mdrew, what is missing from my calculations?
for the 'as is' calculation
At the instant before tipping all of the weight will be resisted by the side that the speaker is tipping towards, so no reaction is shown on the left feet.
summing moments about point A (clockwise +):
P*(30)-56.8*(9.5/2)=0
solve for P and you get 8.99lbs
for the 'extended base' calc I just changed the equation to
p*30-56.8*((9.5/2)+4)=0
This assumes that the base extension is some kind of a point load similar to the carpet spike.
Edit: i did just realize that I used 9.5" for the width of the m80 in my calcs, not 9.25 as shown correctly in the sketch- this would of course be a 'conservative error'.
using 9.25" p changes to 8.75 and 16.33
