This excert is written by someone else, but as pointed out in reply's to this post, this doesn't compensate for any tempo dependant filters DDL'S and the like. But it's a neat trick.



OK, first of all, there is no way to automate tempo in Reason. It's the worst thing there is in Reason, but we have to live with it. So, we know what we don't have. But what do we have?

We can move and stretch notes without the magnet, that way we can adjust the right duration and position of every note. So theoretically it 'IS' possible to make tempo changes in the score by scaling the note durations.

This is not a nice solution, but it is the only one I could think of, and it actually works. My latest production (almost ready) had 3 tempo changes, and it sounds all great.

One thing to keep in mind, is that once we scale the notes, we have to forget the ruler, and forget the quantization.

I will explain a good trick on how to do a flawless tempo change in a song, making examples.

Say you want to have a first part in 125bpm, and a second part in 160bpm. You would start composing the first part in 125bpm. Later, you program reason's speed to 160bpm and start composing the second part (the first one should sound much more faster, but ignore that). Now this is important: complete your second part before doing the tempo change. You can switch the tempo back to 125 if you need to re-hear the first one.

Once you have both parts ready, here comes the trick. Select ALL Notes in all instruments from the second part, right click over one and click Change Events.

There is an option to scale the notes. Here comes a bit of math. You must calculate the percentage that should be multiplied to the note's position and duration. You do that by dividing in our case 125/160, and then multiplying by 100. That gives 78,13%.

If you now scale the complete second part with a value of 78,13%, and you set Reason's speed value back tot 125bpm, you will have the effect that you wanted. For the ears, the second part will be at 160bpm.

Hope that this helped you.