06-10-2012, 12:23 PM
I need the advice of the experts for this one. I've started to strip and re-build what was the donor Radialva Groom. Because of the mods done to it before, the whole speaker assembly is now missing so I will have to replace it. I'm sure I'll have to replace it with a permanent magnet type (unless I'm luck and find a field coil one on eBay) but I won't find one of the same impedance as the original. When I measure the one in the other set it reads about 2.5 Ohms and the lowest I'll find in a PM speaker is normally 4 Ohms.
Question 1 - is this critical in terms of how it matches with the audio output TFO? A static resistance measurement of the TFO secondary reads about 2 Ohms. If I need to match them accurately how do I do that?
Question 2 - how do I replace the 'choke' now that I'm using a PM speaker? Do I need to replace with a separate choke or could I uses either a resistor or and R/C combination?
One of my goals in doing this re-build is to learn as much as I can and getting into this sort of area is new for me so all help and advice is greatly appreciated.
Cheers, John
Question 1 - is this critical in terms of how it matches with the audio output TFO? A static resistance measurement of the TFO secondary reads about 2 Ohms. If I need to match them accurately how do I do that?
Question 2 - how do I replace the 'choke' now that I'm using a PM speaker? Do I need to replace with a separate choke or could I uses either a resistor or and R/C combination?
One of my goals in doing this re-build is to learn as much as I can and getting into this sort of area is new for me so all help and advice is greatly appreciated.
Cheers, John
Time flies like an arrow, fruitflies like a banana!