Guitar Amplifier Upkeep: What You Can Do Yourself at Home, and When to Call in a Professional!
Updated: Jul 13
The chassis is absent the brass grounding plate used in narrow-panel tweed amps; instead, it has individual ground connections to the board. Photos and amp courtesy of Robert Stamps. Courtesy of Vintage Guitar by Dave Hunter.
Taking care of your amplifier can be just as important as maintaining your electric guitar. Amps are what translate your musical ideas to where they can be heard to an audience, and let’s face it, sometimes parts just go bad from too much rocking out. In this Tone Talk installment, I’m going to go over what you can work on yourself, what you can diagnose and replace yourself, and when is it time to call in a certified amplifier repair guy or electrical engineer.
I’d like to preface this article with a strict HIGH VOLTAGE WARNING: electric guitar amplifiers are high voltage devices and run on a significant amount of current that can be deadly! BE AWARE THAT SIMPLY TURNING YOUR AMPLIFIER OFF AND UNPLUGGING IT FROM AN ELECTRICAL OUTLET DOESN’T ALWAYS MEAN THAT CHARGES ARE NOT BUILT UP IN COMPONENTS. PLEASE DO NOT GO INTO A CHASSIS OF AN AMPLIFIER IF YOU DO NOT KNOW WHAT YOU ARE DOING FOR YOUR SAFETY.
-Happy New Year to all my students, and guitar lovers one and all!
I’ve been busy at work recording new music at Reddotte Studio with new clients since the week before Christmas, and I haven’t had anytime to contribute any blogs to all of you! I’m super excited to get the chance here shortly to share all the music I have been involved in nurturing and helping become born. It really is some special stuff!
However, I did have something happen to me while I’ve been recording that inspired me to share some session musician tips with you about amplifiers. On day 2 of recording Erik Nichols’ new, currently untitled project before Christmas, I blew up a vintage 1966 Deluxe Reverb. We had been getting some righteously varied tones with this classic amplifier plugged straight in with a Blackguard Telecaster. We were getting country twang, rocking solos, and thick bluesy rhythm tones and then all of a sudden, my workhorse vintage Deluxe Reverb amplifier started to sputter and sound much weaker. Upon swapping Erik over to another Deluxe we had in house to continue recording, I quickly started diagnosing the problem. I checked the speaker leads, the input jack connection, and then the dreaded tube check.
After checking a few preamp tubes with a tube tester, it turned out it was time to replace some tubes in my amplifier.
That brings us to what the hell are tubes, and why should you have to check them periodically? Most vintage amplifiers run on the outdated technology of vacuum tubes to help boost electrical signal to a stronger level. In fact, most technology of most of the 20th century were powered on vacuum tubes, including military radar, televisions, radios, stereos, amplifiers, long distance telephone networks, and even early computers. You’ll recognize vacuum tubes as the glowing light bulb things that sit in the back of your guitar amplifier. Vacuum tubes help your amplifier work by controlling the electric current in a vacuum space. When too much current is applied to your amplifier, or if you turn the volume up more than the circuit can handle, you’ll get the tubes to overload and get that beautiful rock n’ roll distortion you love on all your favorite records!
Unfortunately, the more you drive the tubes in your amplifier, the more they get worn out. At some point that will fail just like any light bulb in your home. The most common tube fix on amplifiers is the preamp tube. These tubes are what provide the gain, or amount of potential crunch, in your amplifiers circuit. When one faulty preamp goes bad, your amp will still function, but for optimum tone it should be replaced as soon as possible. Otherwise your amp will sound like it’s only running at 75%.
Before swapping any tubes, be sure to read your amplifier’s user manual or online guides, so you can see what tubes are suitable for a replacement and what won’t void your amp company’s warranty if you have a new amplifier. The good news is that most amplifiers have convenient access to easily swap preamp tubes! To take out your preamp tubes to test them, and then replace the faulty one is super simple. Turn your amplifier off, unplug it from the wall, and let it cool down for at least 15 mins. Tubes get hot when current runs through them, and you don’t want to burn yourself. Unplugging it from the wall helps prevent you from getting electrocuted. I recommend you pull tubes with a clean, soft rag so you won’t get any of your hand’s natural oils on any tube that might be good after a diagnosis. Natural oils can make hot spots on your tubes, and make them burn hotter where you last touched them. This destroys good tubes fast, so take it slow and pull them out one at a time with a rag.
After you pull your preamp tubes, check them with a tube tester to see which one has gone bad. In the process, if you discover any other weak tubes in your amplifier consider changing them as well. For modern tube replacements, I really like Electro Harmonix. Many years ago, Mike Matthews from EHX bought the last tube factory in Russia, and continues to manufacture high grade audio tubes for musicians and music lovers around the world! Preamp tubes are easily changeable because they do not require an electrical engineer to rebias the amplifer to the new tube. Biasing refers to going inside your amplifier and establishing electrical voltages levels within a circuit so it can work properly. DO NOT ATTEMPT TO BIAS AN AMPLIFIER UNLESS YOU ARE A QUALIFIED AMP TECHNICIAN!
The good news for me all my vintage Deluxe Reverb needed was a single new preamp tube to get it back and rocking again for Erik’s recording session. We keep single preamp tubes on hand for such occasions, so all I did was make the swap after I diagnosed the faulty tube. I also did some other quick Do It Yourself maintenance fixes for my amplifier while I had it on a workbench. Most of these fixes are from your amplifier’s vibration rattling things loose!
These can include:
Tightening your amplifiers handle and handle mountings
Tightening speaker mounting bolts, and the bolts that hold the speaker onto the cabinet (do not overtighten)
Checking the speaker cable that connects to the amplifier and making sure it’s secured
Tightening chassis bolts and screws (just enough to make sure that nothing is wiggling and making audible noise)
Cleaning your amplifiers input jack with DeOxit (spray a small amount into the jack and take a guitar cable and plug it in and out repeatedly to work the cleaner around the contact)
When to Leave It to a Pro:
That leaves you with plenty you can do on your own to upkeep your amplifier at home and to keep it running at its best, but it’s important to make a distinction with what should be left to a qualified professional in your area. Here are some jobs that are best to leave to the professionals.
Replacing Filter Capacitors: (You’ll Need a Fix Hint- declining low end, increasing 60-cycle hum, or dissonant ghost notes after you play harmonics)
Tightening Pins in Tube Sockets: (You Need a Fix Hint-occasional crackling sounds or intermittent problems including volume change)
Internally Cleaning or Replacement Pots (You’ll Need a Fix Hint- “scratchy noise when turning volume or tone controls)
Replacing Power and or Output Transformers: (You’ll Need a Fix Hint- frequently blowing fuses, total loss of power or output volume)
Replacing Components on Your Amp’s Circuit Board