Bent top mandolins

[Don Grieser]

You see a lot of mandolins from the early 1900's with bent tops. What was the purpose of this design? What's the difference in tone between a flat top or a carved top versus a bent top? Advantages, disadvantages?

Signed, Curious in New Mexico

[Bob A]

Bent tops allow you to put more pressure on the bridge, which usually provides more volume. On bowlbacks at least, the tops are not only bent, but the halves of the top are arched so that the center seam is several mm higher than the sides. this provides an extremely strong structure which resists the downward pressure of the bridge. (Think of an egg).

By bending and arching you can build a responsive instrument that can provide the characteristic bright treble tones because the top wood is thin; carved Gibsons have so much wood in the top that a lot of treble is suppressed.

Advantages: a light, bright sounding instrument.
Disadvantages: well, it won't fit into bluegrass tonality. Also medium and heavy strings will wreck the neck, but of course you don't NEED heavier stringing. The whole package is extremely efficient as an amplifier of light gauge strings.

[CraigF]

BTW, the bend is called a "cant".

[JEStanek]

BobA, I'm having a hard time seeing where my Spira cant top has a disadvantage you're describing! http://www.mandolincafe.net/iB_html/non-cgi/emoticons/biggrin.gif Ha. These cant topped instruments (flat backed like mine or older Martins) really have their own voice. very sweet and full sounding. When I got mine I played it with a guy who had a Collings MT. Now, my mando is pretty loud and has a nice rich tone. His had a punchy chop and when he played it felt like the music pushed through me like a prow of a boat through water. When I played mine it felt more like the water going around you. More immersed in than sprayed with... For whatever those descriptions are worth.

I really like the way medieval music, folk, melodic music sounds on mine. It sounds different from the Eastman F4 style I had too. But it was closer to the F4 than that Collings A5 sound. I think the arch tops makes the instrument punchier regardless of hole shape.

Hope this helps. Here's a picture of mine from the side.
Jamie

[Jim Garber]

As far as I know, there is no truly flat topped mandolins: all have some sort of induced arch, however slight. Otherwise I think the downward pressure of the strings would cause the top to sink.

[Bob A]

Well, as to flat-tops, my P.Kevorkian Greek bowlback has a flat top, though it is sinking a bit. But according to Victor Kioulaphides, who hunted it down for me, this is the typical Greek construction method, and it's supposed to sink.

It has another peculiarity: the top is quite thick, but thins down considerably at the edge, which seems to give it a fair amount of flex, like a speaker cone. It's a few years old now, and the sound is really coming into its own, loud and rich.

Jamie, I'm hard pressed to list DISadvantages of these instruments. Even the fact that they're looked down upon by the vast majority of US players strikes me as advantageous, as it's kept prices nicely affordable. But don't let's tell anyone, OK? More toys for the Bowlback Boys.

[brunello97]

I love the double cross section of the bent and arched bowlbacks, particularly when they are a bit pronounced. #Fitting a bridge is a truly custom act. #There was an interesting discussion on another thread about the necessary cutting and bending of the two-piece canted tops.

Nice imagery in your comparison, Jamie. #And Bob, I do think the word is slipping out. #We may have to bring Don into the Loyal Order or else make him swear to secrecy. #

Hmmm. #My quasi-Portugese/German style Paracho cedar top is pretty much as flat as I can gauge. #The slightly honed 2x4 brace is steady in place up under the bridge. #If that ever fails the 'structural lacquer' should really kick in as a safety net.

But it sounds really good, I keep saying. #I'm serious.

Mick

[JEStanek]

Bob, the secret is safe with me, man! I'll be hunting for a decent bowl in a couple of years.... shhhhhhh! http://www.mandolincafe.net/iB_html/non-cgi/emoticons/wink.gif

Jamie

[Don Grieser]

Thanks to all for sharing your expertise. I'll let you know when I join the Loyal Order. http://www.mandolincafe.net/iB_html/non-cgi/emoticons/coffee.gif

[allenhopkins]

As far as I know, there is no truly flat topped mandolins: all have some sort of induced arch, however slight. Otherwise I think the downward pressure of the strings would cause the top to sink.
Would that include the Gibson Alrite/Army-Navy, and descendants, the Flatiron "pancake" models? My Gibson A/N Custom doesn't seem to have a perceptible arch.

[Celtic Saguaro]

Yep, the original Flatirons (now called pancakes) were all real flat tops. Their arch tops came later. I believe Mid-Mos are as well.

[Bill Snyder]

A lot of instruments that look like they have truly flat tops have a little arch cut/sanded into the braces. It can be very slight such as a 25' radius. That would be almost inperceptible and with the downward pressure of the strings it might be flat.

[David Newton]

I make my New-Navy mandolins with a 15' arch to the braces. Depending on the bridge height and string gauge, it can go dead flat under tension. If it were built dead flat, it would sink and I don't think that is a good look.

On a note in conformity with the original thread, I bought a case for a New Navy Mandola and it doesn't fit, it is a case for a Sobell shape or a "trinity college" shape. Since it doesn't look like I will be able to return it, I am going to have to build a Cant Top Mandola to go with the case. Kinda basackwards, huh?