Prototype Tongue Drum

[bobasaurus]

I made this prototype tongue drum as a test before attempting a bigger, nicer drum in a woodworking class. It's constructed from maple, with some odd bookshelf backing for the bottom (since I had a piece of scrap lying around). Maple did not make for a very good sounding board, unfortunately. Need something harder for the main project. I made an attempt at tuning the drum by experimenting with undercutting and shaving heads, but there ended up being too many confusing overtones to get it dialed in. The best (more like only) information I found on the matter was from this book:

http://books.google.com/books?id=CuH...s0J7KDedpiDQ8Q

I made several mistakes on this thing. By convention, the sound board should extend to cover the shorter sides, the short sides should have vertical grain, and there should probably be no sound holes in the long sides. I didn't like how the polyurethane gloss coat looked... next time I'll try using tung oil. My next attempt will have a padauk top, red oak short sides, "country" maple long sides, and a plywood bottom. I'll try to make some nice splined miter joints for the sides and rabbet in the plywood bottom to hide it. Hopefully I'll be able to tune it to an A pentatonic minor scale. Anways, here are some pictures of the drum:






Here is the result of my tuning experiments: The bottom tongue in the first picture below ended up with the best sound.




Any suggestions for improvement are welcome. I've heard of some tongue drums using a sheet of aluminum for the bottom. Seems like this might give it a sound similar to a steel drum.

[Sebastiaan56]

Looks great Bob,

Did you tune on or off the soundbox? did the tuning alter much when you added the box to the soundboard? I have a couple planned for nieces and nephews for Xmas so this is timely.

In reference to your comment about the soundholes, its the total area of soundholes that matters from what I read, that would include the areas around the tounges.

Sebastiaan

[bobasaurus]

Looks great Bob,

Did you tune on or off the soundbox? did the tuning alter much when you added the box to the soundboard? I have a couple planned for nieces and nephews for Xmas so this is timely.

In reference to your comment about the soundholes, its the total area of soundholes that matters from what I read, that would include the areas around the tounges.

Sebastiaan

I tuned it on the sound box. Trying to tune without a sound box is about impossible... the sounding board does not make much sound on its own. For tuning, I used a microphone attached to my computer and ran this program:

http://accordeur.sourceforge.net/

Accordeur identifies the frequency, note, and octave of incoming notes in the microphone. Pretty handy. It's sometimes difficult to identify the tone of a particular tongue when the others are also ringing.

[Scally]

That is a good looking tongue drum Bob.

It is a tricky process getting them in tune. I have not ventured far from one I know is in tune which is a lot easier than starting from scratch.

Your drum has big tongues so it would take a bit of energy to get them to move. That is probably why the the one with the most thinning at its base sounds best.
You sure have needed to do a lot of work to get them in tune.

I like the book you referenced. It has a lot of good advice on difference instruments.
The general principal is to make the tongues longer until you get close to the desired note. Then you shoud only need to do a little tuning.
Do you plan to maintain the general tongue dimensions?

Sebastiaan is right about the soundhole. I would try your drum without a soundhole because you might have enough 'hole' around the tongues.
My tongue holes are getting smaller with each new drum and I have seen some with only a 25mm diameter soundhole. They don't appear to need a large one.
Mine are in one of the long sides.

Why the backing board on the bottom instead of solid timber?
Solid timber looks better IMHO.

Padauk will should give great sound.

[bobasaurus]

That is a good looking tongue drum Bob.

It is a tricky process getting them in tune. I have not ventured far from one I know is in tune which is a lot easier than starting from scratch.

Your drum has big tongues so it would take a bit of energy to get them to move. That is probably why the the one with the most thinning at its base sounds best.
You sure have needed to do a lot of work to get them in tune.

I like the book you referenced. It has a lot of good advice on difference instruments.
The general principal is to make the tongues longer until you get close to the desired note. Then you shoud only need to do a little tuning.
Do you plan to maintain the general tongue dimensions?

Sebastiaan is right about the soundhole. I would try your drum without a soundhole because you might have enough 'hole' around the tongues.
My tongue holes are getting smaller with each new drum and I have seen some with only a 25mm diameter soundhole. They don't appear to need a large one.
Mine are in one of the long sides.

Why the backing board on the bottom instead of solid timber?
Solid timber looks better IMHO.

Padauk will should give great sound.

I'll try to leave the tops of the tongues looking the same while removing material from the base and head underneath to change vibration frequency. I'm aiming to tune it to this scale:

A pentatonic minor scale (A, C, D, E, G) note # note perfect octave 1 A 110 2 2 C 130.81 3 3 D 146.83 3 4 E 164.81 3 5 G 196 3 6 A 220 3 7 C 261.63 4 8 D 293.66 4 9 E 329.63 4 10 G 392 4 11 A 440 4 12 C 523.25 5
I read a few different tongue drum plans that used a thinner panel material as a backing instead of solid stock. My guess is that it vibrates in a similar fashion to a speaker cone, which normal stock might not be capable of. Here are some more design drawings for the next drum:

[Scally]

Hey Bob, have you been working on your next drum?

I'd be interested to hear of your progress.

I have a Purpleheart board that I would like to try for my next drum.
My preference would be to decide on a thickness, around 20mm, then cut out one tongue at a time.
When I have the note I am after, I would add it to the template for a 12 tongue box.
There will still need to be further tuning once all the tongues are cut into the board but they hopefully will be close.

This means I will probably use up a fair bit of purpleheart in the testing. Obviously, the closer I am to start with the less waste there will be.

Did you use your prototype to decide on the dimensions of the tongues in the new drum?

[bobasaurus]

Hey Bob, have you been working on your next drum?

I'd be interested to hear of your progress.

I have a Purpleheart board that I would like to try for my next drum.
My preference would be to decide on a thickness, around 20mm, then cut out one tongue at a time.
When I have the note I am after, I would add it to the template for a 12 tongue box.
There will still need to be further tuning once all the tongues are cut into the board but they hopefully will be close.

This means I will probably use up a fair bit of purpleheart in the testing. Obviously, the closer I am to start with the less waste there will be.

Did you use your prototype to decide on the dimensions of the tongues in the new drum?

I have gotten pretty far in building the full tongue drum. Since it is for a class, I unfortunately have a very limited time to work on it. I jointed/planed all my solid stock down to 3/4" (~20mm) before building the box. I ended up using a scroll saw to cut out all the 12 tongues... but the kerf was quite small so the tongues might vibrate against each other. I copied most of the pattern from an existing drum I found somewhere online, then tweaked the area ratios of the tongues so that they would be close to a pentatonic tuning (so I thought at least... didn't seem to turn out that way). I haven't yet started tuning the drum. I plan to start this week, though. I'll create a full thread about it soon. Here is an in-progress picture (very rough, before sanding or finishing):

[Scally]

You got a nice neat job on the cutout with the scrollsaw.

I have been using narrow jigsaw blades.
Another member suggested cutting them down even further by grinding the backs.
I plan on giving it a go so it is easier to get around the sharper bends.

I am sure you expected the tongues would need tuning even after the careful planning.

How much timber removal do you think you will need?

On the bought drum that I have there is only a small amount of thickness taken from less than half the tongues. They are all in tune.
The timber is 20mm brush box, a heavy, native hardwood.

The trick is getting the first one right.

[bobasaurus]

Scally, I would love to see a picture of your bought drum if possible. I'm curious how the professionals go about tuning these things. On my prototype drum, I had to remove quite a bit of material before any real note change resulted, but that was using soft maple which really wasn't suited as a sounding board material.

[Scally]

This link has my limited knowledge.

https://www.woodworkforums.com/f98/tongue-drums-72650

My bought drum had a small amount chisseled off the tip of some of the tongues. On the underside. There was nothing removed from the base of the tongues.
Certainly nowhere near as much as you removed from your prototype.

The idea would be to get the shape and thickness right so you only need to do minimal tuning. This would be different for each timber species, if not each board.

I have only used hardwoods but have found significant differences from one species to another.
With the board thickness at 20mm I didn't have a problem with the tongues rattling or ringing when other tongues were struck.
This was a problem when I used thinner boards.

Sometimes the tongue moved after it had been cutout. I used a strip of sandpaper from the belt sander to take a bit off the edge of touching tongues.
When they rattled badly, I ran the jigsaw along the cut to widen the gap.

Your Padauk board should sound great,

[Scally]

A little more information on my Zyladrum tuning.
Blue gum timber in the Key of F
These are the notes for each tongue.

Starting with the sound hole away from you-

The top left tongue is A................Top Right C
next row D
..............Middle row C
next row Left D...................Right is G
Bottom row is Left F............................Right F

I have tuned an African Balafon with a chisel. More correctly I retuned it.
I didn't need to remove much from the centre or ends to adjust the notes.
The planks were 20-25 mm thick by about 40mm wide and ranged from 20cm to 40cm long and made from an unknown African timber.
The deepest cuts would have been less than 5mm.

[bobasaurus]

Hmm, it really sounds like you don't have to remove much material. I think the soft maple was very inappropriate for the top of my original drum. I was also wondering if I should drill holes most of the way through the material on the underside of the sounding board between tongue bases. This might help separate the tongue bases, making more resonate pitches without disturbing the tongue pattern on top. Maybe I should practice up a bit on my chiseling skills on some scrap first, as I am rather inexperienced in using them.