Hello,
i acquired a new B&C 18SW100. In the attached picture you can see the colourless substance in question (probably silicone). It is unevenly spread, being mostly in the grooves of the spider. I assumed that coating should be a smooth surface instead of this sprayed-on mess of spots. I would like to know if this is normal.
Thanks for taking your time and kind regards,
Mathias
i acquired a new B&C 18SW100. In the attached picture you can see the colourless substance in question (probably silicone). It is unevenly spread, being mostly in the grooves of the spider. I assumed that coating should be a smooth surface instead of this sprayed-on mess of spots. I would like to know if this is normal.
Thanks for taking your time and kind regards,
Mathias
Attachments
As EPA noted, the silicon bubbles seem to be apparent on another B&C driver.
I only have a pair of B&C18SW115-4, don't recall as many bubbles as in your photo, but I doubt they would make much, if any difference in performance.
Do some free air tone sweeps starting conservatively and up to around Xmax in the 30 Hz range to make sure there are no buzzes, if there are, submit for warranty repair/replacement.
I only have a pair of B&C18SW115-4, don't recall as many bubbles as in your photo, but I doubt they would make much, if any difference in performance.
Do some free air tone sweeps starting conservatively and up to around Xmax in the 30 Hz range to make sure there are no buzzes, if there are, submit for warranty repair/replacement.
it IS silicone. A few other manufacturers are using silicon doped spiders to help achieve their desired stiffness. It likely is "evenly" applied, except the part that seems to be missing is probably on the underside within the rolls that appear "upward" in that orientation. Upside-down, the peaks then become valleys.
Looks to me like they spray coated the spider. Once side A was done side B was sprayed forming bubbles between these two layers. It's more of a cosmetic issue more than anything. I don't doubt they have addressed this Q already through QA, simply so people would stop asking 😉
That is their special technique which they expertize in. Not only them, RCF & 18 sound too. They call it the "double silicone spider". They do it in- house. It has a vital role in the overall build design of the speaker. Visit their site to know more.
That arrangement has a vital role to play in the overall compliance, dc-offset & voice-coil rest position & also in the cooling system of their voice coil and gap. 18 sound has gone further and introduced triple silicon spiders in some of their current drivers.
The uneven distribution of silicone which you see across the spider top surface has nothing to do on its behavior. The real area between the spiders has that required uniform coating. The outer uneven silicone you see is the excess silicone which leaks or pop's out from the spiders fabric mesh.
That arrangement has a vital role to play in the overall compliance, dc-offset & voice-coil rest position & also in the cooling system of their voice coil and gap. 18 sound has gone further and introduced triple silicon spiders in some of their current drivers.
The uneven distribution of silicone which you see across the spider top surface has nothing to do on its behavior. The real area between the spiders has that required uniform coating. The outer uneven silicone you see is the excess silicone which leaks or pop's out from the spiders fabric mesh.
The silicone is mainly used to dampen the spiders. In the past non-hard resin (not sure if this is the correct English word) types were used but these suffer from aging, are not heat resistant and can be anoyingly sticky. By impregnating you increase the contact surface between the fibres of the spider-fabric and the silicone, which result in better damping properties compared to (surface) coatings. Chinese attempts to copy these Italian drivers have silicon coated spiders among other cut-off's.
The newest thing from Italy might be silicone free spiders from new 'hybrid' materials. They promise to have a lower mass, higher internal damping and an improved stifness constant troughout excursion. Research will tell if they can deliver the same strength and durability to be applied in these 'extreme' PA drivers of today.
The newest thing from Italy might be silicone free spiders from new 'hybrid' materials. They promise to have a lower mass, higher internal damping and an improved stifness constant troughout excursion. Research will tell if they can deliver the same strength and durability to be applied in these 'extreme' PA drivers of today.
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Glad the bubbling isnt anything mechanically. It would annoy me seeing the bubbles.
Adding to Djim's comments on silicon free spiders.
http://www.oeb.it/landing-savings.aspx
Adding to Djim's comments on silicon free spiders.
http://www.oeb.it/landing-savings.aspx
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According to this "article" I found..
Cardboard and copper: the song doesn’t remain the same
The spider suspension that RCF uses eliminates sagging and ripping altogether. Even though someone somewhere will be able to rip it somehow. 😀
Cardboard and copper: the song doesn’t remain the same
The spider suspension that RCF uses eliminates sagging and ripping altogether. Even though someone somewhere will be able to rip it somehow. 😀
Interesting read.
"It is so tough that if you have to re-cone the driver, this suspension must be removed with an angle-grinder with a rotating wire brush."
"It is so tough that if you have to re-cone the driver, this suspension must be removed with an angle-grinder with a rotating wire brush."
Still nobody found the exact reason why was silicout perform on particularly. It is clearly described in 18 sound tech papers. Other hybrid materials and laminating resin to avoid long term sagging is not the main objective behind using the technology. Silicone plays a critical part over here. It the unique characteristics of silicone which counts here.
As for the toughness of the spider clamping area to the frame. The adhesive is very strong and has to be so to take the enormous pressure of the excursion force acsoss the spider area generated at exteme power.
The oeb new silicone free dual spider had not found it's way into Italian drivers yet.
We will have to wait and see if it ever does and outperforms it's silicone counterpart technically.
As for the toughness of the spider clamping area to the frame. The adhesive is very strong and has to be so to take the enormous pressure of the excursion force acsoss the spider area generated at exteme power.
The oeb new silicone free dual spider had not found it's way into Italian drivers yet.
We will have to wait and see if it ever does and outperforms it's silicone counterpart technically.
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Still nobody found the exact reason why was silicon used particularly. It is clearly described in 18 sound tech papers. Other hybrid materials and laminating resin to avoid long term sagging is not the main objective behind using the technology. Silicone plays a critical part over here. It the unique characteristics of silicone which counts here.
As for the toughness of the spider clamping area to the frame. The adhesive is very strong and has to be so to take the enormous pressure of the excursion force acsoss the spider area generated at exteme power.
The oeb new silicone free dual spider had not found it's way into Italian drivers yet.
We will have to wait and see if it ever does and outperforms it's silicone counterpart technically.
As for the toughness of the spider clamping area to the frame. The adhesive is very strong and has to be so to take the enormous pressure of the excursion force acsoss the spider area generated at exteme power.
The oeb new silicone free dual spider had not found it's way into Italian drivers yet.
We will have to wait and see if it ever does and outperforms it's silicone counterpart technically.
There was an error in typing in Post # 12.
The correct line is re drafted in post # 13 .
Still nobody found the exact reason why was silicon used particularly.
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Hello,
thanks for all the responses! It did turn out to be quite the interesting topic. I contacted B&C tech support for a clarification and the response was:
"the spider is ok since the silicon glue must flow through the cloth frame. Even if it does not look very attractive, this kind of spider assembly is very effective and mechanically very strong.
Each assembled speaker is tested before shipping, so compliance and resonance frequency is therefore continuously checked during production to assess its conformance to the QC accepted tolerances ( for example Fs must stay within +/- 15% the reference value)."
thanks for all the responses! It did turn out to be quite the interesting topic. I contacted B&C tech support for a clarification and the response was:
"the spider is ok since the silicon glue must flow through the cloth frame. Even if it does not look very attractive, this kind of spider assembly is very effective and mechanically very strong.
Each assembled speaker is tested before shipping, so compliance and resonance frequency is therefore continuously checked during production to assess its conformance to the QC accepted tolerances ( for example Fs must stay within +/- 15% the reference value)."
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