I'm sorry this is a bit of a repost. But I"m really hoping to get a few fresh eyes on this question.
I have here a Peerless poly cone 6.5 mid driver. The vendor assures me this bead of tacky sealant is added by the manufacturer to dampen edge resonance on Peerless's poly coned drivers. Legit? It is evidently hand applied. I wonder a bit at the likelihood of Peerless opting to hand apply this remedy in production of a 50USD mid woofer. Anyone at all out there that can verify this is the case?
I have here a Peerless poly cone 6.5 mid driver. The vendor assures me this bead of tacky sealant is added by the manufacturer to dampen edge resonance on Peerless's poly coned drivers. Legit? It is evidently hand applied. I wonder a bit at the likelihood of Peerless opting to hand apply this remedy in production of a 50USD mid woofer. Anyone at all out there that can verify this is the case?
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Peerless by Tymphany 830874 6-1/2" PPB
Sorry. I meant to type Resonance in the title. Fixed it.Here's three images from the web of the rear of Peerless poly cones. The seam is clearly factory/machine done. The bead/seam on the drivers I have is pretty clearly hand applied and kinda sloppy. I just don't feel good about this.
I wouldn't worry too much about it looking inconsistent. Was that your concern or are you thinking they produced a bad woofer and tried to fix it after production?
I presume you were going to measure it?
1) polypropylene is notorious for being hard to glue to
2) that is not "doping" (it would need to cover all the edge surface for that, internal or external) but a thick gluing/seam bead, its purpose is not to ,damp resonance or add mass to the moving parts, although that will be a side effect, but to keep cone and edge together.
3) admittedly it looks "ugly" or "sloppy" but I guess it´s doing its job, so ....
4) I guess they had a rash of cone-edge separations, specially dreaded consumer complaints and warranty replacement; even if as low as 1 in 20 that is 1 too much, specially if discovered at customer´s home, some time later (not at the Factory because they wouldn´t pass the most basic tests) , remember "bad news spread fast" so I bet assembly instructions added the line "add a reinforcing glue bead around 6.5" PP cones".
Obviously hand applied, not as automated as at the cone Factory itself.
Doubtlessly accompanied by instructions to cone Factory: "hey guys, please make sure you glue them WELL, do as many tests as needed to ENSURE that"
5) I guess these reinforced adhesive speakers work fine and within spec, although a slight variation in resonance wouldn´t surprise me.
As long as they are used in pairs from the same batch .....
6) IF you measure their parameters, please do and post them, if having a non reinforced speaker for comparison, even better; TS parameters "should" show a small difference (a couple grams tops) in "moving mass" and very slightly lowered resonance frequency, although that should still be well within parameters.
Added weight there will not audibly change sound; now IF it were at the voice coil/cone junction yes, you would lose some high frequencies; a couple extra grams at the voice coil are significant.
2) that is not "doping" (it would need to cover all the edge surface for that, internal or external) but a thick gluing/seam bead, its purpose is not to ,damp resonance or add mass to the moving parts, although that will be a side effect, but to keep cone and edge together.
3) admittedly it looks "ugly" or "sloppy" but I guess it´s doing its job, so ....
4) I guess they had a rash of cone-edge separations, specially dreaded consumer complaints and warranty replacement; even if as low as 1 in 20 that is 1 too much, specially if discovered at customer´s home, some time later (not at the Factory because they wouldn´t pass the most basic tests) , remember "bad news spread fast" so I bet assembly instructions added the line "add a reinforcing glue bead around 6.5" PP cones".
Obviously hand applied, not as automated as at the cone Factory itself.
Doubtlessly accompanied by instructions to cone Factory: "hey guys, please make sure you glue them WELL, do as many tests as needed to ENSURE that"
5) I guess these reinforced adhesive speakers work fine and within spec, although a slight variation in resonance wouldn´t surprise me.
As long as they are used in pairs from the same batch .....
6) IF you measure their parameters, please do and post them, if having a non reinforced speaker for comparison, even better; TS parameters "should" show a small difference (a couple grams tops) in "moving mass" and very slightly lowered resonance frequency, although that should still be well within parameters.
Added weight there will not audibly change sound; now IF it were at the voice coil/cone junction yes, you would lose some high frequencies; a couple extra grams at the voice coil are significant.
