When shopping for tubes, there are a number of issues to consider such as price, longevity, testing, and tone. Some amps such as the Vox AC-30 can be tough on power tubes, and when power tubes are replaced it is also a good idea to replace the driver.
If you are considering buying used vacuum tubes, all of the same issues still apply. If you are just looking to save money, there are some very good sounding new tubes that are not very expensive. The JJ EL84 sounds great in my AC15 and I doubt I could find a used matched pair for less cash. If you are looking for a specific old tube, however, and you can’t find it NOS, then maybe buying used makes good sense, providing you can be sure that the tubes in question are properly tested.
Some of the more famous tubes are becoming nearly impossible to find. The Mullard ECC83 is a good example. NOS pieces are increasingly rare. Considering that many of the best NOS tubes are known for being built to a high standard of quality, it is not unreasonable that you could find a used tube that is still in good enough shape to last you for a good long time. Unfortunately, because NOS Mullard tubes are so rare the prices are incredibly high. This means that even used Mullard tubes can be pricey.
Unless you are planning on buying large lots and checking them yourself, there are a few other considerations when buying used. Have the tubes been tested for mutual conductance, shorts, gas, and grid leakage? Have they been tested for microphonics? The JAN-GE 12AX7WA can be found used for about half of what they cost NOS, but if you have to buy twice as many to be sure you are getting good tubes then it is not a good deal. Are they in good physical condition? Inspect their bases for damage, rust, or even broken/missing pins. If the pins are bent a little they can be easily straightened. However if they are bent too much it is possible to break the vacuum seal while straightening. The getter coating on the glass should be a dark shade of grey to black. If it’s missing or turned white it will indicate the tube is unusable. We have more information about getters posted at our website.
Another thing to consider is that often a tube tester will only tell you part of the story. Read our blog entry “What you Thought You Knew About Tube Testers” for more on the limitations. It will not tell you the tube still has any good sound quality left. If it was well used, it may test OK, but have lost its dynamics and sparkle. This is the main reason thetubestore.com rarely will sell used amplifier tubes. They will sell rigorously tested rectifier tubes because they are known to last for decades and not lose strength.
My town of Ann Arbor, Michigan has a neat little place called the Re-use Center. They sell pretty much anything that most people consider obsolete. Many towns have places like the Reuse Center. I used to buy boxes of old tubes from them and try them out in my Vibro-Champ. Of course I didn’t realize that I could have damaged my amp with a shorted tube, but I did end up with a great sounding Mullard ECC83 that cost me all of $2!
Buying used tubes from people who don’t have any return policy is a lot like buying anything else used. You might get a great deal or you might get burned. On the other hand, if you must have those old tubes, you might have to switch to used as the NOS stockpiles inevitably run out.
Alex’s Bio: Alex Anest has been performing, recording and teaching music in the Southeast Michigan area since 1996. He was a founding member of the Jericho Guitar Trio, Never Nebula, and Delta 88. With Delta 88 Alex performed across the Midwest and played at the Ann Arbor Folk Festival in 2004. Since then he has toured Switzerland, Germany, Austria and Italy with songwriter Kevin Meisel. Alex currently performs with Ryan Racine and Gas for Less and the electric anti-jazz ensemble Giraffe. Giraffe is a chance for Alex to bring his many musical influences together – a very enjoyable, though sometimes difficult task for a musician who finds inspiration from artists as varied as Paco de Lucia, George Harrison, Thelonious Monk, and Jimi Hendrix. The common thread among these giants (and the goal to which Alex aspires) is the ability to transcend stylistic boundaries while keeping their own unique musical voice intact.