Quote Originally Posted by 6L6 View Post
Neal,

Great info!

Why does the zener noise decrease with an increase in current? I'm not familiar enough with this to know about it. I will give it a go when I wire it up on stripboard.

I like the idea of the temp compensation with a 'normal' diode in the reference string as well. (Which will help trim the voltage, as I'm using a string to get to the reference voltage...)

As for the ground, the idea of putting it straight to the load is quite sound. But where would that actually be on the motor board?
Jim, the answers are in the acoustica pages. Also on the Ron Elliot site he talks about setting the current of the zener at 25% or slightly above of its rating so as to operate it at its most linear point which a 100R resistor would just about do or you could bump the current up a touch more if you felt like it.

http://sound.westhost.com/appnotes/an008.htm

Re the ground connection, I'm not sure, I don't know the circuit layout. What is the regulator powering? It maybe just fine with the original connection point.