F5 and F4

[John Bertotti]

I have some Loar style prints and some other F5 plans. Hogo's are on the way I have Siminoff and a couple of others. I would like to find some F4 or find a reference describing the differences between F5 and F4. Does anyone have some suggestions? And while we are at it whats and F9, how many F models are there? I do tend to prefer oval hole instruments but I am getting the itch for an F-hole model as well and I have to do something with the curly redwood I have been asking about so I think you can see where I am going with this. Thanks, everyone!

[peter.coombe]

The main difference you need to worry about is an oval hole mandolin top is carved thicker than a F hole mandolin, and that does not matter whether they are A or F style. The oval sound hole weakens the longitudinal stiffness so you need to carve them thicker or the top will sink. So if you are going from an oval to an F you need to carve the F thinner. How much thinner will depend on the individual piece of wood, but on average I would carve my A5 tops around 2mm thinner. Gibson F4's had a single cross brace behind the sound hole whereas the F5's have tone bars. However, you can brace either of them with an X brace. The F5 has a longer neck than a F4. The crosspiece is at the 14th fret on a F5, but is at the 12th fret on a F4. Note that the scale length does not change so the position of the bridge is more foreward on a F5. Those are the main differences.

[John Bertotti]

Great to know thanks!

[John Bertotti]

Is there any significant tonal difference between the transverse brace and an x brace? Thanks!

[Marty Jacobson]

Also, an oval-hole top is graduated in a different pattern. I've posted this a bunch of times, just because it really helped me visualize the difference in a way that the numbers never did for me.
Oval hole with X or transverse bracing:

F-holes (or whatever) with parallel or X bracing:

[John Bertotti]

So, Am I correct in thinking the blue areas are thinner and the redder are thicker?

[Marty Jacobson]

Aye.

[Greg P. Stone]

I can answer the F9 question as I've played my friend's. The F9 is an unornamented F5 like the Martin D-28 is to the D-45: cheaper with same basic construction and sound.

[peter.coombe]

Is there any significant tonal difference between the transverse brace and an x brace?

It depends of how you define "significant". There is a difference, but it is more of a subtle difference but certainly audible. I have made both and prefer the X for my oval hole mandolins. An X also has the advantage of more gluing surface so is less likely to fail.

[John Bertotti]

It depends of how you define "significant". There is a difference, but it is more of a subtle difference but certainly audible. I have made both and prefer the X for my oval hole mandolins. An X also has the advantage of more gluing surface so is less likely to fail.

Those subtle differences can make all the difference in the world. Thanks!