Need help with Sonicator

[Toumy Guettouche]

Hi Folks,

I am trying to follow a protocol that calls for the following sonication 
values: 2X5s pulses of sonication at 25% full energy (55 milliwatts) with 
30s of chilling between pulses in an ice/ethanol bath using a model W220 
ultrasonic cell disruptor from Heat Systems (now Misonix Corp.).
Taking my limited knowledge of sonicators into account I suppose that the 
55milliwatts in the protocol above are a typo and it should really state 
55 watts(given the 25%full energy statement).
Now, my problem is that I have a Misonix Model XL2007 Sonicator. It has a 
power output of 100Watts and a power setting from 0 to 20. I suppose 
that a setting of 1 corresponds to 5 watts using a Microtip. 
So, I guess to get a power output of 55watts, I should use setting 11, 
right?
Unfortunately, the company was not very helpful in resolving this 
matter, so I would appreciate any help from you.
Thanks in advance

Toumy