Metronome settings for 6/8

Question

I am playing a piece that has 6/8 as the time signature. The tempo is Allegro.

I have adjusted my metronome app's setting as below (120 bpm and 6 eighth note beats per measure). Is this correct?

Answer 1

You can use a metronome in a lot of ways; it's not really a matter of "correct." But the short answer is "this probably isn't what you want."

6/8 is a somewhat problematic time signature. The over-simplified explanation of time signature that we often learn first is "the top number tells you how many beats are in the measure; the bottom number tells you what kind of note gets the beat." Thus 3/4 is three quarter note beats. This works fine for bottom numbers of 2, 4, 8, etc. These are “simple meters”; each beat can be felt to contain two smaller notes inside it, like the two eighth notes inside a quarter-note beat (and more multiples of two inside those). But 6/8 is a "compound meter"; that is, what we "feel" as the beat, or what a conductor is likely to wave their arm to, is actually a group of three eighth notes. In other words, 6/8 usually has only two big beats per measure, and each beat is three eighth notes long, or the same as a dotted quarter. (If you ask why we use such a confusing system, it's because a note "three eighth notes long" is hard to indicate as a bottom number.)

So while it's true that 120 might be a good "Allegro" tempo, maybe a bit on the low side, you probably want only two of those beats per measure, and then should subdivide that into three in your head to represent eighth notes. Also, "Allegro" is a range. It literally just means "happy." So figure out what "feels right" to you for a given piece, what feels fast and lively but not holy-crap speedy. It’s common to find pieces for which the tempo that “feels right“ for the musical material lies outside the “official“ bpm range for its tempo marking (this is even more common in pieces from before the metronome was invented!).

Now, all that could be useful if your goal is to know how the piece should be played. If you're using the metronome as a practice tool, none of that matters if you can't play the piece that fast. Set it to something slower, maybe 60 instead of 120 for the dotted quarter beat, and increase gradually. There’s also nothing that says that, for practice, you have to set the metronome to the value of the true “beat.“ If you’re practicing very slowly, say if a dotted quarter is 50, it might be easier to actually set the metronome to equal the eighth note subdivisions. But you would multiply by three, not two, and set it at 150.

Also, I personally hate using metronome settings that make different sounds for different beats. If I'm practicing in 4/4 at 60, and the metronome makes a higher "ding" every four beats, and I mess up a note, then I have to stop and wait for four seconds before I can go on, to be on the proper beat. And it's very easy to get off and just ignore the fact that the "ding" now falls on the second beat, or the third, and if you're ignoring it, why use it in the first place? I find it much more helpful to just set it to one identical sound for all beats.

Answer 2

Allegro on one of my metronomes is 120 - 168 bpm. Another is 152 - 178. It's only a vague guide to tempo, giving the player some leeway. Merry, quick, lively, bright. So its interpretation is quite wide.

The problem with 6/8 is that it's compound rather than the simple 3/4, or 4/4. So, as Andy says, the metronome can be set in various ways to accommodate the 'beats'.

You've set it at 120bpm. That's the low end of allegro. I'd equate each click as one quaver, there being six in each bar. Far too slow for a performance, but not at all bad for learning the piece. At 120, the actual performance is three times faster - as in three quavers per beat, two clicks per bar, or if you like, pretty damned fast.

Basic use of any metronome is to keep time regularly, not fluctuating faster or slower. I'd advocate setting the metronome at 210/220 bpm, if you want to build up speed while learning the piece, with the possibility of a ping on the first of each three clicks. You could then drop the tempo to, say, around 60 for performance level, equating to one click per bar, if you're brave!

Answer 3

6/8 is a 'compound' time signature. What we need to know here is that it indicates two beats in the bar, each beat consisting of three 8th notes.

When playing a piece in 2/4 you would set two metronome clicks to the bar. Yes, each quarter note can be divided into a pair of 8ths, but we set our count to the quarter notes.

Same idea in 6/8. The beats are dotted quarter notes. Yes, each can divide into three 8ths, but we click the beats, not the subdivisions.

Set your metronome to something in the 120-160 range, as appropriate for this piece of music.

If you wanted to do very slow, meticulous practice you could certainly 'count' 8ths instead, whether the piece was in 2/4, 6/8 or anything else. It might help you decipher the rhythms. But to PLAY a piece in 6/8, count 2-in-the-bar. And 'Allegro' applies to that 2-count, not to the 8ths subdivisions.