I have a Williams Blackout and Black Knight that I wanted to replace the speakers in. I looked at the manual as saw the manual calls for a 6.5 inch 8 ohm speaker. I couldn't find them from the usual pinball parts stores so I found some and replaced them. Sound is clear and better, but both of the old speakers are 4 ohm and identical. I doubt these have been replaced but maybe, do you all think it matters that the new speaker is 8 ohms and not 4? I understand over the years non original parts get substituted, but both old speakers are identical. Or, could Williams have substituted 4 ohm speakers because a supplier ran out? I'm curious what you all think and are the machines okay with the 8 ohm speakers or could I fry the sound board?