Re: calf skin heads
Stern Tanning is the place for calf heads, they're in Chicagoland somewhere. Always see them at the Chicago Show.
I looked up Earth Tone, they boast "genuine skin" which means not calf. I'm pretty sure one of the guys with the company said goat. Also, they mount them in a standard metal hoop. Traditional calf heads are wrapped/tucked onto a wood hoop (also known as a flesh hoop.) Again, not sure if that makes a difference in the sound or mounting.