Monday, August 09, 2010

How to Tell if a Piece of Wood Will Make a Good Musical Instrument - Part Dieux

How To Do a Tap Test

Wood that your are looking at for a musical instrument can come in a wide range of colors, grain patterns and hardnesses as we saw in my previous post. Depending on the kind of instrument you’re building, you may choose a wood that produces a bright and brassy tone, a soft and mellow tone or a deep, rich tone. The dulcimer at the right was made with a less expensive wood that absorbs some of the sound and gives it a thin, soft tone than doesn't carry well. It's pretty, but nowhere near performance grade sound-wise. Even if you are not an expert, though, and this is your first attempt at building an instrument, you can get an idea of the sound quality of the wood you select for your musical instrument before you start cutting it up. Here's how....

1. Hold up the piece of wood your will be using by pinching the edge of the wood about a fifth of the way down its length. Don't hold it by the top or from the center. Harmonics for a musical chord are divided into what are called fifths.  Turns out the best place to hold something that you want to tap on to hear its true tone, it's a fifth of the way from either end.

2. Put your ear next to the edge to hear the tone of the piece of wood best. You can hear the tone much better from the edge than if you put your ear at the face.  At the face, the vibrations from the wood get muddled.I like to squint one eye real tight when I'm sounding the wood. It makes the wood salesman think I know what I'm doing and he'll bring me better wood and give me discounts and stuff -- that's my story and I'm sticking to it.

3. Give the wood a sharp tap with your knuckle or a metal object. Try both to get an idea of the two types of sounds generated by a padded tapper like your finger and a hard tapper like something metal or wood. Find a place where you can tap the piece of wood so that it doesn’t wobble when you hit it. When you find that sweet spot, tap just above and below that spot to listen to the difference between the sounds.

 4. The wood will have a pitch to it. It may be pitched higher, mid-range or lower more bass tone. There will be a ringing aftertone that persists after the initial tap dies away. This sound will tell you a lot about what the instrument will sound like. Choose a higher pitched piece of wood if you are looking for a brassier sound for an instrument like a bluegrass banjo or mandolin. If you’re building a larger instrument or one from which you need a deeper tone (a viola or bass for instance), you’ll want a wood that resonates with a deeper tone when you thump it.  If you're really having trouble hearing the difference in tone, you should try skrinching up your mouth on one side. The wood salesman will run screaming in terror to his manager.  Only then will they bring out their secret stash of Madagascar Rosewood, retrieved from the hold of the HMS Dingleberry, which sank in the Thames river in 1832 with a cargo of Madagascar lumber, where it soaked for 180 years.  Recovered in 1994, the freshwater-soaked rosewood sheets were dried in the humidity controlled drying sheds of Fishgill, Thimblequack and Dimbulb, Ltd., wood merchants to the greatest luthiers in the world, then shipped to your local wood merchant where they can be had for the ridiculously low price of $9.99 per sheet.  And yes, "skrinching" is a real world. I made it up, but since you understood the word meant "making a face like the one in the picture above", communication, therefore, took place, which is what you use words for.  Call Webster.  Tell him to stop the presses. We've got a new one for the "S's".

5. Consider the shape of the instrument you are designing. A teardrop shaped dulcimer, for instance, should have a balanced, mellow sort of tone. You’ll need wood for the back, where the sound resonates, that has a higher baritone or tenor tone and a pronounced ringing aftertone. If you use a rich bass/baritone piece of redwood or something similar for the top, you can create a harmonic interplay between the two pieces, especially if you “tune” the pieces beforehand by selecting two pieces of wood that make a nice harmony when tapped. Pair a tenor with a baritone harmonic or baritone and bass for throatier instruments.  An hourglass shaped dulcimer produces a deeper, but more crisp sound. Pair a baritone back with a tenor top and you get that full sound while preserving the crispness of the string sounds in the aftertone.

It takes something of an ear for music to do this effectively. If you’re like me and have something of a tin ear, get your wife who has perfect pitch to help you do the selection. You’ll be glad for that extra edge that someone with good pitch brings to the process. The beauty of hand made instruments is that you get to select the pieces of wood and mechanical parts that you want. A musical instrument, lovingly made is a joy to play.

Have fun making your dulcimer.  If you want to make one that looks really odd, hang on a couple of days.  I'll be posting a rectangular dulcimer design that's super easy to build and really unusual. How it sounds will depend entirely upon the wood you use, but as big as the box is, you should get guitar level volume from the thing.  I'm assuming you'd want to build this one out of the harder stuff.  Just guessing.  Haven't found the right wood to build my own version yet.  I'm thinking of building an octagon shaped dulcimer and painting a stop sign on the back. 


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