I am writing a bluesy piece. I tried a 15/8 and it works great. It sounds interesting but i don't think the band will be able to play it in that time signature. I was wondering if there is a good solution to play it 15/8 live. Any ideas?
Tim's comment is great. I just wanted to add that 15/8 can also be understood as compound quintuple meter. As he pointed out it depends on the rhythmic structure of the melody and a complex time like this could be broken into several different smaller rhythmic groupings. If it turns out that the melody mostly fits into five pulses with triplet division then I would suggest practicing it as the meter I described above. If this is the case then it could be useful for your group to learn take five by the bruebeck quartet in order to solidify your familiarity with 5/4 time. It should be easier to do compound quintuple after getting good at simple quintuple and the swing of take five can justifiable give it a compound feel making for even better preparation. If you have questions about harmonizing or arranging this song for your groups instruments please feel free to contact me at firstname.lastname@example.org or find me on Facebook as Guy Gastineau. I've arranged it for solo guitar and for a four piece. It's also a great song to have in the rep to play before breaks.
The final arrangement will very much depend on the positioning of accents in the parts you have right now. As evidenced by the comments on your question, there's a number of ways to subdivide 15/8 time and the final choice will very much depend on which approach you will take.
There are several standard approaches, however, that I'd like to mention - as a jumping off point:
The 5/4 shuffle
Since it's a bluesy piece, the time signature suggests a triplet subdivision, possibly with a shuffle feel. If that is the case, the underlying rhythm can be viewed as 12/8 + 3/8 - essentially a four-beat shuffle (4/4 with triplet subdivision) with an extra beat tacked on the end.
The 10/4 shuffle
Essentially the same approach, but with a rhythm pattern that stretches for two bars of the basic time signature. It might alternatively be read as 12/8 + 12/8 + 6/8. The advantage of this approach is that the drummer can keep an alternating kick and snare every dotted quarter, which keeps the underlying beat easy enough to follow.
Depending on how the accents are distributed in the main parts, some hits may have to be moved around, but otherwise this would appear to almost be a standard even beat, so that the listener would really have to be paying attention to notice there's something strange going on. I consider this to be a benefit: overemphasis of the fact we're playing odd timings seems to me a cop-out.
The truncated 16/8
This even subdivision works out as 8/8 + 7/8 - two bars of 4/4, less an eighth note. It does require the band (especially the drummer) to be capable of playing 7/8 time.
This approach involves the rhythm section keeping a straight beat, extending over four bars of the underlying time signature. Again, accents may need some moving around, but this should feel more like syncopation than a non-standard time signature. It is equivalent to 7 bars of 4/4 (56/8) + 2/4 (4/8). As you can see, here - as in the 10/4 shuffle - the drummer can keep an alternating kick/snare pattern (this time falling on the quarter notes), whilst all the tricky compound stuff is happening over the top.
I've purposefully avoided more convoluted approaches, since you mention the band having trouble with compound time signatures. The 10/4 shuffle and straight 60/8 should be well within reach of just about any rhythm section.