For a long time we have believed that most hammered dulcimers are too ‘ringy’. That high ‘zzzzing’ that you hear when you strike a string. Now granted, that’s part of what is attractive in a dulcimer, but too much is really grating on our nerves. We went through lots of designs in an effort to control tone before figuring it out several years ago.
We discovered, and there’s lots of research out there to back this, that a string vibrates two different ways when struck. It vibrates in the familiar wave shape which you can see, but it also vibrates in compression waves all the way from end to end. This compression wave is where the offending zzzing comes from, and once we understand this we can figure out ways to control it and get the sound out of the instrument that we want.
Now the familiar wave form that we see is what produces the tone that we want to hear, the fundamental and all the overtones. These are generated on the side of the bridge that is struck. But the zzzing wave travels all the way from end to end of the string, right over the top of the bridge and the side rods.
You can demonstrate this for yourself by striking any string on the right side of your treble bridge, and listening to the tone. Then strike the same string in the same place while damping that course on the other side of the bridge with your finger. The sound is different, isn’t it? This ‘zzzing’ sound is also relatively unaffected by the tension the string is at. You can actually hear a difference on some dulcimers if you damp the string with your finger between the side rod and the hitch pins where you wouldn’t think any tone at all is generated.
There are two ways to get the sound you want out of a dulcimer. One is to control the string itself, and the other is to let the string do what it wants but control the sound the body projects to the world by design changes. We tried the second approach for years, and learned much, but were never quite happy with the results. But after we discovered where the zzzing was coming from we decided to control it at the source.
These are our findings:
- We could use different materials for the side rods and get different effects.
- A wood rod goes a long way toward getting the sound we wanted.
- On some of our dulcimers, depending on how the body projects sound, that we should also put some little felt pieces on top of the side rods. This method is used on pianos for the same reason.
- Depending on how much and where we put the felt, we could tune the sound to exactly what we wanted to hear.
We introduced our system, and right away caught a bunch of questions and flak from folks because we were doing something different than everyone else. But the dulcimers sounded great, and people just bought them. Lately we’ve noticed other makers who’ve been adapting some of our theories to their instruments. I think it’s great! We’ve only wanted to advance the art anyway.
Some Notes on Plywood
If there’s one thing that 20 years and building over 8,000 hammered dulcimer has taught me it is that the anti plywood bias is nothing but mythology. I have built lots of all solid dulcimers. But call me a Philistine, give me plywood any day. If you want a great sounding, durable dulcimer that will stay in tune, and last into the next century, build it of plywood. They can also be made beautiful.
Plywood is a negatively charged word, it is part of our culture. The anti-plywood bias dates back to the craftsman era over 100 years ago, and was a reaction to cheap, shoddy manufactured furniture. Eventually the folk wisdom became that anything made of plywood was inferior. Not true! All material is processed somehow before use, and plywood is just one way of doing that. So it is just a material choice. The maker of any item chooses the right material for each part, and a proper grade of plywood is a very good choice for hammered dulcimer tops and backs
You see, wood is what is called Hygroscopic. Meaning it absorbs moisture from a humid atmosphere, or releases it to a dry one. This makes the wood shrink or swell with changes in the humidity of the atmosphere. And it can swell or shrink a lot! But wood only shrinks or swells across the board, not along its length. The standard wisdom in the wood working world is not to glue a board cross grain of more than 8 inch width. That is the reason for frame and panel doors. That large panel in the center is free floating , and won’t crack. But in the dulcimer world, we commonly glue tops up to 20 inches wide or more right onto the pinblocks. This is very risky, and why some dulcimers crack. If the top itself is very dry when glued on, we can probably get away with it. It will swell with humidity, but won’t crack, though some joints may creep. But this also means that top is straining against the rails, and there is tension in the instrument. Things move, and it goes out of tune.
But plywood is layers of wood with alternating grain directions at right angles to each other. This effectively eliminates wood movement in the plywood. So a dulcimer with plywood top and back isn’t undergoing the stresses that a solid wood dulcimer is. And that is why I like it. As a trained luthier, for most of my life I have heard the folk wisdom that solid wood develops a richer tone than plywood over time. Not necessarily. It depends on how the instrument is played. All instruments develop a richer tone over time, but good regular playing helps it develop farther. The instrument and player adapt to each other, and good playing helps a plywood instrument, too.