A guitar amplifier is an electronic device that transforms a board and six strings into a furious agent of cultural change. The amps most coveted by guitarists do this with vacuum tubes. These archaic bits of technology heat electrodes in evacuated glass chambers, amplifying an electric guitar's signal while also introducing much-desired distortion. Give a vacuum tube too much power and the sound it produces starts to break apart. The sunny hum of a plucked string becomes a raspy howl. This is the essence of rock and roll. When the invention of semiconductors made it possible to use more durable parts to amplify sound cheaply, guitarists wanted none of it. They stood by their tubes.

To show you where all that classic sound comes from, we got our hands on Fender's '65 Princeton Reverb amp. Like rock stars, we smashed it. Then we got Chicago Amp Works technician Patrick McKeever, who counts Wilco and Red Hot Chili Peppers as clients, to explain the parts.

Todd McLellan

1. Cabinet: The box that holds everything. This one is made of pine.

2. Main Circuit Board: Connects all the amp's components, including the vibrato circuit, which varies the current in the power tubes to temporarily lower the power and create "vibrato." (Technically this is "tremolo," but Fender confused the terms in the 1950s and it stuck).

3. Skirted Knobs: Sadly, these only go to 10.

4. 5AR4 Rectifier Tube: Converts AC electricity from the power transformer to DC. Rectifier tubes lose power when subjected to a lot of current—which tends to happen when a guitar is played hard and loud. This sag causes audio to break up, a trademark of the tube-amp sound.

5. 6V6GT Power Tubes: The last section the signal passes through before the speaker, these crank up the audio signal.

6. Preamp Tubes: Increase the amplitude of the audio signal from the guitar and send it to circuits that introduce effects like reverb and tremolo.

7. Power Transformer: Converts the 120 volts of power from the wall socket to a higher AC voltage and sends it to the rectifier tubes.

8. Ten-Inch Jensen C10R Speaker: The transducer that converts the electric audio signal into airborne vibrations.

9 Foot Switch: Because a guitarist generally has both hands occupied, this is used to trigger the reverb or tremolo effects.

10 Reverb Tank: A metal box containing four springs. As the audio signal enters, it is converted into mechanical action on the springs. Differences in the springs' length and stiffness cause sound to exit the tank at different times, creating reverb.

11 Isolation Bag: A sheath for the reverb tank that protects the springs from vibrations that don't come from the guitar.

Where you can hear classic guitar amp sounds

You can hear the Fender amp's bright sound best on songs like "Not Fade Away" by the Crickets. Here's where you'll find a few of the other effects we mention.

Distortion

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"Maybellene" by Chuck Berry

Reverb

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"Rumble" by Link Wray and His Ray Men

Tremolo

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"Gimme Shelter" by the Rolling Stones

Photographer Todd McLellan is the author of the book Things Come Apart. He's also really good at destroying perfectly good appliances.

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