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Let’s talk about another tube stage that is common in Marshall amps but isn’t a gain stage, the cathode follower. Take a gander: This looks familiar, but different. The guitar signal enters pin 7 of V2 and exits pin 6 as a standard gain stage. This time, the signal next enters directly into pin 2 (note there isn’t a coupling capacitor to block DC.) Pin 1 does not have a plate load resistor like other gain stages. High voltage is placed on both pins 1 and 2, forcing the signal

Now might be a good time to talk about coupling capacitors. They connect different circuits together by blocking the high voltage DC but allowing your AC guitar signal to pass through. Just like the tone stack capacitors, the choice of capacitor value will effect the frequency range allowed to move on to the next stages. C12 .022μF below is an example of a capacitor used to connect the V2B gain stage to the rest of the circuit. Let’s start talking about gain stages that have

Are you strapped in? Let’s look at a common 12ax7 tube gain stage. This is found in many guitar amp circuits. Let’s continue where we left off, as the signal path from the previous section enters pin 2 (the control grid) of the V1A 12ax7 tube. Looking at the image to the left, the role of the 12ax7 type vacuum tube in this circuit is to take your tiny signal going into pin 2 and have it come out of pin 1 much much much bigger. Much bigger. Bigger than you think. 100 times big

Let’s start at the beginning. Genesis 1:1, the Big Bang, the giant chicken egg. Your instrument’s signal will need to enter the amp circuit. The most popular method is the 1/4” jack. One simply acquires or makes a 1/4” male to 1/4” male instrument cable, plugs one end into their guitar jack and the other end into the jack on our amplifier. “Ahem, excuse me, Author. Duh, I know that! Now what?” Let’s take a look at a Fender Deluxe Reverb input. The guitar signal enters the fir

About once per week since 2021, I’ve been asked if I’m looking to hire an intern or apprentice. I never was and I’m still not but I sometimes bring them on anyway. The intern has always been a young guitarist looking to learn and possibly start a career as an amp tech. When a repair comes in the first question is, “What do you think is wrong with it?” And I respond, “I have no idea!” And I don’t. I could guess but that would put me in the same camp as those hundreds of intern