There are many different tunings for the guqin.
To string a qin, one traditionally had to tie a butterfly knot (shengtou jie ãÂÂ/èÂÂ头ç»ÂãÂÂ) at one end of the string, and slip the string through the twisted cord (rongkou ãÂÂ/ç»Âæ£ãÂÂ) which goes into holes at the head of the qin and then out the bottom through the tuning pegs (zhen ãÂÂ/轸ãÂÂ). The string is dragged over the bridge (yueshan ãÂÂ岳山ãÂÂ), across the surface board, over the nut (longyin ãÂÂé¾Â齦ã dragon gums) to the back of the qin, where the end is wrapped around one of two legs (fengzu ãÂÂ鳳足ã "phoenix feet" or yanzu ãÂÂéÂÂ足ã "geese feet"). Afterwards, the strings are fine tuned using the tuning pegs (sometimes, rosin is used on the part of the tuning peg that touches the qin body to stop it from slipping, especially if the qin is tuned to higher pitches). The most common tuning, "zheng diao" ãÂÂæ£調ãÂÂ, is pentatonic: 5 6 1 2 3 5 6 (which can be also played as 1 2 4 5 6 1 2) in the traditional Chinese number system or jianpu ãÂÂç°¡èÂÂ/ç®Âè°±ã (i.e. 1=do, 2=re, etc.). Today this is generally interpreted to mean C D F G A c d, but this should be considered sol la do re mi sol la, since historically the qin was not tuned to absolute pitch. In fact the same tuning can also be considered as 5 6 1 2 3 5 6 when the third string is played as do. Thus, except when accompanied by other instruments, only the pitch relations between the seven strings needs to be accurate. Other tunings are achieved by adjusting the tension of the strings using the tuning pegs at the head end. Thus manjiao diao ãÂÂæ ¢è§Â調ã ("slackened third string") gives 1 2 3 5 6 1 2 and ruibin diao ãÂÂè¤è³Â調/è¤宾è°Âã ("raised fifth string") gives 1 2 4 5 7 1 2, which is transposed to 2 3 5 6 1 2 3.
In early qin music theory, the word "diao" ãÂÂã meant both tuning and mode, but by the Qing period, "diao" meant tuning (of changing pitch) and "yin" ãÂÂã meant mode (of changing scales). Often before a piece, the tablature names the tuning and then the mode using traditional Chinese names: gong ãÂÂã (do), shang ãÂÂã (re), jiao or jue ãÂÂã (mi), zhi ãÂÂã (sol), yu ãÂÂã (la), or combinations thereof. A more modern name for tunings uses the word jun ãÂÂã to mean key or pitch of the piece, so for example, zhonglü jun ãÂÂ仲åÂÂÃ¥ÂÂã means "F key", since zhonglü is the name of the Chinese pitch which Western equivalent is "F".
There are more than 20 different tunings used in qin music, out of which only between two and four are commonly used. Some of these, however, are actually alternate names for the same tuning. A single tuning can have several different names depending on which system the composer was taught and used; an additional confusion is caused by the fact that two different tunings can share the same name. For example, huangzhong diao ãÂÂé»ÂéÂÂ調/é»ÂéÂÂè°Âã could mean either "lower first string and tighten fifth string" (e.g. Shenqi Mipu, etc.), "lower third string" (e.g. Qinxue Lianyao), or normal tuning (e.g. Mei'an Qinpu). Another potentially confusing problem is the naming of some of the tunings which may have misleading names, like the ruibin tuning. Ruibin is the name of the Chinese pitch which Western equivalent is "Fâ¯", but that note does not appear or is used in the tuning, and so it is difficult to explain the logic in the naming.
Although Chinese music is often said to be pentatonic in scale, this is not strictly accurate. In qin music, if one examines the modes and scales, one can often find many pitches beyond a pentatonic scale. Examples include pieces like "Shenren Chang" [Harmony Between Gods and Men] which uses a lot of "strange" notes not much heard in modern Chinese music. One might say that Chinese music was not truly pentatonic in the beginning, but became so because of standardisation. Thus, many of the more "popular" Chinese instruments such as the erhu, dizi, or pipa adopted more purely pentatonic scales and modes, whilst the qin which was secluded from such standardisations kept much of the old tradition of music. We can see from older, more ancient scores, such as Youlan using such rare notes; comparing that to a more modern piece one can hear the difference in tonality, scales and mode.
The qin is one of a few instruments which changes the pitch tunings in order to change the key. The qin is tuned using the tuning pegs to adjust the pitch. The method of finding to right pitch to adjust to is straight forward. One way is to tune by ear, plucking the open strings and picking out the relation differences between the strings. This method way of tuning requires a very accurate sense of pitch. The next method is by comparing open and stopped notes, by playing an open string and pressing on another string at the correct position and adjust if they sound different. This has the advantage of only needing to adjust a string to match a reference note, but has the disadvantage of open and stopped notes sounding different in tone; it can only be used for pieces without harmonics. The generally preferred way is to tune by harmonics. This is the easiest method since it only requires that two sounded harmonics are in unison. Two harmonics are sounded on two strings and the pitch can be adjusted whilst they still sound.
Below is a list of common tunings for the qin. Note that some tunings have more than one scale and names, and that the relative relations are transposed (i.e. the do note is shifted to the appropriate string) in accordance with Chinese music theory. There can be several different names for a single tuning, and some even overlap, creating confusion. The table below uses the most common name for the tuning and lists the variants.
Note: This list is not exhaustive.