I'm tempted (that is to say planning) to add a 'multi-pattern tube mic'
to my collection and, until just now, was mystified as to how a mic like
this one:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...MEWA:IT&ih=005


....could provide the various patterns (with in-between settings, it
appears) simply by fiddling with the power supply?? Anyway, a bit of
Googling has cleared this up (to a point) with information like this...

http://www.tvtechnology.com/pages/s.0071/t.433.html

http://www.tonmeister.ca/main/textbook/node469.html


Now the questions a Is there any downside? Are there any reasons to
avoid these 'dual/variable capsule' arrangements? (Especially at the the
lower price point of these cheerfully cheep chinky chappies, or is it
like everything else from the Land Of The Noodle - if the basic
principle is sound, one takes one's chances, sucks it and sees...??)

The alternative is to stick to a straightforward cardioid design like
this one:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...MEWA:IT&ih=005


Suggestions/caveats welcome....