From your post i cannot see clearly what your intention is.
If you talk about the surround of conventional speakers a
treatment of the surround or parts of the cone may be used to
- make the surround airtight, if the cloth used is leaky
- introduce damping to the surround (and maybe parts of the cone)
I do not think there is a general recipe used, every manufacturer
will use its own.
Of course most treatments will usually also introduce stiffness and the
resonance frequency of the system can be expected to increase, since
the surround contributes to the stiffness of the suspension of the cone.
There may be several kinds of resins used, i think in earlier times when
the surround was often made of paper and was one piece with the cone,
also bitumen based paints were used. That coating may also prevent
the surround from ageing if the coating/doping has the right consistency
not to brittle during the time the system is used.
I do not know what is commonly used but
- Poly Acryl
- Poly Urethane
- Silicone
- Bitumen
- Poly Vinyl based
are some stuffs which come to my mind ...
What is important is good robustness against the UV radiation
which comes with the sunlight.
If the meshes in the cloth are very fine, even some kind of oil might be
sufficient to make the surround tight. I think it depends on what you want
to achieve.
If you talk about the surround of conventional speakers a
treatment of the surround or parts of the cone may be used to
- make the surround airtight, if the cloth used is leaky
- introduce damping to the surround (and maybe parts of the cone)
I do not think there is a general recipe used, every manufacturer
will use its own.
Of course most treatments will usually also introduce stiffness and the
resonance frequency of the system can be expected to increase, since
the surround contributes to the stiffness of the suspension of the cone.
There may be several kinds of resins used, i think in earlier times when
the surround was often made of paper and was one piece with the cone,
also bitumen based paints were used. That coating may also prevent
the surround from ageing if the coating/doping has the right consistency
not to brittle during the time the system is used.
I do not know what is commonly used but
- Poly Acryl
- Poly Urethane
- Silicone
- Bitumen
- Poly Vinyl based
are some stuffs which come to my mind ...
What is important is good robustness against the UV radiation
which comes with the sunlight.
If the meshes in the cloth are very fine, even some kind of oil might be
sufficient to make the surround tight. I think it depends on what you want
to achieve.
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Thanks for your reply. There are two vintage Fostex coax speakers that I can't find the replacement so rather than throw it away I was wondering if I can make my own surround. Since Fostex are quite sensitive I guess putting some fine clothe will be good but what kind of oil would greatly help if you can suggest one.
I really cannot tell what kind of stuff certain manufacturers
use, but i remember a german manufacturer, who mentioned to use
phenolic resin as doping for his tweeters - which is another
stuff in the list ... but that was decades ago ...
I experimented with all kinds of stuff, rubber solution is not
very durable when exposed to sunlight. And it is rather
aggressive against some kind of plastic parts when it comes
in contact with. Application is not very easy because it
dries fast.
If your meshes are very fine and you want mainly the airtightening
effect i would give a slowly hardening silicone oil a try.
That stuff is rather durable AFAIK and keeps its flexibility over
long time.
The question is whether you want the doping to be the same
material as the glue between surround/cone and surround/basket.
Won't work with silicone.
If your cone is paper and the cloth is cotton based
white wood glue can be used (maybe dilluted) to glue the cloth
to the cone. For the basket side you will need something different.
Maybe 2-Component Epoxy resin mixed with less hardener to stay
a little soft over time, there are also Cyano Acrylate based Gels
which may be ok for that.
Then maybe apply the oil afterwards to the surround.
But hey, there are very much possibilities ...
I would test the doping on the cloth first to see whether
it leads to the desired result. Then test the glues for
the paper and the basket side separately.
use, but i remember a german manufacturer, who mentioned to use
phenolic resin as doping for his tweeters - which is another
stuff in the list ... but that was decades ago ...
I experimented with all kinds of stuff, rubber solution is not
very durable when exposed to sunlight. And it is rather
aggressive against some kind of plastic parts when it comes
in contact with. Application is not very easy because it
dries fast.
If your meshes are very fine and you want mainly the airtightening
effect i would give a slowly hardening silicone oil a try.
That stuff is rather durable AFAIK and keeps its flexibility over
long time.
The question is whether you want the doping to be the same
material as the glue between surround/cone and surround/basket.
Won't work with silicone.
If your cone is paper and the cloth is cotton based
white wood glue can be used (maybe dilluted) to glue the cloth
to the cone. For the basket side you will need something different.
Maybe 2-Component Epoxy resin mixed with less hardener to stay
a little soft over time, there are also Cyano Acrylate based Gels
which may be ok for that.
Then maybe apply the oil afterwards to the surround.
But hey, there are very much possibilities ...
I would test the doping on the cloth first to see whether
it leads to the desired result. Then test the glues for
the paper and the basket side separately.
I thought I'd document my recent experience erroneously substituting a "foam" half-roll surround on a classic (1960) fine 15-inch woofer that had a beautiful accordion cloth surround.
Fs hideously went from about 20 Hz to about 34 Hz*. Here's why.
Classic woofers had light cones and wonderful compact edge-wound coils, say 80 grams, because you want to push light air around with vastly heavier cardboard and copper. Accordion fabric surrounds are very flexible. But they "oil can" by having a motion of their own and are none too forgiving or too linear for large excursions. Half-round surrounds are better in those regards, including the AR half-round fabric experiments.
Today's woofers are expected to be able to play loud - mostly a battle of advertising claims since the loudnesses are unrealistic and also would destroy your hearing in short order. It is common to see cone assemblies weighing half a pound (230 gr) or more in order to handle the load and the related current. Corresponding, they need strong support and so few have really nice low Fs. I'd say that's as doubtful a design as the incandescent bulb of recent memory.
So, if you have a classic fine woofer that you (probably erroneously) want to re-surround, you have to decide if Fs matters to your system. If it does, stick with an accordion surround (or if you can find a certifiably light rolled surround).
B.
*unfortunately, I haven't been able to dig up suitably matching before-and-after performance records; THD with the foam surround seems to be pretty fair, maybe 50dB down from mid-bass up
Fs hideously went from about 20 Hz to about 34 Hz*. Here's why.
Classic woofers had light cones and wonderful compact edge-wound coils, say 80 grams, because you want to push light air around with vastly heavier cardboard and copper. Accordion fabric surrounds are very flexible. But they "oil can" by having a motion of their own and are none too forgiving or too linear for large excursions. Half-round surrounds are better in those regards, including the AR half-round fabric experiments.
Today's woofers are expected to be able to play loud - mostly a battle of advertising claims since the loudnesses are unrealistic and also would destroy your hearing in short order. It is common to see cone assemblies weighing half a pound (230 gr) or more in order to handle the load and the related current. Corresponding, they need strong support and so few have really nice low Fs. I'd say that's as doubtful a design as the incandescent bulb of recent memory.
So, if you have a classic fine woofer that you (probably erroneously) want to re-surround, you have to decide if Fs matters to your system. If it does, stick with an accordion surround (or if you can find a certifiably light rolled surround).
B.
*unfortunately, I haven't been able to dig up suitably matching before-and-after performance records; THD with the foam surround seems to be pretty fair, maybe 50dB down from mid-bass up
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Wharfedale used flat felt back in the 50s-60s, which worked for short excursion drivers. If you are making your own surrounds then some shaping will be called for unless something elastic is used (like felt). Are you sure no foam surrounds are available in the size you need? They can be doubled to increase stiffness.
Or do you have intact surrounds that just need re-doping?
Or do you have intact surrounds that just need re-doping?
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Many thanks for your information. But my interests just now are experimental* rather than vintage restoration. My purpose was just to ensure Google archives the data (and musings) posted above so others can find it.
B.
*I'm trying to figure out how to attach an accelerometer to an absolutely rigid but removable "dust cap" structure. And how to attach a shielded lead to it. And how to get that lead out from the cone assembly to the motional feedback circuit.
to the OP try this Speaker Repair Latex Adhesive - Professional Grade for Surrounds Cones Dust Caps and more.
as to fabric types for cloth surrounds there are so many types with varying characteristics that that is ultimately up to the end user.
on the cheap if you need to re-seal a cloth surround glycerine can be used.
note: neither of these have any documented benefits for motional feedback experiments
as to fabric types for cloth surrounds there are so many types with varying characteristics that that is ultimately up to the end user.
on the cheap if you need to re-seal a cloth surround glycerine can be used.
note: neither of these have any documented benefits for motional feedback experiments
Liquid EPDM Rubber. Some of which is used by the roofing trade. Possibly research what solvent base it is and thin it accordingly. Linen would make a suitable surround. Ideally a die could be made to shape the accordion feature, perhaps with plastic spline cord that could be rolled into the grooves until the rubber set up like when rescreening a window.
Exactly that is what i have had to do with about 80% of the FE103A i pulled from Admirals Tunnel Reflex boxes.
dave
Hi Dave!
Happy New year!
So glad that you've brought this up!
How (in your opinion) does the once much vaunted FE103A stand up in 2018?
Is there an optimal box for this aged beauty?
I've go t a pair in TQWP that I enjoy, and have been wondering whether to go next to a Karlsonator or perhaps a Frugelhorn.
Your thoughts? TIA
Happy New year!
So glad that you've brought this up!
How (in your opinion) does the once much vaunted FE103A stand up in 2018?
Is there an optimal box for this aged beauty?
I've go t a pair in TQWP that I enjoy, and have been wondering whether to go next to a Karlsonator or perhaps a Frugelhorn.
Your thoughts? TIA
apologies for the Hi-jack...
Thanks for the reply, Dave, and thanks for your expertise with our Full Range eccentricisies(sp)
Back to my FE103A's...
1) should I move on to something in the 21st century? <grin>
2) what other cabs best suit the FE103A?
mini Karlsonator? Zigmahornet? Frugelhorn?
I'm not unhappy with my TQWP, but I can't help but wonder if there isn't something else to be had.....do you have any thoughts on Bert Doppenbergs variant? (I've collected a few pair of the FE103A)
Thanks Dave for your insights!
All the Best,
Mike
Thanks for the reply, Dave, and thanks for your expertise with our Full Range eccentricisies(sp)
Back to my FE103A's...
1) should I move on to something in the 21st century? <grin>
2) what other cabs best suit the FE103A?
mini Karlsonator? Zigmahornet? Frugelhorn?
I'm not unhappy with my TQWP, but I can't help but wonder if there isn't something else to be had.....do you have any thoughts on Bert Doppenbergs variant? (I've collected a few pair of the FE103A)
Thanks Dave for your insights!
All the Best,
Mike
Frugel-Horn Mk3, & Aiko are proven good (Aiko the best we’ve heard). They would probably also do well in Vampyr-V. It is also possible a pair could be used in the miniTower (the casle version is preferred by builders), and maybe a variation of the big Woden BVRs.
Because the T/S can be quite variable due to aging one of the horns (were the box dominates) is the better bet. If you weant to use 2, perhaps the double FH3 (drivers wired in series, one with a big cap shunting it).
Bert’s double ML-V is OK, but was done before good modelers came out.
dave
Because the T/S can be quite variable due to aging one of the horns (were the box dominates) is the better bet. If you weant to use 2, perhaps the double FH3 (drivers wired in series, one with a big cap shunting it).
Bert’s double ML-V is OK, but was done before good modelers came out.
dave
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