Some things to know about vacuum tubes

Something really appealing about vacuum tubes. Especially on amps like this McIntosh MC240 where you can easily see them.

Do tube amps sound better than solid state ones?

In short, no. There are indeed some tube amps that listeners would choose over a pure transistor unit. Those that do are typically perceived to have a mellower or "warmer" sound, and possibly a greater sense of space in the soundstage. Solid state amps on the other hand, almost always outperform pure tube units in terms of bass performance.

I just found a tube amp that has been unused for decades

Probably not the smartest thing to just plug it in. You risk doing some serious damage if capacitors are shorted, or output tubes are weak. Mid century equipment with original capacitors will need some, if not all replaced in order to be reliable. Some amplifiers need to have the bias set in order to operate correctly, and to prevent damage to expensive output tubes.

Replacing vacuum tubes

Life with a tube amp means eventually having to replace tubes. Preamps and tuners often run for years on a set of tubes. Power amps and receivers will need output tubes(the big ones, and possibly driver tubes (smaller ones) replaced periodically.

How do I know if the tubes are bad?

You would need a tube tester to know for sure. Another approach is to simply replace the complete set of tubes. Not such a big deal, if they are only two. Tubes usually degrade gradually. Usually. As a result, the performance will also degrade slowly. Power tubes, can sometimes fail dramatically. Unfortunately, they can cause damage when they do. If you see the internal gray metal glowing red, remove power immediately and seek service.

Bias setting for select tube amplifiers

This is a very important step to do when power tubes are changed. Common amps that need this are the Stereo 70 and MKIII amps from Dynaco as well as some Eico and Heath amps, as well as earlier Conrad Johnson amplifiers.

Where do I get replacement tubes?

A number of web sites offer replacement tubes. Tube Depot, and Tubes and More are two popular sites. Tubes can range quite a bit in price. Power amplifiers, integrated amps and receivers will need good quality, and possibly matched pairs of power output tubes. It may be possible to substitute one tube for another. Certain substitutes may be of higher specification and performance than the original.

What about NOS tubes?

"New old stock" tubes can be found on eBay, Etsy, and other web sites. Once upon a time, tubes were made in the USA and throughout Europe. With some rare exception, these tubes are superior to modern Chinese, Russian, and Slovakian tubes. When Chinese tubes first began appearing in the US in decades past, the quality was very poor. In recent years, the gap is much smaller. Even so, the performance from old stock, or even used U.S. and European makes will be more reliable and sound better. At a very premium cost in most cases.

Should I buy a tube amplifier?

There is some modern era vacuum tube hybrid equipment that is reliable, and offers some aspect of tube sound. If you have spent time with a pure tube system, you probably have already made your decision. If you still have have doubts, or any of this worries you, or you maybe just want a trouble free sound system, we would not recommend it be a tube type amplifier.