TheKorn's
Do-It-Yourself Guide
to Pinball Speakers!



Replacing the panel speakers


HTML, plans, and pictures copyright by TheKorn@hotmail.com.

Last modified date: July 26, 2003.
Page is freshest if read before: August 13, 2084


If you've been directly linked to this page, click here to read the rest of this guide (lots of good stuff!):


Replacing the panel speakers

So hopefully at this point, you've already read the speaker selection guide. If you haven't, go back and read it; speaker selection can make the difference between an enjoyable project and one that takes twice as much work to accomplish!



Supplies

For this project, here are the tools and supplies you will need. Most of this stuff you can find at a hardware store, home improvement store, or at a craft supply store. I'll provide a link if you can't find the stuff there:


Here are the tools that are optional, but are highly recommended. These basically make the difference between a professional looking (and sounding!) installation, and one that looks half-assed and/or fubar. Tools are listed in the order of preference (most preferred, still OK, and "can get away with"):


Before you do anything... (legal disclaimer)

If you don't know how to solder correctly, go read Clay's guide HERE. There is not a lot of soldering in this project, but there is some. (This would be a good "my first project with soldering!")

All the information provided on this page is provided with the understanding that if you use this information to modify your game, it is At Your Own Risk. Although modifying my games has worked splendidly well, it might cause yours to blow up, catch fire, or run off with your wife. I accept no liability of any kind by providing this information, provide no warranty for this information, provide no guarantee of correctness or statement of fitness, or in general accept any legal responsibility for the use of this information.

With that said, I do actually believe that this will work in many pinball machines. I just don't want to get sued if your machine makes off with your house and burns your wife down.

And as always, keep that fire extinguisher handy, just in case! :)



A little bit of prep work...

First things first, you need to remove the speaker panel entirely from the game. If you've never done this before, don't worry. It's so easy I didn't even bother taking any pictures of it. No really it's easy. Things to remember:

It's pretty hard to screw this part up, but it never hurts to be careful, either. Note that for the speaker connectors themselves, on most games you will have to either desolder them or cut them. I usually cut them right behind the speaker lugs. (If one of the speakers has a capacitor attached, leave the capacitor attached to the speaker; we will not be using it.)

Remove the backglass channel...

Next up, remove the backglass channel and wire guides from the top of the speaker panel. These are held in place by four phillips head screws. Save everything!

At this point, your panel should look something like this:


speaker panel removed from machine (nothing done to it yet)
(Looking at the back side)

Remove the DMD

This is pretty easy. Take your nut driver, loosen and then remove the four nuts that hold the DMD in place. The DMD then simply lifts off. Note which way is up on the DMD. Save the nuts and the DMD; you'll need them later.


panel with DMD removed

Remove the Craptastic stock speakers

Pretty easy here, four screws each and you're done! (Save the screws.)


panel with speakers removed

Remove the plastic speaker cover

This looks like torture, but really it's not bad. It requires a firm but light touch. What you want to do is separate the decorative plastic (the part you normally look at when playing a game) from the wood. These are simply glued down at the factory, so many of them are quite loose. The trick is that you don't want to bend the plastic too much, because it's possible to snap the plastic in half. But you need to bend the plastic some in order for the glue to let go.

Don't use anything but your fingers for this step! DON'T, whatever you do, DON'T stick anything under the plastic to try and pry it up!! You'll destroy the graphics on the plastic and be very unhappy! The glue on these old panels is pretty dried out, so I've never had one that needed anything more than firm finger pressure to get the glue to release. That being said, it's possible that if you were doing this to a (much) newer panel, that the glue might be a bit tougher. If so, I'd heat up the plastic & glue with a hairdryer to soften it up. Again, I've never had to do this, but if I ran into a really stubborn one, that would be what I would try.

I had to fake the picture below, because I accidentally proceeded several steps without photographing anything. But in any case, it should show you how far you can bend the plastic safely. (You can actually bend it quite a bit more than this, but this is roughly all you should need in order to get it to separate from the panel.)

front side of panel with finger jammed between wood panel and plastic panel
(looking at the front side)

Remove the speaker grills

At this point, you should have a panel with no top plastic, no backglass channel, and two speaker grills staring you in the face:

front of panel with plastic panel removed

This part is easy. Although you can't see it in the above picture (d'oh! I took the picture AFTER I removed the staples!), each grill is held down by two staples. Using your jeweler's screwdriver, gently pry up one end of the staple without nicking, touching, or scratching the speaker grill below. Then simply grab the staple with your long nose pliers, and pull it out. Throw away the staples, but keep the speaker grills.

It's not required that you remove the speaker grill that covers the larger speaker hole (since we're not going to cut on that side), but I usually remove it anyway because it's tough to work on the assembly without scratching the heck out of the grills. It's your call, but remember, I've done this before! :)

Mark the new T-nut holes

Flip the panel over and grab your square. You want to measure where the T-nuts are located on the left side of the panel, and transpose those marks to the right side of the panel. (Pretty simple, right?) Easiest way to do this is with a speed square, which will make sure that your measurements are perpendicular to the edge of the speaker panel.

back side of panel with a speed square measuring t-nut locations
(looking at back left)

The easy way to get all of the measurements right is to measure how far down (from the top of the panel) one pair of holes is. Go to the other speaker location and make a mark at the correct distance from the top of the panel. Then put the speed square on the side of the panel and draw a line going through the mark, parallel to the top of the panel. This sounds more complicated than it is; once you see the results, it will make more sense.

t-nut positions transposed to the right side
(looking at back right)

Repeat the process for the other three T-nuts.

Remove the old T-nuts

To easily remove the old T-nuts, take one of the screws that was originally holding the speaker to the panel and screw it partially into the T-nut. Then, take your hammer and hit the head of the screw to dislodge the T-nut. Obviously, save the T-nuts!

using a hammer and screw to dislodge t-nuts from their old location

Mark the new cone hole

Grab the compass, and set the tip of it in the center of the left speaker's hole. Adjust the compass (without moving it) so that the lead is on the edge of the hole. Then move the compass (without adjusting it) to the center of the right speaker's hole, and draw the circle.

Hint: to easily locate the center of either hole, put a piece of paper underneath the speaker panel, then (with a ruler) draw a line from the upper left t-nut to the lower right, and from the upper right to the lower left t-nut. The center of the hole is where the two lines cross.

using a compass to mark the cut line for the new speaker

Everything should look pretty symmetrical. If things don't look right at this point, they will definitely look very wrong when you put the panel together later. So take your time, and don't be afraid to erase and draw again. In the same breath, if things aren't perfect it's OK. But make sure (at the very least!) that things look OK at first glance.

Drill the holes for the T-nuts

No pictures are necessary for this part. Grab your drill, and where the straight lines (drawn three steps above) cross, drill a 1/8" hole. Piece of cake!

Cut the new cone hole -- This is the point of no return!

First, take a deep breath. In, out, in, out, and all that. This is the step where if you go any further, you cannot go back. So make sure everything looks good before going any further!

What we're going for is a hole that's big enough so that the cone and surround aren't obstructed, but isn't so big that the speaker falls through it. Click on the picture below. What you want to see through the hole is marked in red, what you don't want to see through the hole is marked in yellow.

Cone and surround unobstructed, but basket still obstructed

Grab the jigsaw, and put in a fine wood or medium metal bit. (Don't use a "rough" wood bit, because the finished cut will look ragged when finished.) Cut along the inside of the circle that was marked earlier.

cutting the panel with a jigsaw -- point of no return!
(looking at back right)

You may be asking why we're cutting on the inside of the mark. The reason we're doing that is just in case any mistakes were made in measuring or marking. It is always possible to go back with the jigsaw and cut out just a little bit more, but it's not possible to uncut something. So better to make a few passes with the jigsaw and get it just right than wind up having the hole too large and not having a way to undo it.

After each pass, you'll want to hold your speaker up to the hole and check your work. Don't feel badly if your hole isn't perfectly round; you can always trim off a little bit more. But don't go overboard; as long as it's generally correct, you'll be OK. Here's what my hole looked like after I was done cutting (pretty decent cut, if I do say so myself!):

checking the cut

Recess the T-nut holes

Now, flip the panel over and grab the Dremel. You want to carve out a recess for the T-nuts so that when they're installed they sit flush (or slightly lower) than the rest of the panel. This step isn't particularly critical; routing by eye for size and depth will be good enough.

dremeling out the t-nut recesses
(looking at front right)

Reinstall the T-nuts

Hammer, meet the T-nut! Repeat for the other three.

Paint it!

Grab the paintbrush, and paint the inside of the cone hole, the T-nuts, the recessed T-nut holes, and any place else on the panel that needs a touch-up using flat black paint.

panel with t-nuts and painted!
(looking at front right)

Reinstall speaker grills

Grab the 3M 467MP and the razor blade. (If you're not using 467MP, grab the hot glue gun.)

Put bluntly, you want to use as much 467MP as possible on the open areas. Unlike the hot glue, you can't use too much, and more is definitely better. I usually cover the big areas, and call it a day.

panel with 467MP stickum applied
(looking at front left)

Next, reposition the speaker grill to its original location. Apply clamps for a few minutes to allow the adhesive to grab.

clamping down the grills and 467MP

Repeat for the other grill. (duuuuuuuuuhhhhhh, really??)

Reinstall front plastic

To reinstall the front plastic, use the same method that was used to reattach the speaker grills, just on a much larger scale. Use a lot of 467MP (or a reasonable amount of hot glue), and clamp it for a few minutes all over (especially the sides!) to allow the adhesive to properly grab.

panel with 467MP ready for top plastic

Reinstall everything else (the home stretch!!)

It sounds rather glib, but the last step is to reinstall everything we took off at the start of the document. In other words, screw in the new speakers, put the backglass channel back on, put the DMD back in, etc. It's not hard stuff (remember how easily these came off??); just some handiwork with a phillips head screwdriver is all that's needed.

Doesn't it look pretty?

all done!

all done!

One thing I should warn about: it's possible (depending on what kind of speakers you use) that the original screws may be too long. If you're screwing down the new speakers and notice the grill on the front starting to bulge out, stop!, and replace the screws with shorter ones.

Wiring up the speakers

Here is where you have a choice. There are two ways to wire up the speakers, in series or in parallel.


In series

If you wire the speakers in series, it presents a much easier load for the amplifier to drive, so the amplifier will run cooler and (theoretically, at the very least) last longer. If you plan on adding a subwoofer to the game without adding an extra outboard amplifier to the game, this is the connection method I would recommend since the subwoofer will stress the built-in amplifier all by itself.

The downside of wiring the speakers in series is that they will not sound as good as speakers wired in parallel. (There's a long technical and very boring reason behind this. Do a regular google search and you'll pull up more hits than you'd ever want to read.)

In parallel

If you wire the speakers in parallel, they will sound better than if wired in series. The downside is that the speakers will present a harder load for the amplifier to drive, so it will generate more heat and generally stress the amplifier more.


If you have no idea which one to pick, wire them up in series and don't worry too much about it. Parallel is for purists. (Damn the torpedoes!)


series wiring diagram (click on either to enlarge) parallel wiring diagram

You're done!

Sorry to burst your bubble, but that's all there is to the project! You're done! Go play a game and enjoy the new sound!

parallel wiring diagram

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