RF in Film: "This Is Spinal Tap" (A Tribute in Technology)
These Go To Eleven
In the ’80s cult classic film This Is Spinal Tap, there is a scene that has become famous in the world of audio engineers and enthusiasts. The band member shows off a Marshall amplifier where all the controls go to 11 rather than the usual 10. He says that when he needs a boost from the typical level of 10, his amplifier can “go to 11.” When asked why not just make the setting of 10 louder, he pauses, thinks about it, and answers, “These go to 11.”
Fast forward several years. Radio Design Group developed the UV-1G wireless intercom for Radio Active Designs. Those folks know audio, and the suggestion was made to make the beltpack volume “go to 11” as an homage to the movie. We all thought it was a great idea, and the first versions of the software did just that: The volume went from 1 to 11. A subtle joke, recognized immediately by audio experts who had seen the movie.
Beyond the Number: The Evolution of Volume Control
In truth, going to 11 doesn’t really mean anything. Whether the top setting is 10, 11, or, as in the case of the current beltpacks, 32, the maximum level is, simply, the maximum level.
In fact, the original version of the beltpack wasn’t loud enough for use in really high-noise environments. Ever been to a Seattle Seahawks game? The crowd noise regularly clocks in at over 120 decibels, the same level as a jet engine! Making the software go to 11 was not going to fix the problem. Instead, the audio amplifier in the beltpack had to be redesigned so that the top setting was, in actual fact, louder. At the same time, it was determined that only 11 settings were not enough to make fine loudness adjustments, so the software was changed to make 32 volume settings available. This practical evolution of volume control not only addressed the issue of loudness but also provided more flexibility in adjusting the sound levels.
Does the fact that the volume control goes to 32 make the beltpack louder? Not at all. What makes the current beltpacks louder than the original is a new, more powerful audio amplifier. The number on the display makes no difference; instead, it’s the capability of the amplifier itself that creates enough power to boost the volume.
So while the amplifiers used by Spinal Tap go to 11, ours goes to 32. Of course, if we used the Marshall amplifier featured in the movie at 11 to drive the headphones on a beltpack, it would blow the eardrums out of anybody that tried to use them. 11 or 32… the number makes no difference; it’s how much power the amplifier can put out that matters.
The RAD UV-1G Belt Pack with original max volume of 11.
The current RAD UV-1G Belt Pack with a max volume of 32.
Powering Up: How Amplifiers Work
Let’s delve into the concept of amplifier volume control and its relationship to actual sound output. While the actual circuitry of amplifiers, which can contain hundreds of transistors, may seem complex, the principle is actually quite simple. Amplifiers work by using the small signal at the input to control the flow of large currents from a power supply, such as the UV-1G beltpack’s battery, to the speaker or headphones.
Over the years, audio amplifiers have evolved significantly. In the early days, large currents were controlled by vacuum tubes, or valves as the British aptly call them. These tubes are still revered in high-end amplifiers for their low distortion performance, a feature highly prized by audiophiles. However, most modern audio systems now rely on transistors or integrated circuits, which can contain hundreds of transistors, to amplify the sound.
In the end, it doesn’t matter what the top number on the volume control is. It’s designing the right fit for the application that matters.