Viberating sounds

[drummingmangos]

I recently reheaded an ivory coast djembe, rings were good, bearing edge is thick but rounded into nice, but the damn thing sounds like its viberating especially on bass hits. the tension seems even too. sounds like a bee buzzing, the slaps and tones do a little but not as much as the bass. is there any way i can fix this, and if possible keep the skin on? iv never had a drum do this before especially on a nice drum like this.

[Dugafola]

there may be a crack in your drum near the bearing edge, or some flesh remnants on the under side of the skin...or something else entirely...

[Onetreedrums]

This can often times be caused if the underside of the skin has any stringy, fatty pieces hanging down. This is pretty common, but can usually be avoided by cleaning up the skin as you assemble the jenbe. You can check by running your fingers on the underside of the skin through the bottom opening of the jenbe. Usually the stringy pieces can pulled out and that should solve the problem. You can also use some fine sand paper on the underside if you are having difficulty pulling any fatty pieces off or don’t want to risk pulling a hole in the skin if any fatty sections prove to be really substantial. I hope that solves it!

[drummingmangos]

I cant seem to find the fatty piece of skin thats causing it, but i have an idea where it is, must be right on the rim underneath the skin. i can kinda feel a bumb in two spots. so lets say i undo the mali and loosen the verticals, would i be able to lift up the skin, with the rings still intact and double check the edge without having the skin slip? Iv takin a head off before without slipping but it was old and very much in place, this drum is about five days fresh. i know theres no cracks on the bearing edge.

[michi]

so lets say i undo the mali and loosen the verticals, would i be able to lift up the skin, with the rings still intact and double check the edge without having the skin slip?

I'd say your chances are slim. Is a skin flap folded over the rings, or is the crown ring exposed? If the former, I wouldn't even try. If the latter, you have a chance. You'd have to mark the exact position of the top and bottom ring against the shell and, when you undo the lacing, make sure that you keep the crown ring and flesh ring together. (If you let them separate, it will be very difficult to fit the flesh ring back onto the crown ring in the exact same place. If that happens, you'll almost certainly get slippage when you reassemble the whole thing.)

But even so, you probably have an even chance of the fixed version being worse than the original...

Cheers,

Michi.

[drummingmangos]

I think im just going to name my drum the jem bee cause it just wont stop buzzing. I got this sucker so tight theirs not really any indicators on the problem except maybe the bearing edge is a half inch thick which could lead to stuff maybee being trapped in there like fatty skin. i cant beleive the tension couldnt fix it if thats the case or else id notice exactly where it is.

[michi]

I think im just going to name my drum the jem bee cause it just wont stop buzzing.

If it annoys you, and you were considering fixing it anyway, why not get a skin and spend a few quality hours with your drum fitting a new skin? The buzz has to come from somewhere and, as far as I can see, it can really only come from the skin (barring some major and serious cracks in the shell). And, while you have the whole thing apart, you can give it some TLC, apply some oil, polish the shell, check that the bearing edge is to your liking, etc...

Cheers,

Michi.

[drummingmangos]

I cant affored any more skins right now.

[drummingmangos]

I took the skin off with the rings still intact, its holding pretty well so ill be able to put it back on later. there was a little skin remnant there but it wasnt very much. i did notice that the edge is a little off in some spots im just afraid to sand it down to much and have to keep sanding back and forth to make it completlly level. could an uneven edge cause the buzzing too? if not id just leave alone because its not to bad.

[michi]

i did notice that the edge is a little off in some spots im just afraid to sand it down to much and have to keep sanding back and forth to make it completlly level. could an uneven edge cause the buzzing too? if not id just leave alone because its not to bad.

It's difficult to know without looking at the drum. Generally, it's a good idea to have a bearing edge that is level and on plane. If there are too many undulations in the bearing edge, that'll affect the sound because it affects the nodal vibrations of the skin. (Instead of being nice and round on the second fundamental, the node gets distorted, and you'll have more parasitic vibration.) In extreme cases, I can imagine that an out-of-plane bearing edge could cause the noise you describe, but I haven't come across that first-hand so far.

Unless your bearing edge is truly out of shape, I think you have a good chance of the noise going away once you re-mount the skin.

Cheers,

Michi.

[bubudi]

a picture of the interior/rim of the shell and underside of the skin would be helpful.

[drummingmangos]

Here is one pic of the ivory coaster.

Snapshot_20100303.jpg (72.7 KiB) Viewed 174 times

And heres another it is pretty level maybe millimeters off in three spots

Snapshot_20100303_1.jpg (68.63 KiB) Viewed 174 times

[drummingmangos]

this drum still buzzes even after removing some skin flesh and evening out the rim. i think maybe the rings have something to do with it or the folds under neath and in between, the rings are bigger then the drum by a half inch at least. only the bass buzzes, but why even at all? the only thing i can do now is make new rings and try a new skin.

[michi]

the rings are bigger then the drum by a half inch at least.

Tighter rings would be better. I aim for around a 3mm gap between the shell and the inside of the crown ring. The flesh ring can be smaller, down to a 1mm gap (but it doesn't really hurt if it's the same size as the crown ring. Basically, you want the crown ring such that, with the loops on it, you can just push it over the head of the drum with bare hands.

only the bass buzzes, but why even at all? the only thing i can do now is make new rings and try a new skin.

Sorry, I can't tell you what causes the buzz. If you get the rings tight and re-head the drum, chances are the buzz will go away. BTW, from looking at your pictures, your bearing edge is quite flat and, with a bit of reshaping, would be more comfortable to play. (See this post.)

While you are at it, you can also check how well your edge is on plane. If you put the shell upside down on a work bench or table top, you can peer along the surface to see whether the bearing edge is on plane. Ideally, the shell will sit on the table without a gap anywhere along the bearing edge. If not, rocking the shell slightly from side to side will help you identify where you need to sand it down.

Cheers,

Michi.

[Beerfola]

I think that flat bearing edge might be the cause of the buzzing. I prefer a minimum of surface contact between the skin and the bearing edge. A more rounded profile affords a more comfortable playing feel and minimizes secondary contact between the skin and the bearing edge when the skin is reverberating. I use a pane of glass to to check for an even plane. If the glass rocks when you press on the edges you can readily see where the gaps are. If you can slip a piece of paper between the glass and the bearing edge you can narrow down where your high and low spots are.