Whats the difference between them and, not… hollow… i mean why are they more expensive and what do you gain 
Hi Darren
They are generally more expensive because of the extra work involved
Advantage is that the drones all phase lock and work a whole lot better and the weight of mainstock is reduced.
Some makers use metal tubes to carry the regulators in a completely hollow mainstock and some just machine a cavity. I fall into this latter category as I dislike putting metal tubes inside wood due to problems with
differing expansion rates for wood and metal
Chris
edited for typos
aha, thanks for clearing that up
You might try reading this: (caution, large file!)
http://billhaneman.ie/HollowStock.pdf
I think there are acoustic advantages to using the thin-walled style hollow stock, as made by Coyne, Kenna, and Harrington. You can hear the reeds clearly through the stock walls, and the walls themselves do seem to vibrate as well (you can hear the difference when damping them with a hand).
Chris, I do use metal tubes inside, as did the makers above, but I don’t think there is a significant worry with these very thin walled tubes for two reasons: 1) they are so thin walled (<0.4mm wall thickness) that even given their round cross-section, they compress inside the wood easily; 2) I don’t fit them tightly into the wood, but pot them in with a flexible adhesive. There’s generally 0.5 mm or more clearance around the tubes.
Given where they actually are placed (inside a quite thick walled front section of the stock), the seasonal stresses caused by differential shrinkage may be greater than those exerted by the regulator feed tubes.
In general I agree that metal inside wood leads to trouble - particularly where the wood in question is relatively thin.
Bill
+1, i have a hollow stock, and the drones really snap in tune. Its weird, even if they are not perfectly in tune they bring them selves in tune.
Darran
IMHO, A hollow stock is well worth the money/ effort. A friend of mine has a beautifully restored antique set with a hollow mainstock that he recently let me try. The difference in the sound quality versus a solid stock was absolutely striking. There was a lovely warm glow to the drones. The bass drone sounded smoother and as a group they seemed to blend together and project better. The drones seemed to take less air for more sound, (again versus mine ) althought I admit this could be a difference in design of the drones themselves or their reeds.
I think there are acoustic advantages to using the thin-walled style hollow stock, as made by Coyne, Kenna, and Harrington. You can hear the reeds clearly through the stock walls, and the walls themselves do seem to vibrate as well (you can hear the difference when damping them with a hand).
Lovely slide show of very nice work Bill!
Chris and Bill, do you know if the old pastoral sets had hollow stocks?? Was this a common feature seen in older sets?
Thanks,
Chad
I would not wish to own a flat set without a hollow stock. Don’t think it makes a difference with the dastardly key of D…too “rough” of a pitch to really matter.
sometime ago, cillian o’ briain wrote an article in an piobaire or the ipc pipers review about sets sounding better without a windcap. this in combination with a hollow mainstock. the harmonics blending and supporting one another.
I would respectfully disagree. The hollow stock on my (D) set was definitely worth it…
Thanks Chad;
The pastoral sets did have hollow stocks, but their design was quite different - the drone quills were set into a “plug” at the end of the stock which was removable, so to service the drones you removed the whole front end of the stock instead of individual drone tenons.
The problem with this arrangement was that it put the regulator reed in the same chamber with the drone quills. This was found to be a bad idea, as sounding the regulator could “pull” the drones out of tune, i.e. the beating reeds would interfere with one another in this case, unlike the case with the drone quills alone, where they support each other. This is, at least, the theory, and there are reports to back it up. Some pastoral sets got around this problem by supplying the regulator (single reg, in this case) with an independent air feed along the side of the stock, an idea which was partly recycled when bass regulators came into use in the “Grand Union Pipes”.
It seems that by about 1800 the notion of isolating the regulators via independent tubes within a hollow stock had caught on, and that idea was used throughout the “golden age” of Union Pipes which I would say ran until the 1850’s; by 1860 the various makers seem to have died in poverty or closed up shop. An exception, where hollow stocks are concerned, seems to have been Michael Egan - I’ve seen several solid stocks stamped M.EGAN but never a hollow one.
Bill
Would you mind, Chris or Bill, or both to post any pic of the hollow stock?
I´ve never seen a Hollow stock in person and I don´t understand where and how the drone shut off key is located.
Thank you
OK Bill it´s done, i´m reading your .pdf, I see now. Thank you
sometime ago, cillian o’ briain wrote an article in an piobaire or the ipc pipers review about sets sounding better > without a windcap. > this in combination with a hollow mainstock. the harmonics blending and supporting one another.
What does “without a windcap” mean - a straight tie to the bag without a transition tube/joint/stop valve? Please explain…or post a photo of what this is.
Thank you for the timeline Bill!
Remebering that Chris makes pastoral sets, I went to his web site where he has photos of a “plug in front” type of stock, exactly as you mentioned. That’s an amazing site with a tonne of useful information that you have there Mr. Bayley!! 
It’s a shame such a design has problems, I could see advantages to such a layout. Something I couldn’t figure out from the pictures; in such a configuration, if you shut off the drones are the regulator/s also without wind or did earlier pastorals lack the drone shut off? If so, that could be another reason for changing the design, putting the regulators on top of those old sets.
The old set with the hollow stock that I played was in D. I doubt the pitch would change the acoustic benefits any. When I’m ready to get a new set, I will look for or ask the maker for this feature.
Chad
BillH wrote
The problem with this arrangement was that it put the regulator reed in the same chamber with the drone quills. This was found to be a bad idea, as sounding the regulator could “pull” the drones out of tune,
Are you absolutely certain of this - a lot of sets were made in this style and have heard and seen sets with this arrangement playing perfectly.
John
Eugene Lambe several times had made this “shuttle drone” that he said he got the idea from Matt Kiernan: An additional tenor drone was fixed to the chanter top. Now - only if the drone was supplied with air from a thin hose (going through the chanter top) that went down into the bag it sounded allright. If not, this awfully loud snare was there as soon as the chanter reed played.
The “shared stock cavity” style was short-lived, soon after the advent of the regulator it seems to have been abandoned in favor of independent supply for the regs. The old makers went to a good deal of trouble to accomplish this, even before the advent of the drone switch (for instance see the separate air feed for the James Kenna regulator in the one-reg D set c. 1775 in SRS v1)..
I haven’t put the notion to the test by making multiple sets in both styles, but this is the consensus among historians of the instrument. Acoustically speaking it makes sense to me as well, but experience does trump theory.
Bill
I have made hollow and solid stocks and my conclusion as both a player and maker is that for wide bore concert pitch, the latter works better. There are less places it can leak and the drones switch on midtune in a far more stable manner. The late Dave Williams was in agreement with me on this. He mostly made solid stocks but his drone sound and response has a great reputation.
Just my two cents!
Just out of curiosity with of these well known sets are solid or hollow stock(if it is known)
Liam O,Flynns -rowsome.
Seamus ennis- Coyne
Paddy Keenans -Williams -solid
Sean Mckeirnan- Taylor
Sean talty - harrington
mick O,Brien - W rowsome
RORY
PS Please add to the list if you wish!!!
I am pretty sure these are all solid ones. Maybe Sean Talty’s is a hollow one (it should be if it’s the original but I somehow seem to remember it might not be, I played that one 15 years ago and I am not sure, can ask him if I see him during the week)