This is the mic I mentioned in my first Reslo post.
The SR1 was actually designed and produced as a studio microphone rather than general purpose/public address and has a longer magnet (around 1/3rd longer than standard) with a stronger ribbon and different transformer.
In good condition, I’m told these hold their own with many classic and modern ribbon mics, so I should really get mine working. The strange thing is that although they appear to sell for around half the price of the smaller and more common RB – maybe because of The Beatles connection – they’re far harder to find and much more useable.
Here’s a great overview on the excellent Xaudia blog – well worth a read.