Got my C drones on my full set snakewood to play the key B by sliding the drone tuning part from C to B and was able to use my B plumwood chanter which sounded great until the bass made a funny sound going out of tune.
Has any of you tried thison your drones to see if you can play in any other keys.
Some sets’ drones will play the 4th if you remove the lower part of the bass drone, e.g. a D set’s drones will jump to G (mine won’t - poor me - maybe a reed issue?). Most drones will play the main note up to just a bit sharp of that, but will go down as much as a half step, as you discovered. How well they will maintain that lower note seems to vary with each maker’s reed design.
djm
Old time Northumbrian pipemaker Robert Reid made a set with 6 drones, played three at a time, controlled by the drone switch somehow (don’t have the details). The drones were dGd or aDa I think. There’s a pic online somewhere. The tonic-fifth-octave drone combination is a very Northumbrian concept of course.
To help facilitate using my D half set in C, Kirk Lynch sent me a tenor drone extension, and I made a bass drone extension, baritone reed also now can play C, so I’ve got an easily convertible D to C half set just by swapping some simple tubing!
Here’s a demo recording of the drones with the Quinn chanter:
http://www.uptospeed.net/mp3/eskin/c_drone_demo.mp3
I think it sounds pretty cool…
Michael
Eskin, what a great idea! Sounds good and much easier than hauling two half-sets around. Also cheaper. Too bad regs aren’t as easy to convert. 
djm
Pipemaking friends have suggested that drone reeds don’t like to play in different pitches.
Tommy Keane used to have a C [half] set long ago that had holes drilled some way up the drones that had little corks stuck in them, if you’d pull out the corks they’d play in D [at least I seem to remember cork, maybe there was some other system to open and close the holes]. I don’t think that idea caught on although I think Alan Ginzberg experimented with that sort of re-tunable drone set ups at the time.