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Some things to know about vacuum tubes

Updated: Feb 20, 2023


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?


Overall, there are some tube amps that listeners would choose over a pure transistor unit. There are also many tube amps that sound too "dark" or "muddy". Some tube amps are perceived to have a mellower or "warmer" midrange. Solid state amps 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, and possibly driver tubes replaced periodically.


What are matched tubes?


Most commonly, the large output or power tubes in most tube amps must be matched. Some higher end units have a separate bias adjustment for each tube, these are a little less critical. It's especially important for amps that have a shared bias adjustment, such as the Stereo 70 and MKIII amps from Dynaco.


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 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 reccomend it be tube type.

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