So in my band, we are working on this song which goes in 6/8. We came up With an idea where it goes from 6/8 to 4/4, but the tempo of the notes remain the same (like, The Mirror by Dream Theater.)

My question is: If my metronome for the 6/8 part is 150BPM, what tempo would I set the metronome to, so that the eight notes have the same speed?
Well, the metronome for the 6/8 should represent the dotted quarter, yes? (Three 8ths per beat)
So 150 of those beats per minute means 450 8ths per minute
4/4 time has two 8ths in each beat, so that equates to a 4/4 of 225 BPM.
six eighth notes is six eighth notes per bar.
if we stay with eighth notes then 4/4 would mean playing eight eighth notes per bar.

so divide by 6 and multiply by 8. 150/6 = 25. 25 x 8 = 200.

Oh wait I have that wrong!!!! jon is right!!! I did it backwards, it should be multiply by three then divide by four. (NOT divide then multiply)

There are three eighth notes per beat (per click of the metronome).

You want to keep the notes occupying the same amount of time but move the clicks so that they fall on every second eighth note instead of every third eighth note.

So with 3 eighth notes per click at 150 clicks per minute you will have 450 eighth notes per minute. You want a click every second eighth note so divide your 450 eighth notes per minute by two to get 225 clicks per minute - one for every two eighth notes. i.e. 225 beats per minute in 4/4 time.

Not sure what you mean by "tempo of the notes". Tempo usually refers to the primary pulse (what you tap your foot to), which usually is a 1/2 note, dotted 1/4 note, or 1/4 note.
So, in 11/8 for example, that pulse is not the 1/8th note, but the 1/4 note.

Are you playing 6/8 with a triplet feel? (these days, 6/8 doesn't necessarily imply compound time). Assuming you are using triplet, the primary pulse could either be dotted 1/4 or 1/4 note (remember that the dotted concept is primarily addressing a notational problem, not how it sounds). If the primary pulse is quarter, you could play three triplet 1/8 notes (the 3 of these together occupy the same time as would 2 1/8 notes) per beat (per primary pulse) when in 6/8 and 2 1/8 notes per beat (per primary pulse) when in 4/4.
Sorry guys, what I meant was 4/4 With triplets, into 4/4 With straight 8th notes. So the triplet 8th's and straight 8th's are played at the same speed.
Really? I've read it three times and I've read three different calculations.

OP, it really helps to visualize the problem before asking.

3 triplets is 2 eighths

150 triplets a minute? Or 150 quarter notes a minute?

For the latter, 150bpm =450 tpm = 450 epm*1b/2e=225bpm.

Else, 150tpm = 150epm*1b/2e=75bpm.
Last edited by NeoMvsEu at Sep 13, 2015,
Quote by tormod.hansen.5
Sorry guys, what I meant was 4/4 With triplets, into 4/4 With straight 8th notes. So the triplet 8th's and straight 8th's are played at the same speed.
Right. I think in that case my original answer is correct - assuming your 150 for the triplets is the speed of the beats and not the triplets themselves.

So if your 4/4 with triplets (12/8 feel) is 150 bpm, then if you want to keep your 8th notes the same value, the tempo will speed up by 50%, to 225.
You will have 450 8th notes per minute both ways.
Jon is right.

150 bpm with 3 eighth note triplets per beat
225 bpm with 2 eighth notes per beat
if you keep the value of the eighth notes constant at 450bpm
Last edited by Declan87 at Sep 13, 2015,