Yeah totally get that as I think I said in the video, it’s a preference thing.
You’ll see in the next video how I approach orchestration, but essentially your not only thinking of register, but your also thinking about timbre and how that sound is going to reinforce the sound already.
I think the reinforcement thing is especially important. The science behind it is that each instrument will produce the same notes… but the reason they sound different is because they produce different harmonic variants after the fundamental. So a good example of “bad ish” reinforcement would be to pair two instruments with similar harmonic content… this would mainly just make the sound louder. But when you pair two very contrasting instruments together you get it louder, but the stereo field widens, the range broadens and you also get harmonic excitement from mixing the sounds with the bud reverb, making the sound thicker.
Bad doubling might be using two types of flutes for example. You’d just get a louder and possibly fatter sound… but the part would still be masked by the rest of the orchestra. This is why flutes are often doubled by either clarinets or oboes, because the harmonics are opposing and that means that the top end cuts through more… making the instruments more complimentary.
Then you’ll also have typical doubling s such as bass instruments, melodies and tuned percussion. These are the straightforward orchestration techniques.
There’s literally so much you can talk about with orchestration so I’ll be coming back to this over and over, just to show as much as I can.