Has anyone ever tried stuffing the air tube that goes into the chanter? It’s interesting, just for the experience, to know what effect a smaller or larger air supply has on the performance of a good reed. It quickly becomes clear how much stuffing is just right for your reed and climate. Look for the effect in both octaves. Some problem notes may clear up or get worse. 
Lorenzo, if partially obstructing the airway is making a big difference for you I would guess you were overpressuring the bag in the first place. Try easing off and see if that doesn’t give you the same effect.
djm
djm…change nothing else about your perfect performance, while playing a good reed in a good chanter, except partial plugging of the air supply with some sort of air filter that still lets a minimum of air through. I tried a swab of cotton, and also rolled up a piece of cotten material off a torn tee shirt. Try less and more. Try other types of safe material. Very interesting and educational, to me anyway, for a large bore D chanter.
I tried this together with my pipemaker.
We made sort of a valve with which you could regulate the air going through a reed.
We noticed no change at all, even when nearly closing the “hole”.
Lorenzo,
I tried a few different chanters without reeds to experiment in back pressure variances between them. I found one reedcap making ‘wind noises’
Removing the reedcap top plug, opening the inlet (with a dremel tool) inside the tube a tiny bit, reduced the noise and it seems to sound better now.
As has been mentioned here before, a minimum of 3/8" i.d. chanter supply tube can make a flat second octave G (a problem with some chanters) easier to get into tune. This has been confirmed by numerous experiments of late. This is not due to a choked air supply, but something in the air column that takes place above the reed. You can also feel the note vibrations in the bag with a more open supply tube. The presence or absence of an air stop key doesn’t seem to make a difference.This may seem counter intuitive, but it seems most air stop mechanisms don’t seem to be at a node in the sound wave and have little influence. Some acoustical engineer can probably shed some light on this phenomenon. A pretty small hole can feed a chanter reed. You may be noticing effects on the wave form. Stranger seeming things than this have been noticed. With an open air supply tube to the chanter, you can hear the difference between a vinyl and a leather bag, for example. Pat Sky, K&Q and others can give lots of examples. Rick’s valve experiment may not have exhibited a noticable difference due to the position of the valve (distance from the reed tip) in the wave form.
Ted
Ted, I’ve been wondering…
If the stop key in the side of the reed cap were just another air hole, letting the air out before it reaches the reed, would this bring the vibration (or sound) of the reed to a halt thereby accomplishing the same thing as shutting the air off? Cracks (open holes) in the head of a wood flute brings the sound to a halt, but I realize the reed is a different principle. If the same amount of air were let out the side of the reed cap, tuning the drones would be much like tuning them with the chanter reed going and bag pressure/bellows effort would remain the same. Just wondering.
I think the interesting thing about choking the air supply is that it may have a different effect on the octaves in different climates and with different scrapes of reeds, but I may be wrong. Something’s going on though…not sure what. I’ve been playing mine with a swab of cotten in the tube for several months. I took it out the other day to change it and noticed that without it the reed responded differently. I didn’t like it, so I put the cotton swab back in because I thought the reed responded more evenly up and down the scale. Also, I noticed the swab was dirty from the air (dust, etc.). BTW, I haven’t had any problems with swab particles blowing off onto/into the reed.
It definately depends on how open the lips are, ie, where the bridle is set.
I’ll just note that it’s an article of faith among many GHBers that the bag type can have an effect on sound, though usually we tend to care more about drone tone than chanter tone (wrongly, IMO, but no-one seems to listen to me). Things like stocks also make a difference.
Cheers,
Calum
Lorenzo,
As to your question-I dunno.
Ted
And then again, some of the greatest Ghb pipers in the world are some of the most superstitious in terms of their understanding of the way reed pipes actually work.
Most bag preferences in the GHB world center around how much moisture they keep off the reed, up to and including elaborate moisture filtration contraptions etc. Dryer reeds are steadier and brighter sounding, usually sharper or higher base pitched.
NSP players usually stuff a little cotton wool into the end of the chanter bell cap to deaden odd squeaks and weird harmonics which practice gives you a clean attack when you open the one-hole-one-note system chanter that is two octaves long and does not overblow for the second octave, using keys and simple chanter length.
Right now I’m debating whether or not to stuff cotton into my treble drone because it’s not stable alone, but locks up OK when the tenor drone is going etc. I’m not sure it locks all that well, since I hate those whiney little things anyway, but when playing alone with the others stopped it’s insanely sensitive to tuning position and does not like to hold still. That may be due to the very long bore, pretty narrow bore at that, resulting from the long mainstock and short little reed. I know some weaker reeds, including my own invention, the zetland pipes, (which use single reeds in the chanter and drones) are very sensitive to the dimensions, length and width of the stock bore. If the cotton has any effect, I’ll also try inserting a cork with a smaller hole in it just far enough the clear the reed.
Royce
VERY interesting stuff. How the hell does that work? 3/8" tube…how about the gooseneck versus “T-Joint” factor, Ted? Does the T cancel out the benefit to the high G, according to the boys in R&D?
I’ve a new D chanter with a pretty narrow inlet around the stop key valve; it doesn’t raise up much when open, but it’s enough for the reed to be happy. I think Lorenzo mentioned earlier his King Kong chanter inlet, 1/2" ID or something. Might as well take the mount off the top and plug it right into the bag! Hey…hmm…
Now, I wonder what a reed would do if you wrapped string all around the winding, filling up the cap? Or took the windcap off as far as possible?
And which sounds better, vinyl or leather? How about Gortex? I’m not too big on Gortex tone… 
Well, didn’t they start that way ??
Kevin…in my “average size” large bore chanter (want to see bigger bores?..look in some old Rowsomes), the air tube sticking out the side of the chanter is 1/2" but the hole in the wood, in the side of the reed cap, is only 1/4". This is what keeps the cotton swab from blowing on through…it stops when it hits the narrower hole in the wood.
So I have a finished air supply opening of 1/4" to the reed. This reed cap was originally designed for a small bore chanter though, remember dude?