R value for clipping diode ?

[petemoore]

  In DOD250 clipping diode scenario, 3k3 sets max gain at 'hot', otherwise the same except 27k's in V divider, 440k Vdivide to opamp resistor.
 Has Si/Si BTB clipping diodes, I want a germanium but not the full clip of it, enough to make assyemtry but not so much as Ge/Si diodes, because that drops output more than I'd like.
 What would be a 'good' starting value for a resistor series with Ge diode across the Si/Si diodes to get noticably assymetric clipping without as much volume drop.
 
  http://www.muzique.com/lab/sat2.htm
 
  I do have room for a pot, but prefer it to be a quick-fixed value, will be fine if it puts the sound in the general ballpark area of assymetric/not to low output.