll open them up again and do as you suggested. I've seen some photos of pretty bad corrosion back there and glue coming apart. I was fortunate to not have this showing in my pair.
 
borealis said:
Hi, Just wondering about alignment for the metal plates on the back of the woofer magnets. I added a red arrow in the photo to point at the part of the assembly I’m asking about. They are not centered on the back of the magnets. I’m going to guess they are dust caps for the back of the assembly, but I’m not familiar with the build or design. The fact that they are ~1/4 inch out of center doesn’t seem to be affecting performance.

Everything else looks good, magnets are centered on the baskets, the glue is intact and not failing, the cones are moving freely and playing OK. I was going to add a bead of epoxy between the magnet and basket to avoid the magnet shift I’ve read about, but I don’t see any need as the glue seems to holding up just fine.

Thanks for any assistance


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That metal is called the "pole" I believe. If you take a look at the pictures I posted when I repaired my 690 woofers you can see the construction of the drivers. I highly recommend you epoxy them because repairing them is a task. I'll try to find a link to my repair and post it.

Yamaha NS woofer shifted magnet video

I came across this while perusing the tube of you. Although it's not English, it's a very good documented process. Hopefully it helps someone.
audiokarma.org
 
Great! Thanks for link. I did read through that thread previously but found it a bit difficult to follow. The video is nice as it has images of all the parts in the assembly, had some good methodology and nice images of the pole piece. I'm kind of surprised my woofers are working as the tolerance inside the coil for the pole piece doesn't look to be very wide. I'll have to take another measurement and think about whether it warrants a reassembly. I'm generally of the, "If it ain't broke..." way of thinking.
 
borealis said:
Great! Thanks for link. I did read through that thread previously but found it a bit difficult to follow. The video is nice as it has images of all the parts in the assembly, had some good methodology and nice images of the pole piece. I'm kind of surprised my woofers are working as the tolerance inside the coil for the pole piece doesn't look to be very wide. I'll have to take another measurement and think about whether it warrants a reassembly. I'm generally of the, "If it ain't broke..." way of thinking.
Click to expand...
100% agree if your driver can be gently pushed in and it doesn't rub/scratch leave it. The tolerance between is very tight. I used a cut up Pepsi bottle to get the thickness required for spacing. Not my idea but it worked for me.
 
Great! Thanks everyone for your info and assistance.

I'll need to haul them downstairs to the workroom again to sort this out. Just need to stop playing and enjoying them and get motivated for heavy cartage. I'll report back when I'm done.

I still find it odd about the pole pieces as they are both slightly off center. But I will leave well enough alone.
 
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