7 String spacing

[mac007]

Hi,

I am adding a G octave string to my latest OM build as per Martin's M7 Johnny Marr .

Any suggestions on spacing the nut?

EG I was thinking of marking it out as per a regular 6 string, then splitting the suggested (StewMac?) .070" between pairs (12 string) either side of the regular G location.

So it would be about 1.778/2=.89mm either side of the 'usual' single G.

I hope this makes sense.

There may be some trial and error to find the best comfortable fit.

Any suggestions appreciated

MK

BTW FWIW Martin don't seem to add an extra pin at the bridge-they just run the paired G from the same hole

[Mark McLean]

I made a 7-string like that, and have also made an 8-string with paired D strings and paired G strings (taking the idea from a Taylor baritone model which I played somewhere once).
My plan, which I won't say is the "correct" method but I have been happy with it, gives a little bit more space to the paired strings. I think if you do it as you describe (fitting the pair into the same interval that you would normally have for a single string) you will find they are not sufficiently separated from the D and B strings.

Before we talk about spacing between strings, what is your plan for the overall width of the fingerboard at the nut? I ended up with 45.3mm, which is 1 and 25/32 inches, i.e. a bit wider than most 6-strings but not as wide as your typical 12-string (often 48mm, or 1 7/8 inch).
I then placed the two E strings as I normally do (3.5mm from the edge for the bass E, 3mm in for the high e). Then I started measuring across the nut using the spacing that would be typical for a 43mm (1 and 11/16 inch) 6-string. I marked the place for the A, then D, then G - and then stoped. Now start working from the other side, measure in from the high e and mark the position for the B, then mark the position for a G measured from that. You will now have two G strings marked with a space of about 2.5mm between them.

[Mark McLean]

Your string spacing ratios at the nut will also be replicated at the saddle and bridge.
It works well to put both G strings in the same hole. You have to use an unslotted bridge pin, and cut slots in the bridge at 10 o’clock and 2 o’clock in that hole to guide the strings on different paths. It would make sense to slot all 6 holes and use unslotted pins so that they all look the same. I use slotted holes and unslotted pins for all of my instruments anyway. You can space the bridge pins evenly (and it might look odd of you don’t) - but it can help to have very slight notches in the saddle to keep the Gs and the D and B strings spaced exactly where you want them at the saddle, which might be slightly different from the straightest path to the pin hole. If that isn’t making sense I can post some pics.

What is your plan for the 7th tuner?

[mac007]

Thanks Mark,

That's really good info on locating the G pair. The tuners are from Guyker

I bought 6+1 as they sell separately.
I haven't used them before but they look cool and have a high ratio with a lock!!
FWIW the Martin M7 is quoted as having a 1 11/16" nut= 42.86mm-quite a bit narrower than yours but I haven't played one to see if it feels 'crowded' around that area.
I suspect adding a little width as you have done is not a bad idea-better to be a little wide than cramped.

My extra tuner is on the treble side of the headstock so 3+4 config.

I'm still playing with the headstock layout to make sure all the string paths are clear

Headstock.jpg (56.05 KiB) Viewed 1663 times

Thanks again

MK

[Mark McLean]

Sounds like you have got it well sorted out.
It might be a good idea to find some pictures online of the headstock and nut area of the Martin guitar and enlarge it and print it so you can take some detailed measurements of how they do the string spacing. It is interesting that they have updated an idea that was actually around in the 70s or 80s as the Roger McGuinn signature HD-7. I guess the younger generation now has never heard of the Byrds so it is a sensible marketing decision to reissue it named for a newer generation guitarist who also likes jangly sounds.

If you haven’t already done so, plot out the path that the strings will take from those tuner positions to their respective nut slots and make sure the angles are OK. Will that 4th string (the octave G) get to the nut without bumping into the post for the other G?

This is my seven string headstock. Seeing it won’t help you much because I did some unconventional things that you probably don’t want to copy - half slotted and half solid peg head, and it is fan-fret multi-scale (just for the fun of doing it, not because it is better). Also has a zero fret.

35ACF80F-7B4D-4C77-BB42-C8896EC7F7DB-592-0000001837189789.jpeg (28.18 KiB) Viewed 1652 times

[kiwigeo]

LOL.....looks like must have been some serious mind altering substances while designing that headstock!!!

[Mark McLean]

Just some of that nice stuff that comes from your neighbors in the Adelaide Hills

[mac007]

Mark-

That headstock is pure genius......