Many guitarists swear there is no substitute for tubes. Tubes add extra warmth and harmonics, and when overdriven, produce a much more pleasant sound than the whining screech of solid-state amps. But tube amplifiers get hot and are more failure-prone than solid-state equipment. The 12AX7 vs 12AT7 are two of the most commonly used preamp tubes. But which tube will make your guitar sound its best?
Tube preamps give you the best of both worlds. The preamp boosts and colors the pickup’s signal as it sends it along for further amplification before being transformed into sound. Because the preamp puts out a lower wattage, it can use smaller tubes that don’t get as hot and have longer lifespans than the big tubes needed to power a high-wattage tube amp.
Main Differences Between 12AX7 vs 12AT7 Tubes
The main differences between 12AX7 vs 12AT7 are:
- The 12AX7 has a gain output of 100, whereas the 12AT7 has a gain output of 60
- The 12AX7’s high gain can make it prone to clipping and distortion, whereas the 12AT7 can give you more headroom.
- The 12AX7 is mostly used in the preamp section of guitar amplifiers to boost the pickup signal, whereas the 12AT7 is also used in phase inversion and effects pedals.
If you’re wondering what all those words mean, read on. By the time we’re done, you’ll not only know the difference between a 12AX7 and a 12AT7, but you’ll also have a better understanding of how tubes work.
Read on for explanations and recommendations on the best tubes for your guitar setup.
Exploring 12AX7 vs 12AT7 Tubes
Since the mid-1950s, the 12AX7 has been one of the most widely-used tubes in the guitar industry. If your amplifier has tubes, it almost certainly has at least one 12AX7 in the preamplifier section.
As the signal from your guitar pickup passes through the 12AX7, it gains strength. The 12AX7 then passes that signal on to the amplifier tubes and the power transformer, and from there, to the speaker driver that turns electricity into sound.
The high gain can also raise the signal past its maximum, which sound engineers call clipping. Prolonged clipping at high volume can damage equipment and eardrums, but rock guitarists have used controlled clipping and distortion since Jimi Hendrix.
When transistors are overloaded, they produce harsh and painful “hard clipping.” As tubes try to pass the signal, they go into “soft clipping” and produce harmonics that we hear as euphonic. The joyful distortion you hear in a shredding guitar solo is created either through a tube preamplifier or a complex solid-state setup engineered to emulate soft clipping.
There are many companies producing 12AX7 tubes under different names and numbers. Here are three of the best 12AX7s on the market today.
Russian manufacturer Sovtek has built a great reputation for their tubes, and the Sovtek 7025/12AX7WA lives up to that reputation. The 12AX7WA has a lower noise floor than a standard 12AX7, which means you get a quieter background against which to play your instrument.
The 7025 signifies that Sovtek builds these tubes to the standard of the RCA 7025 tubes used on vintage Fenders. All tubes pick up sound vibrations to some extent. But if the tube is too sensitive to outside noise, it can begin reproducing those vibrations alongside the signal like a microphone, producing painful high-pitched feedback.
This can become an especially big problem with high gain tubes like the 12AX7. The Sovtek 12AX7, like the RCA tubes, will avoid microphony even at rock concert levels of noise.
- Suitable for use at very high volumes
- Low noise floor
- Recaptures the sound of vintage Fender amps
- None, really – the 7025/12AX7WA is a world leader
Slovakian tube maker JJ Electronics makes reliable tubes with a neutral sound signature and a modest price tag. Their version of the 12AX7 is sold under European standards as the ECC83, and JJ has many fans who swear by the brand’s durability and flexibility. The JJ ECC83 gives you lots of gain with rich harmonics and a tight, transparent low end. (Bassists, take note!)
If you want to roll the tubes in your current amplifier, or if you want to keep spares around in case of issues, JJ tubes will improve your sound without breaking your budget. JJ Electronics must be doing something right; as in 2018, they were shipping approximately two million ECC83s a year.
- Very reasonably priced
- Touring musicians swear by JJ’s reliability
- High-quality control means consistent sound
- Some find their consistent, neutral sound signature a bit bland
Wathen uses a proprietary cryogenic process which they claim results in improved sound quality and longevity. They also hand-select their tubes and test with microwave and x-ray devices before putting their tubes on the market.
Whatever their secret, Wathen tubes are noted for their clean sound and the rich complexity of their sound when driven into distortion.
Wathen tubes don’t come cheap: the CryoTone 12AX7 costs over 300% of the price of our other listed tubes. But if you are looking for the ultimate guitar sound, the Wathen CryoTone might be a worthwhile investment in your musical future.
- Perhaps the best-sounding 12AX7 tube on the market
- Smooth, refined highs and punchy, articulate lows
- Easy next-level upgrade for your favorite vintage amp
A high-gain tube raises everything in the signal, including the noise. The higher the gain, the higher the noise floor as the tube amplifies unwanted interference and background hum.
The 12AT7 has less gain than the 12AX7, which means it produces a cleaner sound.
The 12AT7 has a maximum gain of 60, so you lose a good bit of volume to the preamp signal.
A few places where 12AT7 tubes are commonly found include:
While some small tube amps use a simple single-ended circuit, most tube guitar amps on the market today use a double-ended “push-pull” or “Class AB” design.
A push-pull circuit uses two tubes or tube banks. Your guitar pickup signal is split by a phase inverter tube that sends the unaltered signal but also creates a mirror image that is 180 degrees out of phase.
Audio signals are sent as sine waves. After the wave is split, one tube reproduces the top half of the wave while the other tube reproduces the bottom half. This means each tube only handles half the work, which means tubes in a push-pull setup last longer than in a single-ended setup.
A push-pull circuit also drops harsh-sounding odd-order distortion and hum while preserving the warm even harmonics that give tubes their special sound.
The phase inverter tube doesn’t need to amplify the signal, but it needs to keep as much current as possible running to the banks. While you can use a 12AX7 as a phase inverter tube, many guitarists find that a 12AT7 gives them a better sound with less distortion and more headroom for soft-to-loud dynamic passages.
While rock guitarists love distortion, jazz guitarists generally want the cleanest sound they can get. The 12AT7 doesn’t go as loud, but its extra headroom means your music will remain clear and crisp at every volume.
The 12AT7 can also be used when amplifying keyboards or using a tube microphone, as it offers high fidelity and higher bandwidth for harmonics and overtones you can’t hear but which still shape the music’s sound.
Even rock guitarists can benefit from the 12AT7’s lower gain when playing in smaller venues. It is easy to overload a small room’s acoustics and turns your music into a reverberating mess. The 12AT7 offers high precision at reasonable volumes while giving you plenty of headroom for a decent dynamic range.
There is less demand for 12AT7s than 12AX7s, and one 12AT7 has risen to the top as the guitarist’s tube of choice.
The Genalex Gold Lion is the world’s best-selling 12AT7 and is considered the gold standard by which other contemporary tubes are measured. New Sensor (the Russian company which also owns Sovtek) produces the Gold Lion to the standards of the legendary Gold Lion KT88 of the 1950s.
The Gold Lion was used in many legendary hi-fidelity amplifiers, most notably the McIntosh 275. If you want the clearest, most accurate sound you can get from your guitar; the Genalex Gold Lion will be a tough act to beat unless you can get your hands on some NOS Gold Lion tubes and are ready to spend up to $1,000 a tube.
- A great option for upgrading vintage amplifiers
- Very linear with top-quality reproduction from high end to low end
- The best 12AT7 available for guitar amplifiers
- More expensive than many other 12AT7 tubes, though much cheaper than NOS vintage Gold Lions
Mesa traditionally used the 12AT7 tube in the reverb stage of its amplifiers, so this amplifier company knows its tubes. The Mesa Boogie 12AT7 is built to Mesa’s demanding standards and is the house brand tube used in many of their amps and effects. If you like the Mesa sound, the Mesa Boogie 12AT7 can help bring your gear closer to that tone.
While the Mesa Boogie 12AT7 has less gain than a 12AX7, it still has plenty of oomph to drive your amp as loud as you want it to go in most situations. Guitarists praise the Mesa for its rich sustain, fast responsiveness, and transparency.
- Recaptures the sound of vintage Mesa amplifiers
- Considerably less expensive than the Genalex Gold Lion
- Excellent, bright highs
- Not quite up to the Genalex Gold Lion in overall accuracy and tone
12AX7 vs 12AT7: Pros & Cons
12AX7 Pros and Cons
The biggest advantage the 12AX7 has over the 12AT7 is its increased gain. Many guitarists have replaced their 12AX7 with a 12AT7, then turned up the volume on their amp to compensate for the 30% lower gain a 12AT7 provides. This makes the power section work harder and can lead to a more distorted and less pleasant-sounding tone. If you like playing loud, you will probably prefer a 12AX7.
The higher gain makes the 12AX7 more prone to overdriving and distortion. If you like the warm overdrive of blues guitar or the crunching distortion of heavy metal, this is a good thing. If you are looking for a cleaner sound that is closer to an acoustic guitar, you may find a 12AX7’s gain overly powerful for your needs.
12AT7 Pros and Cons
The 12AT7 gives you a clearer, crisper, less distorted signal than the 12AX7. If you are playing jazz guitar or you want the cleanest signal possible, the 12AT7 will suit your needs better than the 12AX7.
Because the 12AT7 has less gain than a 12AX7, the signal coming out of your preamplifier will be around 30 to 40% less loud when you swap the tubes. If you want an amp that goes all the way to 11, you may find the 12AT7 runs out of steam before you hit your desired decibel level.
Are There Any Alternatives?
If you like the clarity of a 12AT7 but want a little bit more gain, you can always try a 5751 tube. The 5751 started life as a military spec 12AX7 that offered less gain but a more accurate signal. The 5751 has a gain of 70, less than the 12AX7’s 100 but more than the 60 offered by a 12AT7.
JJ Electronics 5751
One of the best 5751 tubes on the market is the JJ Electronics 5751. You can swap in a JJ 5751 for any 12AX7 and get less gain but more clarity and a lower noise floor. The JJ 5751 is very reasonably priced and can serve as a happy medium between a 12AX7 and 12AT7.
Frequently Asked Questions (FAQ)
Answer: On average, the tubes in your amplifier will last between 500 and 1000 hours of usage before needing a replacement. If you rehearse several hours a day, you could be changing tubes as often as every three months. When you start noticing declining sound quality or volume, there’s a good chance you need new tubes.
Answer: If you hear a persistent hum from your tube amp, disconnect all cables. If the hum goes away, you may have a ground loop or an issue with a cable or an effects pedal. If the hum continues, your amp may be dealing with dirty AC power or with interference from fluorescent lights. A power conditioner may help clear up the current going into your amp, or you may need to move the amp away from the interference source.
Answer: If you hear a hiss, crackling, and popping in your amplifier, your preamp tube is beginning to go bad. You may also hear a piercing squeal or unpleasant feedback after you go above a certain volume. This means you have a microphonic tube. In both cases, you will need to replace the tube with a new one.
Final Thoughts – Which is Better, 12AX7 or 12AT7?
Tubes are built for many different purposes. If you want a fatter sound with more sweet distortion, you will appreciate the extra gain that a 12AX7 provides. For those purposes, the Sovtek 7025/12AX7WA is the best 12AX7 tube you can buy for your guitar amp. Whether you want to refresh a vintage tube amp or upgrade to a new one, the Sovtek tube will rise to the occasion.
If you want a cleaner and more detailed sound – more Wes Montgomery or Mark Knopfler and less Jimmy Page or Stevie Ray Vaughan – you may find a 12AT7 better suited to your purposes. A Genalex Gold Lion 12AT7/ECC81 will be the best 12AT7 tube for jazz guitarists or for guitarists playing in smaller venues.
Tubes interact differently with different amplifiers, circuits, and instruments. To find the tube that works best for you, you may have to try out a few different tubes and decide which produces the sound you want with your equipment. Only you know what sound you want, and only you can decide which tube works best for you.