Trying to make an 8 string bass

Discussion in 'Luthier's Corner' started by h8mtv, Nov 29, 2012.


  1. h8mtv

    h8mtv

    Joined:
    Nov 29, 2012
    I recently picked up a Kramer (!) marked Schaller 471 8 string bass bridge. I generally play a Mustang bass. I really want a short scale 8 string but the Schaller has too wide a string spread for a Mustang or Bronco bass. I am considering buying an Ibanez Mikro bass 5 string but I do not have any clear direction honestly. I can't find any good info on the spacing of the strings. Any advice would be much appreciated.
  2. ctmullins

    ctmullins Registered 8er Supporting Member

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    Apr 18, 2008
    Location:
    MS Gulf Coast
    Just looked up the Mikro 5 - the string spacing on it will work fine, and you will probably be able to use the stock electronics too. But you will have two, possibly three, issues with using that as a basis for an eight.

    First, you'll have to fit eight tuners where there are five. It's doable, but not trivial. How good are your woodworking skills?

    Second, while the spacing is fine, 28.6" is pretty short. I think you'll have trouble finding strings of a suitable gauge. Not without quite a bit of experimentation, anyway. I built a 32" eight, and the standard packs of eight-string strings are too floppy - I'm having to look for beefier strings myself. 28.6" will magnify this issue.

    Third, and this depends upon the string gauges you wind up with, the ability of the Ibanez neck to handle the increased tension is unknown. It might work fine; it might not. Won't hurt to try, though!
  3. h8mtv

    h8mtv

    Joined:
    Nov 29, 2012
    My woodworking skills are rather good. I have done hobby woodworking for years. I'm figuring I'd have to drill the original 5 tuner holes, plug with dowels, re drill for the 4 bass and 4 guitar tuners, them repaint the headstock. I have built a half dozen or so guitars from kits over the years.

    I am wondering where you are finding the specs? I can only find a last fret and nut width.

    The Schaller 8 string bridge puts the hi/lo strings right on 69mm apart at the bridge. I'd like to find an actual measurement of the bridge on both Mikro versions (4 an 5 string). I have also seen an ESP LTD mini that caught my eye.
  4. ctmullins

    ctmullins Registered 8er Supporting Member

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    Apr 18, 2008
    Location:
    MS Gulf Coast
    I did a quick Google search and found the official Ibanez site for the Mikro 5:

    http://www.ibanez.com/BassGuitars/model-GSRM25

    They list a nut width (45mm) and a neck width at the 22nd fret (67mm), so you can extrapolate from there - it should be set up pretty well for the Schaller 471.
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  6. HaMMerHeD

    HaMMerHeD

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    Norman, OK
  7. Steve Dallman

    Steve Dallman Supporting Member

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    Mar 5, 2006
    Location:
    East Central Wisconsin
    I turned a Fender Musicmaster bass into an 8 string in the early 80's. (Sorry, no pictures.) There was a lot of neck set into the body, so I moved it out an inch or more. I moved the bridge up, and made a new pickguard.

    I cut and routed the body so the tuners fit behind the bridge on the body. I think I drilled more holes in the bridge for the octave strings to pass. I drilled simple holes in the headstock to anchor the strings in, and made a new nut.

    I changed the pickup to an EMGSA which I got for free. It worked very well. The bridge saddles were threaded rod types, so I kept those saddles.

    I changed a Vox Phantom over at same time. With that bass, I had a new bridge plate made at a sheet metal shop, using a sort of Z shape, and mounted the tuners on top of that plate. I put a brass holder on the headstock to anchor the octave strings, using some square stock. New nut, and Dimarzio J pickups completed that one.

    With both, I used standard bass strings, and the low 4 strings from a guitar set. I used pretty light guitar strings from a 9-42 set. Even with the long scale Phantom, they fit.

    With the Musicmaster, I drilled two holes to anchor the octave G. I had a couple octave G strings break at the bridge, so I drilled a hole high on the headstock and one closer to the nut, so if one broke, I could just move the string, and reuse it.
  8. h8mtv

    h8mtv

    Joined:
    Nov 29, 2012
    I am still a bit nervous on pulling the trigger to order the 5 string Mikro in regards to bridge. I keep reading they use the same 5 string bridge as other models, so that makes me nervous about the fingerboard being too wide with the Schaller 471.

    As far as string gauge goes I am not real concerned, I figured on using the same size as on the 4 string version plus the guitar strings. Also my experience has been that with the shorter neck it should hold up well to the tension as it is stouter, plus dropping the low B should help.
  9. ctmullins

    ctmullins Registered 8er Supporting Member

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    Apr 18, 2008
    Location:
    MS Gulf Coast
    I did a quick calculation - if the nut is 45mm and the 22nd fret is 67mm, then, if you extend those lines out to the bridge position, it would wind up around 75mm. Mind you, that's the imaginary "neck width" at the bridge. The strings should be 2 to 4mm inboard of that. So if you lop off 3mm from each side of that measurement, you wind up right at 69mm!

    But - it certainly wouldn't hurt to call Ibanez (or one of their dealers local to you) and ask for verification.
  10. h8mtv

    h8mtv

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    Nov 29, 2012
    Math has all the answers doesn't it? Thank you very much.
  11. ctmullins

    ctmullins Registered 8er Supporting Member

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    Apr 18, 2008
    Location:
    MS Gulf Coast
    No prob. I happen to be building a pair of basses right now - one eight-string and one five-string. The eight is using the 471 bridge, and the five is using whatever-the-number-is-for-the-five-string-roller-bridge. I like narrow-spaced fivers anyway, but the neat thing about these builds is that the same neck dimensions will work for both instruments - 44mm at the nut and overall string spacing at the bridge of around 2.6" (sorry for mixing English and metric....). When I place the two Schaller bridges face-to-face, the fiver is only a couple of mm wider than the eight. :)
  12. h8mtv

    h8mtv

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    Nov 29, 2012
    One mikro inbound from MF. :)
  13. h8mtv

    h8mtv

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    Nov 29, 2012
    Are these 471 bridges hard to come by? Warmoth had gold,chrome, and black in stock, now nada. They are not terribly expensive. Love Schaller stuff.
  14. HaMMerHeD

    HaMMerHeD

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    May 20, 2005
    Location:
    Norman, OK
    Nah. Stuff goes in and out of stock all the time. They should be back around soon.
  15. h8mtv

    h8mtv

    Joined:
    Nov 29, 2012
    The spacing is perfect for the mikro 5. Can't wait to get going. Pics to come. Thank you all for your help. :)
  16. ctmullins

    ctmullins Registered 8er Supporting Member

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    Excellent! Continue this thread, or start a new one - either way, I'll be watching! :)
  17. Ric5

    Ric5 Supporting Member

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    Jan 29, 2008
    Location:
    Colorado
    They are not that hard to come by ... I have one in my workshop for a future (not yet started) 8 string project.

    Converting an 5 string Mikro into an 8 string bass is an interesting idea.

    I have wanted to build a 8 or 10 string bass for a while. I might start with a 5 string paddle head neck or maybe a warmoth 8 string neck.

    If I do an 8 I will tune it DGCF.
  18. h8mtv

    h8mtv

    Joined:
    Nov 29, 2012
    So I plugged the holes with dowels. I am arranging my headstock now. Seems easy enough. Made a tracing of the headstock, marked the layout of the nut and laid out the tuners. All the angles are easily achieved. Nice amount of real estate on the 5 string headstock. Any tips before I lay it out and throw a forstner in the press?
  19. ctmullins

    ctmullins Registered 8er Supporting Member

    Joined:
    Apr 18, 2008
    Location:
    MS Gulf Coast
    Sounds good - just be sure and use a piece of scrap hardwood behind the headstock.
  20. h8mtv

    h8mtv

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    Nov 29, 2012
    Can do. :)
  21. h8mtv

    h8mtv

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    Nov 29, 2012

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