Tube Amp Care & Repair
By Jeb Silburn, Twin Town Guitars Staff Writer
Little else can top the wall shaking power of a tube amplifier. Any guitarist who has plugged into one has felt that deep sense of wonder as they let their first few strums come through the speakers. Whether you’re a beginner in the tube wattage world, or an expert in the tone field, a tube amp is a needy little monster- there’s some maintenance and care required. Knowing how to care for your Chariot of Tone (we’re coining that) will ensure a full life of playing together. All of those wanton nose-to-the-grindstone & cares-to-the-wind rock and roll sensibilities may not imply such an amount of upkeep, but taking good care of your amp will make sure it sounds its best, and let you rip your hardest. We can’t always just Hendrix our gear aflame, sadly.
Whether it’s a Peavey Deuce or a Marshall Plexi, amps need some love. Some basic safety that’s inherent to all electronics is the first key to taking care of your amplifier. Your amp comes with a three prong power supply cord, and you should leave it that way. Often enough, someone wants to plug their amp in to a two prong wall outlet, so they simply truncate the third leg of their cable. This takes away your ground- electricity now has nowhere to go other than through the amp chassis, your guitar, you, or all three. All of these outcomes are less than ideal, and even dangerous. If you have a vintage amplifier that only has a two prong plug, it can be modified in most cases to adopt a grounded power supply. We highly suggest this for the aforementioned reasons.
Liquids- Morning coffee, a favored cocktail or brew, even just the water bottle. All are deadly hazards to a tube amplifier. Sure, everyone knows that a vintage head or combo makes the best cup holder, but the combination of wet + electrical has never been a fortuitous marriage. At best, you’ve marred the finish of your amplifier. No big deal, but the only other outcome could prove fatal for the amp, or painful for you. A spilled beverage can short out your amplifier, causing extensive internal damage, and possibly even shocking the user.
Vacuum tube amplifiers need to be treated a bit differently than a solid state amp. The virtue of patience will take one far on this road. When powering up a vintage amp, there’s a small delay before signal will pass through the speakers. During this period, it’s best to let your amp do its thing and resist the urge to play. If possible, you may even want to leave the standby switch, your magic best friend, on to let the amp warm up for a minute or two before playing. Flip that standby off when it’s time to start rocking.
Bringing your amp in from the cold? Even a small car ride in the middle of a Minnesota January can freeze your Fender Twin solid. When bringing your amp inside from the wintry weather, there are a few points of caution one should take. Let your amp warm up to room temperature, gradually. Turning it on immediately when it’s cold can wear on the tubes immensely from temperature shock as they rapidly heat up. In some cases, the tube sockets are more brittle than the tubes themselves when frozen, and great care should be taken to avoid breaking these when moving an amplifier. Condensation will form on almost anything that’s too cold and introduced into a warmer environment. If you notice condensation forming on your tube amp after bringing it out of cryo-sleep, do NOT power it on! Wait for all of the moisture to evaporate before turning the amp on to avoid shorting it out.
Another factor in caring for your tubes is their age and amount of use. Over time, tubes wear out and need to be replaced. Knowing when to replace your tubes can be a tricky endeavor. Luckily, there's a few visual and auditory cues one can follow to know when it’s time to make the ol’ switcheroo. When the amp is on and playing, look at your power tubes. If one is glowing far less than the others, this dimmer fella is probably close to biting the dust. Too, some tubes will glow much whiter than their candle-yellow counterparts, and this can be a sign of wearing out as well.
Sometimes an amp with old tubes can have excessive hum, or even seemingly phantom notes. This can be a sign that power or preamp tubes have become microphonic, and need to be changed. One way to test this is to lightly tap the tubes individually while the amp is on using a pencil, chop stick, or whatever small wooden tool you might have on hand. A good tube will just make a glassy ‘plink’ as one might expect. A microphonic tube will pass a thumping or rattle through the speaker; this should be interpreted as a cry for help. Your amp is in need of professional guidance to make it through this hard phase of its life. Consult an amplifier tech to diagnose any further issues, and fix up your treasured amp.
In any case, these cautionary practices are well worth the time. A tube amp can be a lifelong companion if you’re willing to invest the time and intentionality into its upkeep. Even when following all the best advice, amplifiers are finicky contraptions and something will inexplicably go haywire. This is okay, and often very manageable. Our amp technicians have seen it all, and are here to help. Many times it’s tempting to take a DIY approach, fix it up yourself, and save a few bucks. If you are one of the rare few who can succeed in this endeavor, I envy you. If not, know that you are in the majority, and consulting a professional amp repair tech for any sort of service is always encouraged when something’s wrong. Twin Town Guitars offers full service amplifier repair every day of the week. Give us a call at 612-822-3334 to set up a repair, or to ask any questions on how to best care for your tube amplifier.