alright, heres the deal... i have this old cab my uncle gave me.. its sort of " customized " .. its a Fender BXR cab, an older model by the looks of it... he threw in an 18 inch black widow.. now my problem! only the 18" is working, and the two 10"s above it arent.. and the other thing.. the 18" speaker is distorted.. and i dunno if its blown.. it shouldnt be?... somebody once told me it was " the cross over ".. and i havent a clue what that is... and a friend told me that its this board inside the amp: here.. since im a horrible explainer...Look at the pictures.. heres a picture of the cab: ( only the bottom 18" is working) and here is a picture of the thing inside of it, that I THINK might be the problem.. what is it? can i replace it ? how much $$$ ?