If you own a tube based guitar or bass amplifier or even a Hi-fi audio amplifier, chances are you will find a 12AX7 under the hood. Maybe even a few of them.
The 12AX7 is the first choice for tube amplifiers because of its high gain and relatively low noise characteristics. But which are the best 12AX7 tubes, and what should you pick?
And even though it is as popular as it is, most people know very little about them. Even changing a one can be a nerve racking experience.
So we are going to change all that with this ultimate guide! We suggest you bookmark this article, so you can return to it when you need to know about the 12AX7!
We have a number of reviews that goes into more detail about our tube selection. But if you are in a hurry, here is our top selection. Depending on your budget, you will find good results from these 3 12AX7 versions.
If you have more time, proceed to read the rest of this article, which also contains more 12AX7 tubes and descriptions of why we like them!
Best For Musical Instrument Amplifiers.
Best For Musical Instrument Amplifiers and HiFi.
Best For Musical Instrument Amplifiers and HiFi.
List of the Best 12AX7 Tubes
Each manufacturer produces a 12AX7 that is their own, and each one has strengths and weaknesses. Some are darker sounding while others are bright. Some are noisy while others are not.
So we have created a comparison chart below with some reviews on what we feel these tube brands bring to the table.
We chose these versions because we feel they are some of the best 12AX7/ECC83 tubes on the market that are still affordable and easy to get. We have created recommendations for both instrument amplifiers and HIFI applications.
The 3 main characteristics we chose to rate below are
- frequency response
These are what we feel are some main things you would want out of a 12AX7. So we have given each tube a rating for each of its strengths and weaknesses.
- Microphonic Rating ( 1 being very low and 5 being very microphonic)
- Noise Rating ( 1 being very low and 5 being very noisy)
- Frequency Response (1 being very dull and 10 being very rich and lively)
Our tests were also conducted using a number of amplifiers capable of different music types:
- Revv Generator Mk2 – High Gain and clean Tones
- Vox AC30 – Crunch Tones
- Marshall JCM 800 – Vintage Crunch and clean tones
- Mesa Boogie Prodigy – Bass Amp
- BoyuuRange Reisong A12- HiFi Amplifier
The JJ ECC83 is a very popular 12AX7 among guitar players and musicians. This tube is well-balanced and is relatively low in noise. JJ has become a very popular and well known brand over the last few decades, making durable tubes with good longevity. They are capable of taking a beating, standing up to aggressive touring and gigging.
This model is warmer sounding than other 12AX7 and is great if you are looking for a darker tone. If you have a harsh or bright sound, this version will tame that harshness. The low microphonics of this tube and good gain structure make this a great choice for guitar amps in the more aggressive realms.
The JJ 12AX7/ECC83 tube is recommended for high gain amplifiers that are focused on warmer rhythm aggressive sounds and music like:
- Hard rock
- Bass Amps
But they are also capable of delivering superb clean sounds and can work for blues, jazz and classic rock tones. For bass amps, this is also a great choice as they pack a punch.
This JJ ECC83S will work better in instrument amplifiers and is not recommended for HIFI applications.
The JJ ECC803/12AX7 is a long plate tube based loosely around the ECC83S. We wanted to include this model in our list because it is quite different from the 83S, especially in the high-end response, which had a bit to do with the gold pins. The low end and mid-range are also different. It is very full and almost sounds like a blanket was removed from a speaker.
As we played it more, over time it seemed to continue to get sweeter. It is a great tube and is well-balanced and musical. Any amplifier can benefit from this one, and it will fit many forms of music. Clean tones were exceptional and vibrant. Being as full as it was, we also found the bass amp to respond well to this tube as well.
One thing with long plates is they are known to be a bit noisier, but we didn’t experience that with this model. It was quiet and did not present any microphonic issues.
Unlike the 83S, we found this to be a better candidate for HI-FI audio as well and would compliment a great system.
This JJ ECC803S will work great in all types of instrument amplifiers as well as HiFi applications.
The Tung-Sol version is another popular model. This tube is very musical and rich in harmonics. The highs are smooth rather than harsh yet pronounced. Tung-sol, which is now owned by Electro-Harmonix, is well received in the amp world because of the durable and very musical products they make. These tubes are trusted and relied on by many musicians, from hobby to pro.
This model has the ability to tame high-end harshness, but isn’t dark or muddy. Good sounding with great drive. Its bright and sparkly sound is perfect for not only clean tones, but is good for searing leads. The low microphonics and robust build make them an amazing choice for many types of music. They work great in any position in your amp because of their low noise.
The Tungsol 12AX7 is a well rounded tube and we recommend it for :
- High gain Rhythm
- Clean tones
- Bass Amps
They will fit any form of music very well because of their clarity and well rounded sounds.
While we would recommend the Tung-sol more for instrument amplifiers, they do a decent job in HIFI applications as well.
The Genalex Gold Lion 12AX7 is smooth and is an incredible tube to increase the performance and definition of your amplifier. This tube has a very broad mid-range that is pleasing to the ear, but isn’t boxy or flat. The detail in note response is rich, tight and articulate, which everything you could need or want.
The highs and lows are well-balanced, giving this tube a very full dynamic sound. This is considered the best 12AX7 in production and the change is noticeable! And thanks to the great build quality, the noise is super low and there were no microphonic feedback issues present. This model can be used in any position or stage of your amplifier.
The triodes inside this envelope are also balanced to within 15% of each other, so they also make a great phase inverter or buffer tube. Effect loops will also benefit from this one.
The Genelex Gold Lion is the perfect tube for:
- Clean tones
- Bass Amps
- HiFi Amplifiers
We recommend the Genalex Gold Lion for both instrument amplifiers as well as HIFI applications.
The Mullard 12AX7 has a long history and has earned a reputation in the NOS hall of fame. Today, the reissue is just as good and a perfect tube for clean or vintage sounds. Because it has a more gritty sound to it when driven into saturation, it serves a better role in the crunch tones. Depending on your amplifier, it may serve well in the high gain arena, but we found it favored classic stuff more.
It has a very warm tone and crisp top end, perfect for low gain feel and leads. When you dig in, the response if everything you could ask for. Good build quality helps keep noise and microphonics very low, making it a nice tube for any position in your amp.
Bass amplifiers will make great use of this tube, as it provides a well-balanced sound with a deep low end. And because it is so well-rounded, it also works like a champ in HI-FI applications as well.
It will serve very well in genres like:
- Classic Rock
- Vintage sounds
- Bass amps
We recommend the Mullard 12AX7 for low gain tones, bass amplifiers and HIFI applications.
The Electro-Harmonix 12AX7EH is another great choice and one that doesn’t get the recognition it deserves. This tube is one that you will find comes stock in a lot of amplifiers. This is because of its great build quality and full-bodied sound. Not only that, but you can also find them in a lot of guitar pedals, as they work so well in many applications.
The lack of noise and microphonics was appreciated, especially when upgrading from lower quality tubes. The articulation in this model was frequency wide, as it kept itself together real well overall. The bass was rounded but not mushy, and the top end response was right on point. It was neither sharp nor dull and was pleasing to the ear.
This is a great tube for:
- Bass amps
The Electro Harmonix 12AX7 is great in both instrument amplifiers and HIFI applications.
Another awesome Russian made tube made to breathe life back into the dullest of amplifiers! The Sovtek 12AX7LPS are a great sounding tube with low noise and microphonics. Its break up character is very pleasing, with chewy crunch tones rich with articulate harmonics.
High gain tones were quite good with well-balanced sound and response. They lean towards the warmer side of the spectrum, but the highs were still present and clear. Being a long plate, I sort of expected more noise from the tube, but was pleasantly surprised at how quiet it was.
For HI-FI applications, this was a great fit, very smooth and full, no odd noises or funny response. Bass amplifiers will benefit from this model because of its warmer mid-range punch.
The type of music i would suggest for this tube type:
- Bass amps
The Sovtek 12AX7LPS is good choice for both instrument amplifiers and HIFI applications.
The Svetlana 12AX7 is a Russian made tube designed after a New Old Stock favorite. This model is well received by those who like the old RCA’s because of its smoother frequency output. It has a great bass response, being quite full in the lows but not over bearing. The mid-range is smooth and very present, which was perfect for lower gain crunch tones.
The top end was open without being too bright. This tube is not harsh and doesn’t have the same gain output as some of our more metal friendly selections. But this makes it perfect for lower gain tones and bass amps. Upon saturation, the structure was not overly gritty or grainy, which was a very articulate and musical experience.
For HI-FI, this tube is a real gem as well. It is well-balanced, refined and less bright than some other models, making it great for this application. It is well worth a try and very affordable.
We suggest this tube type for:
- Classic rock
- Bass Amps
- HiFi Amplifiers
The Svetlana 12AX7 is great choice for instrument amplifiers and HIFI applications.
Groove Tube ECCC83
The Groove Tube 12AX7 is a Fender branded model, and it sings. This one has a stronger output, putting more bite into your high gain tones. Its ability to add beef to a saturated tone is over the top. This is the type that opens up your sound by providing a great presence across all frequencies.
Clean sounds were very rich and chimes providing a nice experience over all. The crunch tones were full of life and very detailed. Compared to other tubes, this one felt a bit more aggressive. The build quality is great, but because of the added aggression, there was a bit more noise compared to other tubes. A couple of the ones we tried had a slight ring to them when saturated, but nothing crazy.
This tube has that Marshall bite yet has a full-bodied mid-range and solid low end. Perfect for both rhythm and leads. Because of the full spectrum of sounds, bass amps will come to life with this model as well.
This is great 12AX7 for :
- Hard Rock
- Medium gain
- Clean tones
We recommend the Groove Tube 12AX7C for instrument amplifiers. There are better choices for HIFI.
The PSVANE 12AX7-T is an amazing tube for musical instruments and HIFI Applications. This version has a full body, deep bass and pristine highs. Compared to others, it has a noticeable high-end performance. The Psvane performed better, is richer, thicker, and more complex.
For musical instrument amplifiers, this tube was very well-balanced. The low end is present, but not overly muddy. When saturated, it was thick and fast enough to fill the room in a pleasing way. The top end was not overly aggressive, but rounded and musical.
If you are running any type of HI-FI equipment that is medium grade quality or higher, you will enjoy these tubes. The experience in both music and movies is well worth the money. They are also very quiet.
We recommend the PSVANE 12AX7-S for all applications.
How to Choose the Right One
Because the 12AX7 is so popular, you are bound to find one or a few in your amplifier. They are used in guitar, bass and HI-FI amplifiers. You will even find them in pedals that use them for their great tone. But how do you go about finding the right sound for you and your rig?
With all the different types we listed with their strengths and weaknesses, it can be tough to decide.
We suggest you read our reviews carefully and then find the ones that best match your music style. If your amplifier is a high gain model, then you might even care to mix and match a few in different positions.
Some tubes are better in circuits designed for crunch sounds, and so you may want to lean towards some of those models that do it well.
As long as you match the tube to the sounds you are going for, you really cannot go wrong. We chose to review and list these models because they are some of the best you can get today. And because a lot of them are very affordable, it is easy to try a bunch out as you discover their great sounds for yourself.
Best 12AX7 Tube For Metal
If you are a metal player, you will need some different high gain tones that are pretty specific. There are some tubes that are better for metal music than others. If your sound is dark, the wrong tube can completely change your desired tone.
The best current production 12AX7 tubes for metal are:
- JJ ECC83S: If you like a darker rhythm sound, this tube can be great for that. They are more warm than bright and pretty aggressive.
- JJ ECC803S: This version that JJ has released is a more balanced sound. It retains the great low end but adds a bit more sparkle to your sound. They are aggressive and can pretty much cover all metal genres.
- Genalex 12AX7: This is an all around great preamp tube for metal. Very balanced sound with a mid-range punch and growl. This is a perfect high gain tone and works in all guitar amps wonderfully!
- Electro-Harmonix 12AX7: The EH version of this tube is quite balanced, but not as bright. I wouldn’t say it’s as dark as the JJ stuff, but pretty neutral in the top end. This can be a great sound for most metal players.
- Groove Tube ECCC83: This is a pretty aggressive tube and is very articulate. The reason for this is because of its brightness. It has a good low-end response and will be great for searing lead tones.
So depending on what kind of sound you need, there are plenty of options. To get an even more in depth description of these tubes, see our comments at the beginning of this article. We go through them all and what they have to offer.
Best 12AX7 Tube for Bass Preamps
While bass and guitar players have different needs when it comes to sounds, the tube options available can serve both. Most tubes can give you a great bass sound, but there are a few that are a bit better for the job.
The JJ ECC83S is a great tube because of its dark nature. For a bass sound, it is a great option and very affordable one too. The Sovtek 12AX7 is another tube that should be considered. It is one of the brands that most manufacturers put into their bass gear because of how well it performs.
The Mullard 12AX7 is also a great, well-rounded bass amp tube that can add some definition to your sound. These options all depend on what kind of bass tone you desire, and so some experimentation can help you.
12AX7 In Rock History
When you think of some of the amplifiers that powered the music scene of yesterday, you probably think of brands like Marshall or Fender.
These are iconic amplifiers for sure, but what about the mighty tube that made it all happen? That’s right, the 12AX7 has been used by amplifier manufacturers since the early 1950s!
These little tubes were the driving force of the rock and roll sound from pretty well the beginning. Yet there is little to no mention of it even though it is one of the cornerstones of guitar sounds!
Even today, amplifier manufacturers use the 12AX7 because it continues to be the sound in a player’s head. It’s time we give them some well deserved recognition!
What Is A 12AX7?
The 12AX7 is a 9 pin dual triode, meaning it has 2 sides or amplifiers in one glass envelope or tube. It is a small signal high gain amplifier. It can take a small input signal and amplify it a great deal.
This is especially handy in instrument amplifiers as the signal from instruments is very low. Normally in the millivolt range. Each triode or amplifier inside the tube have 3 pins each that control the amplifier and a shared heater element.
This heater element stimulates electrons inside and is seen by a faint orange like glow. The 12AX7 is a part of a large family of twin triode vacuum tubes, each with their own characteristics.
They span a wide range of voltage gain, ruggedness, micro phonics, stability and even lifespan. But the 12AX7 is the most commonly used type of them all, with over 2 million being produced annually.
12AX7 Technical Information
12AX7 Specification And Max Ratings
The label 12AX7 is a series of designates that describe what the tube is capable of and how it is to be used. It is not simply just a model number.
For example, the 12 indicates that the heater will require 12 volts. “A” indicates it is an amplifying device.
The X indicates its electrical characteristics, while the 7 indicates the number of active pins.
Filament Voltage: 6.3-12 V
Filament Current: 300-150 mA
Plate Voltage (max): 330 V
Plate Current (max): 6 mA
Max Plate Dissipation: 1.1W
12AX7 Pin Out
- Plate 2
- Grid 2
- Cathode 2
- Filament 2
- Filament 1
- Plate 1
- Grid 1
- Cathode 1
- Shared Filament
For those that are looking for the datasheet on the 12AX7, we have linked to a few pages that may come in handy.
- Click Here for datasheets to many different tubes including 12AX7.
- Click here for the JJ ECC83 (12AX7) Datasheet.
- Click here for the Tungsol 12AX7 datasheet.
Different 12AX7 Names And Labels
12AX7 Vs The ECC83
If you have ever opened up your amplifier expecting to find a 12AX7 but found some ECC83s instead, fear not!
There is actually no difference between them except for the name and place of manufacture. The 12AX7 label is what was used when this type was manufactured in North America.
Today there are no factories in North America making them anymore, but by request manufacturers will label them as such. After all, the design is the same.
The ECC83 on the other hand is the label that was applied to this type by European manufacturers, yet it is the same tube. So if you ever find an ECC83, you can replace it with a 12AX7 and vice versa.
They are the same tube type with just a different nomenclature, so go ahead and use that ECC83 in place of a 12AX7!
7025 Pre-Amp Tube
The 7025 is a name that was given to an upgraded version of the 12AX7 in the 1960s. The upgraded version was quieter and more robust than the standard version of that time.
They were less microphonic and just an all around better product. A few years later, manufacturers of the 12AX7 began to make their versions in the same manner as the 7025. The new design became standard, and the model was a better production tube.
Today, some manufacturers still claim to make a version of the 7025 with better metals for a more robust product. They are a bit more expensive, but are quieter than the standard 12AX7. These quieter versions are only beneficial when used as the first stage in a preamp.
The noise floor is very low at the input tube and so the quieter the better.
5751 Pre-Amp Tube
The 5751 version of the 12AX7 was created as a military spec. This tube was given extra support internally and had matched triode sections.
The amount of gain produced by a 5751 is also lower than the 12AX7. Your standard model has a gain factor of 100 whereas the 5751 is 70.
Some people refer to the 5751 as being a 12AT7 because it too has a gain factor of 70. But this simply is not the case, as the plate resistance of a 5751 is the same as a 12AX7. You can use a 5751 in its place, but keep in mind it will produce lower gain.
So if you want to tame an amplifier with too much gain, this is the tube you want to use in select spots of a pre amp.
You can also use this tube in the position of the phase inverter to produce less power from an amplifier.
12AX7 “A” and “B”
The 12AX7-A and “B” are two tubes that are identical in nearly every way.
You may have come across these two labels in your hunt and were curious about the differences.
They are made in the same batches and are the same tube, but some of them come out producing high gain.
The 12AX7-A is a higher gain version of its counterpart. For all intent and purpose, the “B” version is simply a screened tube selected for its high gain and low noise.
The ones that had higher gain and were noisier may have simply been named 12AX7-A.
Mesa Boogie and Peavey use 12AX7-A labelled versions because of the higher gain, but this comes at a price of a noisier output sometimes.
But if you want a gain monster for an amplifier and are not worried about noise, the 12AX7-A is your animal.
If you want high gain and a quieter, even softer tube sound, the “B” version is your best bet.
Microphonics And Noise
Checking a 12AX7 For Microphonics
One of the common terms used among tube amp owners is microphonic. This is a go-to term used when issues with an amp arise.
But what does it really mean? When manufactured, they are tested for a number of different things to verify they are a good tube.
Noises are one of those tests, and in particular, whether there are microphonics.
A microphonic tube is susceptible to external noise and amplifies it. In most cases, it will ring like a bell if tapped on.
Now, most will make noise when they are used in the input position. So it’s important to note that it will make a sound when tapped on because of the noise floor.
It’s just that a rugged tube with low microphonics will normally make a thud type sound, but the flip side of that, is that it will ring and produce very high frequency noise.
Just a word of caution, when you tap on a tube to check it, don’t tap too hard. It is an electronic, mechanical device that can be damaged if it is hit too hard.
Are Microphonic Tubes A Problem?
It’s a fact that tubes produced today are not what they used to be.
In some cases, there are little to no tests done by some manufacturers. Most tests are done by amplifier builders to weed out any poor ones.
Sometimes batches of very microphonic tubes will make their way to an amplifier manufacturer, but this does not mean that they are all unacceptable.
In fact, some microphonic tubes have the potential to outlast those that are not. And all are to some degree, so it’s impossible to have a perfect version.
The trick with above average microphonic types is making sure to prevent using them in a position with a low noise floor.
For example, you do not want to use a one that is noisy at the input position of a pre-amp or a tube driven effects loop.
The noise floor at these positions is very low, and the “ring” sound of a tube will be very noticeable here.
It is always better to use a microphonic tube in a position where the signal levels have already been amplified and are larger.
Some are more so than others, however, so it’s important to keep that in mind.
If the tube is so poor that it is unstable, it is best not to use it at all. If it is got a slight ring to it but is somewhat stable, it will probably be okay.
Tube Dampers For Microphonics
There are products on the market that can help with This. Tube dampers can be slipped over the outside in order to prevent the ring of a microphonic individual.
Dampers can also help with mechanical noises that might be heard from noisier units. Aramox makes a great damper that can be reused with any tube you install to prevent any noises and are extremely affordable.
Have noises you want to get rid of? Try their dampers and see if it solves your issues.
Understanding 12AX7 Tube Noise
So now that we have touched on microphonics, it’s important to talk about tube noise.
A noisy unit will make noises, hum and even pop occasionally, which is not appreciated, especially in an amplifier designed for high gain guitar or a Hi-fi stereo system!
But all types have a noise floor, this is not avoidable. Typically, a tube will produce a soft hiss or white noise, as it is often referred to. This is normal and will be different between tubes, as some produce more than others.
You are more likely to notice white noise in a guitar amplifier built for high gain.
Amplifiers like this have many triode stages connected in series. Each stage will amplify the white noise of the input stage, making it more noticeable.
And so using the quietest tube you can find in the input or first stage will always be your best bet. Some amplifier companies like Mesa Boogie take the time to find the quietest within their batches.
They then sell them for the first stage or input stage of high gain amplifiers. So if you play with high levels of gain, you are more likely to have a better experience with these quieter tubes.
They will produce less white noise and are perfect for the first stage in all amplifiers!
Crackles And Pops
So what kind of noise does a tube have to make before it should be replaced? If your 12AX7 begins to make any pops or crackles, it is probably time to replace it.
If they are brand new, and you put them in, and they crackle. Don’t worry, in most cases this is just the tube burning in and cleaning impurities off of its internal parts.
We recommend that you leave the amp on for a few hours to let them settle in. If after a few days it continues to make these sounds, it is probably an inferior tube.
But if you have had yours in an amp for years, and it starts making noises, it’s time for a replacement.
Vacuum Tube Pin Straightener
From time to time preamp tube pins can get bent. This can do damage if it is not straightened properly. If you have paid a lot of money for tubes, last thing you want to have happened is a crack due to bent pins!
Bent pins or even slightly bent pins will also make it harder to insert tubes into their sockets. This as well can do damage and wear sockets.
Riverstone Audio makes a great stainless steel straightening tool for 12AX7’s, that every tube owner should own. They are super affordable and are a much better alternative to needle nose pliers.
Best 12AX7 Tube FAQ
Which 12AX7 Sounds Best?
This depends on the sound you are going for. If you are looking to open up your sound, giving it blossom and a very dynamic sound, the Genalex Gold Lions will get you there.
They are an incredible tube and will work in most circumstances. If you are looking for a darker sound, the JJECC83 is pretty dark to the point of being almost muddy in some amps.
If that isn’t quite right for you, then the Tungsol would be next in line. It isn’t quite as dark, but is a pretty balanced tube with great projection. Less congested than the JJ.
For those looking for a tube with great high gain bite that is less expensive, then you may want to consider one of the Shuguang versions.
Over all, the Tungsol would probably be the best bet for bang for your buck in most cases. But if price is not an issue, you will want to try the Gold Lions.
How Long Do 12AX7 Tubes Last?
A 12AX7 is generally designed to provide 10,000 hours of service before you should consider changing it.
However, tubes are like light bulbs and can just stop working one day out of the blue. Even under the 10,000-hour mark.
A 12AX7 is an electromechanical device that also contains a heater element. Shock to the tube could displace the elements inside, causing issues.
Even the heater element could just burn out. Nothing is guaranteed! One tube may give you the full 10,000 hours, while another only give you 4.
This is the way it goes with tubes. However, most manufacturers provide great warranties to make sure you get good products. So always buy from a good vendor. This is why we recommend Amazon.
My 12AX7 Flashes At Start-Up
A flash from a 12AX7 is normal at start up and is nothing to worry about. Over the course of time, this may even go away. New tubes will often do this for the first few start-ups, as there may be some gasses that remain from manufacturing. But we have found that it stops flashing after a few uses.
If you see your power tubes flash at start-up, this is not normal! If this happens, turn your amp off and get it serviced. Flashing is bad and could cause damage to the amp.
More Great Articles