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"Denis Robinson" <dj.robinson@auckland.ac.nz> wrote, Thursday, December 14, 2000:

I'm interested in the discussion which has come from the question:

Does the design of the djembe come from particular regions?... i.e. Large bowl, short fat stem ( my
personal favorite).

I wonder whether one factor may be regional preferences for different sound qualities, as in timbre, sustain, and so on. I have some impressions about this but only tentative, and I wonder what others think.

How much difference does actual head diameter make? I would guess that if you tuned up an 11" djembe and a 14" djembe to get the same pitched slaps, still the sound quality would be different, with a richer mix of overtones from the larger head. Anyone have a view on this? Maybe variations between the skins themselves make it hard to generalize like this.

I'm particularly interested in the way the design of the base may affect the bass. There seems to be evidence that the bass note is mostly affected by the shell design, not by skin or tension (though the loudness and sustain of the bass certainly is affected by skin tension).

When I look at a djembe, the things I look at in the base are: i) how big is the hole where the base meets the bowl? ii) how long is the base, absolutely, and relative to the height of the bowl, iii) how much flare is
there in the base (I mean on teh INside, of course) -  are the sides sort of parallel, or more like a cone shape, and iv) does the base kind of narrow slightly below the hole in the bowl, before widening out again, or is the hole itself the narrowest point?

I have conjectures about how these different features affect the sound, but  they are only conjectures. Trouble is, you'd need to compare dozens and dozens of djembes to make confident judgements. I've got some hunches though.

Some djembes have a prolonged, rich resonant bass note; others may have good emphatic bass but with less of the sustained resonant thing. One kind of bass sound I like often reminds me of the sound of a distant axe chopping in a forest: "THUNK!". Very different from "BOOOooooom".

My feeling is that a base pipe which is more "open"  -  big hole where it joins the bowl (significantly bigger than required for a clenched man's fist to git into)  -  no narrowing, wide slightly flaring sides all the way
down  -  gives more of the "thunk" kind of bass note  -   specially if the pipe is short (this is the "short, fat" base style), while a slightly smaller hole, with a slight narrowing of the tube curving round to flare
outwards, with a fair length, gives more of the prolonged rich resonant bass sound.

Any input?

I also suspect that how tones sound is affected by how much of the bottom of the bowl is near-horizontal, forming a "lip" where the hole is, as against more of a funnel effect. But very unsure about this.

Anyway: my suggestion (conjecture) is that djembe subcultures in different regions (at different times), have different preferences regarding how they like djembes to sound, and that they vary the shapes in various ways in order to control this. Expert comment sought.

Cheers,

Denis

Then, Adama Rugo, wrote, Friday, December 15, 2000

Hi, Denis, and all,

Very interesting topic. Your hunches seem confirmed by my own experience.
Here are a couple of observations:

I like the sound of the really monstrously big lenke drums: bass says "FOOM!" and tones are big and fat. But the Ivorian drummers I was playing with this summer liked the sound of the narrow, tall iroko drums, with a really tight "thunk"y bass and super dry tones. This is the kind of drum Madou Dembele, a drummer from the Ivory Coast resident here in the U.S., favors. Paper-snap slaps. My Malian friend, Abdoul Doumbia, plays big drums with a big bass and really wide, tight tones. Pebble-hitting-a-window slaps.
When I saw Famoudou Konate this summer, he played a smallish drum with a huge fat tone and kind of a boxy bass. Whip-crack slaps. This anecdotal evidence might confirm that there are regional differences in the sounds people favor, even if this doesn't necessarily provide a model of "the Ivorian sound" v. "the Malian sound" v. "the Guinean sound."

Madou's tones say: "pih"
Abdoul's tones say: "peh"
Famoudou's tones say: "poh"

This comes not only from their personal styles of playing but also from the kind of djembe sound they favor.

My 14 francs CFA.
Peace,
Adama.

Then Beverly Nadelman wrote:Hi all,

I have a tamarind djembe from Mali-short and stubby, very heavy, pretty even bowl depth and pipe length.
The hole at the base of the bowl, however is very large.The drum has an amazingly booming bass, but
there is a bass overtone to the upper notes, and it is WORK get out a decent slap because of the bass ring.
The bass is wonderful in some rhythms but doesn't work well where the rhythm is quick and there are many slaps and tones close together. I constructed an inset which narrows the hole for these circumstances. That brings the tones and slaps online but takes some of the resonance out of the bass, which becomes somewhat more "thunk" like. However, when I am willing to carry this drum to events it gives me the best of both worlds, albeit in a rather peculiar manner.

And, Denis "Merlin" <Merlin@silvercircle.org> wrote:

Basic acoustics will confirm that a "flared" or "trumpet" like stem will  greatly amplify the bass tone, whilst a straight cylindrical stem will not   amplify the bass at all. Most djembe's are somewhere in between, from what   I've seen, although some types definitely have the "flared" stem. If you
like a lot of bass, go for those types first!

You can even try the difference: if you stand with your djembe, and with your back to a wall, and aim the bottom of the stem to where wall and floor meet (djembe at 45% angle), then wall and floor will create an extra "flare" to the stem (even pointing in the reverse direction!), for the bass sound to be amplified.
It is not "just" reflection but real acoustic amplification. Read some literature on acoustics, or loudspeaker design as I was interested in that.

If you're browsing, look for the theory behind "bass reflection" speaker design. It will explain all this better than I can. The designs will show you the trumpet like channel that goes from behind the speaker to a hole in the cabinet. The length of the trumpet and the flare are designed to ge the sound in phase with the speaker itself (rather than cancelling each other out again!), and all this greatly amplifies the bass notes.

Your inset, Beverly, is that only to narrow the hole where bowl and stem meet? Or something else? How did you make it?

Acoustic theory would suggest that if you use like a PVC drain pipe the width of the hole where bowl and stem meet, and insert that (basically converting any flare to a straight cylindrical shape), you would take most of the "boom" out of the bass, but keep the energy.  If you only narrow the hole, you don't change the amplification, but the narrow hole means there is little left to amplify, and the direct change from little hole to wide start of the "trumpet" shape means the sound loses most of its energy at that point. Net result is a softer bass that still says boom instead of thunk.  And of course, any bass that is present in tones or slaps, will become amplified proportionally. Playing tones and slaps more towards the rim of the drum, or "aiming" them towards the rim, may make a difference as well.

Hope this helps!
Dennis (Netherlands)

Then, Walter Alter <limejello@earthlink.net> wrote:

Denis Robinson <dj.robinson@auckland.ac.nz> writes:
> Some djembes have a prolonged, rich resonant bass note; others may have  good emphatic bass but with less of the sustained resonant thing. One kind  of bass sound I like often reminds me of the sound of a distant axe chopping in a forest: "THUNK!". Very different from "BOOOooooom".

I made a stave djembe according to the specs in the djembe/ashiko design program with the resonator equally long as the bowl is high..  It has a 14" head and a bass sound that rattles the windows- long & thwangy like them ghetto car stereos.  The head is tuned very tight.  It's a thin gauge goat skin.  I think a larger head size is going to be a major factor.  I also have the edge where the skin meets the drum with a sharp inner edge, with the outer edge of course rounded, so the skin leaves the drum sharply and
doesn't suffer any dampening at that critical standing wave node..

Cheers,
Walter
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