BTH C2 horn loudspeaker - UK Vintage Radio Repair and Restoration Discussion Forum

Pine Marten · 16th Nov 2023, 1:37 am

I recently bought a quite dirty example sold as untested and the seller knew nothing about it. Barn find. To cut to the chase it had good resistance across the very rough cable of 1890ohm when tested. On disassembly, all seems fine. Diaphragm plate rusty round the edges, cork gaskets as hard as oak, some green dust on coil leadout wires and lots of cobwebs. I cleaned up the innards carefully with an artists camel hair brush, a bit of wet and dry paper on the diaphragm edges and new card gaskets. New cloth covered leadout wires. Works very well with my Marconiphone 220.
I want to apply something to the coil leadouts to prevent further corrosion. Ideas?
The card gaskets work, but I suspect I can do better. Cork sheet is available from the railway modeller suppliers, but I'm thinking gramophone soudbox gasket rubber.
Advice from anyone who has restored a similar horn speaker gratefully accepted.
I do not intend to repaint/polish the horn , as it has a nice 100 year patina and is in good overall condition, the odd tiny ding and chips in the paint.
Cheers!

Techman · 18th Nov 2023, 5:09 pm

I can't offer any advice regarding your question, but just to say that you're lucky that the coil still has a circuit through it, as most of the ones that turn up have gone open circuit by now. Possibly a thorough search of this forum and the wider internet will throw up some more of the information that you require.

16th Nov 2023, 1:37 am	#1
Pine Marten Triode Join Date: Dec 2016 Location: Huddersfield, West Yorkshire, UK. Posts: 47	BTH C2 horn loudspeaker I recently bought a quite dirty example sold as untested and the seller knew nothing about it. Barn find. To cut to the chase it had good resistance across the very rough cable of 1890ohm when tested. On disassembly, all seems fine. Diaphragm plate rusty round the edges, cork gaskets as hard as oak, some green dust on coil leadout wires and lots of cobwebs. I cleaned up the innards carefully with an artists camel hair brush, a bit of wet and dry paper on the diaphragm edges and new card gaskets. New cloth covered leadout wires. Works very well with my Marconiphone 220. I want to apply something to the coil leadouts to prevent further corrosion. Ideas? The card gaskets work, but I suspect I can do better. Cork sheet is available from the railway modeller suppliers, but I'm thinking gramophone soudbox gasket rubber. Advice from anyone who has restored a similar horn speaker gratefully accepted. I do not intend to repaint/polish the horn , as it has a nice 100 year patina and is in good overall condition, the odd tiny ding and chips in the paint. Cheers!

18th Nov 2023, 5:09 pm	#2
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 4,829	Re: BTH C2 horn loudspeaker I can't offer any advice regarding your question, but just to say that you're lucky that the coil still has a circuit through it, as most of the ones that turn up have gone open circuit by now. Possibly a thorough search of this forum and the wider internet will throw up some more of the information that you require.