Fuzz lovers, this one’s for you! If you’re constantly chasing that elusive tone, listen up: the magic of your tube amp isn’t just in the speaker or fancy caps – it’s in the tubes. Vacuum tubes physically amplify your guitar’s signal, boosting it to speaker-moving power. This amplification is referred to as “gain”. Where the fun comes in is that playing with preamp tube gain dramatically alters not only your amp’s character but your fuzz pedal character as well, unlocking a world of new tone!

We talk so much about the mighty 12AX7. The legendary compact preamp tube that made rock and roll roar! Most guitar amps use this sonic powerhouse in their first gain stage (V1) for good reason – it’s loud, clear, and packs a punch. But here’s the secret: preamp tubes are swappable! Wherever you’d normally find a 12AX7, you can switch it out with a 12AU7, 12AT7, 12AY7, 12AV7, or 5751 without harming your amp.

Combing a lower gain tube with a hot fuzz pedal can be game changing. We have a 1972 Fender Champ here in the shop. And when we run a Big Muff through it, we can never turn the gain of the pedal past a fourth of the way without it getting much to loud. This kind of makes the pedal less fun to use and explore. So, by changing the gain of the 12AX7 to something with less again we can explore the tones of our pedal more!

A vintage NOS tube on top of an amp set against a sunset scene

How Gain Factor Works

Preamp tube gain refers to the amount a preamp tube amplifies the incoming signal from your guitar. Think of it as the tube’s “boosting power.” Tubes with higher gain will significantly amplify the signal, leading to more distortion and overdrive. Conversely, lower gain tubes produce a cleaner, smoother, less distorted sound.

Each type of preamp tube (like the 12AX7, 12AT7, etc.) has a specific gain factor measured on a numerical scale. The higher the gain factor, the more amplification that tube provides. For example, 12AX7’s have a gain of 100, while 12AT7 have gain of 60, meaning that 12AX7’s are louder than 12AT7.

The amount of preamp gain alters how your overdrive and fuzz pedals will react. More gain from the preamp means your pedals will be pushed harder, creating thicker, more saturated distortion. Less gain on the other hand leads to smoother sounds, while simultaneously giving a wider variety of tones because your amps headroom in increased.

Preamp Tube Gain: The Voice of Your Amp

Tinkering with tube types can be as transformative as changing out your guitar’s pickups or strings. For instance, the 12AY7 will push your fuzz pedal into a new realm of sonic exploration, with less gain it introduces more headroom, allowing the true character of your pedal to shine through without being overwhelmed. On the other hand, a 5751 gives you a bit more grit than a 12AY7, perfect for those who want a bit more bite without going full throttle. Each swap is like finding a new voice for your amplifier, one that can whisper softly or scream with the turn of a knob.


  • 12AX7: The King (100 Gain)– The industry standard, known for its high gain and rich harmonic content. Expect serious crunch and saturated fuzz tones.


  • 5751: Tame the Beast (70 Gain) – With about 30% less gain than a 12AX7, the 5751 gives you more headroom before distortion kicks in. Think articulate, slightly cleaner fuzz sounds while retaining warmth.


  • 12AT7: Versatile Tone Shaper (60 Gain) – Often found in reverb circuits, the 12AT7 offers moderate gain levels. Great for vintage-style fuzz that’s a touch smoother and less aggressive.


  • 12AY7: Smoothing Things Out (45 Gain) – This tube has even lower gain, which means you really start having to rely on the gain of your fuzz. This can unlock a whole new world of tone from your pedals are you will have much more headroom.


  • 12AU7: The Low-Gain Champion (20 Gain)  – This tube gives you minimal gain, pushing clean tones that maintain pristine clarity. If you really want to hear the full potential of tones your fuzz pedal can make.

Experiment and Conquer

The true magic of preamp tubes lies in experimentation. Trying out different tubes lets you dial in specific flavors of fuzz:

  • Want tight, focused distortion with plenty of bite? Stick with a 12AX7
  • For vintage flavored or bluesy fuzz try a 12AY7
  • Need extra headroom and clarity? A 5751 might be your answer.

Final Thoughts: Preamp Tube Gain and Fuzz Pedals

Vintage Tube on Effects Pedal | Fuzz Audio

Remember that tube amps for the longest time had one goal in mind, clean signal amplification. It was the rockers and rollers who eventually started moving the tubes amps into devices that intentionally had nice breakup sounds, but this was not until the mid 60’s or so at the earliest. It is our duty as rockers to continue to experiment with new sounds and techniques.

Preamp tubes are your gateway to unlocking endless sonic potential of your fuzz and overdrive pedals. Remember, tubes are responsible for the amplification of the guitar signal, and that is why you can dramatically influence the gain characteristics of your fuzz by experimenting with different tubes. Don’t be afraid to try different combinations and trust your ears! While there’s no single ‘best’ tube, understanding their different gain and tonal quirks will take your fuzz obsession to the next level.

For more helpful vacuum tube tips and trick check out our Tube Buyers Guide! For more tone tips try our Tone 101 blog.