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Thread: Converting bass to double octave mandolin

  1. #1

    Default Converting bass to double octave mandolin


    I thought I would share a project that I am getting started on. I'm converting a short scale Teisco-style 60's or 70's bass into a double octave mandolin. It will be tuned in 5ths starting on the low G on a bass. I play bass and mandolin and I'm looking forward to having a double-coursed instrument that can cover bass, chords, and a fair bit of melody.

    Here is the bass the day I bought it in September. No name plate, odd cross between SG and Tele bass styles, 30.5" scale, beat up but not hideous. I like the sound of the pickup and it doesn't hum. Not bad for $60!
    Click image for larger version. 

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    My initial plan was to set it up as a mandocello, but I decided that the pickup would not handle a mixture of plain and wound strings because it is not adjustable (yet). So I went lower: GDAE two octaves lower than a mandolin. I'm calling it a double octave mandolin. For the past 4 months I have had it strung up with a custom set of D'Addario chromes flatwounds (0.065,0.048,0.032,0.022) and I like the tuning. Playing towards the nut requires a lot of shifting, but the high frets are very usable because the body gives a lot of clearance. Intonation and tension on the G string would be better with a thicker string, but the next size up is 0.075 and I'm trying to stay conservative on the string tension since it will be double coursed. Intonation and tension on the other three strings is great.

    I had some free time today so I decided to start modifying it for double courses. I was pleasantly surprised to find out that the body is solid wood, maybe even mahogany. It was routed out at the factory, so it should be straight forward to make the pickup height adjustable by cutting an opening in the pickguard and mounting the pickup to the body.
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    Somebody before me mangled one of the tuning holes, so I am going to have to cut the headstock down. That's not such a bad thing because it is very neck heavy.
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    The bridge is already has multiple notches for each string, which I think will help with double courses. My plan is to run both strings for each course through the same retaining slot, so I going to cut a channel in the body right behind the bridge to make room for the string ends.
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    I bought some basic 4-per side mandolin tuners. The next step is to figure out the headstock design, cut it, and fill the old tuner holes. I'll post updates as I make progress.


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  3. #2
    coprolite mandroid's Avatar
    Join Date
    Oct 2002
    Outer Spiral Arm, of Galaxy, NW Oregon.

    Default Re: Converting bass to double octave mandolin

    FWIW, because of the Bass scale length Mando Basses are still tuned in 4ths like bass viols,
    (& bass guitars)..

    Should be able to glue a plug in that last hole and repair it without sawing it off..

    but have fun with experimenting.

    writing about music
    is like dancing,
    about architecture

  4. #3
    Registered User
    Join Date
    Jan 2003
    Southern Maine USA

    Default Re: Converting bass to double octave mandolin

    Great idea, but fretting a double set of bass strings sounds like
    a strain on one's hand.

  5. #4

    Default Re: Converting bass to double octave mandolin

    Maybe try stringing it like a 8 string bass, with octave strings.

  6. #5
    Moderator MikeEdgerton's Avatar
    Join Date
    Mar 2007
    40.191N -74.2W

    Default Re: Converting bass to double octave mandolin

    Even the Gibson mandolin bass was tuned in fourths.
    "Bargain instruments are no bargains if you can't play them". These are the words of J. Garber.

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