Different sizes and materials of construction of chanter cap have a fairly significant effect on tuning and tone of chanter.
Based on an ever growing body of evidence, I believe this to be true.
As the exam papers say: Discuss (intelligently)
Hi David
What have you found to work best for your own chanters? I have wondered about the effect of a slightly wider chamber for the reed.
I had thought this topic had been argued to death here previously. Those who scream the loudest and are the most insulting have sworn up and down that the materials used for the cap make no difference. I suspect, however, that the interal size would have some effect.
djm
To get the ball rolling, I’ve noticed an improvement in timbre with a wooden cap over a metal one
I’ve also noticed a back D being flattened by a cap with a larger volume
I’ve been told by those who measure and know, that a larger diameter feed pipe from the bag to the chanter cap can sharpen the second octave G, a note which frequently presents itself slightly flat and could drive you to the nut-house
Addendum;
To be confident in the observation of these differences, I find the reed needs to be resistent to change under a certain range of blowing pressure
It also helps if the different caps fit the chanter easily without having to add or remove too much hemp, else the time lost between listenings makes it hard to do the comparision.
I wrap a piece of blotting paper of the appropriate length around the tenon for a quick change
I don’t think it was argued… and I’m sure there wasn’t any screaming, unless it came from your house. 
There seemed to be agreement that windcaps of the same inside dimensions did not make a siginificant difference in sound from metal to wood. The wood probably offered more insulation with less transfer of heat while the pipes were sitting and also had greater aesthetic value.
David… was this difference noticed while playing or as a listener several feet away?
do you have any recording equiptment to make some AB comparisons?
hey David,
In regards to the improvement in timber, what tonal difference are you observing? I assume you are experimenting with your C chanter (doesn’t matter either way I guess) but is the brightness of the chanter easing off, or increasing? I ask bc I am noticing that my BK chanter when recording is coming off rather nasally-bright to my ear… more so at least than it sounds ambiently (i.e. not recorded). As we are working on a CD, I am desperately hoping to find something to improve this tone w/o digital adjustments.
john
(florida john)
While we’re on the topic of chanter wind caps, they can also be used to smoke rabbit tobacco, provided you put a screen on the tube that connects to the bag mount. You inhale from the part that connects to the chanter. The advantage wood has over brass is that it gets less hot after smoking a few bowls, but, of course, it is flammable, so one should be careful to keep it from getting too hot.
I was playing the C chanter when I observed the difference between the metal and wooden cap. I don’t have any way of recording the sound difference.
By improvement in timbre, I mean an increase in richness of sound. The metal cap was definitely more bright by comparison, not in this case what I was looking for.
To answer your question Douglas, I’d be tending towards a larger sized feed-pipe to the chanter cap, and a larger diameter cap to give a wider head-space to the reed, on the D Froment chanter anyway. I’ve no doubt this is completely specific to your chanter design.
Perhaps you could give a live demonstration. Let’s say Montreal, next Sunday evening at about 7.30 pm.
From experience with mouth blown reed instruments - the sax and bassoon - the shape of the the throat is widly observed to have an effect on tone production. especially on quiter, double reed instruments. The volume of the cavity up-stream of the reed does seem to influence tone. A constricted throat = poor tone.
Interesting. I had just switched nearly-identical brass windcaps on my D and C chanters. Playing the C this morning, I noticed a nice, subtle buzz. The only difference between the caps is the diameter of the connector pipe (the one that goes into the bag). It is possible that there is enough turbulance as a result of this constriction to set this buzz in motion. ?
I will look into this some more.
Ronan Browne brought up the topic of the curved bag neck (that goes directly into the top of the chanter) as also having an effect and the sound/tone/vibration. On his B set anyway.
t
I’ve been told by those who measure and know, that a larger diameter feed pipe from the bag to the chanter cap can sharpen the second octave G, a note which frequently presents itself slightly flat and could drive you to the nut-house
That larger diameter feed, in my experience, will have effect the back D too.
I find on some chanters, it can give a weak tone and result in the back D cracking.
I have cured chanters with cracking back D’s by inserting a rolled piece of card or paper into the chanter feed, thus reducing the diameter and voila,
stronger back D.
I think it was Kevin Thompson who told me about this.
tommy
I agree with David. I switched from a brass cap to a wood cap on my Gallagher D last year and noticed an improvement in tone straight away.
I haven’t topped any of my chanters with anything but ebony in years so I’m a bit out of the loop. My best Bb reed is a titch flat on the high G and I tried the plug-straight-into-the-bag approach hoping it would improve, but no such luck. The chanter was made with a top that tied right into the bag, too, it’s a reed defect I guess. Other reeds have had better high G’s, I’m going to mess about with the tops a bit tonight and see what happens.
Somebody here said Ronan found the straight-into-the-bag setup helped the high G, and certain other notes? But certainly there have been plenty of chanters with the gooseneck or T top that worked fine without it.
Sean Folsom wrote here about blowing in reeds without the stop key mechanism in place, to drive them a little harder. Velly innerestin’!
Actually I’m using a boxwood top on the ebony Bb right now, I wonder if an ebony top sounds different?
At least part of this is the fact that the chanter reed can be heard through the cap (much as drone reeds can be heard through the walls of a stock, particularly a hollow one). The wooden cap may help dampen some of the high harmonics issuing from the reed itself.
The volume and feed size (i.e. acoustic impedance) of the reed chamber is IMO a tertiary effect, but I don’t doubt that it’s there. In particular the reports of an effect on the second octave G are something I’ve heard from several independent sources, though I haven’t done much tinkering with it myself.
Bill
You’d think that reducing the volume of the windcap might have an effect. Well I followed that Hutchinson guy’s plans for adding a stop valve (http://www.uilleannobsession.com/docs/patrick_hutchinson_valve.pdf) all of which I’m sure reduced the volume. No effect on tuning whatsoever. There you go.
I wonder if that Hutchinson fella has a stop valve design for swan neck windways?