Forum: music.stackexchange.com
Tags: <theory><rhythm><time-signatures>
Title: Triplets in 9/8 time
Question: How do eighth note  triplets work in 9/8 or 6/8 time?  I know in 4/4 they take up the space of two eighth notes but haven't been able to figure out how they work in 8.

Answers:
sents: text: I think triplets are always 2/3 of the duration of the 3 notes regardless of the meter indicated by the time signature.
text: So a triplet of quarter notes will take up the space of a half note (or two quarter notes).
text: A triplet of eighth notes will take up the space of a quarter note (or two eighth notes). ...and so on.
text: I pulled up some useful links in discussion, for further information: Counting Musical Triplets Triplets in 8-time signatures
answer_details: author: music.stackexchange.com/users/9877/Lee Kowalkowski
score: 7
sents: text: Lee is right, but there is a simpler way to think of triplets.
text: Typically we break notes up into sets of 2 (or duples).
text: For example, two half notes make a whole note, two quarter notes make a half notes, two eighth notes make a quarter note etc.
text: All a triplet is is putting 3 notes where 2 normally go.
text: So 3 eighth note triplets will always equal a quarter note or two normal eighth notes.
text: In 9/8, you only have 4 pairs of eighth notes and 1 unpaired so you cannot have a whole measure of eighth note triples.
text: You can have up to 13 eighth note triples, then you need something to take up the last 1/3 of an eighth note (aka a sixteenth note triplet).
answer_details: author: music.stackexchange.com/users/7222/Dom
score: 7
sents: text: The question has already been answered correctly by Lee and Dom, but I would like to add some pictures as clarification...
text: I don't have an example right now from an actual piece, though I'm quite sure I've seen something similar.
text: Anyway, it's not hard to come up with your own examples, so here's one which shouldn't even sound that odd: This should at least show that it is completely possible to have 8th note triplets (top staff) in 9/8 which are different from the triples (bottom staff) of 8th notes associated to the time signature.
text: You can also see how it works.
text: As has been said, you just cram 3 8th notes where two would go.
text: The following way of writing might make it easier to see: In the first beat you play three against two as usual for the first two eight notes, and then play one more eight note.
text: Of course, you can also cross beats like this:
text: This might be quite rare in general (and if the pattern continues, I would probably write the time signature for the top staff (or both staves) as (3/4)+(3/8)).
text: It is certainly not exotic compared to a lot of contemporary classical music, though.
answer_details: author: music.stackexchange.com/users/3300/nonpop
score: 6
sents: text: I suspect that there might be some confusion in the question.
text: As I see things, 6/8 is a way of notating a 2/4 rhythm whilst showing that there is a triplet beat; 9/8 is a way of notating 3/4.
text: I came to this backwards, hearing songs which I considered to be in 12/8 then discovering that they were notated in 4/4.
text: One can count songs both ways as the rhythm can be discerned on two levels: the 'outer' level having four beats to a bar, and the 'inner' level in which each beat is further subdivided into three beats (triplets).
text: 4/4 is the 'outer' rhythm and 12/8 in the 'inner' rhythm.
answer_details: author: music.stackexchange.com/users/8587/No'am Newman
score: 2
sents: text: Think of 9/8 like this: 3/8 + 3/8 + 3/8
text: So therefore 9/8 is basically a combination of 3 8th-note triplets.
text: If you want the original triplets, you will have to go for 16th-note triplets for each of the 9 8th notes.
answer_details: author: music.stackexchange.com/users/12823/Jimmy
score: 2
sents: text: I would be curious as to see a real life example as to why this would happen.
text: Time signatures at there core tell you how many beats there is in a bar and also what each beat consists of.
text: When you take 3/4 time.
text: It tells you in essence that we have three beats of crotchets.
text: If you would take this and make a compound time signature you would basically put a dot next to the groups of crotchets giving you three groups of dotted crotchets or 9/8 time.
text: If you take 3/4 and make a full bar of triplets you in essence also have nine notes but they are played slightly differently.
text: You would have three notes played in the time of two, played three times in the bar.
text: This is slightly different to 9/8 where you just have 9 quavers in each bar.
text: They should be approached slightly differently although the playing has only a slight difference between the two.
answer_details: author: music.stackexchange.com/users/7306/Neil Meyer
score: 0

Summary of the answers:
All a triplet is is putting 3 notes where 2 normally go.  In 9/8, you only have 4 pairs of eighth notes and 1 unpaired so you cannot have a whole measure of eighth note triples.  
Triplets are simply when you play three notes where two would normally be. However, since 9/8 does not have an even number of notes, you cannot have a full bar of triplets in 9/8.