When is a flat top guitar not a flat top?

[nkforster]

Not a riddle folks but the subject of my latest blog post. Take a look, I'd be interested to hear your take on the subject - what you've learned over the years.

http://www.nkforsterguitars.com/blog/fl ... inder-top/



nigel

http://www.nkforsterguitars.com/book/

[Kamusur]

I have the answer Nigel, "Definitely when it has a top like yours its not a flat top". At least to my way of thinking building a cylinder top or shape from timber/wood etc seems to make a little more sense as it is only bending in one plane and would have more chance of success ie staying put so to speak than trying to "dome" (in the partial spherical sense) or hold the timber/wood stable in more than one plane. So perhaps we ask or expect a little to much sometimes Nigel.

Steve

[Bruce McC]

Hi Nigel

I'd put it down to common usage of the term "flat top guitar", just as we use the term
"acoustic guitar" to distinguish between the way god meant guitars to be and electric guitars.

[charangohabsburg]

I have the answer Nigel,

I have the other answer: when it is not an archtop (= carved top) it is a flat top. This is how I perceive the term "flat top guitar" generally was used in the past decades, and in spite this is in most cases not technically correct I am not tempted to take part in a linguistic revolution.

[nkforster]

I have the answer Nigel, "Definitely when it has a top like yours its not a flat top". At least to my way of thinking building a cylinder top or shape from timber/wood etc seems to make a little more sense as it is only bending in one plane and would have more chance of success ie staying put so to speak than trying to "dome" (in the partial spherical sense) or hold the timber/wood stable in more than one plane. So perhaps we ask or expect a little to much sometimes Nigel.

Steve

Why do you feel it might have little chance of staying put Steve? My own cylinder top Howe Orme is over 100 years old, it's had a few repairs in that time but it's still in perfect playing condition:



But my main question was chaps - what are your thoughts on the shape you put the soundboard in? Most of us have views on materials, bracing, thicknessing, but what about the actual form?

[charangohabsburg]

what are your thoughts on the shape you put the soundboard in?

No special thoughts here, just common knowledge: doming (or also the cylindrical shape I only know from pictures) allows to make a thinner top providing the same strength as a thicker, not domed top, and also is to a certain degree an insurance against cracks due to excessively low RH compared to RH at assembly stage.

Further I believe that different doming shapes also can have a great influence on tonal colouration, but it is beyond my knowledge how much and how exactly which doming degrees and/or shapes have an influence on tone, hence I don't spend too many thoughts on it.

[Kamusur]

Nigel my vote was for 'easier to constrain the curvature in 1 plane' the cylinder top than the dome.

Steve

[Taffy Evans]

I don't think I've ever noticed a flat top guitar. If the dome radius was not put there by the maker, it's put there over time even if slightly by other forces, strings. I did build a Weisenbourn style guitar with a flat top and back and the plates looked a bit sunken even tho they were flat.

[Taffy Evans]

Oh!, I meant to add, my understanding is the same as Markus mentioned, If its not arched top guitar its a flat top guitar.
I don't know when the term flat top first came into use but maybe back in the 1920's - 30's it was a quick way of sorting the Gibson L5 style guitars of the day from the Martin Dreadnoughts of the day.

[nkforster]

Oh!, I meant to add, my understanding is the same as Markus mentioned, If its not arched top guitar its a flat top guitar.
I don't know when the term flat top first came into use but maybe back in the 1920's - 30's it was a quick way of sorting the Gibson L5 style guitars of the day from the Martin Dreadnoughts of the day.

I think you're probably right, the name "thin top" might have been more accurate, but doesn't sound as good.

The reason for posting this is to see how many of you are actually experimenting with soundboard structure as a tool for shaping sound, beyond using spherical formers?

It's a really worthy avenue to go down folks. As when you experiment with the shape, it influences so much more - thicknessing (mass), bracing, even materials and decoration. And SOUND!

Here is one of my cylinder tops getting a good thrashing:

http://www.youtube.com/watch?v=N0zz4Pu8wyU

[Dennis Leahy]

I know Dave White builds using a cylindrical rather than dome shape, and every guitar of his I've heard recorded was "sumptuous"... maybe he can chime in.

Dennis

[Parlourman]

I'm really interested in this - i think it looks great.

I am just finding my way into the world of guitar making - I've made my first as per Cumpiano's book - I've just bought the Gore-Gillet books for number two - so maybe a cylinder for number 3?!

Maybe you can elaborate on your technique Nigel and give up some starters - do you have any plans?

Steve

[Dave White]

I know Dave White builds using a cylindrical rather than dome shape, and every guitar of his I've heard recorded was "sumptuous"... maybe he can chime in.

Dennis

Dennis,

I don't use "cylindrical" as there is some degree of curvature longitudinally on my instruments but I don't use radius dishes either and the curvature on my tops is complex. My braces are profiled to around 13' radius for the top and 10' radius for the back when glued on but where the tops and backs end up I've never measured. I've never worried about the fingerboard and top being a perfect match and have essentially a floating fingerboard as I believe that the upper bout is an important tone shaping part of the instrument especially for the complexity of the upper harmonics and definitely like a large degree of curvature in this area of the top. My overall scheme of things is to have the top thicker than most in the centre of the lower bout together with curvature to deliver the mids and trebles I want and then hunt out the lower registers from there (easier to do). The higher arching also helps with forward projection of the sound and volume (no need for messy double tops top achieve this).

If you put ladder braces on a top then there will be a degree of longitudinal curvature also and for a true cylindrical shape you have to shape the sides to take this out when you fit the top. Like Nigel I'm a believer of learning the art of shaping the sides to get the complex curvature of the tops and backs that you want. I think radius dishes came in as an easier way of putting the box together (braces rims and everything shaped in them) and don't think that they deliver the sound that I'm hunting down. Also when I read of people talking about 25' as being significant curvature I'm tempted to use an adapted version of the Crocodile Dundee line "That's not a knife . . .". I've always been curious about when using radius dishes came to be the accepted way of making a steel string and according to Somogyi it was the American maker Roy Noble that was the pioneer - at least in modern times a with all things guitar related if you look hard enough there will probably be someone in the 1500's doing a similar thing.

[Kamusur]

Great response Dave and thanks Dennis for asking the question.

Steve

[nkforster]

I'm really interested in this - i think it looks great.

I am just finding my way into the world of guitar making - I've made my first as per Cumpiano's book - I've just bought the Gore-Gillet books for number two - so maybe a cylinder for number 3?!

Maybe you can elaborate on your technique Nigel and give up some starters - do you have any plans?

Steve

I've a couple of Howe Orme's now and will draw up some plans when I learn how to do it on a computer. Does anyone know how? What programs work well for Mac that are free?

[Craig Bumgarner]

Interesting thread!

I build Selmer style guitars and one of the main characteristics is the arched top and "pliage" (fold) at the bridge area. The purpose is for the same reason other guitars use arched, domes, cylinders, etc., to provide more stiffness with less weight.

Selmer style guitars have about 7-10mm of arch across the grain, induced by ladder braces. With the grain, they are flat from the head block to the bridge and then the top is folded down to the top piece. The top edge of the sides is straight so this is how the tail of the top gets back down to the sides from the arch in the braces up from the tail. The long grain stiffness is so great that without the pliage, the grain stiffness overcomes the light bracing and much of the arch is lost. The pliage is done with heat before the two top halves are joined. A couple pictures:

Not all Selmer style guitars have a true pliage, though the originals always did. Many copies avoid this by reducing the arch or thinning up the top enough that it can bend in both directions with (beefier) braces alone. Some builders use radius dishes. The result is often an overly braced top and the high part of dome is up hill of the bridge area, not the ideal location. The pliage takes a little time and practice to make, but once figured out, it makes a world of sense. Keep in mind these guitars have floating bridges and a tail piece like a carved archtop guitar.

In fact it is hard for me to consider Selmer guitars as flat tops, there are so many differences. They are not archtops either. The are, well, Selmer style!

You might know of the DiMauro brothers who built Selmer style guitars in France from the 1940s to the 1960s. One of their guitars is the Chorus model, with a true cylinder top, ladder bracing and f holes instead of a pliage. The edges of the sides vary considerably so the cylinder shaped top can meet the sides without a pliage or otherwise much bending with the grain. These still fall in the family of gypsy guitars and has a similar sound, primarily because of the ladder bracing.

neuvebombe.jpg (92.95 KiB) Viewed 20455 times

[Stephen Kinnaird]

Nigel, I use a domed top mainly to get my neck angle geometry to work like I desire.
As a by-product, the tone has become more complex. I really hear more power in the mids, and a *lusher* sound overall. The true flat tops we've built have more force in the bass, generally, so as you say it becomes a tool to zero in on a customer's needs.

Steve