The Supro Thunderbolt is a modest amplifier, but it plays a big role in the legend of Led Zeppelin. It’s generally considered to be the amp of choice for Jimmy Page’s incendiary playing on Led Zeppelin, the band’s 1969 debut album. “Communication Breakdown,” “Dazed and Confused,” “You Shook Me,” “How Many More Times”… all supposedly are the result of this modest creation of the now long-shuttered Valco Company of Chicago.

But the years have rolled by and Page has refused to confirm or deny his use of a Supro Thunderbolt on Led Zeppelin. In fact, he’s muddied the waters by stating that he owned as many of 50 Valco-made amps in the ’60s and ’70s, which monkey-wrenches the Thunderbolt legend because Valco also manufactured amplifiers for the Airline, National, Gretsch, Silvertone and Harmony brands.

Regardless of what Valco product Page plugged into, what is certain is that he used a small, low wattage amp to make those gargantuan sounds. Valcos from this era are incredibly harmonically rich and responsive, but Page’s secret was really in the way he miked his small amplifier for that big debut album.

During his pre-Yardbirds and Led Zeppelin years, Page was a session musician and had the opportunity to watch many producers and engineers do their thing recording The Who, The Kinks, Marianne Faithfull, Van Morrison and others whose songs benefited from his playing. As a guitarist, it was only natural that miking technique caught his interest. Getting a great guitar tone on tape was a struggle with the recording methodology of the day, which was often limited to live settings with too much bleed or employed small, stifling insolated chambers for amps.

By the time Led Zeppelin entered Olympic Studios in London, Page had developed a strategy for ambient miking for his small amps as well as John Bonham’s drum kit. In addition to his own studio experience, he drew on the past. The classic blues and rock recordings of American labels like Chess and Sun often had killer guitar tones achieving by careful microphone positioning, sometimes of just one microphone. The key is the axiom that distance equals depth. Sound waves coming from an amplifier take a certain amount of feet to reach their full amplitude and harmonic colors – to open up and sound their best and most accurate. Finding that sweet spot with an ambient microphone yields superb sound on tape.

So when Page tracked guitars in the spacious Olympic he’d put one microphone an inch or two in front of the speaker of the amp he was employing and another six to 20 feet away, depending on where the sound was in full bloom.

Since the late 1960s ambient miking has become common, largely thanks to Page’s bone-crunching guitar sounds on the early Led Zeppelin albums. During mixing, the ambient signal typically gets preference over the close-miked track, and engineers who use multiple ambient mikes will hunt for the track that has exactly the tone they’re looking for and cluster the rest of the guitar mike tracks around that tone to contour it according to taste.

When first trying these techniques, it’s best to experiment with a variety of mikes. Workhorses like the SM-57 can get superb results close up. For mikes with switchable polar positions, try ’em all before settling into a comfort zone. For example, a microphone set to a figure eight pattern placed directly in front of an amp picks up not only the close signal from the speaker, but the ambient acoustic reflections of the room as well, doing double duty.

When you move a microphone farther away from an instrument, you will need to increase the gain on your pre-amp in order for it to pick up enough volume. The sensitivity of condensers and ribbon microphones means that they need less gain to accurately capture an instrument at a distance, so they make excellent ambient microphones.

Generally speaking, dynamic mikes like the SM-57 don’t have the right juice for distance recording. Nonetheless, it’s practical to put at least one of those directly in front of an amp’s speaker and then use a more sensitive condenser or ribbon mike at distance.

And remember, when recording – or even live miking – an amp, never place the microphone dead in front of the speaker. The best sound, and less of the mechanical noise produced by speaker flex, comes off the side of the cone. In the studio, start by trying a spot about two inches into the speaker, record a bit, listen back, and repeat until the sweet spot is revealed.