A Tweak Shop Guide to
Zen and the Art of
Vacuum Tube Maintenance
So you've crossed that bridge and gotten into tubed electronics. Congratulations!
We carry a wide variety of tubes here at The Tweak Shop, with sources from around the world including Russia, Slovakia, and China.
There's a tale about a Soviet pilot who decided to defect in 1976 by landing his MIG-25 in Japan. People were fascinated at the prospect of, finally, getting a look at this, the Soviet Union's most advanced fighter jet. Imagine their surprise when they realized that the fighters communications gear was based on vacuum tubes. (It was discovered that modern solid-state devices fail during the event of a nuclear pulse, while tubes continue operation!) I love that story...
|There are a few things you should know now that you've chosen this rewarding audio path, and that's what this page is for: To explain the basic care and feeding of your tube components.
First of all:
Handling Vacuum Tubes
Simple: DON'T. Tubes don't appreciate contact with oils and such from your hands. Oils and dirt build up on the glass envelope of the tube, eventually causing it to run hotter than it should, shortening its life. If you have to remove or replace a tube, wait until it's cooled, then use a paper towel or lint-free cloth to grab it.
Let me re-emphasize this: Try to avoid handling a tube when it's hot. Before trying to remove a tube, make sure the component is turned OFF and UNPLUGGED and the tubes have time to cool (usually just a few minutes).
When removing a tube from its socket be sure you don't jam it back and forth trying to pry it out; gentler is better, here. Grip the tube firmly and pull straight up while gently rocking it a couple of millimeters from side to side if necessary. You should be able to remove even the most stubborn tubes in this fashion.
Cleaning Vacuum Tubes
Over time, most tube pins begin to oxidize, and it behooves you to give them a good cleaning at least once a year. This can be accomplished with any number of contact cleaners or with good, clean Isopropyl alcohol (96-99% pure if possible; DON'T use rubbing alcohol - it contains minerals and oils that tubes don't like). We recommend using wooden-handled Q-Tips for the actual application and scrubbing (the paper-handled Q-Tips fall apart under pressure). If you still have some of the original Tweek Contact Enhancer around, good for you, but DON'T use it on tube pins. Tweek is not at its best in high-voltage applications.
Sometimes the easiest way to re-establish good contact for the pins is simply removing the tube and putting it back in! This often cuts through the oxidation and re-makes the contact.
Tube sockets should be cleaned as well. Pipe cleaners work fine for larger-pinned output tube sockets. (Again, not to state the obvious, but please only attempt this while the amp or preamp is turned OFF and UNPLUGGED!).
Should I Leave My Tubed Component On All The Time?
In 95% of the cases, no. There are a few components out there (like the T+A V-10 Integrated Amp) that have special circuits that provide a "trickle" voltage to the tubes, even when the component is turned "off". This does two things: It prevents the tubes from being "slammed" into operation when the unit is on, and it also means your "warmup time" to optimum listening is considerably reduced. Components like this are, therefore, "on" even when not "turned on", but this is a rarity. Energy-wise, a constant "trckle" voltage is not something we can recommend, as it can add up to a massive waste of resources. (Fortunately, that feature of the T+A V-10 can be switched in and out.)
In an ideal world, we'd all use massive Vari-Acs to slowly bring our tube equipment up to operating voltage. But that's an impractical fantasy.
It's something of a trade-off. Tubes don't like being turned on and off, but they also don't like being left on all the time just cooking. So it's sort of "six of one/ half dozen of the other". We think the tubes will last longer if not left on continuously, and many components feature a "soft-start" circuit that helps lessen the shock of turn-on.
Bottom line: Unless you really do listen to your system 18 hours a day, turn off your tube gear and prolong the life of your tubes (and save big on your energy bill!).
Situating Tubed Components
In case you haven't noticed, tubes get HOT! The single thing that will shorten their lifespan is making them run even hotter than necessary, so make sure the unit is installed someplace with good ventilation. This DOESN'T mean a wooden, designer-type cabinet with closed doors on the front and a small hole for wires in the back! Open equipment racks and simple amp stands may not be the last word in stylishness, but it's a safe bet your tube equipment will last longer and even sound better with an equipment rack designed for the purpose. If you HAVE to put it in a cabinet with closable doors, always leave the doors wide open when the equipment is on. (This is even a good idea with most solid-state components.)
As to the various forms of isolation feet, we have a rule of thumb: Sorbothane (or equivalent material) pucks under tubed preamps (in places that don't get too warm), and either cones (with solid metal tips) or a combination of cones and pucks under tubed amps. When choosing the soft, Sorbothane types, remember to provide enough of them to support the component without having them "squish" down to the point of losing their damping qualities (10-15% is usually the max). In some cases, proper placement of support is critical for best performance. ASK us about this; every component is different.
There are only a few things we recommend for improving the performance of tubes or prolonging their life. Our current favorites, the new Cool Dampers from EuroAudioTeam, are good for damping the glass envelope of the tube AND cutting down on microphonics (in some circuits you can actually hear the tube "ring" when the component is tapped). We can't recommend use of Sorbothane rings for this purpose and the reason why is simple: THEY MELT! We've seen examples of this, especially when used in preamps that run hot, where the Sorbothane melted down the sides of the tube and onto the adjoining parts and circuit board. Worse yet, once melted, the stuff STAYS melted, making for one hella mess. We also aren't too fond of devices that you have to glue to tubes with silicone or such. There are even some devices that make the tube run HOTTER! Is this a good thing? Of course not.
Well, that's enough to get you by. We've been afficianados of tube gear for a long time so, if you have any questions regarding their maintenance, give us a call at (707) 575-8626.
(Oh, and watch out for that nuclear pulse - your tubes may continue to operate, but you might not!)