Mandolin: Frequently Asked Questions
 
    What is a mandolin? A mandolin is a 'floating bridge' instrument, with a scale length of around 330-350mm. It has 4 courses of paired strings. It is tuned to GDAE as is a violin. Contrary to expectations, the bridge should never be glue on!
    What is scale length? When any instrument is designed, the scale length must be decided, because upon this depends it's structure, bracing and construction. It is defined, in theory, as the distance between the bridge and the nut... the distance over which the strings will be stretched, and at half this distance, will be the 12th fret. It will be this length that determines the notes and thus the string diameters used, from which any instrument will derive its character.
    What is a compensated bridge? It is a bridge which tries to accommodate the need for slightly different scale lengths of different strings.  This is because lower strings are thicker and stiffer than the high strings, and this affects their ability to vibrate to the expected frequency. The open string is expected to behave like a perfect half-sine-wave, but because of its stiffness this behaviour isn't really reached near the bridge and near the nut for the thicker strings. To achieve optimal vibration, you need to compensate by giving the string a little more length. 

   On bouzoukis, the saddles are often slanted slightly to achieve this, but on the much shorter scale length of the mandolin, where 4 strings are wound, this does not work so well, but a compensated bridge is sometimes used. See Puglisi bridge page.
    What is a floating bridge? A floating bridge instrument is one where the strings run from the nut to the tail of the instrument, over a bridge that is not fixed... thus floating. A guitar by contrast (other than jazz guitars) normally has a fixed bridge, and the strings stop there. Thus the dynamics of a floating bridge instrument are fundamentally different... rather than the pull  of the strings on the bridge and therefore the table, found on a guitar, there is the push down as the strings cross the bridge on this group of instruments. A 'tensioner' is sometimes used behind the bridge, as on de Meglio mandolins, to increase this downward push by increasing the break angle.
    What is the problem with octave strings? With octave strings, you have a thin and a thicker string side by side. If you have the longer scale length correct for the thicker, stiffer, octave string, the thinner of the two will be over long, and all the notes be slightly flat, the more so the further up the fingerboard you go. You are now restricted to play only near the end of the fingerboard.
     What's the difference between a mandolin and mandola? A mandola is a 'floating bridge' instrument, with a scale length of around 420mm. It is normally tuned to CGDA, though the classical Italian tuning is sometimes GDAE, an octave below a mandolin, with low tension strings.. It may be played as a mandolin by playing with capo on 7th fret.... otherwise its just the same as playing the bottom 3 strings of the mandolin, with an extra lower string.
    When is it a bouzouki? An Irish (or Octave) bouzouki is a 'floating bridge' instrument, with a scale length of around 420mm. It is usually tuned to GDAD or ADAD, which tuning is particularly suited to Irish folk music. It is frequently used for chords like a guitar. It has a shorter scale length than the original Greek bouzouki, but longer than a mandola. See Tuning page for extra tunings. There is no accepted definition of what is and isnt an Irish bouzouki.... they come in a variety of scale lengths.
    What is a mandriola? Essentially, a mandriola is to the mandolin, what a 12 string is to the guitar. It is tuned as a mandolin, GDAE, but with a string an octave down on the lower side of all four courses. This does cause intonation problems up the fingerboard because of the thickness of the low-octave strings. Alternatively, it is sometimes unison tuned, with 4 courses of 3 identical strings. It has a fuller sound than a normal mandolin.
    What gauge strings do I use? The gauge depends on the scale length of the instrument, and on how it is to be tuned. Another considerations is whether you want it lightly strung, or heavily strung. Many players feel heavier strings give more volume. I feel lighter strings allow the wood to vibrate more freely, and give a better if not always louder sound. For an in depth answer, as far as it is possible to make one for each of the instruments, see the Tuning page.
    What is a 'radiused' fingerboard? A 'radiused' fingerboard has a slight, violin-like outward arc (side to side, not lengthwise) as opposed to a flat fingerboard. The feature probably was first applied to bowl-backed Roman mandolins of the late 1800s by builders like de Santis (1834-1916) and Embergher (1856-1943). It can also be typically found on fado instruments from Portugal.
   Can I change the tuning? Any instrument has a scale length, and the choice of strings is designed to produce certain notes at this scale length, without damaging the instrument. If you want to change this, to produce other notes, unless they are VERY close to the original notes, you are inevitably going to have to change the string gauges. Depending on the original notes, the strings will be either too light or too heavy..... too light and they will rattle around causing buzzes, and too heavy, they will either break before you can get to the note required, or put undue stress on the instrument. In order to find out what the new string gauges should be, you need to work with a string calculator. See links page.
   If I change the strings, do I need to change the bridge? Again, the original bridge slots should be cut to accommodate the original string choice. If you change the string choice, you will need to adjust the bridge. What you can do will depend on whether the strings are heavier or lighter than the original setup. With lighter strings, you may get away without any alterations as long as you don't get buzzes from slots that are too wide. With heavier strings you will need to widen the slots or the strings will either not sit correctly, or bind in the slot which is too small.
   How do I widen string slots? If you need to widen slots for heavier strings, and don't have a set of graduated saws.... (who has??) then you two choices. Needle files are cheap and readily available, and the various shapes can be used to widen/deepen a slot. Very fine slots can be deepened in a V shape, where the string sits at the bottom of the V. Alternatively, the new strings can be used as files, particularly if they are wound. Most strings have a certain surplus at the top end, with the bridge clamped in a vice, pull this surplus this back and forth across the slot to widen it. It will then be the perfect size for the new string. For extra help see the bridge fitting page.
   Is perfect intonation possible? this is a thorny question, because many people think there is something wrong with the instrument if intonation is not perfect for all strings on all frets. This situation has been exacerbated by electronic tuners, which shown up the slightest discrepancy in intonation. The truth is, because of varying string thickness, perfect intonation on all strings for all frets is not possible. It is always a compromise. Even if a compensated bridge is fitted, to extend the length of heavier strings, the individual frets for that string cannot be moved to suit the slightly altered length. In most instances, slight variations in intonation that show up on a sensitive electronic tuner, will not be picked up by most human ears.
   Where exactly does the bridge go? This again is not evident. I have restored many instruments which retain a 'bridge shadow' on the top, which showed that the instrument cannot ever have really been in tune other than on open strings. The bridge should stop the strings, theoretically, at twice the distance between the nut and fret 12. However, because of string thickness which inhibits vibration, its often necessary to add a couple of mm to this distance. Another factor which affects this is the playing height of the strings. With strings set higher, so needing to be stretched more to reach the fingerboard, the length may need to be marginally longer than for an instrument with a low string set-up.
   What is the ideal string height? This depends on the instrument and the style of play, and to some extent on the frets. Generally the smaller instruments should have a height of between 1-2mm at fret 12, and the longer 2-3mm at fret 12. This is measured from the fret top to the bottom of the string. Some players prefer a slightly higher string height, others lower. For fast play and a light action, on a mandolin, you need relatively low frets (...and they do vary) and a low action, perhaps as low as 1mm at fret 12. On a bouzouki, for example, a string height of 1.5mm at fret 12 gives a fairly light action. However, before you try and make the action too low..... you must absolutely check that the frets are level. If they are not, a low action will cause buzzing. Check the page on mandolin set up.