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Sep 23, 2020 - 9:42:31 AM
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1445 posts since 4/13/2017

I realize that rim thickness plays a part in sound and tone, as does basically every other variable in a banjo. Also, Tony Pass wouldn't have found a market for his ThinSkirt if it didn't affect tone.

My question is this: What affect do thinner rims have on tone as compared to the traditional 3/4"? What about thicker? Also, I realize that the I.D. of OPFs affects the thickness of the lower portion of the rim.

Sep 23, 2020 - 9:48:57 AM
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Eric A

USA

840 posts since 10/15/2019
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I've been trying to figure this out myself. Bluegrassers worship at the alter of the "full thickness 3/4" rim. But plenty of Whyte Laydies and Tubaphones sound fantastic with much thinner rims.

In other words, I dunno...

Sep 23, 2020 - 10:02:55 AM

1093 posts since 5/19/2018

Hunter, That is a wide open question.

I am very fortunate to own a few all original Gibson Prewar banjos. They all sound completely different from each other. The one that absolutely mystifies me the most is my 1937 RB-00. Single piece flange on the thinnest rim Gibson ever made and zero tone ring. Nothing.

That particular banjo is loud with an incredible bass and a lot of dynamics and response. Currently my favorite instrument to play.

Based on that I am completely confused by these things even after 45+ years of collecting and playing them. There is a “sound” that Flat heads deliver, unquestionably so. One would think that a thin rim would sound just that, thin, but it’s completely opposite, so there are other aspects that if my Acoustical Engineer Father was still with us I would ask about and get a scientific answer to. I’m sure it’s about mass and other aspects that are beyond me to know.

I think it all boils down to personal preferences and that definitely changes over time. When I finally had the good blessings to get my first Mastertone decades ago I thought that the Flathead sound was the end all- be all at the time. Here I am now thinking, many years later that the lowest end Banjo that Gibson ever made, no tone ring, super thin rim, is now my best sounding instrument.

Experiment, as you have the years and time ahead of you to do so, and hopefully you will come up with the answers to your questions.

Sep 23, 2020 - 10:52:16 AM

13352 posts since 10/30/2008

I think for the "best" Gibson flat head sound, it is the balance or ratio of wood to metal. The one piece flange is typically on a 9/16" or 5/8" thick rim. Not 3/4" -- that is the two piece flange rim which is more characteristic for the classic Ralph Stanley arch top sound.

The "classic" flat head sound (yeah, I know there's not just one single flat head sound, every banjo is different!) has something to do with the balance or ratio of total metal weight (zamac one piece flange and tension hoop, and 3 lb flat head tone ring) with the 9/16" - 5/8" pre-war 3-ply rim weight. Just my opinion.

A 3 lb flat head tone ring on a two piece flange 3/4" rim is loud but has a "deep" sound, very pleasing indeed, but not the same "crack" as on the thinner one-piece flange rim. In my experience.

Sep 23, 2020 - 1:03:52 PM

1445 posts since 4/13/2017

quote:
Originally posted by Alvin Conder

Hunter, That is a wide open question.

I am very fortunate to own a few all original Gibson Prewar banjos. They all sound completely different from each other. The one that absolutely mystifies me the most is my 1937 RB-00. Single piece flange on the thinnest rim Gibson ever made and zero tone ring. Nothing.

That particular banjo is loud with an incredible bass and a lot of dynamics and response. Currently my favorite instrument to play.

Based on that I am completely confused by these things even after 45+ years of collecting and playing them. There is a “sound” that Flat heads deliver, unquestionably so. One would think that a thin rim would sound just that, thin, but it’s completely opposite, so there are other aspects that if my Acoustical Engineer Father was still with us I would ask about and get a scientific answer to. I’m sure it’s about mass and other aspects that are beyond me to know.

I think it all boils down to personal preferences and that definitely changes over time. When I finally had the good blessings to get my first Mastertone decades ago I thought that the Flathead sound was the end all- be all at the time. Here I am now thinking, many years later that the lowest end Banjo that Gibson ever made, no tone ring, super thin rim, is now my best sounding instrument.

Experiment, as you have the years and time ahead of you to do so, and hopefully you will come up with the answers to your questions.


How thick are these rims above the flange?

Sep 23, 2020 - 1:05:26 PM

7734 posts since 8/28/2013
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Because, as you say,tone is affected by basically every other variable in a banjo, I doubt that this queation can even be answered. Metal to wood ratios, densities of woods, rigidity of the entire structure, pot depth, and probably other things all help to determine a banjo's tone and response, as does the player himself. Can anyone truly say that a thick rim will sound better if the thin rim it's to be compared with has other features that the thick rim doesn't?

I always hesitate to say much about the rim because the basic tone is produced by strings and amplified by the banjo head. Maybe the rim supplies a little "color," but is just one of many parts such as the neck, the resonator, and the picking tecnique that also add "color." So long as the rim is rigid enough to keep the energy confined as much as possible to the head, I believe that the rest, that "color," is in the ears of the beholder.

Sep 23, 2020 - 2:06:23 PM
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13207 posts since 6/29/2005

A very complex question with no simple answer.  I have spent a LOT of time working on this to arrive at good designs for my own (not Gibson copy) banjos.

I engineer my rims, and operate under the assumption that the sound preferred by many many banjo players centers around a red maple rim that has a stiffness of 1.64 Mpsi and a density of 39@ cu/ft.  In order to maintain that at a thinner rim, you have to use a different combination of woods in the laminations. Tony Pass (my heart be still) used birch in a "static" block rim construction, which is stiffer but heavier for the thin skirt rims— I use birch as well as inner laminations as needed.

In an attempt to confuse this issue ha ha, there is an optimum wood-to-metal ratio for every type of sound, and it is variable—pick your favorite construction—the one on the far right is the "thin rim".

I did a lot of measurements and comparisons like this on Gibsons, Vegas, and my own banjos—you do what you need to do—disregard what I say, and draw your own conclusions.

I will say this much—wood species can be an important determiner of stiffness and density, and the thickness of the rim as a contributor to stiffness depends on on the construction method and woods used in the lamination.

Go forth and do good work.

Edited by - Ken LeVan on 09/23/2020 14:07:16

Sep 23, 2020 - 2:23:53 PM

1445 posts since 4/13/2017

Ken LeVan

Would this be a safe bet to say this...?

If hard maple has a density of 44lbs/cu-ft, and birch has a density of 43lbs/cu-ft, and a Flathead OPF rim has a volume of (insert number here)...

Like set it up as a proportion like...

Maple Density Birch Density
_______________ = ______________
FlatheadOPFvolume X

then cross multiply to get...

X(Maple Density)=(FlatheadOPFVolume)(Birch Density)

then simplify and isolate the variable to get the proper density for a birch rim

I don't think I said exactly what I was trying to, but do you understand what I'm trying to poke at?

Sep 23, 2020 - 2:24:10 PM

PaulRF

Australia

3111 posts since 2/1/2012

Rim thickness would also affect the chamber area as well.

Sep 23, 2020 - 2:34:56 PM
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13207 posts since 6/29/2005

quote:
Originally posted by PaulRF

Rim thickness would also affect the chamber area as well.

 


Only a little bit— the vibrating area of the head is much more significant.

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