I am very happy with the way the speaker has turned out with the new diaphragm surround.
As I mentioned before the original surround was made of an extremely thin chamois leather, which had gone very dry and was crumbling away every time it was touched. I really had a bad feeling about how it would stand up to the vibrations of the diaphragm in use, considering the radio was supposed to have an more than 1 watt.
Anyway the plan was to make a new surround out of ripstop nylon.
An actual size drawing was made on the computer and then printed onto 4 sheets of A4 paper, they were glued together to make a life size template.
I glued the paper template onto the nylon, with Pritt glue on the water proofed side, and then cut around the inner most circle which represented the inner edge of the overlap to glue to the rim of the diaphragm. I then made 1/4 inch cuts into this edge of the circle to make it possible to turn the edge in, to glue to the rim of the diaphragm.
Once the PVA glue I used to fix the nylon to the diaphragm had dried I fitted the diaphragm into the basket and magnet and wedged it in at its lower limit with 3 plastic shims in the speech coil gap, this helps to centre the coil and holds the diaphragm steady whilst the outer rim of the nylon surround was glued to the rim of the speaker basket.
There was a concern that the diaphragm must not move too far in to the magnet as the spider mounting bolts would cause damage to the diaphragm.
Here is the speaker
I still have to fix the outer rim onto the basket, I will probably use rivets here.
Here is a short video of the speaker in operation. It starts off with the left channel of the ITT music centre on faintly, with the balance control turned right over to the KB 214 speaker on the right channel.
https://youtu.be/CI55YDSsWkQ
Mike
As I mentioned before the original surround was made of an extremely thin chamois leather, which had gone very dry and was crumbling away every time it was touched. I really had a bad feeling about how it would stand up to the vibrations of the diaphragm in use, considering the radio was supposed to have an more than 1 watt.
Anyway the plan was to make a new surround out of ripstop nylon.
An actual size drawing was made on the computer and then printed onto 4 sheets of A4 paper, they were glued together to make a life size template.
I glued the paper template onto the nylon, with Pritt glue on the water proofed side, and then cut around the inner most circle which represented the inner edge of the overlap to glue to the rim of the diaphragm. I then made 1/4 inch cuts into this edge of the circle to make it possible to turn the edge in, to glue to the rim of the diaphragm.
Once the PVA glue I used to fix the nylon to the diaphragm had dried I fitted the diaphragm into the basket and magnet and wedged it in at its lower limit with 3 plastic shims in the speech coil gap, this helps to centre the coil and holds the diaphragm steady whilst the outer rim of the nylon surround was glued to the rim of the speaker basket.
There was a concern that the diaphragm must not move too far in to the magnet as the spider mounting bolts would cause damage to the diaphragm.
Here is the speaker
I still have to fix the outer rim onto the basket, I will probably use rivets here.
Here is a short video of the speaker in operation. It starts off with the left channel of the ITT music centre on faintly, with the balance control turned right over to the KB 214 speaker on the right channel.
https://youtu.be/CI55YDSsWkQ
Mike
