This old microphone by Philips came from a seller in Egypt - I have a vision of it being used back in the 1940s and 50's, broadcasting out in the desert, near the Pyramids and Sphinx....
The mic was in pretty bad shape and in need of a full restoration. The ribbon was broken, and it was missing a yoke and several other parts. However, it's a pretty interesting microphone and so gets to be our microphone of the month for December.
The magnetic field is provided by one large permanent barrel magnet. This microphone had a measured field of about 1200 Gauss between the poles, with ribbon dimensions of 5.5 mm wide by 67 mm long.
I haven't seen another one like this - either in life or on the web. If you have any further information on this, I'd love to hear from you.
Bob Crowley has a few things to say about these mics - not all of them nice!
The motor of this model is based on a single cylindrical permanent magnet, clamped to a pair of metal plates which make up the pole pieces of the assembly. Because of the positioning of the magnet, the magnetic field is uneven, with a significant difference in field between the top and bottom of the motor assembly. In our example we found that the field varied from around 700 gauss at the bottom to 1000 gauss at the strongest point. This is very low for a ribbon mic, and, along with the oxidised ribbon is responsible for a low, noisy output.
Pansy the cat has got it in for the MacBook, and launches surprise attacks like this, usually whilst I'm writing an important email, a blog entry, or leaving feedback on ebay.
At least it explains the spelling!