Understanding Drone Reeds

Drone Reeds Made Simple

Rain or shine, if you are lucky, your drone reeds will sit happily in your pipes and sing beautifully whenever you play. More likely, your reeds might sometimes seem temperamental and need an occasional tweak to keep them working in all conditions. This is where having an understanding of how they work is useful. Once we know this it’s easier for us to make simple adjustments to keep them playing at their best. In this article we’ll look at the most common drone reed designs and how they work.

Types of Drone Reed

There are three common reed designs and these are shown here.

The top reed is made from cane. Similar reeds might be made from elder or other hedgerow plants. David Burleigh probably made more of these reeds than anyone else and many of his sets still have them.      

The second reed has a brass body with a cane tongue bound on top. If your pipes were made by Colin Ross you will probably have these reeds.

The third reed is a square section of drilled brass with a plastic tongue held in place by rubber bands. Richard Evans and Mike Nelson have done much to develop this style and if you have their pipes you could well have this type of reed.

While these three reeds look very different, many parts are interchangeable. For example, the tongues of the bottom two reeds can be made from other materials, so both types could easily be made with tongues made from cane, plastic, metal or carbon fibre - or any other suitable material. What all three types have in common is how they work, and if we understand that we are well on the way to being able to maintain and adjust them when necessary.

The Parts of a Drone Reed

Drone reeds have three main parts - the reed body, the reed tongue and the bridle. In the photo below you can see the body on the left. The reed body is a hollow tube through which the air must flow as it passes from the bag to the main part of the drone and it forms the narrowest gap on this route. The air flows in through the slot on the top of the body and out of the tubular end of the reed body. All reed types are designed to do this even though they may look different.

The tongue is attached to the reed body at one end. In this picture it is held in place with a rubber band. Ross style reed tongues are tied on with thread and in all cane reeds the tongues are part of the body, where the tongue is split away from the body but remains attached at one end. The other, free end of the tongue lies just above the inlet hole. The tongue is slightly flexible.

The bridle is a rubber band or wraps of cotton around the reed body and tongue and forms the hinge point where the two are in contact with each other. The bridle can be moved along the reed when adjustments are necessary.

How Drone Reeds Work

This is simple. When we inflate our bag the air tries to escape. One route out is through the hollow tubes which form the drones. To escape, the air must pass through the reed body. Just like putting your thumb partially over the end of a hose to form a water jet, the air has to accelerate as it passes through the narrow drone body. As it does so, Bernoulli’s Principle comes into play. This says that as the air speeds up it’s pressure drops. This means that the air pressure is higher just before it gets to the reed but lower inside the reed body. Because the tongue is flexible, the higher air pressure on top of it and the lower pressure below it pushes it down and it blocks the inlet hole in the body. As the flow is blocked the air pressure equalises and the elasticity of the tongue causes it to spring open again. Once it is open the whole process is repeated, opening and shutting the tongue against the reed body - very quickly!

I like to think that the tongue operates a bit like a school rule overhanging the edge of a desk. Press down and release the free end and the rule vibrates and makes a sound. You can change the pitch of the sound quite easily. By lengthening the overhanging part you increase the mass of the rule and the pitch drops. You can achieve the same thing by keeping the length as you first had it but add sticky tack on the end. In the reed, it’s the air pressure changing which causes the tongue to vibrate and make the sound.

Managing the Variables

For the reed to work properly a few variables need to be managed. Firstly, in order to sound a note at all the tongue needs to be flexible enough to be bent by the air pressure changes so it can shut off the air flow through the body. However, it also needs to be elastic enough to spring back open afterwards. This means that if the tongue is too stiff the air pressure won't be able to bend it to close the reed. If it’s too flexible it won't be strong enough to spring back open. The reed maker must select the material and dimensions of the tongue to allow this vibration, and set the gap between the drone body and the tongue to match the degree of swing of the tongue. The gap is usually set by bending the tongue if it is made from cane or by leaving the tongue straight but shaping a bend in the body as in the picture below.

Once made and sounding, the maker will aim to make the reed as stable as possible. By stability, we mean that it will play at the bag pressure we like and it will play at the same pitch even if we make small changes to the bag pressure as we play. This can be achieved by adjusting a bridle.

In this photo you can see two rubber bands. The one on the right is simply to secure the tongue to the body. The band on the left is the bridle and this is used to make the reed more stable. When playing, if the reed note goes up unacceptably as bag pressure increases you can make it more stable by moving the bridle to the left and shortening the tongue. If the pitch drops as pressure increases then move it to the right and lengthen the tongue.

You can do this with all types of reeds. For cane reeds you will see a thread bridle which you can slide up or down the reed. Cane reeds don't need the second elastic band shown in the photo above as the tongue and body are physically joined and not separated when the reed is made. The Colin Ross style reeds don't have separate rubber bands but instead have thread wrapping which both joins the tongue to the body and acts as a bridle. There’s usually enough spare thread to add a few more wraps if you need to shorten the tongue or you can unwrap some thread to lengthen the tongue.

Once the reed is stable you might need to adjust the pitch slightly for the drone to play in tune. As we saw above, this can be done by adding mass to the tongue to lower the pitch. For all three reed types you can add a small piece of soft wax or putty to the end of the tongue, like we did to the school rule earlier. Pitch can be increased by a small amount by reducing mass at the tip of the tongue perhaps using sandpaper. For the Evans style brass/plastic reed, the tongue mass can be changed by moving the tongue itself along the drone body while making sure that the bands don't move.

Hopefully, your reeds will be trouble free, but if you do end up with reeds which don't work often the first thing to do is give them a clean. If they still dont work then I’d encourage you to experiment with some of these variables we’ve looked at here. The sequence I would follow is-

  1. Can I get it to sound? Experiment with the tongue stiffness and gap between the tongue and body.

  2. Is it stable? Adjust the bridle.

  3. Is it at the right pitch? Adjust the tongue mass.

You have nothing to lose by having a go, and as your skills develop you can even start making your own reeds and become more self-sufficient as a piper.