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Thread: Scale length for an octave mandolin build

  1. #1
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    Default Scale length for an octave mandolin build

    I am in the process of building an octave mandolin with a small guitar shaped carved top to be tuned G D A E.
    I have seen scale lengths mentioned from 21 to 23+ for these instruments; is there any standard scale length?
    Since scale length determines the location of the bridge, and the bridge should rest at the top of the arch, how much leeway is there for placing the arch top?

  2. #2
    Jo Dusepo, luthier Dusepo's Avatar
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    Default Re: Scale length for an octave mandolin build

    I've seen a wide range, from about 500-580mm. 520mm seems common.
    I am a luthier specialising in historical and world stringed instruments. You can see more info at my website.

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  4. #3

    Default Re: Scale length for an octave mandolin build

    There is no standard scale length. It can be anything you want with infinite variation of total length between what ever you believe are your minimum and maximum ideas of functionality are. 21 to 25.5" are ballpark numbers for what I'd build but these numbers aren't restrictions. The only restriction comes from your decision to use a preslotted fretboard, a fretting template or devise your own process of slotting the fretboard. You can enter any number into the fret position calculator at stewmac.com such as 22.63 and it will tell you where the fret positions need to be. With any given scale length, the actual position of the bridge will be determined by where exact intonation occurs and that is an offset determined by a completely different discussion. However, it is a position that does not have any leeway once the scale length has been decided.

    If you don't fully understand, its difficult to describe all of the things that matter in text. The full understanding of this is best learned over a pizza from someone who does understand it on a one to one discussion.

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  6. #4
    Mandolin tragic Graham McDonald's Avatar
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    Default Re: Scale length for an octave mandolin build

    I suggest 22" as a good length for an octave mandolin. It is a good compromise between string gauge and playability, in that strings from .012"-.046" suit a GDAE tuning and the frets are close enough together to make melody playing comfortable. It is around 3 frets shorter than a longish guitar scale, so you can capo a guitar at the third fret to get a sense of what it might feel like. Check out some archtop guitars to get an idea of where the bridge sits on the body, usually around a third of the way from the waist to the tail, and work out how many frets you need to the body join.

    Cheers

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  8. #5
    Mandolin & Mandola maker
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    Default Re: Scale length for an octave mandolin build

    What Graham says. I use 21 inch scale length on my octave mandolins, but they are specifically designed to make it easy for playing melody. I use mandola strings on them so string sets are readily available and they sound good enough to me. As you go shorter, you need thicker strings and the G string starts to sound "thumpy" when fretted. I have seen shorter scale OMs, but the G string sound was not good, so 21 inch is as short as I would go. There are many opinions about this subject. Longer scale -> better sound, shorter scale -> easier to play. It is a compromise and basically whatever floats your boat.
    Peter Coombe - mandolins, mandolas and guitars
    http://www.petercoombe.com

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  10. #6
    Registered User
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    Default Re: Scale length for an octave mandolin build

    Thanks everyone. I do understand the relationship of the bridge for compensation. My concern was how much leeway there is between the bridge and the carved top and where the f holes are set. 22 inches sounds like a good choice for playability. I will take a look at some archtop guitars to see if that will put the bridge in a reasonable place on my top which is 18.375" long, assuming joining at the 14th fret.
    Thanks a lot
    Bob Schmidt

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