Vintage Installs: Madman Muntz Made Mobile Music More Manageable

Sections: Car Audio, Installations

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The Stereo-Pak receiver

Earl “Madman” Muntz’s Stereo-Pak receiver was manufactured in a variety of styles for home, car, and boat, according to this period advertisement. (Image courtesy

First came the Highway Hi-Fi and other turntable-based audio systems, then California’s Earl “Madman” Muntz modified a medium used by radio broadcasters to bring us music on tape cartridges.

Muntz was by all accounts a colorful figure. His Wiki entry details his “Madman” persona as an over-the-top alter-ego known for unusual stunts, colorful costumes, and outrageous claims. It may well have seemed outrageous when he told attendees at the 1967 Consumer Electronics Show that they could listen to their favorite LPs on a much smaller cassette tape cartridge that would not skip like the earlier phonograph-based efforts, but that’s exactly what he offered motorists.

"Madman" Muntz stands beside a sign

Earl Muntz was known for his colorful “Madman” persona, which he often donned in advertising. Here, he poses next to a billboard advertising one of his car dealerships– another of his many enterprises that eventually led to him building a now-rare car known as the Muntz Jet. (Photo courtesy

The thing was, Muntz had already become pretty successful with the invention by that time. A 1963 article in Time mentioned that the Autostereo, as it was called, was already becoming a big hit with Beverly Hills’ cast of characters, from Red Skelton to Frank Sinatra. Muntz had the units manufactured in Japan, then a cheap source of such labor, and then sold them at a $129 asking price– the equivalent of nearly $1,000 today.

The Autostereo was designed to play Muntz’s four-track tape cartridge. That cartridge was itself based on the Fidelipac or NAB (National Association of Broadcasters) cartridge, a medium normally used for playing commercials or public service announcements over the airwaves at radio stations.

Muntz modified the NAB cartridge’s playback speed in an effort to get more playing time, as the original NAB cartridge was good for only 10 minutes, 30 seconds at its 7.1 inches per second rate of playback (IPS). Muntz cut that rate in half, to 3.75 IPS, which would give 21 minutes of playback time. Then he effectively split the 1/4-inch tape into four tracks, giving the potential for a little over an hour of playback in mono or up to 42 minutes’ playback in stereo format. He called the cartridge– or CARtridge, as he preferred– Stereo-Pak.

By 1962, the year before the piece appeared in Time, Muntz was doing well enough at the business that he canceled contracts with tape duplication companies and started his own, licensing music from the major labels– most of whom did not get directly into the business of manufacturing Stereo-Pak cartridges.

When the tape reached the end of one “program,” the listener had to manually flip a lever to slide the receiver head on the tape. The Stereo-Pak carts also lacked the built-in pinch-roller of the later eight-track cartridges, themselves an outgrowth of Muntz’s work after tweaks made by Lear Jet maker Bill Lear. This lack of pinch-roller meant the cartridges had to feature a hole large enough for a roller to be inserted from the tape machine itself, making it easy to get dust and dirt inside that would erode playback quality.

While the format had its shortcomings and was largely dead by 1970, “Madman” Muntz moved us one step closer to the modern music mobility we now enjoy with his Stereo-Pak cartridges.

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  • Haydn Kirby

    I have a pair of Muntz floor speakers from sometime in the 1960s. Is there a market from them anywhere?