Hollow main-stock

[Ballygo]

Hi.
Does anyone know what is the advantage of a hollow main stock , as opposed to an ordinary one.

[Thies]

I once got several good reasons for that. All I remember is:
- less weight
- interaction of drone reeds; giving a better sound (has something to do with the physics and vibrations ... don't ask me for details)

I'm sure some others can give more (and better) explanations.

/TiE

[billh]

The big acoustic advantages are these:

* the drone reeds, by sharing a common chamber, tend to 'phase lock' more strongly, and thus seem to stay better in tune with one another;

* there's a significant audible increase in the amount of high harmonic "buzz" that can be heard. This may be partly due to vibration of the mainstock walls themselves, though my impression is that it's mostly due to the actual reeds themselves being heard _through_ the walls of the stock.

If you cover a hollow mainstock with your hand while sounding the drones, you can hear a dramatic "muting" or dulling of the tone.

There seem to be differing opinions on whether this effect is mostly audible only to the player, or whether the audience hears it as well. I think one can hear a difference even from several feet away.

Bill

[pudinka]

I read somewhere that Michael Egans mainstocks were solid - true? Does anyone know how those sound?

[billh]

The stamped Egan mainstocks I've seen have all been solid.

Solid mainstocks don't "sound" like much of anything. The difference in sound has to do with drone stability, and the acoustic transparency of a hollow stock, and in the latter sense, a hollow stock could be said to have a characteristic "sound".

In other words, other than the drone stability issue, I think the difference is in what you _don't_ hear from a solid stock.

One significant issue for hollow stocks is that they are more fragile, especially when a bass bar is attached. I get the impression from hollow stocks I've seen that most did not originally have bass regulators attached (there may be exceptions), and that solid stocks may have become more popular as bass regulators became more common.

(Of course the fact that hollow stocks are more labor intensive to make is a very big factor nowadays too; hollow stocks require independent feed tubes and enclosures for the regulators, to isolate them from the drones).

Bill

[Kevin L. Rietmann]

Hey Bill, is it true Ennis's pipes had the solid stock? Possibly not original? Craig F. told me that years ago.

[Cayden]

Ennis had a solid stock.

[tommykleen]

(Of course the fact that hollow stocks are more labor intensive to make is a very big factor nowadays too; hollow stocks require independent feed tubes and enclosures for the regulators, to isolate them from the drones).

Bill

That is interesting and explains alot about the much-higher price for hollow stocks that pipemakers (who offer them) charge.

Question: Is a hollow stock, by definition, made out of wood? Would a pipemaker use the same wood as for a solid stock, or would a maker want a less dense, or more dense wood?

t

[djm]

That depends on the maker. I have had a solid stock made of ABW, but that was not necessary, and since the wood was not cured properly, turned out to be a mistake. I know Geoff Woof makes hollow stocks, but I don't know what type of wood, or if it varies. Joe Kennedy makes hollow stocks usually from cherry.

djm

[Cayden]

TI know Geoff Woof makes hollow stocks, but I don't know what type of wood, or if it varies.

djm

Ebony

[glands]

The K&Q beehive set in Cn has a hollow stock that was purchased and added as an aftermarket option. The soundscape of the drones and regs is much more captivating and encompassing than when the solid tunneled stock was used. I'd be interested to see a 3-D computerized graph of the harmonic overtones comparing drone soundfiles generated from solid and hollow stocks on the same set. Phase locking is a real advantage. The transmitted vibration of the air in the bag while playing is much more noticable as well. The set seems much more alive. My own opinion is that flat sets would greatly benefit from this treatment. I'm not sure it would make much of a difference for one of those harsh cantankerous D sets that just don't sound like pipes to me anymore. Flat sets rule.

[pudinka]

So if the back of the drone stock is open, why would the reeds not vibrate through the open back into the bag?

Doesn't some of this have to do with the bag? The first bag on my set, that I had to replace for all the leaks, literally seemed to shake when the drones were out of tune...I could feel it when the frequencies meshed up (the wah-wahs) but the smooth skin-side was face in. When I made a new bag I turned the skin-side out, without a cover, and this sensation seemed to be less pronounced - if not gone completely. I figured the rougher side simply absorded some of this, like an accoustic ceiling in a building. The stock is hollow - always has been - the reeds & drones have not changed - just the bag skin. Each drone is in it's own tube which goes through to the back of the stock to the shut-of valve but each has a small connection hole to the hollow chamber between all of them.

[ausdag]

Question: Is a hollow stock, by definition, made out of wood?

Some are all brass.

[MikeyLikesIt]

Question: Is a hollow stock, by definition, made out of wood?

Some are all brass.

Would this have any effect on how the sound waves interact? All brass vs. wooden?

[billh]

So if the back of the drone stock is open, why would the reeds not vibrate through the open back into the bag?

Most stocks aren't that open in the back - since the drone stop switch has to function somehow, there is a quite narrow inlet or set of inlets. In many solid stocks, each drilled drone socket has an independent small feed hole bored from the back switch "seat". Not much opportunity for the reeds to "couple" in these cases.

...

For the above reason, I don't think the bag itself comes into play an awful lot, at least for most solid stocks.

The stock is hollow - always has been - the reeds & drones have not changed - just the bag skin. Each drone is in it's own tube which goes through to the back of the stock to the shut-of valve but each has a small connection hole to the hollow chamber between all of them.

I don't quite follow that last bit - if each drone has its own "tube" and are only indirectly connected via one or more small tubes, then they are not able to couple effectively, thus the phase locking advantage of a hollow stock would IMO be largely lost.

I suspect there may be disadvantages to a metal hollow stock - not sure what the transmission of sound through such a stock, as compared to transmission through a thin walled wooden stock, would be.

Bill