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To Dope or NOT

StimpyWan said:
The dope was a sealant, as you guessed. Being acoustic suspension, the speakers wouldn't perform properly without the dope. The cloth surrounds would be too porous otherwise. Plus, I expect the dope would affect the Q of the woofer as well, tuning and tightening bass response.
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Yes, that's what I was searching for in my layman's words:p--"tightening" bass response. Also, did you notice I was replying to someone who asked if they should apply the dope to the paper cones as well? To me it seems that would completely alter the sound. Dope's for cloth only, I reckon, right?
 
Parts Express sells a product called Wet Look, that's used to treat paper cones. It's black in color, and coats the cones. It seals it from being damaged by moisture and mold. Kinda shiny, but it works well. Some people use watered down white glue, as a paper cone sealant too. It rejuvenates the look of the cone, especially if the cone material has faded from UV exposure.
 
Not the cones, the dust caps - the little round bit in the middle of the cones, that covers the voice coil. KLH made theirs of a porous material and recommended that they be doped as well if it was necessary to do the surrounds.

In any case just start with a light coat on the surrounds, try a '''push test" and see where you're at.
 
N8Nagel said:
Not the cones, the dust caps - the little round bit in the middle of the cones, that covers the voice coil. KLH made theirs of a porous material and recommended that they be doped as well if it was necessary to do the surrounds.

In any case just start with a light coat on the surrounds, try a '''push test" and see where you're at.
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Yea, I know. The dust caps, on some designs should be sealed too. I was just making an additional suggestion about treating the cone, separately from the surrounds. Some people like to, even though its not completely necessary. I should have been more clear about that, in my earlier post. :p
 
N8Nagel said:
Not the cones, the dust caps - the little round bit in the middle of the cones, that covers the voice coil. KLH made theirs of a porous material and recommended that they be doped as well if it was necessary to do the surrounds.

In any case just start with a light coat on the surrounds, try a '''push test" and see where you're at.
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Yes, I meant dust caps. They are paper on these Utahs. Interesting to know that KLH dust caps were of porous material also. Thanks.

Oh, as far as the push test, unfortunately that's somewhat of a tedious procedure with these speakers. The grills don't come off like they do on, for example, the Advents. They are sandwiched in between blocks of wood screwed together. I was hoping I wouldn't have to undo all of that. I can tell you, pushing down on the cones, I do notice the surrounds are firmer.
 
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StimpyWan said:
Parts Express sells a product called Wet Look, that's used to treat paper cones. It's black in color, and coats the cones. It seals it from being damaged by moisture and mold. Kinda shiny, but it works well. Some people use watered down white glue, as a paper cone sealant too. It rejuvenates the look of the cone, especially if the cone material has faded from UV exposure.
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I've heard of Wet Look in the forum, but I just keep thinking, anything applied to the paper cones has to change the sound or somewhat deaden the cones. It kinda reminds me of ArmorAll tire shine--more for looks but offering some protection.
 
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So why some did it and others never. Foam surrounds I'm assuming was cheaper than butyl rubber even in the numbers needed. Heck cones themselves have changed in both design and structure. Also I don't think the builders of these things thought that far ahead that environmental changes can do bad ju ju to speakers ie: sunlight, temperature changes and uv rays. Polk still treats there's and I have to believe in their business model it makes sense. I wouldn't coat my non coated go to speakers but if I had some Radio Shack drop ins and some clear dope then let the experiment begin. I just might call Polk c/s tech dept.later today to see if there is a good answer for this.
 
Grid said:
Yes, I meant dust caps. They are paper on these Utahs. Interesting to know that KLH dust caps were of porous material also. Thanks.

Oh, as far as the push test, unfortunately that's somewhat of a tedious procedure with these speakers. The grills don't come off like they do on, for example, the Advents. They are sandwiched in between blocks of wood screwed together. I was hoping I wouldn't have to undo all of that. I can tell you, pushing down on the cones, I do notice the surrounds are firmer.
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KLH sealed the dust caps at the factory as well.
When you pushed down on the woofers, did they return slowly, or right away? Slowly is good and they don't need any additional sealer. Fast, and they need the surrounds resealed.
 
Grid said:
Update: Just hooked up the speaker to my Sansui AU-7900, with four times the watts than the Advent 300. Speaker plays fine--and loud--and so does the amp. No blown fuses. As a precaution, I only did this for about half minute. I next hooked up the Advent 300 receiver to my Advent speakers (OLA). Again, no problems, loud and clean, even to 2 O'Clock.

Why does the Advent blow a fuse only when connected to this speaker? Before the recap, it wasn't blowing a fuse. If there is something wrong with my recap, why does the more powerful Sansui play these speakers with no issues?
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Grid, I'll bet that your blown fuse on the Advent receiver was nothing more than a fluke. Who knows the cause? If it does it again on the same channel, then you should have concern. Otherwise, I wouldn't worry about it at all.

By the way, there is no danger in using your higher-powered amplifiers on the Utahs, regardless of their power rating.

GeeDeeEmm
 
I've tried Wet Look before, and didn't hear anything negative after. I mainly used it to help improve the appearance of some old, mildew stained woofers.

Members over at DIY Audio did some tests on woofers, before and after, using Wet Look. As far as they could tell, it didn't adversely affect performance. Most felt it stiffened the cone, improving transient response and bass detail. With the weight of the coating, it could slightly lower the resonance frequency of the woofers. But, that might not be a bad thing either. Heck, a lot of British speakers used to have doped paper cones, prior to polypropylene, I suppose. The cones must have been doped, due to someone in design, believing there was a benefit?
 
StimpyWan said:
I've tried Wet Look before, and didn't hear anything negative after. I mainly used it to help improve the appearance of some old, mildew stained woofers.

Members over at DIY Audio did some tests on woofers, before and after, using Wet Look. As far as they could tell, it didn't adversely affect performance. Most felt it stiffened the cone, improving transient response and bass detail. With the weight of the coating, it could slightly lower the resonance frequency of the woofers. But, that might not be a bad thing either. Heck, a lot of British speakers used to have doped paper cones, prior to polypropylene, I suppose. The cones must have been doped, due to someone in design, believing there was a benefit?
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Thanks for those detailed insights. And again you have the words layman-me was looking for: "resonate frequency"
 
gdmoore28 said:
Grid, I'll bet that your blown fuse on the Advent receiver was nothing more than a fluke. Who knows the cause? If it does it again on the same channel, then you should have concern. Otherwise, I wouldn't worry about it at all.

By the way, there is no danger in using your higher-powered amplifiers on the Utahs, regardless of their power rating.

GeeDeeEmm
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Hello and thanks. Yes, it did it twice, brand new fuses. Only with the Utah speaker. Plays three other speaker types I have just fine. The biggest drag is, I was thinking of selling the Advent receiver as a healthy receiver, but now I'm in doubt.
 
GD70 said:
KLH sealed the dust caps at the factory as well.
When you pushed down on the woofers, did they return slowly, or right away? Slowly is good and they don't need any additional sealer. Fast, and they need the surrounds resealed.
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Don't the speakers have to be mounted and the enclosure sealed closed to perform this test? I tried the test on my Advents. It's easy just to take off the grill and push down on the woofer. With the Utahs, the grill does not come off--you have to removed wood blocks on the inside that sandwich it in place. So, I'm just hoping I hear a fuller, tighter bass.
 
leftfielder said:
So why some did it and others never. Foam surrounds I'm assuming was cheaper than butyl rubber even in the numbers needed. Heck cones themselves have changed in both design and structure. Also I don't think the builders of these things thought that far ahead that environmental changes can do bad ju ju to speakers ie: sunlight, temperature changes and uv rays. Polk still treats there's and I have to believe in their business model it makes sense. I wouldn't coat my non coated go to speakers but if I had some Radio Shack drop ins and some clear dope then let the experiment begin. I just might call Polk c/s tech dept.later today to see if there is a good answer for this.
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Yeah, let me know what they say. I did just want to clarify, the surrounds on these Utahs are cloth coated with butyl (not butyl in their composition). And here's an interesting aside: Utah's Celeste line has an accordion-like cloth surround that is NOT butyl coated.
 
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