64. Chimes and Bells
Next time you're watching a TV show or movie, and you notice a pinball
machine being played in the background, pay attention to the sound
effects. I can almost guarantee you that the sound effects will mimic
the bells and chimes from a 1960s electromechanical machine, even if
the on-screen machine is a 1980s or 1990s solid-state table. You and
I know that those solid-state machines actually have electronic sound
systems that include speech and music, but when you see them in TV and
movies, the sound effects will almost always be EM chimes. Why is
this weird technical gaffe so comically predictable? Maybe in part to
avoid music licensing costs, but the main reason, I think, is that the
sound designers know that those chimes are what most people think of
when think of pinball. They're not going for technical accuracy with
those sound effects; they're trying to create a sonic impression.
EM chimes are the "audio icon" for pinball.
Which brings us to the topic at hand: chimes and bells in a virtual
cab as physical feedback devices. Before the solid state machines
came along in the 1980s, pinball machines made those iconic bings and
bongs with little solenoid-driven percussion instruments. These
instruments came in two main types. The first is known as a "chime
unit", which is essentially a miniature xylophone consisting of three
or four metal keys. The second type is bells, typically the circular
half-shell type you might find in an old-fashioned alarm clock or fire
alarm.
If you play only games from the 1980s and later, these will be of
little interest to you. If you enjoy games from the electromechanical
era, though, real chimes and bells can be a great enhancement.
Recorded effects played through speakers can't approach the visceral
impact of real percussion instruments.
Chime units
A chime unit is a
miniature xylophone played by solenoid-actuated hammers. The
xylophone keys are metal bars tuned to selected musical notes, and
each key has a solenoid positioned underneath with its plunger aimed
at the key. When the solenoid fires, the plunger pops up and strikes
the key, setting it ringing.
The chime unit pictured at right is a classic Gottlieb model, which
was mass-produced and used in numerous Gottlieb EM titles throughout
the 1960s and 70s. The black box at the back is a resonance chamber:
an enclosed air space sized to resonate at each bar's fundamental
frequency, to amplify the sound and make the ringing last longer. The
resonance chamber is probably the most important part of the design
acoustically, since it can make the notes sound richer and warmer by
sustaining the ringing effect. Williams and Bally also manufactured
chime units with similar basic designs, but Gottlieb's is widely
considered to be the most sonorous, thanks to its particularly
well-designed resonance box.
Where to buy an off-the-shelf chime unit
New units: The pinball manufacturers had a few standard chime
unit designs that they mass-produced during the 1960s and 1970s. The
originals went out of production for many years after pinball shifted
to all solid-state machines in the late 1970s, but they seem to have
made a comeback lately. As of early 2026, Marco Specialties is selling
complete, newly manufactured replicas of the Gottlieb chime units
used in Gottlieb games from 1969 to 1979. Those appear to be faithful
reproductions of the original Gottlieb design, so I'd expect them to
sound authentic. Search for part number B-12023.
Used: Chime units were ubiquitous in EM machines made in
the 1960s and 1970s, so there are a lot of them out there, sitting in
old machines that people have in their collections. Those come up
for resale on eBay and similar sites pretty regularly as people
salvage parts from machines that are no longer operable, so you can
probably find a decent used unit if you're willing to watch for
them on eBay for a couple of months. Search for pinball chime unit.
Used units might need some refurbishing, since some of the parts wear
over time. If that's necessary, all of the common wear parts (the
rubber grommets, coils, and coil sleeves) can be sourced at Marco
Specialties or other vendors.
Replicas: Apart from the modern replica of the Gottlieb unit
that Marco Specialties sells, there are a couple of other off-the-shelf
designs available:
- McCullough's Chime Unit, available at www.chimeunit.com. This is a custom design, not an exact replica of any particular manufacturer's original. I haven't seen these in person; the reviews I've read are positive but say that they don't sound quite as good as the original Gottlieb units. About $150.
- Pinball Atelier sells their own custom-designed unit, currently €174. They sell direct from their site at www.pinballatelier.com, and they also sell on eBay; their eBay shop is named pinballatelier. They also make their own replica pinball shell bells.
DIY chime unit
If you'd prefer to build your own chime unit from scratch, there are a
couple of DIY plans posted on the Internet that might
make a good starting point.
Youtuber Way of the Wrench
posted a great video with detailed instructions for building a chime unit
using a combination of Gottlieb replacement parts and 3D-printed
plastic parts:
The 3D-print design above has a simple resonator box with a single
chamber for all three chimes. The original Gottlieb units are
more sophisticated, with three chambers, tuned to the individual
chime frequencies. RickH on vpforums
created an upgraded 3D-print model that more closely replicates the
Gottlieb design, which he says produces a richer sound:
RickH's improved resonator (github)
Here's an older forum post offering an alternative DIY chime unit,
which uses metal pipes for the chimes, instead of the traditional
bars. That might make it easier to fabricate from off-the-shelf
hardware.
Homemade Tubular Pinball Chimes (vpforums)
Design your own
If you don't want to go with one of the plans above, designing your
own chime unit isn't out of the question, as the basic principles
are pretty simple. The only tricky part is building a good
resonator box, since you have to tune the dimensions to the
frequencies of the chime bars. That takes a little knowledge
of acoustics to do properly, and it's important to do properly,
because it's the main thing that determines the quality of the sound.
The basic components are:
- Metal bars to serve as the xylophone keys
- Solenoid hammers to strike the bars
- A resonator box to sustain the ringing effect
The solenoid coils are easy to find. You need nylon-tipped plungers
for the coils to serve as the hammers; the ones used in replay
knockers should work. You could just buy a replay knocker coil and
plunger for each key, although knocker coils are probably overpowered;
the original chime units had smaller 24V coils.
You can find replacement metal bars for the original chime units from
online pinball vendors. Here are the part numbers for the Gottlieb
chime bars:
- A-12016 (large)
- A-12017 (medium)
- A-12018 (small)
It's also fairly easy to create your own from raw metal stock, which
you can find at hardware stores or online. You just need to cut bars
to appropriate lengths for the different chime tones. There isn't a
simple formula for length vs. frequency, since many variables go into
it; it depends on the type of metal as well as the thickness and
length of the bar. Other things being equal, though, a longer bar
produces a lower tone. You can find Web sites on the subject if you
want to work out the math, but I think it might be easier to do some
ad hoc experiments by cutting metal bars to different lengths until
you find a pleasing set of tones.
Some additional tips:
- Use a solenoid plunger with a nylon tip, not a metal tip. A metal tip will make a sharp metal-on-metal sound; a nylon tip will just set the bar ringing, producing the bar's pure tone without any sharp contact noise.
- Support the bars with small rubber grommets, to minimize damping (you want the bar to ring after being struck). You can find purpose-made grommets as replacement parts from pinball vendors, but generic grommets from a hardware store will probably work just as well.
- Place the supports at two points, centered relative to the bar's width and inset from each end by about 22% of the total bar length. To find the exact positions, sprinkle some sawdust or salt evenly over the bar and give it a whack with a hammer. The dust/salt will settle at the nodes of the bar's acoustic vibration waveform, which are the stationary points in the waveform. These are where the supports should go.
More on the acoustics of xylophone-type chimes:
www.mmdigest.com/Gallery/Tech/XyloBars.html.
Aside from the xylophone keys, a good chime unit also needs a
resonance chamber: a rigid box with an opening on the side facing the
chime. This serves to sustain the ringing sound for a time after each
hammer strike, which creates a more sonorous effect than the chimes
alone. The size of the box has to be tuned to the frequency of the
adjacent chime, so there should ideally be a separate chamber for
each bar. There's a science to this: you can find mathematical
formulas for calculating the relationship between chamber geometry and
resonant frequency in the
Wikipedia article on acoustic resonance.
As in most matters of engineering, though, there seems to be an art as
well as a science. RickH on vpforums discovered
that the original Gottlieb resonators don't quite match the sizes
that the acoustic resonance formulas prescribe, and yet sound better
than ones that do. Rick speculates that the Gottlieb engineers tweaked
the chamber sizes to emphasize particular harmonics that just empirically
sound nicer to the ear.
The resonator boxes in the original chime units were made of some kind
of hard plastic. I don't think the material is critical, as long as
it's something rigid and fairly smooth, so that it doesn't absorb much
of the sound energy. 3D-printed plastic parts work well in practice.
How many chimes?
Gottlieb and Bally each mass-produced their own three-chime units in
the 1960s and 70s, and used them as standard parts in most of their
games during that period. That makes the three-chime setup by far the
most common in EM games you're likely to see re-created in the
simulators.
In addition, Bally created a four-chime system that they used in a few
machines from about 1976 to 1979. This wasn't actually a whole new
design; it consisted of their pre-existing three-chime unit, plus a
second unit with a single, extra-long chime bar installed. The
combination extended the three-tone set to four tones, with the fourth
tone being a new extra-low note.
DOF has a provision for a fifth chime bar as well, but as far as I can
tell from reviewing IPDB game descriptions and
other sources, there were never any real machines that actually used a
fifth chime. DOF's use of it appears to be entirely in the "fantasy"
realm - an embellishment for virtual pin cabs, not something that
replicates a real machine feature. So if you do install a fifth chime,
it's completely up to you what tone it plays: there's
no authentic reference point from the real machines for what it
"should" sound like.
For a pin cab, I'd personally go with a three-chime unit. Only a
few real games were made with the four-chime units, so the extra work
and cost of a fourth physical chime probably isn't worth it to most
people. And DOF's fifth chime slot is purely a DOF embellishment,
and is only used by a handful of tables.
You can always map DOF's fourth and fifth chimes to fire your
other physical chimes, so you'll still be able to get something to happen
when it fires, even though it won't be a distinct tone.
Musical notes
The real three-chime units typically play notes in the fifth octave,
about two musical notes apart. If you're designing your own chimes, a
good target set of notes might be C5, E5, G5 (that is, the notes C, E,
and G in the fifth octave). The extra chime on the Bally four-chime
setup is reportedly about a C4 (one octave lower than the lowest
bar in the three-chime unit).
RickH at vpforums analyzed the sound produced
by an example of the original 1970s Gottlieb model, and found that the
frequences are, respectively, 554.37 Hz (C♯, bordering on C),
622.25 Hz (D♯), and 739.99 Hz (F♯, bordering on G♭).
These are all in the fifth octave musically.
Shell Bells
Chime units weren't the only type of percussion instrument in the EM
machines. Some machines had bells instead: circular shell-shaped
bells, with solenoids positioned to strike them at the edge. These
bells are similar to those on old-fashioned alarm clocks or bicycle
handlebar bells.
Machines equipped with bells usually had two of them, one larger and
one smaller, to produce different tones. Most commonly, the small
bell was 3" diameter, and the large 5".
You can buy similar bells as replacement parts from the pinball supply
vendors; look for "bell" and "bell assembly". You can also sometimes
find used pinball bells on eBay.
You could also use any sort of similar bell, such as a bicycle bell, a
bell from an old alarm clock or phone, from a fire or burglar alarm,
etc. You can improvise your own firing mechanism using a pinball bell
strike coil assembly, or using a cheap eBay push-type solenoid.
Chimes and bells were mutually exclusive in the real machines, as far
as I've seen. They serve exactly the same purpose and worked the same
way, the only difference being the shape of the ringing element. The
pinball manufacturers probably chose whether to use chimes or bells in
a given machine according to parts cost and availability, and perhaps
the whims of the game designers.
For a virtual cabinet, should you install bells, chimes, or both? In
my opinion, a chime unit should be your first choice. Chimes were by
far the most common noisemaker in the real EM machines over the years,
so a chime unit will create the most authentic simulation for most
games; and a chime unit can easily stand in for shell bells for games
that used those instead. My second choice would be a chime unit
plus a pair of shell bells (one large and one small), if your
budget allows it and you have space in your cabinet. Shell bells do
have a different tonal quality compared to chimes, so they'll add some
variety to your EM games, and they'll give you better authenticity for
games that used them.
If you do install shell bells, you can assign them to the Shell
Bell Large and Shell Bell Small devices in the DOF Config
Tool.
Vibrating/repeating bells
This isn't exactly the same category as chimes, but it's closely
related. A few arcade pinball machines over the years featured
vibrating bells, also known as repeating bells, which work like the
ringers in old-fashioned telephones, alarm clocks, and fire alarms.
The key is that the hammer rapidly hits the bell over and over as long
as the bell is energized, rather than just hitting it once.
The bell unit from Taxi, Williams part number C-8461-1.
The same part is used in Taxi, Big Guns,
Black Knight, and a few other games from the same era.
A short video of the Taxi Bell in action:
Space Shuttle (Williams, 1984) has a bell like this that fires
each time you complete the stand-up targets, and also serves as the
replay knocker. Taxi (Williams, 1988) also has a bell like
this, which sounds when multiball starts or when you collect a
jackpot.
Used originals: The most authentic option is to find a used
Williams bell assembly from a Space Shuttle, Taxi, or
other machine that featured a bell. They're no longer in production,
but used units are available from time to time on eBay. The best
search term is the Williams part number, C-8461.
You might also find units with part number C-8461-1, which is
identical to C-8461 except for the type of coil installed in the unit,
which determines the input voltage:
| Assembly Part No. | Coil type | Voltage |
|---|---|---|
| C-8461 | SM-29-1000 | 38VDC |
| C-8461-1 | SM-26-600-DC | 25VDC |
The two part numbers are otherwise identical and sound the same. Both
coil types are readily available from Marco Specialties and other
pinball vendors, and they have identical physical dimensions, so you
can easily swap the coil if you find a used unit with the "other" coil
type from the one you prefer. For a virtual pin cab, you'll probably
prefer the SM-26-600-DC for its lower voltage. And note that
SM-26-600-DC will even work fine with 12VDC; it'll just be slightly
less loud.
Substitutes: The Williams bell assemblies were only used in a
few machines, and are long out of production, so used ones on eBay are
relatively rare. Fortunately, you can get a very similar sound effect
with a general-purpose alarm bell. Many types are available on Amazon
and eBay; try searching for vibrating fire alarm bell. The
Williams assemblies used 4" steel shell bells, so look for a unit with
a 4" bell to approximate the original sound.
One specific substitute I can recommend from hands-on testing: Edwards
Adaptabel 435-4 series. These are similar in size and mechanical
design to the Williams C-8461 assemblies, and produce a similar sound.
The specific models that will be easiest to work with in a virtual
pin cab are 435-4E1, which runs on 12VDC, and 435-4G1, 24VDC. These
are currently readily available on eBay for about $30 to $50.
I've also tried a couple of very cheap vibrating bells sold on Amazon
(in the $10 range), and I can't recommend any of those that I've
tried. They're too weak and tinny in comparison to the original. A
quality fire alarm or burglar alarm bell is a better bet.
The DOF Config Tool has a device type called Repeating Bell
that you can assign to a physical device like this, if you install
one.
Topper bells
Large decorative bells make good backbox toppers. Some real machines
used bell toppers as part of their theming, most famously Fire!
(Williams 1987).
You might be able to find the specific replacement part for
Fire! form a pinball vendor or used on eBay, but it's probably
easier to find a random decorative bell with the right size and shape.
As with the shell bells, you can improvise your own firing mechanism
using a pinball bell striker coil assembly, or a cheap eBay push-type
solenoid.
If you install a decorative bell topper, you can assign it to the
DOF device named Bell in the DOF Config Tool.
Placement in a virtual cab
The placement of bells and chime units isn't very important for
authenticity, because the original machines weren't all that
consistent about it. It seemed to be mostly a matter of finding
enough room somewhere. I also don't think different placements will
affect the acoustics enough to require strict imitation of the
originals, even if there were a consistently applied standard location
for everything.
As a practical matter, chime units usually have to go in the main
cabinet, simply because they're too big to fit in a backbox. In the
original EM machines, they were often mounted in the front corner of
the main cabinet, under the plunger, since this was often an otherwise
unused space.
Individual shell bells are small enough to fit in the backbox, which
is where they were usually situated in the EM machines. Virtual pin
cabs often have less free space in the backbox, though, since the
backbox monitor often nearly fills the space. Again, I don't think
it will hurt the acoustics if you have to mount your shell bells in
the main cabinet instead.
The vibrating bells in Taxi and other machines of that era were
located in the main cabinet, mounted to a side wall.
Wiring
Bells and chimes are wired just like any other output device,
as described in Feedback Device Wiring.
Each chime in a chime unit has its own coil, so simply wire each
coil to a separate output controller port.
If you're using the Pinscape expansion boards, you can connect a chime
or bell directly to any MOSFET Power Board or Chime Board port. If
you're using an LedWiz, don't connect a chime coil directly to it,
since these coils use more power than the LedWiz can handle; you'll
need some kind of booster circuit to use chime with an LedWiz.
Always use diodes with coils. Diodes are required to protect your
output controller and other electronics from the
voltage spikes generated by a coil. See Coil Diodes.
If you're using a vibrating bell (the type where the hammer strikes
repeatedly), it might cause even more electrical interference than a
regular coil does. These bells usually achieve their rapid repeat
firing via a mechanical switch connected to the hammer, so that the
switch interrupts power to the coil when the hammer strikes, and then
reconnects power when the hammer springs back. The rapid high-voltage
switching can inject a lot of electrical noise into the circuit, on
top of the noise from the solenoid activation. If you start seeing
new problems with your other electronics after installing a vibrating
bell (for example, the output controller resets or disconnects from
USB when the bell rings, or other devices fire, or you get random
keyboard input on the PC), try adding a small ceramic disk capacitor
in parallel with the coil diode, 0.1 uF to 1 uF, with a high voltage
rating. (The Williams C-8461 bells use 0.1 uF, 500V. The high
voltage rating is necessary because the flyback voltage from the coil
can be in the hundreds of volts.) If possible, place the capacitor
close to the mechanical switch terminals inside the bell, since the
switch itself can be the source of a lot of the noise. If that's not
possible, connect the capacitor across the bell's main electrical
terminals. The Williams vibrating bell mechanism should come with a
capacitor already installed across the switch terminals, so there's no
need to add another one.
Timer protection circuits
Pinball coils like those used in bells are designed to be fired in
short bursts only. They'll overheat if they're energized for long
periods. Under normal conditions, this isn't a concern for chime
coils, since games that use chimes should naturally fire them in short
bursts, exactly as they're designed to be used. However, PC software
sometimes has bugs or glitches, and one of the things that can happen
when something goes wrong on the PC is that an output port can get
stuck on. This can destroy a pinball coil if it's not quickly fixed.
The Chime Board from the Pinscape expansion boards has a dedicated
hardware timer for each output to protect against exactly this failure
mode. If you're using the Pinscape boards, it's recommended to use
Chime Board outputs for chimes and bells.
Note that this doesn't apply to vibrating alarm-type bells, since
those are specifically intended to fire for a longer periods.
If you're using the Pinscape software but not the Chime Boards,
you can still get some of the same protection by using the
"Flipper Logic" feature for your chime ports.
See Coil Timers for more details.
DOF Setup
In the DOF Config Tool, go to the
Port Assignments page. Find the port numbers where you wired your
chime/bell coils. Assign to the appropriate DOF devices:
- Chime Unit High Tone through Chime Unit Low Tone are for traditional three-bar chime units. Assign the shortest bar to Chime Unit High Tone, since the short bar has the highest-pitched tone. Assign the remaining bars in descending tone order.
- Chime Unit Extra-Low Tone is for the fourth chime in the Bally four-bar chime units from the late 1970s. If you have a fourth chime bar, assign the Extra-Low Tone DOF slot to the physical bar that produces the deepest tone (the one with the longest bar). If you have a more typical three-chime unit, you can assign this DOF slot to the same physical chime as your "Low Tone" port.
- Chime 5 is an extra DOF chime that doesn't correspond to anything from a real machine. It's just a DOF embellishment, used in a few tables to add some extra variety to their sound effects. If you have a fifth physical chime device, you can assign it here. If not, you can assign this to the same physical device as one of your other chimes. Very few games use this, so you won't miss much if you just leave it unassigned.
- Shell Bell Small and Shell Bell Large are for shell
bells like those found in some 1960s machines (see
shell bells above). These work exactly
like chimes, but use circular metal bells rather than bars as the
ringing element, for a different tonal quality.
If you install physical shell bell devices, assign them to these DOF slots. If you don't have physical shell bells but you do have a chime unit, assign Shell Bell Small to your shortest chime bar, and assign Shell Bell Large to your longest chime bar.
- Repeating Bell is for a vibrating bell that rings continuously when energized, like on an old-fashioned telephone or alarm clock (see vibrating bell above). If you have such a device, assign it to this slot. Since this slot is specifically for vibrating bells, I wouldn't map it to any other single-firing chimes or bells; I'd just rely on the digital sound effects recordings in the games instead for this one.
- Bell is intended for a large novelty bell of the sort found as the backbox topper on Fire! If you have a device like this, assign it here. If not, and you have chimes or shell bells, I'd assign this slot to fire the one with the deepest tone.
