White dust means zinc plating "sacrifices" itself, not kidding, to otect iron from rust but I have NEVER EVER seen so much.
That speaker must have lived years in a VERY humid place or near the Sea.
If even 1/4th of the crust I see on the back plate appears inside the voice coil gap it will block the voice coil from moving.
Some numbers: gap is typically around 1.2 mm wide, former + 2 layers of wire + adhesives take about 80 or 90% of it, leaving 0.1 to 0.15mm between former and polepiece or VC external face and pole plate surface.
*Anything* in that space causes scratching, but you can easily have the full space clogged with Zinc oxide (yes, the white stuff).
Again: I have never ever seen so much, not even in abandoned ships.
That speaker must have lived years in a VERY humid place or near the Sea.
If even 1/4th of the crust I see on the back plate appears inside the voice coil gap it will block the voice coil from moving.
Some numbers: gap is typically around 1.2 mm wide, former + 2 layers of wire + adhesives take about 80 or 90% of it, leaving 0.1 to 0.15mm between former and polepiece or VC external face and pole plate surface.
*Anything* in that space causes scratching, but you can easily have the full space clogged with Zinc oxide (yes, the white stuff).
Again: I have never ever seen so much, not even in abandoned ships.
1. There are tutorials on how to measure resistance using a digital multimeter (DMM) on the interweb. 3 Ways to Measure Resistance - wikiHow
2. Don't you think you should establish the condition of the bass driver before worrying about the insulation? Perform the 9V battery test I recommended.
P.S. Thanks JMFahey, the oxide could well be present in the magnet gap and restricting the movement of the voice coil.
Alternatively, the voice coil wire could have corroded and gone open circuit.
I found the speakers in an attic. I have no idea how long they'd been there but it could have been 2 or 3 decades. Now that I look again at the photos i posted the zinc has completely reacted away around the edges.
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You're absolutely not going to damage an amplifier by removing a driver from a speaker.
Apparently, when you remove a driver from a 2nd or higher order crossover, a resonant circuit is formed which will present a zero ohm load at the crossover frequency (or at some multiple of the crossover frequency).
The load seen by the amplifier at the resonant frequency (and multiples thereof) will only be the sum of the resistances of the speaker wire and the inductor, which may stress some amplifiers.
I hope soon to take the speaker apart and post pictures of the crossover. This thread isnt dead yet!
Need to find out still, havent touched the speakers in a while. But will do that this week.
The woofer looks like the A26/A26.
Perhaps just loose the mid & tweeter and with a new tweeter make one of these: https://www.diyaudio.com/community/threads/seas-a26-devore-style-build.369124/
dave
Perhaps just loose the mid & tweeter and with a new tweeter make one of these: https://www.diyaudio.com/community/threads/seas-a26-devore-style-build.369124/
dave
Yeah, they look exactly like the old Seas woofer.👍
Looks like this speaker belonged to a similar line from Sony.
jeff
Haven't forgotten. I'll be up for a visit in the near future.🙂
The weekends seem to go by in the blink of an eye. 🙁
jeff
The weekends seem to go by in the blink of an eye. 🙁
jeff
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