I think all of you know that the chime units on Williams EM machines are a bit lacking in sound quality. Sure you can tune them up a bit with a rebuild kit, but they never seem to sound correct (ear pleasing) to me. I dug in to this a bit and found couple reasons why their chimes are below most peoples standards. First (and foremost) is the lack of tuned resonation chambers under the chime bars to give the tone a long lasting sound. The plastic catch-all bucket underneath (even though it helps) just doesn't cut it. Each bar should have its own resonation chamber below it that is sized to the frequency of the bar. Gottlieb had the correct idea on this issue (probably why their chimes sound the best by most peoples standards). The second applies to all of the big three during the EM period. The first fundament frequency (and the loudest) of a rectangular metal bar (like a chime bar) has two nodes (places on the bar that basically have no movement during the ringing). These nodes are located at approximately 22.4% from each end of the bar. Ideally that's where your two hold down points should be to maximize the tone amplitude of each bar when struck by the (plastic tip) solenoid plunger. All three manufacturers use some sort of rectangular frame to mount the three chime bars which provides the same hold down spacing for all three chime bars. If you measure the distance from the bar ends to the hold down points, you will most likely find that they tuned the center bar correctly at the 22.4% node points (that's why the middle one sound the best). The outboard bars (smallest and largest) are compromised by have their hold down nodes not at the optimum location. I understand from a manufacturing standpoint this probably the way to go, but if anyone out there likes to work with sheet metal and can bend up a non square frame (or build some kind of adaptor) to locate all three bars at the correct node points, just use the 22.4% rule from each end and you will have a better sounding unit. Also, this approach requires you to make two new chime bars (the small and large ones) with the correctly calculated node spacing. Aluminum works well and it's also easier to cut than steel. Let me know if you found this post helpful. I'm currently drawing up a new frame design for my Williams Travel Time EM along with running some resonation chamber calculations. Thanks and keep your playfields waxed kids.