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What's on my mids/tweeters?

M

Mr grooves

New Member
So I've been rebuilding and modifying a number of Nova 8bs, these ones I found at a thrift store for $10. All the drivers work, but I've attached a picture of what I thought looked like strange burn marks at first... But I'm thinking it might be mold? What would you do if you saw this? The other speaker had no marks on the drivers. I was finally doing a pair for myself, and this is the first 8b I've gotten that I wasn't sure about.:bs:1000001584.jpg
 
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Right, I'm starting to think it was some kind of patch as well. Tried dabbing it with a tiny bit of isopropyl, and it didn't do anything. Though I noticed the tweeter has a pin sized hole, and I think one of the mids has a little hole as well, but it's really hard to tell with the black on it. I guess they might have been pushed in and "fixed" with a pin and some odd adhesive or something...
 
It looks like someone used a pin to poke a small hole in them to pull out pushed in dust caps, then used something to try and seal the holes.
Ive done this same thing in the past to pull out pushed in dust caps.
Smaller dust caps are difficult to pull out. Larger dust caps I use sticky tape like duct tap and even a vacume cleaner hose to suck them back out.
 
Lavane said:
It looks like someone used a pin to poke a small hole in them to pull out pushed in dust caps, then used something to try and seal the holes.
Ive done this same thing in the past to pull out pushed in dust caps.
Smaller dust caps are difficult to pull out. Larger dust caps I use sticky tape like duct tap and even a vacume cleaner hose to suck them back out.
Click to expand...
Yeah, that's what I was thinking when I noticed the holes. Now I'm just curious what the used to try and seal it. Or if maybe they didn't, and tried to use sharpie to hide the holes.
 
Ya, looking closer at the pictures it does look like he used a Sharpie.
Are those Optimus 5's or Nova 8B's?
 
They're Nova 8B's. I think the tweeter actually did just have sharpie, there is a crusty torn piece of paper glued with sharpie over it on one of the mids though, think I'll just get the crusty paper off and glue another piece of deli paper until I find another mid.
 
Mr grooves said:
They're Nova 8B's. I think the tweeter actually did just have sharpie, there is a crusty torn piece of paper glued with sharpie over it on one of the mids though, think I'll just get the crusty paper off and glue another piece of deli paper until I find another mid.
Click to expand...
Keep that one as a spare though. The glue used by RS to secure the magnets didn't age well. All it takes is one good bump moving the soeakers around and the magnets can shift, locking up the coil. Its always a good idea to use an epoxy, JB Weld, etc to keep them centered. Just run a few beads of it around the magnet and the basket. Also around the top plate on the magnet if there is one. Polk had the same problem with magnets.
Hopefully I'll be getting a pair of Nova 8B's soon. I want to try the VL mod on the crossovers. I did a similar thing to a pair of Nova 7B's.
I replaced the old electrolytic capacitor for the tweeters with a polypropylene film cap. Then added a coil to force the woofer to roll off where it should, added a bypass cap on the woofer, and reversed the phase of the tweeters. The bass is better controlled, and the midrange is more detailed sounding. I also made new grills. I'm not a fan of lattice grills. But they can be installed again if someone else wants.
 

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Lavane said:
Keep that one as a spare though. The glue used by RS to secure the magnets didn't age well. All it takes is one good bump moving the soeakers around and the magnets can shift, locking up the coil. Its always a good idea to use an epoxy, JB Weld, etc to keep them centered. Just run a few beads of it around the magnet and the basket. Also around the top plate on the magnet if there is one. Polk had the same problem with magnets.
Hopefully I'll be getting a pair of Nova 8B's soon. I want to try the VL mod on the crossovers. I did a similar thing to a pair of Nova 7B's.
I replaced the old electrolytic capacitor for the tweeters with a polypropylene film cap. Then added a coil to force the woofer to roll off where it should, added a bypass cap on the woofer, and reversed the phase of the tweeters. The bass is better controlled, and the midrange is more detailed sounding. I also made new grills. I'm not a fan of lattice grills. But they can be installed again if someone else wants.
Click to expand...
Ah, will do. Thank you! Yeah actually, I love the VL mod. Since I've first done it, Nova 8Bs have been my go-to for trying to get people into audio on a budget, and for teaching beginners DIY. Cheap, easy enough, and the drivers are generally consistent enough where the crossover almost never needs modification. I agree on the lattice grills, I can never decide whether to keep them or not, but when they're plastic, they always get put in the closet for if someone really wants them on.
 
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