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Voice coil rub and cloth surrounds?

watt

watt

no on
Well, I thought that it was a stroke of luck: I've been looking for a pair of woofers to use in an Altec Santana ewave project (the cabs had been stripped of their original drivers by the time I got them), and I found a pair of Utah WD-90s in my local thrift. Unfortunately, playing them a bit yesterday to test out the LF response, I noticed vc rubbing in one of the woofers. If you look at the attached pics, you can see where the cloth surround has started to ripple. If I apply pressure to the woofer near the rippled area (mimicking the tautness that the surround would normally supply), there's no rub. I turned the speaker upside down yesterday and last night, which cuts down on the rubbing, but it doesn't solve the problem completely.

If the usual fix is to shim and refoam, what do you do when you have cloth surrounds? Should I just wait longer for the 180 rotation to take effect? Any suggestions are appreciated.

(Pics won't upload at the moment--I'll post later this evening.)
 
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Can you cut the cloth to release the ripple then patch from the back ?
Using a nylon stocking and silicone glue thinned some to hold it , I've done a rip to a cloth surround a few times and it seem to work out fine . They do have cloth surround replacements in most sizes .



Barney
 
Sometimes with stamped steel baskets you can do a lot to stop misalignment rubbing by CAREFULLY selectively tightening and/or loosening some the mounting screws such that you're actually manipulating the geometry of the basket to a degree. This won't help if the cause of the rubbing is a warped former, debris in the gap, or some other partial failure of the voice coil or it's assembly.
 
If all else fails, Speakerworks on Western could fix them but then they're not much of a score anymore. Sucks. Jon Van L can fix almost anything....he'll rewind the voicecoil if he has to.
 
utah speakers have not reached the popularity level that some of the other manufacturers have, thus are not as expensive on the open market. and they are common as dirt. you should be able to pick up a replacement from that auction site for very little scratch.
 
Pics this time

Thanks, everyone, for the replies.

You can see the ripple most clearly in the second image. Access to the surround from the back is pretty limited--the spokes of the basket are too close together, except for under the terminals, to even get a finger through. But I do like the nylon/silicone glue fix. I wonder if it could work from the front by applying over the rippled part and using the elasticity of the nylons to take up the rippled slack in the surround. I may not have to resort to this, though, because I tried bowtie's suggestion of changing the frame's geometry by adjusting the tension of the frame nuts. This seems to have worked. Now I'll just have to remember how to orient the woofer when I put them in the Santana cabs.

Van L is a great resource to have so close, but I think you're right, John. A visit to the driver hospital at Speakerworks would likely take the E out of Ewave. :D
 

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andy said:
You might be able to peel the surround away from the basket, and re-glue it.
Click to expand...

I thought about this, but they have a masonite ring attached to the top of the surround. It's on there pretty good, and I'm afraid I'd damage the surround trying to get it off. Unless there's a good solvent to use. :scratch2:
 
What kind of shape is the spider in? Generally the spider is doing much more to hold the coil in alingnment than the surround is.
 
i'd replace the surrounds. bootapest2 on ebay often has cloth surrounds in 10,12,15 " .
and sells some rubber ones too. about $6-$10/pair . use a 1.5v battery to center.

you don't mention how the 'good' woofer sounds -is it a practical app for this speaker?
 
Tom Brennan said:
What kind of shape is the spider in? Generally the spider is doing much more to hold the coil in alingnment than the surround is.
Click to expand...

As far as I can tell, it's in good shape. No breaks, and the material is supple. Should I be looking for anything else?
 
karlo said:
i'd replace the surrounds. bootapest2 on ebay often has cloth surrounds in 10,12,15 " .
and sells some rubber ones too. about $6-$10/pair . use a 1.5v battery to center.

you don't mention how the 'good' woofer sounds -is it a practical app for this speaker?
Click to expand...

Thanks for the heads-up on a supplier for cloth surrounds. I've only redone foams before, and it's not too hard (a little time-consuming, maybe, but not very difficult) to rub the foam residue off of the cone. How do you get the old cloth off of the cone?

As far as the practicality of using this woofer in the ewave project, all I can say is that it's an experiment. From the way the good woofer sounds--and even the "bad" woofer, as the rub isn't the worst I've heard--I'd say that it has a fair amount of potential. I don't have very much invested in the Utahs, but I'm interested in hearing the result, if it's possible to get them to work.
 
bowtie427ss said:
Sometimes with stamped steel baskets you can do a lot to stop misalignment rubbing by CAREFULLY selectively tightening and/or loosening some the mounting screws such that you're actually manipulating the geometry of the basket to a degree. This won't help if the cause of the rubbing is a warped former, debris in the gap, or some other partial failure of the voice coil or it's assembly.
Click to expand...
+1 -- bowtie speaks the truth. Works most of the time, and is reversible.
 
Where do you see the water stains, bowtie? Discoloration on the woofer itself or on the surround?
Click to expand...
I've highlighted the most obvious portion, but it looks as if there's more as you move in toward the center. Seems to be a lot of darker area, and a darker "boundary" below the area i've outlined, and the cone itself looks dimpled and irregular in the area where the surround attaches to it especially in the 9-10 o'clock area, not smooth and curvelinear as it should be.

waterstain1.jpg
 
Thanks, bowtie. Great catch. I didn't know what to look for.

Well, I suppose I'll start looking for a replacement, as the rub is definitely there again. At least I have the dimensions to move forward with cutting the baffles.

Thanks again for the replies.
 
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