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Alternative tuning变化调弦

Alternative tuning refers to any open string note arrangement other than that of standard tuning detailed above. Despite the usefulness and almost universal acceptance of standard tuning, many guitarists employ such alternative tuning arrangements in order to exploit the unique chord voicing and sonorities that result from them. Most alternative tunings necessarily change the chord shapes associated with standard tuning, which results in certain chords becoming much easier to play while others may become impossible to play.
变化调弦指的除上述标准调弦外的任何一个空弦的变化组合。虽然标准调弦用处很大，而且几乎是一个通用的标准，很多吉他手仍然用变化调弦来开发独特的和弦音及其产生的明亮音色。大部分变化调弦必需调整标准调弦有关的和弦形态，这样会产生某个和弦很容易演奏，而其他的和弦就有可能变得无法弹出来的情况。

As a standard set of guitar strings is designed to be tuned to the standard notes, alternative tunings may require not just a different tuning, but re-stringing of the guitar with strings better suited to the open string note. In turn, further adjustments to cope with the different tensions placed on the guitar may be required, and in extreme tunings, fitting different components to cope with the different gauges used.
由于吉他标准套弦都是为标准调弦音所设计的，变化调弦可能不仅仅是改变一下调弦，还可能要重新设计吉他的琴弦以使其更加适应发出空弦音。同样为了应对吉他所受的不同张力而做一些调节也是必要的，在一些极端的调弦法里，还会用到一些不同的组件来应对不同型号的弦。

Rock music tunings
Guitar tunings in rock music and metal are employed in order to make power chords easier to play and/or to make the sound "heavier".
摇滚乐调弦
在摇滚乐及金属乐中，使用此种调弦以便更容易按出强力和弦，也使得声音更有“劲”。

Dropped D: D-A-D-G-B-E'
This tuning is not only used by metal and rock bands, but also folk musicians. It allows power chords (also known as bare fifth chords) to be played with a single finger on the lowest three strings. It is also used extensively in classical guitar music and transcriptions since it allows open strings to sound the tonic and dominant as part of the bassline in the keys of D and D minor. Some guitarists choose to use a capo on the second fret with this tuning so that they can retain the ease of playing power chords without the darker sound created by the D tuning.
降 D: D-A-D-G-B-E'
此调弦不仅于金属及摇滚乐队用，民谣乐手也用它。它使强力和弦（也称横5和弦）用一根手指按在后面三根弦上就可以按出来了。它同时也在古典吉他音乐及典藉中被广泛使用，因为它可以在D大调及D小调中的低音进行中使空弦音的更浑厚有力。一些吉他手在用这个调弦时，用一个变调夹夹在第二品，这样他们可以保证强力和弦易按性的基础上，不致让音色因使用D调弦而变得黯淡。

Dropped C: C-G-C-F-A-D'
This tuning is the same as dropped D, but each string is lowered an additional whole step, or two semitones. Technically a "drop C" tuning would be C-A-d-g-b-e'. However, the tuning technically known as "Dropped D tuned down one whole step" is commonly referred to as "Dropped C" tuning, as very few people drop only the sixth string. This gives the guitar a very low and heavy sound, and usually requires extra-thick strings to maintain tension. This tuning is frequently used by hardcore and metalcore bands as well to achieve a lower sound. Tuning a standard, non-baritone guitar any lower than this is difficult.
降C： C-G-C-F-A-D'
这个调弦与降D调弦是一样的，但每根弦都多降了一个全单，即两个半音。其实降D可以是C－A－D－G－B－E。不过技术上来说，降D向下调一个全音即是降C调弦，因为很少人只是调一下第六弦。此调弦赋于吉他一个非常低且重的音色，经常要用特粗的弦来保持弦紧。此调弦常会被一些重型音乐，金属音乐的乐队所用来达到低音效果。很难将一把标准的，非低音吉他调得比这个调弦更低。

Dropped B: B-F#-B-E-G#-C#' or B-Gb-B-E-A-D' or Bb-Ab-Db-Gb-Bb-Eb
This tuning is the same as dropped D and C, but lowered from dropped C an additional semitone, or half step. This tuning is very popular with alternative metal/post-grunge bands. It has also become popular with doom metal/post-metal bands. Heavier gauge strings are required for this tuning, which may also require widening the string grooves in the nut of the guitar as well as re-adjusting the tension in the neck.
降B调弦：B-F#-B-E-G#-C#' 或 B-Gb-B-E-A-D' 或 Bb-Ab-Db-Gb-Bb-Eb
这个调弦与降D降C也是一样的，但是在降D的基础上降了半音。这个调弦在金属及前GRUNGE乐队中很受欢迎。它也在末日金属及前金属乐队中很受重用。这种调弦要用到更粗的弦，这样就需要加宽琴枕上的开槽，还要重新调节琴颈的强度。

Dropped A: A-E-A-D-F#-B or A-A-D-G-B-E'
A very low drop tuning used in metal and death metal bands. As with the Dropped B tuning, heavy gauge strings are required, and even minor modifications to some guitars. The second version (A A D G B E) has been used by Thrice in songs such as "The Earth Will Shake" and "Firebreather and Nile as their main tuning."
降A调弦A-E-A-D-F#-B 或 A-A-D-G-B-E'
金属及死亡金属用的一种很底的调弦。跟降B调弦一样，需要装特粗的弦，甚至要对吉他进行一些小的改造。Thrice在歌曲“大地震颤”及“吸火人”，“尼罗河”的主调弦中使用了这个调弦。

Eb tuning: Eb-Ab-Db-Gb-Bb-Eb'
This tuning is achieved when all the strings are flattened by a half step. This can be combined with other tuning techniques such as dropped D tuning and makes no difference to fingering. Often the key will be considered by the players as if played in standard tuning. This tuning can be used for a number of reasons: to make larger strings bend more easily, to make the tone heavier, to better suit the vocalist's range, to play with saxophone family more easily, or to play in E? pentatonic minor formed by the black keys of a keyboard.
降E调弦：此调弦是将所有的弦降一个半音。可以与其他调弦技巧如降D调弦等一同使用，在指型上不需做出变化。通常演奏者在根音上把它看作与标调一样。此调弦的使用基于以下几个原因：更好地在粗弦上推弦，加重音色，更好地适应歌手的音域，更容易与萨克斯一同演奏，弹奏键盘黑键形成的五声小调。

The tuning was made famous by Jimi Hendrix who used it extensively during his career and on all songs after Are You Experienced. Guns N' Roses also favoured E flat tunning because it allowed Axl Rose's voice to be accentuated on the high notes. It is also used by Metallica to compliment James Hetfield's voice.
因Jimi　Hendrix在其音乐生涯中大量的使用这种调弦，且在《在你经历了以后》这个曲子后所有的曲子都是用这个调弦，从而使得这个调弦声名大噪。枪与玫瑰也是用降E调弦润色，这样使得AxlRose的嗓音可以着重在高音上表现，同时Metalica也用这个调弦来衬托Gakoo的嗓音。


D tuning D-G-C-F-A-D'
Also known as "One Step Lower" and "Whole Step Down", this tuning is basically E Standard with all six strings tuned one whole step down. Although mostly utilized in heavy metal, one sometimes find this tuning in Blues, where guitarists use it to accommodate string bending.
D调弦D-G-C-F-A-D'
也称作“低两格”或“低全音”，这个调弦是在E标准调弦的基础上调低一个全音，虽然大都是重金属才使用它，有时候也可以在布鲁斯里看到这个调弦，这里吉他手用它来适应推弦。

C tuning: C-F-B?-E?-G-C'
C standard tunes the strings of the guitar to produce a low tone. This tuning is commonly used by metal and hard rock artists as it is two whole steps below standard tuning. This tuning can also be written as C-F-A?-d?-g-c'. It allows for a low, heavy sound, while still maintaining the intervals present in standard tuning.
C调弦 C-F-Bb-Eb-G-C'
C调弦将吉他的弦调出一种很低的音色。这个调弦被金属及硬摇滚的音乐人所用，它比标准调弦要低两个全音。这个调弦也可以记作：C-F-B?-E?-G-C'，它可以弹出又低又重的声音，同时又保留了标准调内部指法。

B tuning:
Also known as "B Standard" or "Baritone" tuning, this tuning is a common tuning of seven-string guitars, which are tuned B,E,A,D,G,B,E. On a six string guitar, the tuning is modified to B,E,A,D,F#,B.
B调弦，也叫“B标准调弦”或“低音调弦。这个调弦是七弦琴的一个很普遍的调弦，各弦音为B,E,A,D,G,B,E，在六弦的吉他上，这个调弦改为B,E,A,D,F#,B.
Bbtuning
Takes B Standard on either a six or seven string guitar down a semitone (or half step). For example, bands such as Nevermore of the progressive metal genre utilize this on seven string guitars. The tuning result is (from low to high) Bb, Eb, Ab, Db, Gb, Bb, Eb.
降B标准调弦在七弦或六弦琴上调低一个半音，如Nevermore的金属改革流派就在七弦琴上用这种调弦。这个调弦从低到高依次是Bb, Eb, Ab, Db, Gb, Bb, Eb.

However, on a six string guitar (from low to high) it would be Bb, Eb, Ab, Db, F, Bb.
不过在六弦的吉他上（从低到高）为：Bb, Eb, Ab, Db, F, Bb.

Miscellaneous tunings
各类杂项的调弦

全四调弦All fourths: E-A-d-g-c'-f'
This tuning is like that of the lowest four strings in standard tuning. It removes from standard tuning the irregularity of the interval of a third between the second and third strings. With regular tunings like this, chords can simply be moved down or across the fretboard, dramatically reducing the number of different finger positions that need to be memorized. The disadvantage is that not all major and minor chords can be played with all six strings at once.
这个调弦是标准调弦的四根低弦。它将标准调弦的第三弦与第二弦的不规则性去除.用这种调弦，和弦可以在指板上下左右移动，减少了和弦指型的记忆量。弊端是并非所有的大调小调都可以用这调弦按出来。



Keven Chambers' Custom Open E: E-B-e-F#-b-e
Used by Guitarist Keven Chambers this is just an alternate version of the Open E Major tuning using an F# on the fourth string instead of a G#.
Keven Chamber开放E调弦：E-B-e-F#-b-e
吉他手Keven Chamber用的一种调弦，这只是开放E大调调弦的变化调弦，在第四弦上用的是F#而不是G#


All fifths: C-G-d-a-e'-b'
This is a tuning in intervals of fifths like that of a mandolin or a violin. Has a remarkably wide range, though it is difficult to achieve (the high b" makes the first string very taut such that it will break easily), and may not play well on an acoustic guitar (the low C is too low to resonate properly in a standard guitar's body). Luthier Todd Keehn claims to have been the first guitarist to adopt an all-fifths tuning, his being arranged G-D-a-e-b'-f#', and he has made an all fifths tuned guitar that can be seen at his website, http://tkinstruments.com/. The guitar is able to intonate in this radical tuning by slanting all the frets and the nut, and allowing each string its own bridge; and thus its own scale length.
全五调弦
这是曼陀玲或小提琴常用到的音程为5的调弦。这个调弦的音域相当地宽，但是也很难达到要求（高音B使第一弦崩得非常紧，容易断）这个调弦在原声吉他上的效果也不理想（低音C太低在普通的箱琴上无法产生共鸣）据说Luthier Todd Keehn是第一个用这种调弦的吉他手，他还用 G-D-a-e-b'-f#调弦，他的全五调弦的琴可以在他的网站上看到http://tkinstruments.com/。在这个调弦里，吉他的品丝及弦枕要调成斜状，每根弦都有自身的琴桥及自身的音阶弦长。



D modal tuning: D-A-d-g-a-d' and D-A-d-a-d'-d'
Popularised by Davey Graham, who had been inspired by Arabic oud tuning while living in Morocco. D modal tuning D-A-d-g-a-d' is now encountered in Celtic music and contemporary music.
形式调弦D　D-A-d-g-a-d' and D-A-d-a-d'-d'
由Davey Graham推广起来的调弦，这个调弦是他在摩洛哥时从阿拉伯音乐调弦中得到的灵感，形式和弦D　D-A-d-g-a-d' 与赛而特音乐及现代音乐中常常可以遇到。


Another similar modal tuning is D-A-d-a-d'-d' from low to high respectively. Used by guitarist Stephen Roy, it makes chords simpler to play. Having a "dropped D" effect in the bottom bass strings makes one finger chords easier. The top two treble strings can be slightly out of tune from each other, creating a chorus double guitar kind of effect.
还有一个形式调弦是 D-A-d-a-d'-d'（从低到高），是由Stephen Roy使用，这个调弦使和弦更容易演奏。它在低音弦上有一种“降D调弦”的效果，使得和弦按起来很轻松。高音弦两根弦可以稍微走调，这样可以营造出一种双吉他合奏的效果。

Hardcore tuning: C-G-c-f-a-bb
- A rather uncommon tuning, "hardcore" tuning is used by bands of hardcore, grindcore, and even some metalcore. It much resembles dropped C tuning, except for the high strings, which, depending on what is most useful for the guitarist, are tuned one semitone (a minor second) apart. This allows the guitarist to easily create the very harsh dissonance of the minor second.
Hardcore 调弦： C-G-c-f-a-bb
这个调弦很少用，Hardcore 调弦在hardcore, grindcore, 还有一些 metalcore的乐队里会用到。这个有点像是降C调弦，但高音弦根据吉他手的需要作了一个半音的调整。这个使吉他手很容易制造出非常刺耳的不协调的小调音。



Robert Fripp's "New Standard Tuning": C-G-d-a-e'-g'
This is a tuning devised by Robert Fripp of King Crimson, used by most Guitar Craft students around the world. The tuning is similar to all fifths except the first string is dropped from b' to g'. Some guitarists maintain that the term 'New Standard Tuning' is a misnomer and consider it to be a source of controversy, but the name appears to have stuck due the absence of viable alternative designations. Time will tell whether the tuning is in fact accepted outside of GC as a viable all-purpose tuning.
Robert Fripp　新标准调弦　C-G-d-a-e'-g'
这个调弦由红王乐队Robert Fripp所创，使用者是世界各地的吉他工艺学员。这个调弦跟全五调弦类似，只不过第一弦从B降到了G。一些吉他手觉得“新标准调弦”这个称呼是用词不当，觉得这个容易导致产生争论，但是这个名字似乎就这么定下来了，因为也没有更可行的称呼。时间会证明这个调弦是否真的能在吉他工艺学员外找到一席之地。

Billy Corgan's "Mayonaise" tuning: Eb, Ab, Ab, Gb, Bb, D
Corgan utilizes this unique tuning on Mayonnaise. The A is raised by a half step, while the D is lowered by 2 whole steps. This allows for Corgan to play the chord formations with all strings being played.
Billy　Corgan的“蛋黄酱”调弦　Eb, Ab, Ab, Gb, Bb, D
Corgan在蛋黄酱这个曲子上使用了此独特的调弦。A升半音，而D降两全音，这样使得Corgan能用到所有的弦弹奏和弦。

[edit] John Rzeznik's "Iris" tuning: B-D-d-d-d'-d'
John Rzeznik of the rock band Goo Goo Dolls uses this tuning on the studio recorded version of his song Iris, an international hit featured on the soundtrack of City Of Angels. It creates a very shimmer-like ringing sound similar to a twelve string guitar. To tune to this tuning on a standard six string guitar the low E string is lowered to a B; the A string is lowered to a D, the D string is left the same, the G string is lowered to a D, the B string is raised to a D, and the high E string is lowered to a D. On some guitars this may require obtaining a thicker low E string than is usual to obtain a full sound when tuned down to B, and avoid the string slapping the fret board.
John Rzeznik的IRIS调弦：B-D-d-d-d'-d'
摇滚乐队Goo Goo Dolls的John Rzeznik，用这个调弦在录音棚录制了Iris这首歌，这首歌是天使之城这张专辑里的主打歌，在国际上取得很大的反响。它营造了一种像十二弦琴那样的铃一般清脆的音色。在一般吉他上调这个调弦低音E要调低成B，A弦调低成D，D弦保留，G弦调低成D，B弦调高到D，*高弦E调低到D。在一些吉他上可能要用一根粗的E弦，这样它调到B时可以得到一个很充分的音色而不会使弦打品。

John Rzeznik uses a different tuning for an acoustic version of "Iris", tuned at D-A-d-g-b'-d'. This allows the above song to be played solo with an acoustic guitar and to retain a fuller sound than is achievable with the B-D-d-d-d-d tuning. Yet this tuning also retains a slight ringing sound due to three strings being tuned to D, the piece being in the key of D major.
John Rzeznik在原声版的Iris上使用了另一个调弦， D-A-d-g-b'-d'，　这使得这个曲子可以用原声吉他独奏而仍能保持 B-D-d-d-d-d上很充分的音色。然而因为三根弦都调成D，这个调弦在弹D大调曲子时，也保持了微微有铃般的音色。

John Rzeznik's song "Black Balloon" is tuned at Db-Ab-Db-Ab-Db-Db. The song can also be played as Db-Ab-Db-Db-Db-Db, although it won't sound the same.
John Rzeznik的Black Balloon黑气球这首歌，调弦为Db-Ab-Db-Ab-Db-Db。虽然它听起来会不一样，这首歌也可以用Db-Ab-Db-Db-Db-Db,弹奏。

Complete range of string pitch combinations
Each of the six strings can be alternately tuned as low as a whole step lower and as much as a whole step higher without stressing the neck or the strings. With five possible tunings for each string (+2, +1, 0, -1, and -2), there are as many as 15,625 possible tunings for a six-string guitar.
弦音高组合音域
六根弦的每一根弦在降低一个全音，或升高一个全音情况下不会增加琴颈及琴弦的受力。每根弦可以有5个音高（+2, +1, 0, -1,  -2）来算，一把六弦琴可以有15,625个调弦。


A standard guitar sounds one octave below pitch as written in standard notation. That is, the first string in standard tuning plays the E note that is a major third above middle C, and is written on the staff as a major tenth above middle C.
一把标准吉他实际音高比谱面低一个八度。这就意味着，标准调弦的第一弦的E音是中音C调第三音，在谱面记的则是中音C调第10个音。


There are also tenor guitars, baritone guitars tuned BEADF?B (or ADGCEA, GDGCDG, GDGCEA, GCGCEG, etc.) a fourth lower than a standard (prime) guitar, treble guitars tuned a fourth higher than a prime guitar and contrabass guitars, which are tuned one octave lower than prime guitars. Seven-string guitars have an extra low string which is a B in standard tuning.
也有高音吉他，低音吉他用BEADF?B (或 ADGCEA, GDGCDG, GDGCEA, GCGCEG, 等)。比标准吉他低四度，高音吉他比普通吉他高四度，而超低音吉他则比普通吉他低一个八度。七弦琴有一根特低弦，在标准调弦里是B音。

To compensate for string stretching when played, intonation or string length tuning can be done by tuning the seventh fret notes to the seventh fret harmonic pitches for each string. The seventh fret harmonics pitch should match the fundamental frequency of the open string notes.
为了弥补弹奏时的琴弦拉伸，可以将每弦第七品音调到第七品泛音音高。第七品泛音音高应与基本的空弦音一致。

Classical guitar tunings古典吉他调弦

The classical guitar developed over a period of 500 years and a number of guitar tunings are commonly used this genre, some based upon historical practice. Unlike other musical styles, in which alternative tunings are used by artists largely as a matter of individual preference, in classical guitar styles, the decision to employ alternative tunings largely resides with composers or arrangers of musical transcriptions. Thus, classical guitarists performing known transcriptions are assumed to be using defined tunings.
古典吉他调弦，古典吉他发展了500个年头，在这个流派中，很多吉他调弦被普遍使用，一些是惯例的做法。与其他的音乐风格不一样的是，这里的变化调弦的使用只是音乐家个人的喜好所致，在古典吉他风格中，是否要用到变化调弦大多取决于作曲者或改编者的谱稿。因些古典吉他手在演奏知名的谱子时，要用谱子所标的调弦。

Renaissance lute tuning: E-A-d-fb-b-e'
This tuning may also be used with a capo at the third fret to match the common lute pitch: G-c-f-a-d'-g'. This tuning also matches standard vihuela tuning and is often employed in classical guitar transcriptions of music written for those instruments.
文艺复兴时鲁特琴调弦：
这个调弦常常在第三品夹个变调夹来与普通的鲁特琴调弦G-c-f-a-d'-g'相匹配。这个调弦也与比尤埃拉琴(西班牙文艺复兴时期的第一种弹拨乐器)相搭配，常常在古典吉他专门为这种乐器所写的手稿中可以看到这个调弦。

"Pseudo Russian" or "g" tuning: D-G-d-g-b-e'
A versatile tuning examples of which can be heard in Choro de Saudade by Agustín Barrios and also in well known transcriptions of La Maja de Goya by Enrique Granados and Sevilla by Isaac Albéniz.
“伪俄式”即G调弦D-G-d-g-b-e'
在Agustín Barrios的Choro de Saudade中可以看到这个调弦的多样化性能，众所周知在Enrique Granados 的La Maja de Goya及Isaac Albéniz的Sevilla曲谱里也用这样的调弦。

Open tunings　　开放式调弦

In guitar playing, an open tuning is one where the strings are tuned so that a chord is achieved without fretting, or pressing any of the strings. With such a tuning, other chords may be played by simply barring a fret or through the use of a slide.
在吉他演奏中，开放式调弦是将各弦调成一个和弦，这样就不需按弦就可以弹出来。在这种调弦下，其他的和弦只要在指板上来回滑动横按就可以了。


Open tunings are common in blues music and some rock and folk music. They are particularly used in steel guitar and bottleneck guitar playing. The names of some tunings vary between genres, for example in Hawaiian Music, for slack-key guitar, an example would be the taro patch, or open G tuning, with strings low-high D-G-D-G-B-D. But in bluegrass music, open G can mean G B D G B D.
开放式调弦常在布鲁斯音乐中，及一些摇滚，民谣中使用。特别是在钢弦吉他及滑棒吉他上，经常都会用到这种调弦。一些调弦的名称会因流派不同而有不同的叫法，比如夏威夷音乐，对于slack key吉他来说，开放G调弦是（低－高）：D-G-D-G-B-D，但是布鲁斯乐中，开放G是G B D G B D。

知名的演奏家包括Kim Thayil, Robert Johnson, Mark Tremonti, Bukka White, Skip James, Nick Drake, Jack White, Nic Jones, John Fahey, Bob Dylan, Alexander Rosenbaum, Keith Richards, Duane Allman, Lowell George, Mick Taylor, Ry Cooder, Richard Thompson, Martin Carthy, John Martyn, Blind Blake, Leo Kottke, Richie Havens, Joni Mitchell, Jonatha Brooke, Mark Kozelek, Michael Hedges, Ted Hawkins, Jimmy Page, Rod Price, Alan Sparhawk, Barry Gibb, Joe Walsh, John Butler, Derek Trucks, Kevin Shields, Sonic Youth, Pete Bexley, Ricky Wilson, Keith Strickland, Devin Townsend, Dan Auerbach, Ani DiFranco, Don Ross, Johnny Marr, Rich Robinson, John5, Jimmie Spheeris and John Rzeznik，　都用开放式调弦。

Examples
例子：
[edit] Major tunings主要调弦
Major open tunings (giving a major chord with the open strings) include:
大调开放式调弦包括：
开放 A: 低-高; E-A-C#-E-A-E
也可以是: 低-高; E-A-C#-E-A-C#
"滑音" 开放 A: 低-高; E-A-E-A-C#-E (注意这个调弦跟开放G类似，只是每弦升高一个全音，即两品)
开放 C: 低-高; C-G-C-G-C-E
开放 D: 低-高; D-A-D-F#-A-D
也可以是: 低-高; D-A-D'-A'-D-D
开放 E: 低-高; E-B-E-G#-B-E (用细型弦，因为三根弦均需要升高)
开放 F: 低-高; F-A-C-F-C-F (少用)
升F调弦 低-高; F#-A#-C#-F#-C#-F#( 只有Curtis Mayfield用此调弦)
开放 G: 低-高; D-G-D-G-B-D
dobro 开放 G: 低-高; G-B-D-G-B-D (普通吉他偶尔会用到，但第五、六弦要细弦，只用方形琴才能受得了标准弦的张力。 but requires lighter fifth and sixth strings; Only square-necked resonator guitars can hold this tuning with standard gauges).
俄式开放 G: 低-高; D-G-B-D-G-B-D (俄式七弦琴的标准调弦).

Open tunings versus altered tunings
Generally, Open Tunings refer to the changing of string pitches to reproduce common Major and Minor chords. One might consider broadening this definition to include more obscure or less used tonalities / chords such as the ones listed below. But these are in kind of a "middle ground" between standard Open Tunings and Altered Tunings. Altered tunings are tunings that don't really reflect any specific chord name. An example would be the tuning Jimmy Page uses on Led Zeppelin's Rain Song (D,G,C,G,C,D). Even though some tunings could be named by "theory" they might lack the gravity or musical cohesion to really represent that chord.
开放式与变化调弦对比。
总的来说，开放式调弦指的是将弦的音高改变，来达到大调及小调和弦的效果。你可以将这个定义用在像下面列出的更模糊或者更少用的音调及和弦上。但这些调弦是一种介于开放式调弦与变化调弦之间的调弦。变化调弦是指空弦音无法构成一组和弦的调弦，典型的一个例子就是Jimmy Page在Led Zeppelin的 Rain Song上用的D,G,C,G,C,D调弦。就算有些调弦可以在理论命名，但它们很可能会缺乏这个和弦所具有的一种凝力或者说是音乐相关性。

Crossnote tunings
The above open tunings all give a major chord with open strings. Since it is highly likely guitarists will need to play minor chords as well, open tunings must be adapted to allow this by lowering the pitch of one of the strings forming the open chord by half a step. To avoid the relatively cumbersome designation "open D minor", "open C minor", such tunings are sometimes called "crossnote tunings". The term also expresses the fact that, by fretting the lowered string at the first fret, it is possible to produce a major chord very easily.
上述的开放调弦的空弦音都是一个大调和弦。因为吉他手也要弹小调，开放调弦要将其中某根弦调低，形成一个小调开放调弦来演奏。为了不必“开放D小调”，“开放C小调”的这种相对繁琐的称呼，这些调弦有时被叫做“共音调弦crossnote tunings”。这个术语本身也反映了一个事实，那就是在第一品按住被调低的那根弦，就可以轻松按出一个大调和弦。
注：1 3 5是大调，1  b3  5是小调。　所以只要把调弦中的3调低半音就是小调。

Crossnote tunings include
共音调弦包含：
共音 A: 低－高; E-A-E-A-C-E
也可以是: E-A-C-E-A-E (rare)
共音 C: 低－高; C-G-C-G-C-Eb
开放 D: 低－高; D-A-D-F-A-D
共音 E: 低－高; E-B-E-G-B-E
共音 F: 低－高; F-Ab-C-F-C-F (非常少见)
也可以是: 低－高; F-C-F-Ab-C-F (Albert Collins用过; 要用特细弦）
共音 G: 低－高; D-G-D-G-Bb-D

Modal tunings 形式调弦
Sometimes a guitarist will want a tuning that will permit very easy chords but not be definitively minor or major. In this case, modal tunings can be used. They can be especially effective with droning open strings, and give "suspended" second or fourth chords:
有时吉他手要按和弦方便，但又不一定要小调或大调，这时就可以用形式调弦。在常用的空弦音的时候它很有用，可以形成一个挂留二或四和弦。

Modal tunings include:
形式和弦包括了
Asus2: 低－高; E-A-B-E-A-E
Asus4: 低－高; E-A-D-E-A-E
C6: low-high; C-A-C-G-C-E
Csus2: 低－高; C-G-C-G-C-D
Csus4: 低－高; C-G-C-G-C-F
Dsus2: 低－高; D-A-D-E-A-D
Dsus4: 低－高; D-A-D-G-A-D
Esus2: 低－高; E-A-E-F#-B-E
Esus4: 低－高; E-A-E-A-B-E
G6: 低－高; D-G-D-G-B-E
Gsus2: 低－高; D-G-D-G-A-D
Gsus4: 低－高; D-G-D-G-C-D


"Extended chord" tunings扩展和弦调弦
These tunings allow a guitarist to play an open seventh, ninth, eleventh or thirteenth chord. One or more of the strings is retuned to the appropriate note of the required scale. Such tunings may be either minor or major.
这些调弦可以让吉他手弹出开放七，九，十一，或十三和弦。其中一根或几根弦要调到音阶上所需音。这种调弦可以是大调，也可以是小调。

Examples are:
Open Dmaj7:低－高; D-A-D-F#-A-C#
Open Dmin7: 低－高; D-A-D-F-A-C
Open Emin7: ; E-B-D-G-B-E (5弦要用细弦)
Open G6: ; D-G-D-G-B-E
Dobro open G6: ; G-B-D-G-B-E  
Open Gmaj7:
D-G-D-G-B-F
D-G-D-F-B-D
F-G-D-G-B-D
Open Gmaj7: D-G-D-F#-B-D  
"Modal" G7: ; F-G-D-G-C-D
"Open G6min7":; F-G-D-G-B-E
Open Cmin7:  C-G-C-G-Bb-Eb
Open Cmaj7:  C-G-C-G-B-E
。。。。。。。。。。。
这个例子是举不尽的


These open tunings offer much room for experiment, but can only be used in a few keys.
这些调弦为音乐试验带来更大的空间，但只有一两个可以用。

Steel guitar　钢吉他
On table steel guitar and pedal steel guitar, the most common tunings are the extended-chord C6 tuning and E9 tuning, sometimes known as the Texas and Nashville tunings respectively. On a multiple-neck instrument, the near neck will normally be some form of C6, and the next closest neck E9.
在板式电子吉他及踏板电吉他上，*常用的调弦是扩展和弦C6的调弦及E9调弦，有时叫作德克萨斯及纳什维尔调弦。在多头琴上，一根琴颈通常用C6，而另一根则用E9。

Noted country player Junior Brown plays his trademark Guit-Steel in a C13 tuning, which is a C6 Chord with an added 7th above the high A (the Steel has 5 strings instead of a pedal's 7)
知名的乡村乐手小布朗的招牌guit-steel钢吉他用的是C13调弦，这个调弦就是用C6和弦外加一个第7音A（钢吉他只有五弦，而不是踏板有七弦）

Necks with 12 or more strings can be used with universal tunings which combine the features of C6 and E9. On a 12 string pedal steel guitar, all 12 strings are tuned and played individually, not as 6 double courses as on the 12 string guitar.
十二弦的吉他可以将通用的调弦与C6，E9合起来一起用。在12弦的踏板电吉他上，所有的的12弦都是独立调音弹奏，而不是用12弦琴那种两两相应地调弦方式。