Richard, Since you don't have a manual, the intensity knob is the top knob, and the threshold is the one below it. Turning these to the right increases their effect. In the previous post, you can turn the top knob all the way to the right, and turn the bottom knob gradually from its leftmost position, until you get the results indicated in Jim Bliss's post. Mary to view the list archives, go to: www.freelists.org/archives/optacon-l To unsubscribe at any time, just send a message to: optacon-l-request@xxxxxxxxxxxxx with the word "unsubscribe" (without the quotes) in the message subject. Tell your friends about the list. They can subscribe by sending a message to: optacon-l-request@xxxxxxxxxxxxx with the word "subscribe" (without the quotes) in the message subject.