Upgrading System 11 speakers

Steps

• The backbox has a 3.5 in round and a 4 x 10 in oval speaker; replace both with a pair of 4 in, 4 ohm two-way coaxial speakers rated 25 W RMS or more.
• Mount both 4 in speakers in the 4 x 10 opening using two of its original screws and two 1/4 in drive screws; leave the 3.5 in hole unused.
• Check the coaxial tweeter does not stand proud of the cone and hit the grille; add spacers if it does.
• The 6.5 in cabinet speaker must stay 8 ohms; any 25 W RMS replacement, ideally coaxial, is an improvement.

Systems

• Williams System 11
• Williams System 11A
• Williams System 11B
• Williams System 11C

Related tips

• How System 11 makes sound
• Which System 11 sound board each game uses
• Using a D-11581 sound board in other System 11 games

Source: Repairing Williams System 11 Pinball 1986 to 1990, Part Three, Clay Harrell