Ric's Moog Filter

[Christopher List]

Hi DIY - 

I have two questions regarding the "heater" in Ric's version of the Moog ladder 
filter (schem can be found at his home page)...

1. How necessary is the LM329? Is a 6.9v zener good enough?
2. How necessary is the 500ohm trimmer in the heater - can I just add 250ohms 
to the resistors on either side? If not, how do I know when it's adjusted 
correctly?

- Thanks,
Chris