Bearing Edges

[Anonimo]

POST REMOVED BY THE AUTHOR

[ABAKUA]

Yes the complained that that the fingers split open , calluses hurt but never bearing edges. This says some thing about today's conga players, they all want to showboat with 3-6 congas but in reality they can't take the heat.

You're right, guys like Anga ( RIP) Giovani, Pedrito Martinez and Paoli can't take the heat!

[BMac]

Leedy says:
This says some thing about today's conga players, they all want to showboat with 3-6 congas but in reality they can't take the heat. Again it refers to hand placement, the add by Pearl is just a marketing tool very well put and illustrated but in reality it does not affect sound as they quote. Sound is produce in any drum at the belly not the edges , Take notice that when you hit a conga drum depending on size of hand you are 5 to 6 inches away from the edge plus you inner knuckle is muffling the edge . So in reality it has no affect what so ever to do with the sound It's just a finishing touch in the wood.

BMac says:
You seem to acknowledge that sharp edges hurt players' hands without improving the sound. If that is the case, why should we not prefer the more comfortable edges? What is wrong with easy? To make a biking analogy, one can dismount a bike tire from a wheel without tools, but with much effort and pain. But there doesn't seem to be any advantage once the tire is changed and you're back to riding. So, I use my tire levers. It's easier. Why should we cling to old discomforts? Should we play to prove we can suffer? I don't.
In any event, I disagree entirely with you that the bearing edge has no bearing on sound. Perhaps I've misunderstood you. But I believe the whole of the drum makes the sound. That includes the belly, the bearing edge, the hardware, the head itself, and more.

Cheers!
BMac

[Anonimo]

POST REMOVED BY THE AUTHOR

[bongosnotbombs]

I just tapped on 3 different makes of drums, Skin on Skin, Resolution and a California Gon Bops. The Skin on Skin felt the most comfortable at the bearing edge. I suggest for this discussione everyone else try on their drums.

The Gon Bops I restored certainly sounded different after I changed the shape of the bearing edge, though I did put a new skin on it. There are other reports of players in this forum that changing the edge of a drum can change or improve it's sound.

Can anyone show us a picture of Vergara's or Requena's bearing edge? King Conga, do you have a pic of yours?

[BMac]

The bearing edge is the interface between the shell and the skin, both of which are integral parts of the sound. Their marriage, at the bearing edge, is very involved in defining the sound. That is my belief, which is contrary to your belief, apparently. That's Ok. I mean no disrespect. But I believe you are wrong Leedy.

I have not carved a conga's bearing edge. But I have re-carved/reformed the bearing edges of three djembes that fell into my hands with poorly carved interiors. For each I reformed the bearing edge and with each the sound was much improved according to my ears. For two of these, I remounted the previous heads ... so the improvement in sound for these was not due to a fresh head being mounted. I also made a dununba and of course formed its two bearing edges. I also reformed the bearing edge of a ceramic dumbek that had poor sound before I ground it, bit by bit, allowing it to cool without potentially ruinous regional heating, to a shape that I believed would improve its sound. Truly my treatment did improve the sound of the dumbek. In making six cajons over the years ... some shaped like cylinders, some shaped like dumbeks, I have also worked with the interfaces between thin plywood heads and their drum shells. I came to the conclusion through those experiences that the interface, defining in a sense the bearing edge, is a place of high concern in producing a musical instrument.

Clearly stated, I believe the same player using the same hand technique, before and after treatment on the drum, will get two different sounds from a drum if the head is dismounted and the bearing edge is reformed in any way. Setting aside any concerns about advertising ploys and theories about where sound is produced, I have reformed the bearing edges of several (non-conga) drums and have come to my belief with my hands and ears.

The bearing edge of a drum, like any other feature of the instrument, is one example of how different makers will differentiate themselves in the market to produce their own characteristic instruments and sounds, and we can expect that each will rightfully boast that their design is best in some way. That's what manufacturers do. I don't know who first rounded the bearing edge of a conga, if any one entity can indeed claim that distinction. My guess is that variations in the formations of bearing edges of conga predecessors predate Gon Bop, and Pearl, and Junior, and LP. In any event, the only sharp edges I have actually seen on congas have been on really cheap congas and on really old Gon Bops. I'm not criticizing old Bon Bops, I'm just stating what I have seen. Most modern congas have rounded bearing edges, most high-quality djembes have half-rounded edges, with the outer edge being rounded and the inner edge falling away like a cliff with no flat spot between the round and the cliff. If you think bearing edges don't define sound, I differ with you absolutely.

But that's ok.

Cheers,
BMac

[Anonimo]

POST REMOVED BY THE AUTHOR

[Mike]

Wow, what a bunch of interesting photos, graphics, information and discussion in this thread!

After all, I´d say fine bearing edges (whatever that means to you) are important, you could not possibly
let a drum skin resonate on a flat rectangular bearing edge!
But on the other hand, it is no rocket science either...

[Anonimo]

POST REMOVED BY THE AUTHOR

[Mike]

Noone here is a pro in physics I suppose. At least not me.

I am just looking at the bearing edge variety of the congas I own or have owned,
from rather round to sharp´n ´slopy

#1 LP:

#2 Gon Bops (vintage International series)

#3 Reiche Trommelbau (vintage mahogany)

Last but not least:

#4 Delaporte

May everybody find his own meaning of the bearing edges to his liking.

[BMac]

Actually, I have a PhD in physics. I don't have any particular mastery of the physics of acoustics and drums. So I don't intend to throw my education around in this discussion to boost my credibility. One loses credibility by referencing expertise they don't hold. Which makes me wonder whether Leedy understands anything at all about "the relativity of Fissics" and "this mathematical equation of the production of sound it will confuse you more."

Posting pictures of bearing edges contributes to this discussion. It is good to see all of these. Thanks to all on that, including Leedy. But pictures don't alone settle any debate about sound. The question is not at all whether different drums have different bearing edges. We already knew that, and the pictures here further support and add development to that point.

The point I refute with the OP here relates to sound. The different bearing edges produce different sounds. Pictures alone of old cuban drums do not address this point. I haven't said here that sharp bearing edges stop a drum from sounding great. I just believe a sharp bearing edge makes a drum sound different than the same drum with an edge of any other shape.

And Leedy, you won't likely influence us by alleging that we are confused about "the relativity of Fissics," indeed that kind of writing makes me think that you are confused.

Cheers,
BMac

[Joseph]

But on the other hand, it is no rocket science either...

Heh-heh...oh the controversy of minutiae.

In the sailboating world there is a term: "clean exit" which refers to the smooth laminar flow of water off the stern end of a boat hull as it moves through the water.
I think that is analogous to the bearing edge, whatever shape it is.

If you have a very defined zone on the edge where the skin quickly, cleanly, transitions from shell contact to freely vibrating membrane one could have a very distortion free vibrating frequency produced by the skin.

If you have a lot of flatness on the top edge, an area perhaps 1/2 to 3/4 inch all around the circumference of the skin, there is the possibility of turbulence as the skin may vibrate or buzz over that area, or the flat area may serve as a dampening ring and eliminate brighter tone (which may be desirable in some opinions). Or if the skin sits on that flat area solidly, it effectively makes for a smaller playing (freely vibrating) surface area.

One reason to use the "Rounded Outside - 45 inside" would be to increase vibrating surface area, thus changing frequency characteristics of head.

Example: refer to Leedy's photo example...the one titled "very sharp edge"
Exhibit 1
Say we have a drum shell 12" outside diameter, shell thickness .75"
Edge profile is rounded outside, flat top.
Inside Diameter is 10.5" {12 - (2x.75)}
Radius = D/2 = 10.5/2 = 5.25"
Using formula for area of circle A=πr2
Area of freely vibrating skin = 103.5 square inches

Exhibit 2
Another drum shell, same outside diameter 12", same shell thickness 75".
Edge profile is rounded outside, 45 inside, similar to Leedy's photo.
By using this profile we have shaved approx .5" off each stave on inside of shell, making each stave .25" at edge. (thinner than I would go, but I'm approximating from Leedy's pic)
Therefore the effective inside diameter is 11.5" {12 - (2x.25)}
Area of freely vibrating skin = 113.4 square inches.

Conclusion:
In comparing 2 conga shells of the same outside diameter (12") and using the rounded outside, 45 inside bearing edge profile on one shell, similar to the one referenced in Leedy's photos, the surface area of the vibrating skin was increased by 9.9 square inches, a 9.5% increase in playing area.

It is a method to achieve a larger playing surface without using any more construction material.

I'm no acoustic engineer, but an increase of that degree in area in the cleanly vibrating skin would seem to allow longer wavelength frequencies to be generated, and thus affect the final tone produced, so to say that bearing edge profile has no effect seems a rather blanket generalization.

I'm largely in agreement that bearing edge profile is a finishing detail.
Sometime in the ensuing years between the early drums with sharp edges and the present, the collective wisdom of the traditional shell builders has evolved towards rounded outer edge profiles.
I credit that not to competition, but to innovation...someone came up with a good idea, and everyone else followed...because it was a good idea.

[Jerry Bembe]

Thanks for the pics Mike. I have modified my Gon Bops like your Pic #2 to match your Pic #3 and experienced a fuller dynamic tone. The previous tone with the Pic #2 bearing edge created a muted to muffled tone.



#2 Gon Bops (vintage International series)

Gon Bops Conga bearing edge.JPG

#3 Reiche Trommelbau (vintage mahogany)

Reiche bearing edge.JPG

[Mike]

Thanks for the pics Mike. I have modified my Gon Bops like your Pic #2 to match your Pic #3 and experienced a fuller dynamic tone. The previous tone with the Pic #2 bearing edge created a muted to muffled tone.

You´re welcome Jerry.
I can concur that my Gon Bops of pic #2 have a slightly muffled sound, at least more than others, but still they do resonate!
The partly epoxied inside of the shell and the (relatively new) skins come into the equation too! When I got the Gon Bops second- to -fourth hand, with those 30-year-old bleached Gon Bops skins on them, they sound like muffled to death.
SO I decided to keep the bearing edges as they were and wait for the refurb, and I am content with them as they have turned out.
Plus I did not know how to reshape the bearing edge properly - to little skills there or I was simply anxious of ruining those beauties.

But I am glad to read that modifying the bearing edges of your Gon Bops worked out fine for you. How did you file it down I wonder - simply with a file?
BTW the Reiche conga (which I sold) of my pic #3 produced a sound with longer sustain than GBs - but great it was.

[Jerry Bembe]

Thanks for the pics Mike. I have modified my Gon Bops like your Pic #2 to match your Pic #3 and experienced a fuller dynamic tone. The previous tone with the Pic #2 bearing edge created a muted to muffled tone.

You´re welcome Jerry.
I can concur that my Gon Bops of pic #2 have a slightly muffled sound, at least more than others, but still they do resonate!
The partly epoxied inside of the shell and the (relatively new) skins come into the equation too! When I got the Gon Bops second- to -fourth hand, with those 30-year-old bleached Gon Bops skins on them, they sound like muffled to death.
SO I decided to keep the bearing edges as they were and wait for the refurb, and I am content with them as they have turned out.
Plus I did not know how to reshape the bearing edge properly - to little skills there or I was simply anxious of ruining those beauties.

But I am glad to read that modifying the bearing edges of your Gon Bops worked out fine for you. How did you file it down I wonder - simply with a file?
BTW the Reiche conga (which I sold) of my pic #3 produced a sound with longer sustain than GBs - but great it was.

Thanks Mike,

I filed (first with a rough file, cleaned up with fine file and sand paper last) the round/round original bearing edge to a round/45 bearing edge (much like Matthew Smith's). I reused the original head. When reseating the original head, I soaked the head on the interior and exterior below the retaining ring wire for 20-30 minutes. I was careful to not over soak the head and losing the grip the skin has on the retaining wire. This way I had a nice firm seating of the head and improved tone.

The bearing edge needs to be even across the top as previously commented. Regardless of the type of bearing edge used an uneven bearing edge will hurt the overall tone. Too sharp of a bearing edge creates a weak point and can promote cracking.