Djembe tuning


"Uncle Larry"
I have a recording studio in my house. One of my sons friends left a djembe there, and I don't think he wants it anymore. It's tuned a little low and I want to tighten it up. What is the proper way to tighten a djembe head? Someone told me to put 1" sections of dowel between the body of the drum and the tightening ropes to increase the tension. While I don't doubt that this will work, I don't know if it's the right way to do it. Is that the way it's done?