I've just bought a pair of Seas CA18RNX/P drivers, and the phase plugs are a hollow moulded plastic item. They sound hollow when tapped and fall off when twisted. So now curiosity has got the better of them, I could fill the hollow with resin or silicone etc to fill and dampen them. Or go full nut job and machine a new pair of plugs from aluminium or copper and fit them with a bolt through the 'pole vent'.
What would be the better option? Is there an issue with copper or aluminium above the gap only, forming an eddy current shorting ring for the positive stroke only?
OR should I just fill them with 2 part silicone to deaden them and stick them back in with some epoxy?
thanks
What would be the better option? Is there an issue with copper or aluminium above the gap only, forming an eddy current shorting ring for the positive stroke only?
OR should I just fill them with 2 part silicone to deaden them and stick them back in with some epoxy?
thanks
CA18RNX doesn't have a phase plug. Did you mean L18RNX?
Filling with silicone sounds like a safe bet. If it's easily removable perhaps try some blutack first so it is a reversible mod. Adding what is effectively a shorting ring could make things worse if they have designed it not to need one. SEAS motors tend to be fairly primative though so I would guess it'll probably improve things slightly.
That said, I wouldn't be surprised if there is absolutely no audible or measurable difference by filling the plug or replacing with a metal one. Typically only hollow bullet shaped dustcap 'phase plugs', which move with the cone are problematic. Then again I've measured drivers with this exact arrangement which performed beautifully.
Filling with silicone sounds like a safe bet. If it's easily removable perhaps try some blutack first so it is a reversible mod. Adding what is effectively a shorting ring could make things worse if they have designed it not to need one. SEAS motors tend to be fairly primative though so I would guess it'll probably improve things slightly.
That said, I wouldn't be surprised if there is absolutely no audible or measurable difference by filling the plug or replacing with a metal one. Typically only hollow bullet shaped dustcap 'phase plugs', which move with the cone are problematic. Then again I've measured drivers with this exact arrangement which performed beautifully.
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Nope definitely CA18RNX/P with a phase plug.
It could be a complete non issue, its just I've pulled one off now 😉 so want to make it better if possible when putting it back on.
They were a discontinued/end of like stock item, so I would assume an OEM driver for someone (be interested to know what they came from). The sound surprisingly nice just playing wide open, considering their simplicity.
It could be a complete non issue, its just I've pulled one off now 😉 so want to make it better if possible when putting it back on.
They were a discontinued/end of like stock item, so I would assume an OEM driver for someone (be interested to know what they came from). The sound surprisingly nice just playing wide open, considering their simplicity.
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Why didn't you leave them alone? Now you have broken them! 😀
Fundamentally the Prestige SEAS CA18RNX/P are designed for phase plugs, that is what /P stands for:
Seas CA18RNX H1215-08 Woofer - Prestige Series
Falcon have shown incredible laziness here with the wrong image. Heads should roll, IMO.
Here's the non-phase plug or regular dustcap version:
H1215-08 CA18RNX
Fitting a phase-plug might appeal to certain people. SEAS will adapt designs to customers as long as it flogs more product. BTW, I see no sign of copper shorting rings. For that you usually move to Excel drivers.
I really doubt if you will hear the difference.
MAYA
Stop worrying and fix the phase plugs back on with epoxy. Usually good for sticking plastic to metal.
Fundamentally the Prestige SEAS CA18RNX/P are designed for phase plugs, that is what /P stands for:
Seas CA18RNX H1215-08 Woofer - Prestige Series
Falcon have shown incredible laziness here with the wrong image. Heads should roll, IMO.
Here's the non-phase plug or regular dustcap version:
H1215-08 CA18RNX
Fitting a phase-plug might appeal to certain people. SEAS will adapt designs to customers as long as it flogs more product. BTW, I see no sign of copper shorting rings. For that you usually move to Excel drivers.
I really doubt if you will hear the difference.
MAYA
Stop worrying and fix the phase plugs back on with epoxy. Usually good for sticking plastic to metal.
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Wood.
And steel screws in the bottom to hold them to the polepiece.
Hollow? Now that is not smart.
dave
I'm not good at leaving things alone, and I haven't broken them (yet!).
Yeah, Falcon were lazy, but also cheap if you read the text it was obvious what was being sold. I've used a few paper drivers and find they do most things rather well, nothing exceptional, but often the compromises are a very easy to work with trade off.
The two regular dust capped versions both are a bit rough in the upper reaches, the larger voice coil version (like this motor) the worse. I made the assumption the roughness could be reflections from under the dust cap, so these should be no worse possibly better.
No there is no copper in the motor. my concern was tapping the phase plug gave a very audible plastic high pitched ring, which can't be good, possibly not that bad, but not good. Now one was off could this be improved? I've some 2 part silicone with a very low shore hardness (5a from memory). I could fill the plug with this mixed with some blasting garnet very easily, and it would be very dead.
I'm going to try crossing these to a pair of Fountek NeoCD3.0 ribbons, which will be a stretch for both drivers, but might work. If not it will be a pair of 3-4" wide range cones.
As you say it may make no discernable difference, but it probably won't make anything worse.
