string calculations help!

[fluxman]

Hello,

I have a cheap octave mandolin (to avoid any confusion that's the one tuned an octave down from a normal mandolin haha) that I want to convert to a Mandola (tuned a 5th down from a mandolin, CGDA).

Currently, I think I have gauge 12 (E string), which are quite floppy, but are far too tight when I start to attempt to tune it up to CGDA.

The scale length of the instrument is about 512mm (20.16"), so I need to know what gauges strings will be suitable. Most mandolin strings I find are more than long enough to fit my octave mandolin, and so I assume a standard set of Mandola strings would also be long enough also (but I assume quite tight when tuned up!).

Is there any magic formula to figure out a suitable set of strings (I expect to have to buy strings individually, so it's no problem).

Since the top string needs to be the same "A" as the "A" on a mandolin, I suppose I could use a guage 10 mandolin E string as the A string maybe?
One thing I could do is Turn the current D string into a C (by tuning down 2 notes), the current A into a G, and the current E into a D (which would be quite floppy, but playable) and then affix a mandolin E string as the A string.

Thanks for any help!

[JEStanek]

You could just put a capo on the 5th fret. That might resolve the string issues.

Jamie

[EdHanrahan]

I'd capo a guitar at the fret close to 20" (guessing the 4th?) and see which strings can be reasonably tuned to the notes that you need. Assuming that some are too tight or too loose, you should still be able to interpolate between them to find the workable gauge for that note at a 20" scale. A 12-string would give even more options.

[Tavy]

I ran this through the string tension calculator here and came up with:

len 512mm

A 20# PL == 0.0105"
D 20# PL == 0.0158"
G, 23# PB == 0.0265"
C, 23# PB == 0.0394"

So basically a standard set of medium mandolin (.010-.040) strings should be somewhere close, after that you're just fine tuning the tensions if those turn out a touch floppy/hard.

You definitley don't want a mandola string set as those are designed for much shorter scales (usually 15inches or so).

HTH, John.

[fluxman]

Thanks for your replies guys (@JEStanek, I could use a capo, but some of the mandola parts I want to play involve frets 12-15, which would be easy to play on a mandola, but quite tricky on my cheap octave mandolin as they would be frets 17-20 haha).

I swapped the strings down the neck (so that the D was where the G was, A was where the D was etc, then tuned down 2 notes..which gave me CGD...then I used a mandolin E string (gauge 11) as an A string..which is a little on the taught side, but works well..the other strings are lose, but the sound is acceptable).
(Although, I had to losen the truss rod a far bit, and stick some card between the G string and the nut groove.)

So that's 011, 014, 022w, 036w

which is pretty close to your calculations, Tavy, and as mine are quite lose, and the 11 is too tight, 10.5, 16, 27, 39 will probably be perfect (good job!).

That's actually quite convenient - if you want to convert a cheap octave mandolin into a mandola, it's actually pretty easy (just buy some standard mando strings)....or you could just buy a mandola i suppose....

[fluxman]

Yup, just put a set of J74's on (11-40) and they work really well, nice sound.

[mandroid]

H scale, shorter, .4M. mandola, I'm using Light OM strings 12,22,32,44 [6 wound] GHS PF285..
same pitch on a longer scale would be lower tension..


.. the pitch set you seek is between OM, and mandolin, the 3 higher strings are the same pitch as a mandolin
only the C is an octave below middle C, middle C is 5th fret note, on the G string..