Commentary on guitar amp tubes:
Today, there are many more choices of tubes than we had even a few
years ago but only 3 major factories still producing tubes. Some
people have a favorite brand, others swear by NOS (new old stock).
Still others say “I don't care, just use the cheapest thing
you can get.” Of course, there are as many opinions about tubes as
there are tubes.
Here is my opinion:
1) The majority of NOS tubes are overpriced, often over $100 per tube. Some are very high quality while many are the left over stock that could not pass inspection after production. Fortunately, there are still a few NOS bargains available so we do use them in some cases. If you insist on only NOS tubes in your amp and you are willing to pay the premium price, please tell me before the repair or estimate is complete. I will use anything you want as long as there isn’t a reliability risk. I continually review current production tubes and make choices based on performance, reliability and value.
2) Chinese tubes have gotten better but it’s important to buy brands that have been carefully tested. Ruby, Tube Amp Doctor and Mesa all do a good job of testing Chinese tubes before putting on their brand label. Like the factories in Slovokia and Russia, the Shuguang factory does a very good job at making some tubes and is not so great on some of the others. See our individual reviews for more info.
3) Like the Chinese tubes, Russian and Slovakian tubes must be chosen carefully. Since all the tube factories are better at building certain tube types and not so good at other types.
4) Groove Tubes, Ruby, TAD, Mesa Boogie, Ruby - There is much confusion in the market place about these brands. None of these companies manufactures tubes. They all buy current-production tubes and test them. Those that pass the tests get the company label and often a higher price tag. We also test all tubes that we use in amp repairs. In addition to standard testing, we actually listen to the tubes and reject them if there are any audio problems. In general, we can supply the same tube without the higher prices labels. For that reason, we don’t sell or recommend Groove Tubes or TAD. Ruby has good pricing and Mesa requires their branded tubes on warranty repairs so we stock those brands.
I'm very particular about which tube I use in various amps and each choice is made based upon several factors relating to sound quality, reliability, voltage and current requirements, microphonics, hum, etc. Each factory seems to have periods of higher quality and periods when we see too many many problems with particular tubes. When that happens, we make adjustments and switch brands for the type of tube that is affected.