Dynaco a25 rubber surrounds source
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There are 335 rubber surround auctions on ebay, Getting the measurements right is confusing.
Search for 10" rubber speaker surround.
Search for 10" rubber speaker surround.
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JRhoBurton
All roads lead to music
The A25 woofs are 10".Lots of them on ebay like these, Getting the measurements right is confusing.
Search for 8" rubber surround.
Correct. My surround is perfect, but some how off center or something. Speaker measures 6.8 ohms but when I manually push in cone it sounds very rough. Is speaker “blown” or did some previous owner install new surrounds and not properly center the voice coil? I just picked these up yesterday. One speaker is fine. I was going to recenter voice coil and see if it helps. Surrounds look more like butyl rubber than common foam rubber.
Yes, Butyl rubber is the formulation and I have only seen them physically damaged with abuse.
It's very common for the voice coils to be fried as people over power highly damped woofers.
The Voice Coil wire overheats and delaminates off the coil former then rubs against the Coil Gap.
Have actually disassembled the cones and rewound the voice coil. NOT recommended!
I doubt changing the surround will change this.
But if it does not sound "Right" not much you can do without inspecting the V.C.
Lots of used A-25 woofers on ebay. Good luck.
Buck
It's very common for the voice coils to be fried as people over power highly damped woofers.
The Voice Coil wire overheats and delaminates off the coil former then rubs against the Coil Gap.
Have actually disassembled the cones and rewound the voice coil. NOT recommended!
I doubt changing the surround will change this.
But if it does not sound "Right" not much you can do without inspecting the V.C.
Lots of used A-25 woofers on ebay. Good luck.
Buck
But would I still be getting an ohm reading?
Yes, The glue holding the wire is damaged by coil over heating, But still has continuity.
You say it sounds "Rough" do you mean it makes a scratching sound when pushing on the cone?
You should be able to move the cone in and out about 1/2" or so without making Any sound.
There is a VERY small gap between the Voice Coil and the magnet.
You say it sounds "Rough" do you mean it makes a scratching sound when pushing on the cone?
You should be able to move the cone in and out about 1/2" or so without making Any sound.
There is a VERY small gap between the Voice Coil and the magnet.
Interesting, my oem are 8 ohm 50v. Should I go with 4.7ohm? I have a new pair of Dayton 5.1 ohm
Yup, Woofer voice coil is toast.
Or the off center cone is making the VC rub.
Surrounds can often look off center and still be assembled correctly.
Or the off center cone is making the VC rub.
Surrounds can often look off center and still be assembled correctly.
Govany
Super Member
My a35s also had 8 uf 50 volt original..I wouldn't change the uf figure, you can go higher on the volt rating without issue
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I haven't seen a rubber surround break, but I have seen them detach from the basket.
Any possibility it was a bad repair?
Any possibility it was a bad repair?
JRhoBurton
All roads lead to music
I would try peeling up the outer perimeter of surround, clean off adhesive, reattach like you would a new surround, using a low frequency or DC signal. That might re-center it.
I prefer + DC over low frequency. It centers the voice coils and lifts the cone to give room to apply glue. Then go slightly - (minus) voltage to pull cone and underside of surround down into the glue.
Sorry meant to say my oem are 8UF , not ohm!
