While on the journey of repairing a vintage Ultra Electric R506 valve radio, one item that I left until the end was the repair of the speaker cone. Trying to find replacements (new old stock) for these devices is very hard and in most cases you end up taking parts from another unit (working or non-working). I try to avoid this practice, as this removes one more vintage radio from circulation.
In this speaker there were two nasty tears and a couple of holes in the paper cone. The centre of the speaker was intact, so that was a good starting point and I decided to attempt to repair the speaker cone.
In some cases replacing the cone would be the only option, but for this repair, I remembered an old trick that my father had used back in the late 70’s. As these old radios use a paper composite speaker cone, it is possible to repair some of the damage. Although it doesn’t look very pretty afterwards, the speaker will still be functional, and should sound better.
What you need is the following:
- PVA Glue.
- Paper towel (kitchen paper).
- Flat piece of wood (lolly stick).
Tear a piece of kitchen towel to cover the tear in the speaker (it should be about 1 cm wide to cover both sides of the tear).
Separate the plus of the paper towel and using just one ply, apply the PVA glue to the paper towel. Ensure the PVA glue covers all of the paper towel. I find it helpful to place the piece of paper on the top of a finger and then cover it with the PVA glue.
Carefully apply this piece of paper towel, with PVA glue, to the tear on the speaker. Using the flat side of the wooden stick, centre the piece of the paper towel over the tear. Spread the PVA glue over the edge of the paper towel on to the speaker cone. This will cause the fibres of the paper towel to break apart and become bonded with the paper in the speaker cone.
So, with my speaker cone, I patched the back where the tear in the paper was bad (as you can see below), to help reinforce the speaker. Once I patched the various holes and tears, it was left to dry for a day.
After a day, upon inspection, I could see that the PVA had dried and the repair was successful. When I checked the patches they still flexed when the speaker cone deflected, which was correct.
When I tested the speaker, it did sound much better than before. Although the speaker did not look very nice, it would be covered by the speaker grill in the radio chassis, so I decided not to spray the speaker cone with any paint.