I have acquired some Heppner full range 8" drivers that have paper cones, which then become folded/accordian surrounds.
It does not appear that the cone or folded-paper surround has ever been treated.
I've done some searching for a definitive treatment, but there does not seem to be one.
Black rubber cement, "Wet Look," and Aleenes have all been mentioned. But whenever this discussion pops up, there are caveats about adding any bulk or mass to the cones and/or stiffening up the surround.
I'd sure like to preserve these cones and surrounds... but wish to do so properly and without negatively affecting sound quality.
Thanks for your suggestions.
It does not appear that the cone or folded-paper surround has ever been treated.
I've done some searching for a definitive treatment, but there does not seem to be one.
Black rubber cement, "Wet Look," and Aleenes have all been mentioned. But whenever this discussion pops up, there are caveats about adding any bulk or mass to the cones and/or stiffening up the surround.
I'd sure like to preserve these cones and surrounds... but wish to do so properly and without negatively affecting sound quality.
Thanks for your suggestions.
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I would start with damping the surrounds. Like everything else around here there are many right ways. My choice is a urethane clear caulk very slightly thinned with latex paint extender. DuPont Kitchen and Bath with Teflon, which sets up without the tackiness of most similar products, and X-I-M Latex X-Tender, which you want around if doing any brush painting. I am one of those who has killed a bunch of decent speakers with too much cone dope, so it can easily be overdone.
If the dust cap goes clack when tapped that would be my second step.
If the dust cap goes clack when tapped that would be my second step.
For soaking and stabilizing paper and foam surrounds I have a certain small-home-stuff silicone glue, which is solved in gasoline. I mix in additional medicinal-grade gasoline, so it soaks in better. The classical stuff is latex but keeps sticky. I would not treat the paper cone, unless it shows mechanical wear. Most necks of paper cones have been factory-soaked by a hardening agent, so there is no need to improve anything. Air-permeable dust caps, often worn or too weak out of factory, are another matter.
Unless there are any significant cracks / tears in the paper accordian pleats, I'd leave them alone.
Treatment of the radiating surface of the cones is a different can of worms, and I'd not expect consensus there, other than that stiffening of a cone that operates over a wide band by effectively "controlled" transition from rigid pistonic motion would not necessarily enhance performance.
Oh, that's silly, there will certainly be arguments there as well.
BTW, how do they sound untreated, and in what type of enclosure?
Treatment of the radiating surface of the cones is a different can of worms, and I'd not expect consensus there, other than that stiffening of a cone that operates over a wide band by effectively "controlled" transition from rigid pistonic motion would not necessarily enhance performance.
Oh, that's silly, there will certainly be arguments there as well.
BTW, how do they sound untreated, and in what type of enclosure?
Thanks for all of the replies... much appreciated.
I got up close and personal with the small cuts in the the surrounds of these speakers. They are just small tears that didn't even open up upon examination.
So... my goal changed to simply prevent anymore tearing. I had some Duco Cement and used a small plastic applicator to get the cement into the small tears... seems to have worked.
Your comments helped. I decided not to treat the cones/surrounds with anything out of fear that any treatment that added something not there would change the character of the sound from these.
I find it amazing that these speakers... I think made in 1964... sound so good. I guess the AlNiCo magnets don't hurt either.
I got up close and personal with the small cuts in the the surrounds of these speakers. They are just small tears that didn't even open up upon examination.
So... my goal changed to simply prevent anymore tearing. I had some Duco Cement and used a small plastic applicator to get the cement into the small tears... seems to have worked.
Your comments helped. I decided not to treat the cones/surrounds with anything out of fear that any treatment that added something not there would change the character of the sound from these.
I find it amazing that these speakers... I think made in 1964... sound so good. I guess the AlNiCo magnets don't hurt either.
Yes they are 8" but Heppner... not Altec. I asked the seller (got them off ebay) and he said this pair came out of an organ. I think from other research I think a lot of these Heppners were in Hammond organs... or something akin to that.
What "surround dope" do you use?
If they are intact after many years, there is little you can do to make them better. It is very likely you will make them worse by meddling.
I would use dammar for the cone if it is thinning. You can buy dammar either in liquid or dry crystal form.
Dammar is also used to preserve some types of paintings.
I have a few field coil speakers that I applied dammar to either treat the cones or reduce breakup. I the case of a Jensen A12 driver, the real problem with breakup seems to be a hard surround.
Read up on application for speakers. The main thing to avoid is having any seep into the voice coil.
Not only is untreated paper hygroscopic, but it can certainly dry out as well, and it seems to me that years of continual movement of an accordion pleated raw paper surround could certainly wear the fibres to the point of changing their mechanical compliance significantly enough to affect measurable and audible performance long before they fray to the point of splitting / cracking.
Careful doping of the surround with a compliant non-hardening elastomer probably couldn't hurt, but I'd be very careful using a hard curing resin such as dammar varnish * to increase the rigidity of a paper cone FR driver in which the extension of wide band performance is contingent on controlled break-up..
Will such treatment make them sound different ?- definitely
Is a discernible difference inherently "better"? - I'd be inclined to say not necessarily, but in the new "alternate fact" universe, we need to remember as one of our sages said - "DIY is all about denial"
* https://www.britannica.com/technology/dammar
Careful doping of the surround with a compliant non-hardening elastomer probably couldn't hurt, but I'd be very careful using a hard curing resin such as dammar varnish * to increase the rigidity of a paper cone FR driver in which the extension of wide band performance is contingent on controlled break-up..
Will such treatment make them sound different ?- definitely
Is a discernible difference inherently "better"? - I'd be inclined to say not necessarily, but in the new "alternate fact" universe, we need to remember as one of our sages said - "DIY is all about denial"
* https://www.britannica.com/technology/dammar
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