Advice and questions on making and fixing instruments
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By Djembe-nerd
#19041
I want to turn one of my djembes into a Bass Djembe. I don't want to do it the traditional way but by the ring system.

So, will a thick cow skin be enough to make it a Bass djembe in principle, or are there any other things that will be needed.
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By dleufer
#19049
I just made a bass djembe a few weeks ago, skinned traditionally. I don't think it necessarily makes much difference if it's with rings or not. I think that the main thing is the shell. Some djembes sound great cranked up for solo but rubbish at lower tension. If the shell has a nice resonant bass and a big ledge for solid tones I think it will make a good bass djembe with a thick cow skin. If it doesn't have big solid tones it won't make a good bass djembe, just a ringy low djembe with no body.
I'll post a few pics of mine when I get a chance.
User avatar
By Djembe-nerd
#19050
Thanks much D,

Thast a great tip. I have one with good bass and tones. I read here in the forum somewhere that good Bass and tones are usually resulting from a shell which has a bigger throat opening.

So, do I look for the biggest throat opening among the shells I have, or just go with the one which is already displaying good tones and Bass.
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By dleufer
#19051
I'd say the bass comes from a big opening (along with other factors) but as far as I can tell good tones come from a nice ledge inside the bowl. This drum has amaaaaaazing tones, slaps and bass.
Here's an example of what I'm talking about
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Last edited by dleufer on Wed Mar 16, 2011 5:48 pm, edited 1 time in total.
User avatar
By dleufer
#19053
Some drums just taper off. I've noticed on all the Ghanain drums I've reskinned, the bowl just goes like a V on the inside. These drums often have huge bass (because of a huge opening) but not one of these drums has ever had good sounding tones in my experience. Here's an example
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User avatar
By Rhythm House Drums
#19057
So a bit of a correction to above... The sound hole in the djembe will determine the pitch of the bass... a big hole means a higher bass note and a quicker hit (more attack, more volume, less sustain) while a smaller hole means a lower (deeper) bass note that lingers longer (less attack and more sustain).

The Ghana shells I've seen have pretty big bass, and pretty small openings, like the one you've pictured.

A good sized hole to me is one that I can just put my fist in (I guess about 4.5-5" diameter) much bigger and the dynamic range tightens (less low end) much smaller the drum gets a little ringy and the bass will linger, and well has make an audible bass rumble when you hit your tones. Really small holes makes the bass super deep like a sub, but not very loud.

The tones are a direct relation to the volume inside the shell bowl. A big will will have deeper tones, a smaller bowl will have higher tones, which is why we get the best dynamic range on a djembe with a good ledge as opposed to one that is tapered like in the photo above. This is also why a lot of Mali shells are known for good tones, cause they have the big round bowl.

The slaps are a direct relation to the tension of the head.... as is all the notes, but the slap more so.

Hope this helps some :)
User avatar
By dleufer
#19058
Thanks for the clarification RHD good to get a professional opinion, I really had no idea just seemed like big hole meant big bass but what you say makes a lot of sense.
User avatar
By e2c
#19064
d-n, I think you'd be just fine with a traditionally-headed bass djembe. Cow doesn't need to be cranked in the way that goatskin does, and after all, you want to break in the skin and get a good-sounding bass djembe... the break-in takes awhile.

If you do a good job of tuning after skinning, you really shouldn't need to worry about having to fool with the drum...

dleufer, that 1st shell looks terrific! Where does it come from, and what kind of wood is it? (Looks like lenke to me, but that's just a guess.)
User avatar
By Djembe-nerd
#19067
e2c,

I don;t want to go the traditional way because its more hassle than the simple ring system while mounting. Unless the sound difference is too much, I would like to have a ring one.

Well I thought of some more questions :roll:

Regarding tuning I was about to ask you guys, what the criteria for tuning a Bass Djembe. Is it tuned when you start getting good tones, without much ringing or something else.

Also, what thickness of cow skin do you prefer for a bass djembe , medium or thick.
User avatar
By e2c
#19071
What you want is a "broken-in" sound, which is not the same thing as the sound you'll get when you 1st skin it.

afaik (which isn't much, since I've never skinned a drum), the trad. method is a better one for the true bass djembe sound.

(I should ask my teacher; he has built a number and has spent time learning how to make them... He never uses rings.)
User avatar
By michi
#19077
dleufer wrote:ome drums just taper off. I've noticed on all the Ghanain drums I've reskinned, the bowl just goes like a V on the inside.
The reason for this is that Tweneboa (which is what most Ghanaian djembes are carved from) is very soft. If the sidewalls of the bowl would be thinner, chances are that you'd end up with cracks.
Rhythm House Drums wrote:So a bit of a correction to above... The sound hole in the djembe will determine the pitch of the bass...
Not just the hole, but the shape and volume of the bowl, and the diameter and length of the stem also determine the bass. A djembe is a Helmholtz resonator, meaning that the bass frequency is determined by the proportions of the shell.
Rhythm House Drums wrote:a big hole means a higher bass note and a quicker hit (more attack, more volume, less sustain) while a smaller hole means a lower (deeper) bass note that lingers longer (less attack and more sustain).
This doesn't line up with my experience. Generally, I've noticed that djembes with a large hole have louder bass that has more sustain, and djembes with a smaller hole have a quieter bass with less sustain and more attack. Not sure why our experience differs here? I might not have enough data points, or there might be other factors that affect this? Certainly, skin thickness enters into the equation. In my experience, thinner skins have longer sustain and tend to go "boiing" more than thick skins. (That's despite people having reported the opposite.)

As usual, lots of variables here that are difficult to control...
Rhythm House Drums wrote:The slaps are a direct relation to the tension of the head.... as is all the notes, but the slap more so.
A correction here: the frequency of the bass is independent of the tension of the skin. Try it.

Basically, the drum itself has a resonant frequency that is determined by its shape. That frequency obviously stays constant. The skin has a bass frequency that is determined by the skin's tension. Lower tension means lower frequency. The issue is that the skin's bass frequency is higher than the drum's resonant frequency, so they fight each other to some extent. The drum wins and forces the skin to vibrate at the fundamental that's determined by the drum, not the fundamental of the skin.

The closer the drum's and skin's resonant frequencies are, the louder the bass will be, and the longer its sustain. As you tighten a skin, its resonant frequency moves further away from the drum's resonant frequency. The skin is still forced to vibrate at the drum's frequency but, because the two are further apart, both volume and sustain of the bass decrease at higher tension. Tighten the skin too much and you will reach a point where the bass almost disappears: no body, very short sustain, and very quiet.

In contrast, tones and slaps depend on the tension of the skin because they are higher-order modal vibrations that are too far from the shell's resonant frequency to be affected by it. Tighten the skin, and both tones and slaps go up in pitch.
Djembe-nerd wrote:Also, what thickness of cow skin do you prefer for a bass djembe , medium or thick.
I'd go for thin. You'll get fuller tones that way at low tension because a thin skin has less internal friction (and therefore dampening) than a thick one. A thin skin also should give you longer sustain, which seems to be what people look for in a bass djembe. If you can, use a shell with a big round bowl. (All the bass djembes I heard in Mali were big and fat.)

Cheers,

Michi.
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By Rhythm House Drums
#19099
Not just the hole, but the shape and volume of the bowl, and the diameter and length of the stem also determine the bass. A djembe is a Helmholtz resonator, meaning that the bass frequency is determined by the proportions of the shell.
True :)

Rhythm House Drums wrote:a big hole means a higher bass note and a quicker hit (more attack, more volume, less sustain) while a smaller hole means a lower (deeper) bass note that lingers longer (less attack and more sustain).
This doesn't line up with my experience. Generally, I've noticed that djembes with a large hole have louder bass that has more sustain, and djembes with a smaller hole have a quieter bass with less sustain and more attack. Not sure why our experience differs here? I might not have enough data points, or there might be other factors that affect this? Certainly, skin thickness enters into the equation. In my experience, thinner skins have longer sustain and tend to go "boiing" more than thick skins. (That's despite people having reported the opposite.)

As usual, lots of variables here that are difficult to control...
There are lots of variables to control.. however, it's not a matter of opinion here... it's the facts. In audio engineering think of a subwoofer, a smaller port means lower frequency. Of course, the head diameter and bowl volume go into account as well as the tension of the skin, but given all this is the same, a djembe with smaller 'port' will have a lower bass with less attack... same as a sub. If you want a sub to have a lot of attack, you dont port it but have it facing out, if you want it to have a deep rumble, you put it in a bandpass box (fully enclosed) and put in a small port.
Rhythm House Drums wrote:The slaps are a direct relation to the tension of the head.... as is all the notes, but the slap more so.
A correction here: the frequency of the bass is independent of the tension of the skin. Try it.
Not really so... if you tighten the head you will bring the bass note up in pitch. So they are not at all independent... a tighter head will vibrate with less movement, causing smaller sound waves = higher pitch.


I'd go with sangban thickness skin :)
User avatar
By Rhythm House Drums
#19100
Skin thickness is personal preference... a thinner skin will have more overtones tuned low, a thick skin will have a more uniform sound tuned low.

Have you seen Mamady's 4th dvd with the solos. Check out the bass djembe on there, its got a nice mellow sound. They def. Have to be broken in. A bit of oil will help, as will wringing out and twisting/beating while wet.

As far as tuning it... tune it for the tones. Tight enough so you loose the wobble and bass when hitting a tone, but not so tight as a sangban. Just a starting point... find a tone that works good with the dununs you are playing with.
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By Djembe-nerd
#19102
Thanks Guys for dippin in.

I have 2 thin cow skin as solo djembes, so what is the thickness of cow skin for Bass djembe. DSD has Bass djembe rounds as medium.

I don't have dunun's yet, so what would be a snagban thickness, medium or thick.

Oil, Hmmmm ! somone posted a pic of the bass djembe in the Axe forum, and it really LOOKED oily :lol: