Hi there,
I have a grampian ribbon mic that came in for re-ribbon but it also has a broked secondary on the o/p transformer. The primary (ribbon side) is OK. The sec. winding is actually 50kOhm on this model (it has rediculously fine hair-like wire), and I was wondering if this is a good opportunity to try to rewind it for 200 ohms output. The lams slide out easily and the plastic bobbin is intact. I have little experience rewinding trafos so I need to know what I'm letting myself in for here.
Does anyone have any thoughts on this, in particular what kind of wire I would need to get for this. I have a salvage transformer from a shure 949 mic which I would be willing to use as a donor - could the wire from this be suitable or is that too simplistic.
What else would I need to do? For a 0.3 ohm ribbon to 200 ohm I calculate a turns ratio of 26, so I can measure the turns on the primary by using the PRR/cj method of wrapping 1 turn around, and then wind the secondary accordingly.
Any other ideas? I know the rewound trafo won't sound like the original, but at least it could be a low cost way of resurrecting the mic.
Cheers & thanks in advance
Stewart
I have a grampian ribbon mic that came in for re-ribbon but it also has a broked secondary on the o/p transformer. The primary (ribbon side) is OK. The sec. winding is actually 50kOhm on this model (it has rediculously fine hair-like wire), and I was wondering if this is a good opportunity to try to rewind it for 200 ohms output. The lams slide out easily and the plastic bobbin is intact. I have little experience rewinding trafos so I need to know what I'm letting myself in for here.
Does anyone have any thoughts on this, in particular what kind of wire I would need to get for this. I have a salvage transformer from a shure 949 mic which I would be willing to use as a donor - could the wire from this be suitable or is that too simplistic.
What else would I need to do? For a 0.3 ohm ribbon to 200 ohm I calculate a turns ratio of 26, so I can measure the turns on the primary by using the PRR/cj method of wrapping 1 turn around, and then wind the secondary accordingly.
Any other ideas? I know the rewound trafo won't sound like the original, but at least it could be a low cost way of resurrecting the mic.
Cheers & thanks in advance
Stewart