Origins of the Knocker
May 7, 2012 6:41 AM   Subscribe

What are the origins of the pinball knocker? It seems to be unique to pinball machines. I would think that there is a story as to how or why this method was chosen to signal the player that they received a free game. Its such a distinct and mechanical sound. I have some theories but cant seem to find any facts related to the origin of the knocker.
posted by jmsta to Technology (10 answers total) 5 users marked this as a favorite
For Would-Be Pinball Wizards, the Thwack's the Thing

That gives a little bit of insight. My guess is that it's supposed to attract the attention of other patrons in the pinball parlor to come over and watch you play.
posted by dgeiser13 at 7:06 AM on May 7, 2012

Best answer: You could try asking this in the newsgroup, but it's been asked before, and nobody can come up with a definitive answer. One poster verified that machines as early as the late 1940's had knockers. Modern pins don't have them, but they emulate the sound through their speakers.

Here's some supposition that might be useful:

Pinball is a profit making enterprise. The more people play, the more money the operator makes. The "free game" is an incentive for the player to deposit their money in the first place. By having the game make a loud noise when that free game is awarded, the machine does a bit of advertising for itself. It also gives the player a moment of pride and achievement. Think of it as the antique version of the Steam achievements.

Now, as to why the knocker is what it is:
The knocker is as simple as things get. A solenoid that fires a metal rod against the wall of the cabinet. That makes the loud "crack" sound. It's made from readily available parts, and can be connected to the power supply already in the cabinet. It might even be that the effect was discovered accidentally.

You may not ever find a definitive answer to this question, because the early history of pinball is tainted by its ties to gambling and organized crime. It's poorly documented, and much of it happened behind the scenes.
posted by cosmicbandito at 7:34 AM on May 7, 2012 [2 favorites]

The device that makes that CRACK! sound is a simple solenoid so the story may be that they were cheap and already common in pinball machines.

The video game Qbert used one of these that triggered down around your ankles a second or two after you jumped Qbert off the pyramid to his unfortunate end.
posted by Kid Charlemagne at 7:35 AM on May 7, 2012 [2 favorites]

Best answer: The more detailed term is "credit knocker", which harks back to the electro-mechanical days of pinball.

Back in those days, the entire logic of the game was done with mechanical steppers, electrical relays, and geared components to do the math of scoring points and awarding various features as you played better.

The number of plays you bought for a coin were (and still are) called "credits". Insert a quarter, get two credits. Almost all games will still award you a credit for making a certain score level or beating the high score, or some combination of that.

In these old EM games, the credits were tallied on a separate scoring reel that was visible through the backglass. This reel was advanced by the aforementioned solenoid that would push the reel one click ahead. Somewhere along the way that mechanism was made louder to signal to the player the goal was made and the credit was given.

Now move ahead to the solid-state era. All computers, no mechanical parts anymore. Well, let's not say "no mechanical parts" so quickly. Early games had solenoids that still hit chimes in the bottom of the cabinet for the old-style sound effects. Along these lines, the solenoid was left in to keep the WHACK sound when you scored a credit. The chimes were eventually lost to synthesized music and voices, but the credit knocker stayed. Experiments were tried here-and-there to replace the knocker with a simple sound effect (right, WMS?), but in the end the hearty knock-on-wood that you could feel through the cabinet is what players wanted. So there it is.
posted by JoeZydeco at 8:18 AM on May 7, 2012 [2 favorites]

It's not just the sound tho, back in the day with the old machines there was a distinct tactile feel as the knocker hit the cabinet - Multi-sensory reinforcement!
posted by mygoditsbob at 10:55 AM on May 7, 2012

It's not just the sound tho, back in the day with the old machines there was a distinct tactile feel as the knocker hit the cabinet - Multi-sensory reinforcement!

This is still present in some newer machines. I remember playing this machine where the knocker was so loud and sudden that upon hearing it I flinched and let the ball roll into the gutter, ending my current game.

This is just idle speculation, but could the knocker have also been an attempt at purposefully disrupting casual players and suppressing high scores?
posted by RonButNotStupid at 11:40 AM on May 7, 2012

"...but could the knocker have also been an attempt at purposefully disrupting casual players and suppressing high scores?

I spent a number of years working for a pinball company. I can tell you that this was not the case at all. We were struggling enough to get people to stay on the games, much less get them angry and scare them off.
posted by JoeZydeco at 12:05 PM on May 7, 2012

Q*Bert also had a knocker.
posted by cjorgensen at 1:11 PM on May 7, 2012

Last fall I bought a 1978 Gottlieb Eye of the Tiger EM machine and I cannot tell you how satisfying the knock is. Having only attained it a few times it's one of those special moments when I like to think there's a little man inside my machine pumping his fist for me. All this despite being far to intimate with the inside of said machine.
posted by FlamingBore at 1:43 PM on May 7, 2012

Q*Bert had a knocker because, big surprise, it was made by Gottlieb, a pinball company. The knocker was a fun hack to simulate Q*Bert falling off the pyramid and into the actual game cabinet.
posted by JoeZydeco at 3:06 PM on May 7, 2012

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