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 1920s speaker with field coil.
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 Return to top of page · Post #: 1 · Written at 8:18:40 PM on 25 May 2017.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1574

I have this old speaker and box which I am going to restore. The speaker has no cone but the coil is intact. Can I still test to see if the coil is ok? Will the 9 volt battery trick move the coil?


 
 Return to top of page · Post #: 2 · Written at 11:48:10 PM on 25 May 2017.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4336

The voice coil requires the cone. Normally the coil has wires to the cone & Litz wire to a terminal from the cone. The coil if it is indeed intact will need to be opened on one wire as it is parallel with secondary.

So the answer is no. Its all an ohm meter job: How wrecked is this?


 
 Return to top of page · Post #: 3 · Written at 1:18:11 AM on 26 May 2017.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1574

The coil and wire is intact . There doesnt seem to be any damage to the wiring its just that there is no cone what so ever. if the speaker coil is ok then a professional recone is in order.

1920s Speaker
1920s Speaker
1920s Speaker


 
 Return to top of page · Post #: 4 · Written at 7:45:05 PM on 27 May 2017.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1574

I have sent some better photos for your perusal Marcc.

1920s Speaker
1920s Speaker
1920s Speaker
1920s Speaker


 
 Return to top of page · Post #: 5 · Written at 12:55:24 PM on 29 May 2017.
Fred Lever's Gravatar
 Location: Toongabbie, NSW
 Member since 19 November 2015
 Member #: 1828
 Postcount: 879

Hi TC, here is a thought:

Just about the missing cone only:

What I can see from the photos is a 90% functional speaker, but with no cone.
The voice coil and back suspension appear to be intact.
The cone seems to have fractured off at the rim and coil former joints.
Assuming this and the voice coil is centered and free to move, then all that is needed is a cone with rim suspension that will fit.

I would be looking through my pile of junk speakers just in case I have one with a cone with the same rim OD, cone angle, depth etc.
If I was lucky and found a close volunteer I would then pull that off and "fit" in onto the old frame.
Of course there is a load of ifs and buts about pulling things off things with fragile materials and such but this may be a better approach than making a cone from scratch, which is not impossible just very difficult.
I have a speaker at the moment where I am doing just that but wont get to it for months as I have to machine up a mould ect ect.

Run your tape measure over some same size dud speakers and Lo! there may be one that with some delicate work and araldite can make your speaker, er, speak again.

Fred.


 
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