I have four 18" subs drivers that have been ridden hard and put away wet for at least 30 years.
None of the coils are rubbing, and the suspensions are OK.
They are 8 ohm drivers, and Impedance reads 5.5 ohm on two of them, 5.8 and 5.9 ohm on the other two.
I'm wondering if they might just be a little "worn out," and so worth re-coning. I will certainly re-cone the two that have higher impedance as that could be compromised voice coils, but is it usually a good idea to just re-cone ANY sub driver that's seen this much use?
None of the coils are rubbing, and the suspensions are OK.
They are 8 ohm drivers, and Impedance reads 5.5 ohm on two of them, 5.8 and 5.9 ohm on the other two.
I'm wondering if they might just be a little "worn out," and so worth re-coning. I will certainly re-cone the two that have higher impedance as that could be compromised voice coils, but is it usually a good idea to just re-cone ANY sub driver that's seen this much use?
It just comes right down to performance and whether you are satisfied with it. Measuring DC resistance of the coils will not give an indication of their condition unless there is a short or an open.
Replacing the surround around the cone is pretty easy. Reconing entirely is a little tougher. I found a powered Paradigm subwoofer in a snowbank last winter, replaced the surround from a kit I found online (about $30), and it works extremely well.
Search keywords:
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But I wouldn't do it if the surround is ok.
Search keywords:
Speaker repair edge kits
But I wouldn't do it if the surround is ok.
I'd highly consider selling them off if they are usable, and purchasing new drivers that will drop into your enclosures with lower distortion, better thermal performance and many other features. They may have been state of the art when produced but time marches on. Strides have been made in reducing motor and suspension induced distortions.
If they work, they work.
If the paper got once wet and instable you can make the paper more stiff again with hair liquid, evaporates fast. Never apply too much and let dry well.
Or you stiffen the loudspeaker paper cone with metal foil.
https://www.diyaudio.com/community/...loudspeaker-sandwich-cone.402917/post-7443474
If the paper got once wet and instable you can make the paper more stiff again with hair liquid, evaporates fast. Never apply too much and let dry well.
Or you stiffen the loudspeaker paper cone with metal foil.
https://www.diyaudio.com/community/...loudspeaker-sandwich-cone.402917/post-7443474
Yeah I'm considering that as well. thx. Something with lighter magnets would be nice.
Seems to be the unanimous opinion.
But I'm surprised you think a slight rise in impedance is normal. I thought that meant the coils are slightly burnt, no?
Also, would it not be worth re-coning something so old just to clean out the gap? Or is that not usually an issue?
I see now. You are looking for a reason to do this. If it is not the voice coil, then surely something else must be near fault. So do it. You will 'clean out the gap', the surround will be replaced, and likely you will learn something in the process.
"Slightly burnt" coils could have shorted coils, which makes the resistance lower, not higher. The 5.5 ohm pair and the 5.8/9 pair were probably assembled from coils made on different dates, and within 10% tolerance.
Junk in the gap is not an issue unless you hear scraping or buzzing noises with a swept tone or moving by hand.