In article ,
Keith G wrote:

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

If you plot out the x and y axis of both an omni and figure of eight then
add them together you'll see where a cardiod comes from. Indeed one of the
first basic such types was the STC 4033 (guiness bottle) which was an
'apple and biscuit' moving coil omni (STC 4021) combined with a ribbon
(STC 4038) - the latter being a production version of the BBC PGS.


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....

Do you actually need a cardiod? All else being equal it's easier to make a
decent omni. They also give less problems in usage. Of course if you need
the separation in a multi mic setup or want to reduce room acoustics a
cardiod could well be the only way.

The capsule(s) is really what makes a condenser mic - the electronics
should be no problem in this day and age.
Oh - I forgot you like valves. ;-)

--
*OK, so what's the speed of dark? *

Dave Plowman London SW
To e-mail, change noise into sound.