Eyeslikefire
Thanks, cunning buggers, it is in a Jansen amp, I had it stolen and 6 years later got it back, when I played it I wasn't happy with the sound so took the back off to check it out.
Thats where I found the Zomax, when it was new it had an Electro Voice, which had a nice sound. Somewhere along the line in the intervening 6 years it's been changed. I emailed Jansen in NZ, who are not the same company as they were and they told me it was an equivalent, it ain't.
Thanks
Clive