Speaker Replacement
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Tony's Do-It-Yourself Guide to
Speaker Replacement on WPC-Era
Bally/Williams Pinball Machines

Last updated: November 25, 2005


It's a commonly accepted fact that the stock speakers used in WPC-era Bally and Williams pinball machines don't do justice to the audio tracks the sound systems in those machines can actually reproduce. Many pinball collectors choose to upgrade the stock speakers for improved sound quality. Speaker replacement kits are available for purchase from Pinball Pro, and many collectors have commented favorably on the performance of these kits.

These speaker replacement kits offer a great deal of convenience. However, that convenience comes at a cost: the seller has overhead, labor costs, and deserves to make a profit for their efforts, so the $65 subwoofer upgrade kit obviously can't contain a $50 speaker. If you have several games and want to upgrade the speakers in all of them you're looking at a sizeable investment.

If you don't mind spending a little time purchasing the individual component parts you need, and if you're moderately handy with tools, you can save money and wind up with an installation that sounds at least as good as the pre-packaged replacements. This do-it-yourself guide will give you the basic information you need to choose replacement components, some suggestions for components that I've found to work well, and the step-by-step instructions to install your new speaker system. 

The information in this guide was developed over the course of more than a year, and is based on my personal experience restoring games for my own use and for sale. I sincerely hope you find it useful! Feedback, comments, and suggestions for improvement are most welcome; please send them to tony@dziedzic.us.

Joseph "Tony" Dziedzic
January 2005

Our Goals

First, let's make one thing clear: We are not trying to turn a pinball machine into a high-fidelity speaker system. We are trying to improve the quality of the sound produced by the machine's sound system. We can do this in two ways:

  1. Replace the back box speakers with wide-range units for cleaner and more balanced sound

  2. Replace the cabinet speaker with a woofer to add additional bass response

We are limited in some ways by the physical environment with which we're dealing. A pinball machine cabinet would never make a great subwoofer enclosure: the volume is too large for the size of speaker we can reasonably use, and the cabinet can't be sealed or vented for a flat response curve. Regardless, we'll still be able to vastly improve the sound quality over the stock speaker system.

This guide does not discuss any of the esoteric schemes that the dedicated audiophile might try, such as tapping the line-level output of the sound board and running the output to active crossover networks, high-power amplifiers, and carefully selected speakers. If you're that crazy you don't need this guide anyway!

Intended Audience

This guide is written for the pinball collector who would like to improve the sound quality of their Bally / Williams WPC-era pinball machine and is comfortable using power tools. You should know how to use a jig or sabre saw, a drill, a circular saw or table saw, and a router. You don't have to be a Yankee craftsman and you don't need a tool collection that fills a barn to be successful. On the electronics front, if you can strip wire, solder wires to terminals, and crimp connector pins onto wires you're all set.

Standard Disclaimers

The material in this guide is provided for informational purposes only. If you choose to use this information you do so with the understanding that you are solely responsible for any personal injury or property damage that may result. You should read the entire guide before beginning any modifications to your game.

This material is copyrighted, and may not be copied or reproduced without written consent. You are of course welcome to print a copy for your personal use!

Safety tip: Wear eye protection when using power tools!


I've made the assumption that the avid pinball collector will choose to replace the back box speakers and the cabinet speaker: this guide is written with that assumption in mind. Replacing all three speakers is the best way to improve the overall sound reproduction quality. I've also included enough information that you can be successful should you choose to replace only the back box speakers or the cabinet speaker.

This guide is divided into a number of sections for easier reference. The best method is to proceed through the guide by clicking on the NEXT links at the bottom of each page. The HOME link will bring you back to this page.

The "how to choose and what to buy" sections:

bulletChoosing Replacement Speakers - what to consider when choosing replacement speakers, plus some recommended models
bulletLevel Controls and Crossovers - you'll need more than speakers for best sound

The "tools and supplies" section:

bulletTools and Supplies - the hand and power tools needed to pull this off, along with a list of all component parts discussed in this guide

The "how to do it" sections:

bulletPreparing for Replacement - a summary of what we'll be doing in the sections to follow
bulletBack Box Speaker Replacement - how to replace the back box speakers
bullet Cabinet Speaker Replacement - how to replace the cabinet speaker
bulletWiring Replacement Speakers - how to wire it all together
bulletFinishing Up - final re-assembly, testing, and adjustments

The "how it works" section:

bulletWPC-era Sound System Information - differences between the sound systems used in WPC-era games, wiring diagrams, etc.

Resources, Web page links, and other useful stuff:

bulletGame-Specific Information - check here for any "gotchas" concerning specific games
bulletLinks and Resources - links to parts suppliers, tech info pages, etc.


A number of people contributed to this guide.  Nearly two dozen reviewers from the ranks of rec.games.pinball took the time to go through this guide and provide very useful feedback; a great big THANK YOU to everyone (Barry, Dan, John (x4), Kevin (x4), Scott, Martin, Mark, Ross, Chris, Scot, David, Tom, Phil, Matt, Mat, Daniel, and a few others I've probably missed). Special thanks go to Cliffy for the pictures of the Bally-style back box speaker panel, John P. for donating a Bride of Pinbot display panel, and to Martin for modeling some of the speaker and cabinet combinations.

Ready, Set, Go! 

OK, that's enough preliminaries. Roll up your sleeves and let's get started!

NEXT: how to choose replacement speakers

Copyright 2005 by Joseph A. Dziedzic. All rights reserved.

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