The Dimo gives the characteristic "sharp edge" to the sound of the Chinese Dizi. It has to be adjusted just right, not too loose, not too tight. If it's too loose, the sound will be fuzzy. If it's too tight, you won't get the sharp edge in the sound. It's definitely worth putting on, if you have a Chinese Dizi.
What’s the purpose of a dimo, can I do without it
It is the part that produces the unique sound of a Dizi. If you replace with a scorch tape, it will sound like a broken recorder.
@Ittybittyguy it won't make sound if there's nothing there. You can put a scotch tape if you do not have a dimo
The Dimo gives the characteristic "sharp edge" to the sound of the Chinese Dizi. It has to be adjusted just right, not too loose, not too tight. If it's too loose, the sound will be fuzzy. If it's too tight, you won't get the sharp edge in the sound. It's definitely worth putting on, if you have a Chinese Dizi.
What to do if i dont have a joint?
You can't tune by turning, only by digging with a carving knive (only experienced players know how to do that)