Yet another Fingerboard Radius thread

[Benthoven]

Hey guys - I've read through many of the threads here on optimum fingerboard radius for various setups, and have learned a very great deal. However, my main question still remained unanswered.

I played a magnificent old bass the other day that was set up for a very famous retired jazz bassist here in town. (it's for sale for $15k too!) The fingerboard radius was very flat compared to mine, and it made playing jazz in the upper register vastly easier. So, since I can't buy this bass, I want to plane my Eastman 305 fingerboard down as close to his radius as possible, but I have two major concerns:

1) As you can see in the diagram of my fingerboard cross section, taking my fingerboard down from a 2.5"R to a 3.5"R will reduce the thickness of the fingerboard down to about .25" on the center line at the end. What are the potential structural/tonal downsides to this much reduction? Is this too aggressive for this fingerboard and is it worth buying a new fingerboard instead?

2) Is this radius too flat for the very occasional bowing I may do?

[Square Bear]

aside from the amount of board that you have to work with, the other big consideration is your string spacing. if it is too narrow, it will make arco playing a lot more difficult. maybe you should split the difference? best thing to do is go to a good bass luthier and ask what they think about it.

[JtheJazzMan]

I find that the strings have to be set to an uneven height in order to accommodate bowing on a FB that is too flat.

Kinda ruins the feel of the bass if you ask me if you want to play arco.

[Fletcher Lanning]

I agree that your biggest problem would be bowing. The flatter the arc is, the harder it will be to play a single string with any amount of force without running across one of the adjacent strings.

[Benthoven]

Yeah, I realize that about the bowing problem, and that's why my question is, "is it TOO flat?" I know there must be luthiers here who've dealt with the limiting geometries in play here. How flat is TOO flat an arc to bow? I'm going from a 2.5"R to a 3.5"R - Is 3.5" too flat or can you go even flatter and still bow? Eyeball tells me this is kinda the outer limit area, but that's why am asking here.

[Matthew Tucker]

It depends on your level of skill. A six-string viola da gamba is bowed, and effectively the fingerboard is much flatter than a double bass fingerboard.

On the down side of flattening your fingerboard, the fingerboard will become more flexible, and my view this will reduce the sound level in the upper registers.

There is no such thing as "optimum", except what is right for YOU.

[ctregan]

Strings tend to bend down with bow pressure. The harder you bow, the more likely the strings will cross.

[Cody Sisk]

The fingerboard on those 305's is intentionally thick IMO. I think you might also have a 2-piece neck. (joined center seam) That much thinning might help your sound some, but risk the structural integrity over the long run. I'd get an opinion from a couple of bass luthiers before proceeding.

[james condino]

I just did the opposite to my bass- changed out a rather flat fingerboard radius to a nice strong radius. I prefer it more for everything.

j.

[Cody Sisk]

What was your final radius James?

[Gearhead43]

I prefer a flatter radius, but I only play pizz and slap.

[Benthoven]

After reading your post I looked very closely and can't find a seam or any other evidence that this bass has a 2-piece neck, Cody, and I think your observation about the thickness of the 305's fingerboard is spot-on.

I'm curious about your thought that thinning the fingerboard might help the sound - For me, the purpose of planing it was to get a flatter radius, but I wasn't expecting a benefit to the sound. Could you elaborate on that thought just a bit?

[Cody Sisk]

Well you're lucky to have found that your neck is one piece. Hold onto that bass!

Changing the mass of an instrument can make a significant difference in tone. This process is best explained in Chuck Traeger's book when he is discussing mode matching. It's a really technical and scientific explanation as to how to "tune" certain parts of the instrument's natural pitch in order to get the bass to produce the best sound it is capable of. If you've had your instrument mode matched already by a qualified luthier and you go in and thin your neck, it will undo whatever tweaks your luthier's already done and can hurt your instrument's tone. (or might have a very slight chance to make it better)

In general it seems that less mass is almost always better, but that's not an absolute..

[Matthew Tucker]

mass is one thing, flexibility is another

[Ken McKay]

That fingerboard is going to end up too thin, I think.