A Tube Primer For Guitarists – Part Two

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Guitar Amplifier Tubes Glowing

Last time, we talked about how tubes work and why they sound the way they do. This time, we will attempt to make sense of their cost. Be forewarned: there will be some “back-in-the-day” references in this installment. We’ll also talk about maintenance of tube amps.

Vintage Tube Amps

Guitar Amplifier Tubes GlowingBack-in-the-day, means the 1950s, ’60s, and into the early (maybe even the late) ’70s. Ancient history for a lot of you. Anyway, during that time when gasoline was $.25-a-gallon, tube amps were a normal thing – everybody that made guitar amps, made them. Fender, Gibson, Epiphone, Marshall, Vox… even Sears, had their own amps, all made in America, less Marshall and Vox of course. Some of them have gone by the wayside, but there have never been more tube amps on the market, from more manufacturers.

Digital amps using inexpensive materials, incredible integration, cheap labor (what there is of it), and big market names like Fender, Marshall, Vox, Peavey and Line 6, to name a few, add up to reasonably priced and capable amps for the mass market. Tube amps, except for the big names, are made by manufacturers that weren’t around way back-in-the-day, or were pretty obscure if they were. Nobody in the US had ever heard of Vox until the Beatles showed up in 1964! The Marshall “Wall of Sound” didn’t exist until The Who deputed here, and theirs was pretty lame by Van Halen standards.

Tube amps used to be all hand wired, the best ones very precisely, their wires twisted to reduce the induction of hum produced by the power transformers. They were quiet and had unreal sound, but required a trained technician, to assemble them. No robots back then, except maybe in the “Mission to Mars” movie. (“Danger, Will Robinson!”) Now, the mainstream tube amps mostly use circuit boards, with actual wiring only to those components that are mounted off the board. The board is cheap, the cost is the labor to wire it in. Also, most tubes use 250 to 350 volts on the plate (see part 1), requiring a big, expensive and heavy power transformer to provide it. (Replace the power transformer in your vintage Twin. Over $100 for the part, plus the labor.)

Tube amps usually use good quality, shielded (from RF frequencies) components to reduce noise. These are more expensive to produce and to buy. The resistors, capacitors and pots (volume, tone, etc…) all have to be top notch, capable of working in a high heat and high voltage environment. Read – expensive. The tubes themselves are costly to make, especially since the music industry is pretty much the only market for tubes in this day and age.

So, the cost for components is high, labor ain’t cheap – and tube amp manufacturing is more labor intensive than digital amps – the market is not mainstream, and there is a ton of competition. That adds up to dollars for the big manufacturers, who sell other stuff to help absorb the costs, Fender, as an example. A boutique amp builder, of which there are many, has to charge the big bucks for a tube amp, but some of those are really sweet.

There Is Good News

Tube amps require very little in the way of maintenance. Considering that digitals require none, tubes are still second place in this department! The big enemy of a tube amp is heat. Tubes produce heat by nature of their design. The interior components of a tube produce lots of heat when working, somewhere around 1500 degrees – hence the “standby” switch. The transformers produce heat, resistors produce heat, high voltage produces heat. The wires in your tube amp can get so hot that the insulation melts off. Guess what that does for you at a gig… can you say smoke effects? (COOL!!)

Visually checking the condition of your tubes depends on the type of hours you put on your amp. If you play in a house band 5 nights per week, and you really make your amp work for it, visually check your tubes every one to two weeks. If you only use your amp occasionally, and then at low volume, you can go one to two months. If your tubes are mounted under the amp chassis (upside down), check them more often.
Look for chalkiness inside the tube, large black areas on the inside of the glass, or pieces laying in the bottom. If you see any of this, take your amp in for a checkup. You could save a bundle in repair costs. For a little more info, try the video at the bottom of this page. It’s Mesa specific but the principles are the same for all amps. Go to your amp manufacturers website for info on your tubes or specifics for your amp.

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Doug Knight

Our “Man on the Street” reporter, with his “What’s New in Music Stores?” series, resides in Coos Bay, OR. You can find him on Friday nights at The Small Events Center at OrCoast Music in Coos Bay.

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