On 2006-06-05, wrote:
Does anyone know where I can source a good quality rotary switch (2
pole and 20 ways) to make a stepped attenuator??

What about a ready-made attenuator, like a DACT CT2?

http://www.dact.com/html/attenuators.html

Not cheap but it saves much work and the UK distributor is:

http://www.audiocominternational.com/

(There's some fault on the webite but a search for CT2 works.)

--
John Phillips