Cotton Wool Plug at the foot of the Chanter

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Cotton Wool Plug at the foot of the Chanter

Postby John Gibbons » Thu Nov 10, 2011 11:04 pm

Barry "The reflection from the tone hole causes constructive interference, enhancing the note. Other reflections will probably cause destructive interference which could weaken the note. This destructive interference can affect the higher harmonics changing the tone quality of the note. I don't think it is possible to do any meaningful calculations on this system, but a general understanding of the processes can be useful."

Vibrato by waggling a lower finger than the open hole has different effects on different harmonics, altering the colour of the note perceptibly. Vibrato by waggling 2 fingers alternately can give a more complex variation in the tone colour. One to experiment with. I finally cured a high b squeak on the E of my G chanter by removing the cotton wool from the bottom. I think the plug was damping the fundamental E, but the harmonic, high b had a node (where the air doesn't vibrate) close to the plug and wasn't damped so much. So the plug damped out the fundamental and the harmonic won. Removed the plug and the problem went away.
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Re: Cotton Wool Plug at the foot of the Chanter

Postby Francis Wood » Fri Nov 11, 2011 7:52 am

It does seem to be an accepted fact that a cotton wool or similar plug is necessary at the bottom of the bore. Like many other accepted facts it is nonsense.
Often it helps. Sometimes it does nothing. Occasionally it is a nuisance as John's experience demonstrates.

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Re: Cotton Wool Plug at the foot of the Chanter

Postby Julia Say » Fri Nov 11, 2011 8:48 am

I find cotton wool necessity is reed specific.With some reeds taking it away improves the tone dramatically. Sometimes it doesn't.

Haven't done it often enough to be more scientific than that.

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Re: Cotton Wool Plug at the foot of the Chanter

Postby Barry Say » Fri Nov 11, 2011 9:00 am

Cotton wool plugs at the bottom of chanter bores are very useful, especially for those players who ( sadly :( )have little inclination to get involved with keeping their pipes playing to the highest standard. I always put a plug like this in any chanter I service.

When I install one of these devices, I 'spin' the tip of the cotton wool plug into a point and put it into the foot of the chanter, pointy end first. This is a technique I learned when investigating ultrasound at work. As a wave travels down the chanter, it encounters a fine thread of cotton wool, which gets wider towards the foot, restricting the wave to a narrower and narrower section near the wall. The wave is absorbed over a length of about 1cm and any reflections will not be coherent. The cotton wool must not be tightly packed. The other point is that the cotton wool must be dry. Oily cotton wool will reflect sound waves.

My chanter has a cotton wool plug at the moment. I may remove it one day.

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Re: Cotton Wool Plug at the foot of the Chanter

Postby Barry Say » Fri Nov 11, 2011 9:16 am

Julia Say wrote:I find cotton wool necessity is reed specific.With some reeds taking it away improves the tone dramatically. Sometimes it doesn't.


That is interesting. I would never discover that.

If I make a reed I do the final adjustments in my chanter with a cotton wool plug fitted. If the tone is not good enough, I make another. So I might well discard reeds which might prove satisfactory if the cotton wool plug were removed.

My tastes in reed tone have changed somewhat of late. While I would still seek what Colin Ross would call a 'free-speaking' reed and would avoid what Margaret Watchorn would call a 'blurty' reed, I now don't like excessively bright reeds and would not spend too much time looking for the last 10% of tone perfection. Tastes vary.

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Re: Cotton Wool Plug at the foot of the Chanter

Postby GrahamRB » Fri Nov 11, 2011 9:30 am

Interesting stuff... as ever there are more questions than answers :)

The 'pointy' cotton wool sounds logical but how does a similarly used sliver of cane achieve the same/similar effect as this would presumably reflect rather than absorb?

The Devil's usually portrayed playing Pan pipes ...how sure are we that he didn't make bagpipes his own :lol:
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Re: Cotton Wool Plug at the foot of the Chanter

Postby Francis Wood » Fri Nov 11, 2011 9:36 am

With some pipes, cotton wool plugs in the ears can ameliorate a few of the worst defects.

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Re: Cotton Wool Plug at the foot of the Chanter

Postby Dave S » Fri Nov 11, 2011 7:40 pm

I still use a cotton plug on my Seitz set, but I used a Q-tip on the Burleigh set I used to own -- without it as has been explained already some of the sum and difference frequencies tend to feed back and unbalance things -- just stuff one end in and find out how much you need and then chop it off with nail clippers "an' jobz a gudd 'un"

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Re: Cotton Wool Plug at the foot of the Chanter

Postby John Gibbons » Fri Nov 11, 2011 10:46 pm

The moral is - if the pipes sound good, leave well alone, but if not,
replacing or removing the plug may help.

The aim, of killing all reflections below the open hole,
is a good one; but real plugs don't always do that.

John
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Questions and Comments

Postby Barry Say » Fri Nov 11, 2011 11:37 pm

I think we have all missed out on a possibility with regard to this bulletin board. When replying to a message we have not been using the subject option. Within a thread, every message is apparently labelled Re: (The subject of the first thread). I have used this post to reply to several messages. If you want to respond, take one of the ideas and give it a new subject name. That way we can discuss several ideas in parallel. As I am typing this, there is a box just above my message labelled 'Subject:'. This allows contributors to post on a different subject, within the thread. -- Is this making sense?

GrahamRB wrote:The 'pointy' cotton wool sounds logical but how does a similarly used sliver of cane achieve the same/similar effect as this would presumably reflect rather than absorb?

Before I walk out onto the thin ice of this question, where does this 'sliver of cane' idea come from? It's new to me.

Francis Wood wrote:With some pipes, cotton wool plugs in the ears can ameliorate a few of the worst defects.

Ca va as they say sans dire.

Dave S wrote: but I used a Q-tip on the Burleigh set I used to own just stuff one end in and find out how much you need and then chop it off with nail clippers

Personally, I regard this as former, or legacy, technology. There are stories of filling the bottom of the chanter with shot and when the right amount is found, setting it in beeswax. These methods may well work but anything which requires adjustment or measurement adds another layer of complexity to the already confusing task of getting pipes in good playing order, and as such, is best avoided if possible.

John Gibbons wrote:The moral is - if the pipes sound good, leave well alone, but if not,
replacing or removing the plug may help.


In one way this is a good attitude, but the downside is that if pipers will not make the effort to understand what makes their pipes so good when they are working well, they wont have a clue what to do when they fall below par.


John Gibbons wrote:The aim, of killing all reflections below the open hole,
is a good one; but real plugs don't always do that.


John, I would be very grateful if you would explain what you mean by "real plugs" in this context.

Barry
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