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An old-but-alive Marconi tube from KGB Radio & Electronics in Toronto. “What sounds the best is subjective . . . . They are all a little different,” says Aspen Pittman of Groove Tubes in California. (DICK LOEK/TORONTO STAR)

RACHEL ROSS, Toronto Star, reports:

It is the void that connected the world.

Long since banished but ever present, the vacuum tube turns 100 years old tomorrow.

It’s quite the anniversary when you consider the deep impact of such a dainty device.

The invention of the vacuum tube is considered by many to be “the essential start of electronics,” says Paul Redhead, researcher emeritus for the National Research Council in Canada.

Redhead is one of several researchers who are speaking tomorrow at the 51st International Symposium and Exhibition in Anaheim, Calif., in honour of the centennial.

Long a staple in radio and early computer equipment, vacuum tubes have retained a place in our microwave ovens and musical equipment. Today’s tubes are reviewed like fine wines; and, in the ultimate compliment, the nuances of sound created by classic guitar amps are being simulated by computers in a new generation of amplifiers.

It is a testament to the tone of the tube.

Basil Sloman remembers the early days of the vacuum tube, some 80 years ago when he sat by the family’s vacuum tube radio in his parents’ home in London, England.

Radios were a lifeline during World War II for men like Sloman who served in the air force and those at home waiting for their safe return. Adults and children alike would gather together to listen to the latest news and entertainment shows.

“We had a big square Marconi box radio. At five o’clock in the afternoon a beautifully modulated voice would come on to the radio and say, `Hello children! This is Uncle Mac’,” says Sloman, now retired in Toronto.

“There were standard programs that you listened to or you died.”

Many people were behind the miraculous little glass tube that so influenced Sloman’s youth.

The most notable of the bunch, though perhaps not entirely deserving of the fame, is Thomas Edison. That’s not surprising when you consider that a vacuum tube is little more than a modified incandescent light bulb. While trying to perfect his electric lights, Edison rediscovered an important process going on inside the bulb that was first noted by physicist Frederick Guthrie several years prior.

Both men noted that when you sucked the air out of a glass bulb and inserted a filament and a metal strip, negatively charged electrons would flow from a heated filament to the metal strip. An electric current, it seemed, was flowing through the vacuum.

Neither man was sure what to do with this information. They couldn’t even explain the phenomenon, though it would later become known as the Edison Effect.

“Edison forgot all about it. He was off developing a method to distribute electricity in cities,” says Redhead.

The British scientist John Ambrose Fleming later found a use for the Edison Effect in his work at the Marconi Wireless Telegraph Company Ltd. Fleming realized that adding a second metal strip (an electrode) to a light bulb made it a useful detector for weak telegraph signals.

He patented the Fleming “valve” on Nov. 16, 1904, spawning the electronics industry and inspiring other scientists to improve on his design.

American inventor Lee De Forest decided to add a metal screen between the filament and the electrode and turned the whole thing into an amplifier. De Forest’s “Audion” tube was critical to the radio revolution and also used to amplify long distance telephone calls.

Percy Spenser was working with radio waves for the military when he discovered they were good for more than just communication. Spenser was visiting a lab testing high-frequency tubes known as magnetrons, when a candy bar melted in his pocket. Spenser decided to test his theory that the waves emitted by the magnetron had heated up his snack. He sent for a bag of unpopped corn, held it near a magnetron and watched the kernels explode. Legend has it that the next day, Spenser brought in a whole, raw egg, put it in a pot with a hole in the side and set the magnetron up against the hole. Always inquisitive, Spenser lifted the lid of the pot just in time to have the now-cooked egg explode on his face.

He perfected his “method of treating foodstuffs,” which we now know as the microwave. While the small appliance has never replaced the stove, it has become as essential as the toaster due to its ability to heat food at a pace that matches our busy lives.

Vacuum tubes were at the heart of computing for many years, back when a single system could take up an entire room. Early computers such as the ENIAC owe much of their girth to the vacuum tube, in fact. It took tens of thousands of the little glass envelopes to power that machine.

Musicians found a good use for vacuum tubes, too: they made instruments louder and altered the tones they produced. When musicians turned up their amps, they found a whole new sound, a kind of distortion that made everyone take notice.

The invention of the transistor in the late 1940s ultimately eliminated the need for tubes in most computers: transistors were smaller and less fragile. But transistors didn’t revamp the musical landscape in the same way. High-end stereo stores still sell vacuum tube equipment for those who firmly believe in the purity of the tube and guitar stores such as The Twelfth Fret in Toronto sell a wide range of old-fashioned amps.

“Vacuum tubes never left the musical instrument industry,” says the store’s David Wren. He said that while tubeless transistor-based (familiarly knowns as solid state) amplifiers are a good, economical choice for someone who is just starting out, most serious musicians prefer the tone of a vacuum-tube amp.

“A tube amp reacts noticeably to how you attack the string and to the guitar you’re playing. It’s a true part of the your sound.”

He says the general preference for tubes is largely a matter of the harmonics, or overtones that make up the sound coming out of an amp.

“Tube distortion emphasizes even harmonics and solid state amplifiers emphasize the odd ones,” says Wren. “For some reason, our ears hear even tones as smoother. It’s a more musical sound.”

Their unique qualities have kept them alive
But Wren admits musical preference is partly based on what a person grew up with too.

Today’s younger musicians, he says, often prefer solid-state amplifiers because the bands they were fans of preferred that kind of distortion too.

But folks who are into the classics often have a penchant for the tone of the tube amp.

Debate still rages on among music aficionados about the relative quality of solid state versus vacuum-tube guitar amplifiers and stereo equipment.

Aspen Pittman is definitely into the classic sound. He sees vacuum tubes as more than just electrical components. To Pittman, they are an essential part of the creative process; they colour the music he plays.

Pittman is the founder of Groove Tubes, a San Fernando, Calif. company that grades vacuum tubes like fine bottles of wine.

“Big, round and clean yet easily compressed,” reads the display for one on the many tubes sold at The Twelfth Fret.

“Decent power, soft distortion, round and warm,” reads another.

Groove Tubes manufactures some of its own vacuum tubes but the bulk of what they sell are actually tubes that have been made by other companies, tested, classified and re-branded under the Groove Tubes label.

“Up until we got involved in the industry, tubes were still measured as electrical components,” Pittman says. “Generally there was an unawareness that one tube sounded different than another. But kids in the music stores could tell.”

The Groove Tubes grading system makes it easy for guitarists to find tubes that will generate the sound they are looking for.

“People often ask me, `What tube is the best tube for my amp?’” Pittman says. “What sounds the best is subjective. It’s like guitars. They are all a little different.”

Groove Tubes also “matches” tubes, Pittman says. Power tubes in guitar amps work in groups of two or more. Pittman said if the tubes don’t have the same qualities the amplifier would be “frequency selective.”

“Some notes will sound louder than others even if you hit the strings with the same intensity,” he says.

A well-matched set of tubes is like a properly balanced set of tires, according to Pittman. You can tell the difference.

Those with an ear for the classics but an eye to the future have another option when it comes to amps these days. Companies such as Line 6 now make guitar amps that use internal computers to recreate the sounds of classic tube amps.

Line 6 co-founder Marcus Ryle describes the innards of his amps as “virtual vacuum tubes” where computer circuits do all the work.

Such an amp can emulate the unique sounds of a Fender Blackface Deluxe, Marshall 50 Watt Plexi Head or Tweed Fender Bassman amp all with the touch of a button.

“Different tube amplifiers have distinct sonic characteristics,” Ryle said. “A musician might want a Fender sound on one type of song and then a Marshall on another. Over the years musicians have found they have to collect multiple amps to have access to a wide range of sounds. For many people that’s cost prohibitive.”

But for the price of one old-fashioned vacuum-tube amp, a guitarist can buy a new Line 6 digital-modeling amp that can provide dozens of different amp sounds, including those from classic vacuum-tube equipment.

“That’s what we sell the most of right now,” says Wren of the Twelfth Fret.

Wren says he still prefers a good tube amp but digital-modeling amps are “getting really close” to the real thing.

Even Pittman — King of the Vacuum Tubes — thinks they’re good for the music industry.

“A lot of people would never get to try those different amps. This way, they at least hear the differences,” Pittman says.

Though they are gone from most other equipment, a hundred years after the invention of the vacuum tube it is hard to imagine a world without them. They formed the foundation of our digital world. They cook our food and they colour our music.

Not bad for a modified light bulb.

Vacuum tubes mightly be bulky, fragile and fickle. But their unique qualities have kept them alive in kitchens and living rooms around the world.

Reach Rachel Ross at

Nov. 15, 2004. 06:55 AM