I´ve dug in the forum and discovered this possible explanation to why some expert pipers only use 3/4 sets (Grasso, Hannan):
Many old hollow stocks were made of boxwood and often dyed black for a set in ebony. The stock wall was quite thin and a nice buzz was added to the drone sound from the vibrating stock. Add a bass reg. and that buzz is cancelled or at least muted due to the bass bar being screwed onto the stock. I have only seen one old 3/4 set with a hollow stock and the sound was great. I have seen others with the bass bar added and could hear the difference.
Use as dense a wood as you can get for the resonance of the stock. Mopane and Nara are good. If desired you can always dye the wood to match blackwood or whatever.
re: a hollow mainstock
there is a school of thought that
there is greater resonance if its hollow, and the air chamber conducts sound better (or differently) compared to a solid wood stock
there is believed to be a greater chance of the vibrations of one reed encouraging another reed to vibrate “in tune” ie the dominant sound waves in the mainstock will encourage co-sinous vibration in less dominant reeds
re: the 3/4 set
Two regulators are easier to play than three, as the norm in playing is to only play 2 reg notes at a time, not three, and the keys of the third reg can sometimes get in the way, so some players like Sean Potts or Robbie Hannan, tend to just play a 3/4 set (but Sean has a removable bass reg which gives him that extra option of plugging on the bass reg…one that he rarely chooses…I think from memory Robbie has something similar but his is an antique set and its a few years since I last saw it up close)
With just 2 regs, there is a little more play in what angle the stock is sitting in the cup, or the positioning of your wrist or hand over the reg keys. Its a little more forgiving.
Of course, you save money if you get a 3/4 instead of a full set…
Or as Robbie has said to me more than once
“why pay £1000 for four more notes?”
(I think he was dropping a hint that I could be just as crap on 2 regs as I could on 3, but save myself a lot of money in the process lol)
Although the mainstock does vibrate it is not an effective resonator and you can demonstrate this by comparing it to a good resonator like a guitar or violin body.
Contrary to Ted’s suggestion a resonator should not be made of a dense wood as it is not flexible enough and this is why the best violins made by Stradivari are made of pine. Linked to this but more importantly the stock doesn’t have sound holes and so sound produced is dependant on the stock surface to create enough air displacement to cause audible sound and it doesn’t, in fact for this reason the bag is probably a better resonator that the stock.
Another misconception is that a hollow stock is better when it comes to promoting phase locking in the drone reeds because they share a single space. The fact is that in either a solid or hollow stock the drone reeds share a single space. The space in the solid stock is a different and more complicated shape but it is none the less a single space. The idea that the reeds have to “see” each other to phase lock is misleading.
Careful there, Rory. If you’re going to pronounce others wrong then at least get your own facts right.
Violins, as a rule,* are made of spruce (top) and maple (back and sides). And the back does resonate, although to a smaller extent than the top. This is easily demonstrated by damping the back while playing, which changes the tone of the instrument.
In any case, comparing stringed instruments with woodwinds is comparing apples to oranges.
* There are always exceptions to a rule; I own a fiddle that is made of redwood and sycamore. It sounds terrible.
It is of course true that a hollow stock isn’t a “resonator” in the same sense that a stringed instrument’s soundbox is - however there is a lot of sound coming from the walls of an old-style hollow mainstock, which can be demonstrated by placing a hand over such a stock to mute it. You can demonstrate that the effects also include some audible wall resonance, since the effect on sound is different depending on whether the stock is physically damped with the hand, or just blocked with some sound-absorbing barrier between stock and ear. One is, in effect, hearing the reeds “through” the stock walls; also the air cavity is indeed functioning as a resonance chamber. The “hand on versus hand over” experiment demonstrates that there is some wall resonance effect taking place as well.
There is some coupling, and thus phase-locking, between drone quills in a solid stock - through the solid material, and also through the small air chambers and even the bag. However, there is much better coupling in a hollow stock. That is the point.
Of the handful of original 19th century hollow stocks that I’ve examined closely, the ones dyed black seem to have been made of cherry or pear, a softer wood than boxwood. Boxwood stocks were used on boxwood sets, no question about that. Whether dyed fruitwood was substituted for ebony for mechanical, acoustic, or cost reasons is unknown.
The sound power given off a vibrating stock is 10,000 times lower than the sound coming from the drones, you could make it a little better by making the stock oval.
As long as the drone reeds are sharing the same air supply phase locking is achived. Better in this instance is subjective.
Rory, have you ever spent any time with a thin-walled hollow stock? If so, I doubt you would be trying so hard to defend this position. I can demonstrate the plainly audible effect to you or anyone else in a few seconds. Whether one prefers it or not is the subjective part.
Anyhow, I don’t buy your math. Even if I did, a 10,000-fold difference in sound power is only 40 decibels which is still audible (hearing being logarithmic). The one ten-thousandth argument applies to wall vibration for a chanter versus soundhole propagation, which is probably where you got the figure, but the argument doesn’t work for the stock wall which is more a matter of attenuation of the quite audible vibration of the quill itself. A 3 or 4 mm stock wall will not attenuate terribly effectively - less than 20 decibels anyhow, and it’s not particularly rigid, especially at high frequencies. The sound spectrum that is being heard through the stock is quite different from the sound that comes from the end of the drone - it includes many high frequencies which don’t make it out of the drone end - which is why the effect is noticeable.
The phase locking part is less subjective - better coupling means better phase locking, which is inherently a good thing. There is no question that the coupling is quantitatively better in a large shared cavity as opposed to multiple interconnected cavities (of if you prefer “one oddly shaped” cavity).
Your right that maths would not be my strong but I think if you look on it in a common sence way a 4mm thick tube of wood with some vibrating reeds inside is not going to be vibrated enough to have any meaniful addition to the sound of a full set of pipes.
I think the effect that you hear when you dampen the stock with your hand is because you are interrupting the vibrations that are travelling through the material of the stock and onto the bag with is a much better resonator that the stock.
What is coupling in regard to the phase locking question ?
What makes you believe a bag is a better resonator than a hollow wooden shell?
Two oscillators or dynamic systems (for instance, reed-air column systems) are said to be “coupled” if they have some connection which causes them to influence one another. In this case the connection is (mostly) via the air. A shared air cavity provides a direct, unimpeded coupling. If instead of an unimpeded air cavity, there are in effect two air cavities connected by a thin tube, the air coupling must be conveyed via the air tube. In this case, the ‘damping’, or energy losses, are much greater due to the resistance of the air in the thin tube to motion, and thus the influence of the two oscillating systems (reeds) on one another is greatly reduced.
There will always be some coupling between reeds via the solid material between them, and even between the ends of the drones via the open atmosphere in the room, but these effects are considerably weaker than the relatively strong coupling between adjacent reed quills separated only by air (in the hollow stock).
Some sorts of coupling may be undesirable - for instance between drone quills and regulator reeds, which is thought to be why pipe stocks have separated regulator reeds from those of the drones since about 1770. The desire to further reduce coupling, or at least to reduce the effect of transient pressure variations on the regulator reeds, has been suggested as the reason why Kenna used very small air feed tubes for the regulator chambers - a subtlety that was discarded by Coyne and most later makers. A few modern makers have put corks in the ends of “drilled through” regulator holes, and then bored small holes in the corks, which seems to accomplish more or less the same thing.
The phenomenon called “phase locking” concerns the tendancy of coupled systems to align with one another if their “independent” modes of vibration are close to an integer ratio. It is thought that the gravitational coupling between earth and moon, via the tides, explains why one side of the moon always faces the earth - the rotational period is phase-locked to the revolutionary period.
For a number of reasons,first of all it has more area on the outside of the bag so there is more material to vibrate and so it will have a stronger air displacement effect and so create sound that we hear.
Secondly when the bag is inflated it is under tension ,admittely not a great amount but enough for it to act in the same manner as a drum skin. If you take the example of a vibrating tuning fork which you can hardly hear on its own but place that tuning on a drum skin and hear the difference, this could be the same effect as the vibrating but inaudible stock touching the bag.
I have been trying to think of a good example of another musical that would be similar to a hollow stock and the only one I can think of is a tubular bell. The amount of energy that you have to impart on a tubular bell (striking with a hammer)to get it to vibrate and produce sound is huge compared to the tickling a stock gets from a vibrating reed inside it and also considering a tubular bell is open ended where the stock is not and the tubular may be three feet long where the stock is only six inches.
Geeze rory, it’s like you’ve never actually tried the things you’re arguing about!
Now try taking that same tuning fork and placing it on a solid wooden table in the same manner that you did the drum. Which one is louder? Don’t guess now!
Again, maybe you should try it. The amount of energy needed to get a tubular bell to sound is remarkably small. Try sitting next to one, say about 5 feet away, and play a note on your chosen instrument that corresponds to the note of one of the bells. See what happens. Now try lightly (very very lightly) tapping the tubular bell with your fingernail. Try increasing the force that you tap it. Note at which force you get a discernible sound. As a thought experiment, try to imagine the energy a drone quill is using or transforming and try to compare that with your experiment with the tube.
Let us know what you find. I know I’ve done much the same things in my relatively short life, so I’m pretty sure I know what you’ll find.
Thanks NicoMoreno,youe gone off on a bit of a tangent there but its OK.The point I was making is that the drum skin or the wooden table top acts as a amplifier for the tuning fork as the bag does for the vibrating stock.
Heres another experiment for you to try.Take your long tubular bell and cut it down to six inches then close off one end ,then try tapping it with your fingernail and see what happens
I’ve never met any luthier that would admit to using pine to build a violin.
Pine and spruce share division, class, order and family in the plant kingdom, but their common lineage ends there. Pines are of the genus Pinus, while the spruces are Picea. They have very different qualities as to color, grain, figure, strength and elasticity.
Spruce is not pine, no matter how much you might wish it to be so, Rory.
And, like Bill, I wonder if I’m wasting my breath…
the debate will probably never be resolved to a final “right” answer and so no-one is gonna really be wrong
but the debate regarding the theory and practical application thereof is pretty interesting
and at the end of the day, each reader (and each contributor) will take away from the debate what he or she wants
and reject what is held to be invalid
The whole post is quite interesting and aside that I´m more on the Billh side and having made a hollow stock for my own set (halfset by now, up to be a 3/4), I found that there is a forgotten idea… which is: bearing in mind that if you put a hand on a Hollow Stock you mute the “extra” sound effect; What happens when you add the plate/bar for the bass reg?
Does it mute the Hollow stock?
On the other side I´d add that if you can mute a hollow stock with a hand, If the bag would be a resonator, Wouldn´t it be muted with the arm? as if you put a hand on a drum skin?
Like all vibrating things the bag has many modes of vibration and not all are muted by your arm.You can easily feel this yourself the next time you are playing you drones ,lightly put your finger tips on any part of the bag you can reach and you will clearly feel the bag vibrating.
Its worth pointing out that this “extra sound” under normal circumstance will not be heard.Who can honestly say that when listening to an unfamilar set,that could tell if it has a hollow stock or a solid one.Two the best sounding set in existance,Ennis’s coyne and O’Flynn’s rowsome have solid stocks.
It could be argued that a set of pipes with a solid stock actually produces more “extra sound” than a hollow stock set. A solid stock is a higher-impedance driver than a hollow stock(which is just a failed helmholtz resonator because it has no sound hole)and so imparts more vibrational power to the bag.
One thing we can be sure of:- vibrations travelling through a complicated shape of a thing made of wood, metal, leather and moving air are going to be difficult to understand. I find stringed instruments a little bit easier to understand than bagpipes:- The vibrations travelling through a soundboard behave differently than those travelling through the rest of an instrument -and are intended to. The light soundboard wood projects the vibrations to the air quickly whereas the vibrations in the hardwood back,sides and neck kind of hang around in there longer, hopefully reinforcing each other but sometimes resulting in disonences and overtones.
Hello all,
As many of you know I am a guitar player from way back. Over the years I have noticed that there are guitars that sound fantastic…to the player. I remember the great blues player, Paul Geremia had a beautiful Gibson J-200 that had a fantastic sound to the player, but you could not hear the guitar from 10 feet away.
In other words the guitar did not project the sound, for some reason the sound stayed inside the guitar.
This phenomenon has been my experiance with sets of antique pipes with a hollow stock. They sounded great to the player but standing a few feet away I could not hear the difference. In my openion it is the arrangement of the bores that make the sound, not the hollow stock or the material. A nice sounding set of drones was made by the late piper Ronnie Wathan, they were made of flexible plastic tubing that flopped around and actually sounded pretty good…Even to Seamus Ennis. Hope I didn’t burst any bubbles.
