The illusive Hard D

[halfirish]

I've read, and contributed to, posts about attaining a good hard D on the chanter but I've never managed to find out about the physics, if you like, governing the hard D.

I appreciate that the note is fundamentally the same frequency as the soft D and that it is rich in harmonics, thus producing the fascinating sound. However, what is actually going on and where is it going on? - at the reed end or at the bottom? Is it to do with sympathetic resonance being set up somewhere? Or is it a complex and impossible question to answer?

Can anyone shed any light on the science of the thing and why it is sometimes not possible to achieve on some chanters?

[tradbanjoman]

the standing wave travelling down the bore is suddenly slowed down when reaching the bell of the chanter in our chanters bore the botom has a faster taper rate than that further up .
hard d hard e and sometimes hard f can be achieved.
puting a roll of paper in the botom of the chanter allthough it makes the bell smaller at that point also has the same effect as the standing wave is interupted. hope this helps you to understand a little more.
jim carroll

[halfirish]

Thanks Jim

So I guess what you're saying is that it's this interruption of the standing wave that causes the hard D. Of course inserting paper or the like into the end also flattens the D somewhat so I guess it's a question of balancing that, with the ease of achieving the hard D.

Interesting. I would welcome other snippets of info on the subject

[Patrick D'Arcy]

You need some poop in your hole.

[John O'Gara]

Patrick D'Arcy wrote:

You need some poop in your hole.

Thank you Bill Nye!

[MTGuru]

I guess this is supposed to be "Elusive". "Illusive" means imaginary or non-existent!

[pipewatcher]

"I appreciate that the note is fundamentally the same frequency as the soft D"
The hard D is significantly sharper on many chanters, while the hard E is often flatter.Has anyone the answer to this little enigma?

[halfirish]

MTGuru

Oh yes, I guess you're right, although either could apply.


Pipewatcher

I believe the hard D just sounds sharper than the soft D because of the harmonics content but that they actually measure as the same frequency. At least that's what I've been told. Perhaps it's the same thing the flat hard E.

[billh]

...

Pipewatcher

I believe the hard D just sounds sharper than the soft D because of the harmonics content but that they actually measure as the same frequency. At least that's what I've been told. Perhaps it's the same thing the flat hard E.

No, this isn't quite correct. What would be more accurate would be to say this:

1) "hard" D sounds the way it does largely due to the stronger proportional harmonic content relative to the "soft" D - in particular the third harmonic ('A') and, if I recall correctly, the seventh.

2) the resonance peaks near these harmonics tend to be sharp in a chanter which gives a cooperative hard D;

3) this means that the stronger third and seventh harmonics tend to "pull" the overall pitch sharp.

However these harmonics are not themselves sharper than the fundamental when the note is playing - they are all aligned and sync'ed with one another as is required by acoustic physics of continuous tones. Thus the resulting pitch, i.e. the frequency of the resulting waveform, is some compromise value whose relative stability and loudness depends on how closely it corresponds to the natural resonance peaks of the bore. The tuning meter shows the hard D as sharper than the soft D because it really is sharper, i.e. the frequency of all the components is pulled higher by the influence of the resonance peaks affecting harmonics 3 and 7.

As to the other explanations made regarding the acoustics of hard D on this thread, I wouldn't really endorse them. Note that standing wave reflection occurs naturally at the open end of an off-the-knee bore, and slight constriction there would not dramatically increase this effect. Some makers flare the bore outwards at the bell and claim that this improves the hard D, others do the opposite and make the same claim...

Fact is, the acoustical physics of the hard D has never been satisfactorily explained in detail - the tonal qualities and tuning behavior has been explained as I attempt to summarize above, but the mechanics of how and why the standing wave changes its "regime of oscillation" between the two forms has not.

best regards,

Bill

P.S. - I could say more about the theory but it would be of little practical value...

[halfirish]

Bill

Hmmm. Very interesting indeed, and the explanation you've given to support your opinion is very welcome. It obviously differs from what I've been told before by many proporting to know. I was particularly interested in the bit that says that pipe makers vary the taper at the end, both ways, suggesting that helps the hard D.

Thanks very much for the detailed explanation. I certainly wouldn't mind hearing more on the subject. So feel free.

Thanks to all contributions, btw, even the less serious ones.

[pancelticpiper]

The hard D is significantly sharper on many chanters, while the hard E is often flatter. Has anyone the answer to this little enigma?

Another enigma is why high F# drops in pitch nearly to F natural when the chanter is lifted, but the adjacent note, high E, RISES in pitch to nearly F natural when the chanter is lifted.

That's the thing I demonstrate to people interested in the physics/acoustics of the pipes, along with the hard/soft bottom D.

Whatever the theory says, no doubt on many chanters hard bottom D sounds much sharper than soft. It's a great chanter/reed on which both hard and soft are available and both play at exactly the same pitch.

[Cag]

Reasonably relevant and accessible scientific description of the behaviour of harmonics in tubes

http://www.phys.unsw.edu.au/jw/pipes.html

[J-dub]

Patrick Murray did his undergrad engineering thesis on the vibrational modes of the reed in response to various notes and modes of the chanter. He used laser doppler velocimetry to map the regions of the scrape that was vibrating when different notes were played. Particular attention was paid to the soft versus hard D issue. The two modes of that note result in quite different vibrational patterns of the reed. Maybe not surprising to any reed maker who knows where to scrape a reluctant reed to make it produce the hard D.

A quick google search reveals that it is still accessible on line...

http://www.tuftl.tufts.edu/mie/Pubs/uilleann_reed.pdf

Curiously, there seemed to be a particular point across the reed that did not undergo significant displacement, at least for the notes investigated. This node was roughly half way between the lips and the bottom of the scrape. Patrick added that at this point the reed slip had the same inner curvature as before being tied to the staple, below this node the curvature was greater (due to being bent around the staple) but less above it (due to the the amount of cane removed). One can imagine how factors like the angle of the staple taper, the depth of the gouge, the stature of the cane slip, depth of the staple and how much tension is introduced into the system by tying on the slips could change the position of this neutral node, possibly in disadvantageous ways.

Nice work Patrick!

John

[sean an piobaire]

HOO-RAY for Patrick Murray's experiments at Tufts, as He and his Team got down to a real examination of the states of wave distribution across the length and width of the Double Reed head.
I love the strange little "Faces" mapped out on the Cane, as it vibrates the different notes of the scale ! Check it out..... in the Illustrations.
Flutes can be forced to reveal a Hard D Harmonic Overtone, an Octave Higher than the Low "D" and it comes out easier on the Reverse Tapered Cones of the 19th century style Flutes, and only a very little bit on modern Flutes, with their Cylindrical Bores.
This Middle D overtone is there all the time, of course, as the Low D note is sounding, but a slight increase of air pressure on the Flute (and the Chanter, combined with Snapping the A with your Ring Finger) brings this higher octave D note UP to an audible volume, for a stronger "mixture" of Harmonic Overtones, sounding along WITH the Low D.
As a result of my experience with Chanter Reeds, I found out (early on),
that there is a relationship of the Tip of the Reed Head vibrating this "Hard" D, and the vibration of a Soft D.

If you want to make the Hard D disappear, just sand the Tip of the Reed, a little bit more than is needed, and you will:
(A) Flatten the Middle D, (B) make the Mid D gargle, as it can't decide what note to vibrate, fluctuating between various in, and out of tune "D"s, AND....you will get only "Soft", not Hard "D"s, coming out of the bell end of the Chanter. Now, for the Middle D Gargle.........
There is a relationship on the Reed Head itself, the Balance of flexibility
between the Tip (or Lips) of the Reed and the area at the base of the
Reed Head next to the Bridle, which vibrates the Low D. Herr Andreas Rogge, takes a scoop-out of the Cane itself on the inside of both blades, with a chisel, at this position on the Reed Head, before he ties the Reed head onto the Staple.
Thus, he gets a Balance going right away, between the Tip, which can now be sanded down to blow easy, but not Gargle, because this thin bottom D "Window" is flexing in a balanced relationship with the Tip.
Now, I can make this "Window" on the outside of both Blades (if needed) at least if it's on the outside, I can see how CLOSE I'm coming to making a hole in the Blade, BEFORE I go too far.
I've had mixed results fixing the holes I have made, with little pieces of paper glued over the hole in the Reed Blade as a patch.
The Paper makes the Bottom of the Reed inflexible again, and it can be sanded a bit, but the whole Reed is really....RUINED, as the 2 blades are now out of balance with each other.
(You just don't want to start over making another Reed, because it's late and the Gig starts exactly at 8 AM, only 5 hours away)

Another factor of Hard, versus Soft "D", comes from the Chanter
Bore itself.
Some Chanters DO NOT have a good, well placed "Throat",
the small cylindrical section of the Bore , just below the Reed Seat. These Chanters will Gargle on the Bottom D.
In this case, the mid D harmonic is asserting itself, and the low D is
being interrupted. At this juncture, some people just dispose of the Chanter in question, others, more valiant, proceed to "line" the Throat, with a rolled-up piece of typing paper to change the Shape and Position
of the Throat (other "Fixes" are Glue, tiny pieces of Drone Cane,etc.).
After some experimentation (cutting to the right length, playing around with the Thickness, (2 sheets instead of one) etc. The Bore can be brought into a more defined, and good, working relationship between
the two (or perhaps more) "Ends" or Nodes, inside the Chanter
The standing wave being generated then "Conforms" to these new "Margins"....playing in-tune and not Gargling.

A Sharp, hard "D" can be made to give an more in-tune hard "D" by inserting a U shaped (Tobacco) Pipe Cleaner ("Rush") into the Bell of the Chanter.
You have to start with a Long bent over "U" up the bell, which results in the soft D being Flat. This can be cured by trimming the ends of the Pipe-cleaner U with scissors, taking it in and out again, until you FIND the proper intonation for both "D"s, or at least, a compromise you can live with.
I believe many of the old Pipe makers purposely made many of the Chanters shorter at the Bell section, to require Rushing to bring the Low D into tune, for both Hard and Soft Ds.
I am truly LUCKY that I can make my old Tayloresque Chanter
have both a Hard D, and Soft D, in tune,with the "U"-Rush, and it does seem to measure shorter in length, than many of the D Chanters made in the 1970s, where the Pipe makers were going for a loud Bell note, right on D (at A=440 hertz) with no Rushing required, at all.
In my Piping,I use both Hard and Soft tone colors, as I feel that only using a Hard D for everything leads to monotony, and is not needed every time a low D is wanted, in a slow Air, or a Dance tune.
Now.....
A note to Richard (PanCelt) the Length and Taper of the Bore, below the F# Finger Hole, really effects the off the Knee, 2nd octave F#.
On the Old "flat pitch" Chanters, THAT WAS THE WAY of obtaining an F natural, for "Limerick's Lamentation", "A&D of Piping" etc. especially
if there was no F natural key on the Chanter (not every Chanter had
a full compliment of Keys). Venting by different Fingerings, and the Closed Bore on the Knee forces that Wave back on itself, for a close
(only the middle finger open) in tune, second octave F#.
I have to remark that by playing my Pastoral Pipe, with it's much longer
Foot Joint, these F note Flattening effects disappear, due to the change in the placement of the internal Nodes of the Chanter Bore.
The Pastoral Pipes had their own set of Drawbacks, of course, so
the Union Pipe makers threw away the foot-joint so (A) to make the Chanter Louder, (B) they could obtain the 2nd octave easier, by stopping on the Knee, and (C) get stacatto closed fingering, to contrast with Open fingering. You had to have Choices, in how you play the Music, with as much Variety as Possible.
Sean Folsom

[Steve Pribyl]

Sean,

Thanks so much for sharing this information about the bottom d! This helps me to understand the mechanics of what's going on. I read Patrick Murray's analysis a while back, but it's clear I need to revisit it. This is quite illuminating.

Steve