The Best 12AX7 / ECC83 Preamp Tubes - Reviews and Guide
Are you looking for the very best 12AX7 preamp tubes for your amplifier? This is the place to start. Check out the following vacuum tube reviews for guidance in getting the best possible tone out of your tube gear.
Another common name for the 12AX7 tube is ECC83 and for premium versions, 7025 and ECC803. Today, a look at almost any guitar tube amp, be it Fender, Marshall, Vox, or any other, will prove the 12AX7 / ECC83 / 7025 tubes are here to stay.
(View our complete selection of 12AX7 vacuum tubes)
Review Notes - how we conducted the review
What makes a good tube? - detailed description of the test parameters
Tube comparison table - reviews at a glance
Full reviews of the tubes we tested (click to go to its review):
Northern Electric 12AX7
Preferred Series 12AX7
Preferred Series 7025
Mullard CV4004 / 12AX7 (reissue)
Mullard 12AX7 (reissue)
Gold Lion ECC83 / B759
Gold Lion CV4004 / 12AX7
Tung-Sol 12AX7 (reissue)
Sovtek 12AX7-WA, 12AX7-WB
JJ Electronic ECC83-S / 12AX7
JJ Electronic ECC803-S
JJ Electronic ECC83-MG (mid-gain 12AX7)
JJ Electronic E83CC / 12AX7
JJ Electronic 5751
Ei 12AX7 / ECC83 (Discontinued)
Tungsram ECC83 / 12AX7
Guitar Amp Tube Reviews by John Templeton
The tubes used in this review were selected at random from thetubestore.com's inventory of untested tubes. For each tube used in the test, two were taken since there was no pre-screening involved. The aim was to get a sample that would be practical to work with but allow for variations in the tubes or prevent picking the only dud in a lot.
The test amplifiers used were very different. One was a 100-watt Trace Elliot Speed King with 4 x 12 cabinet, and the other was a Fender Blues Junior combo amp. This allows the high power, high gain crowd and the more conservative players to get the fairest evaluation possible. Some tubes were clearly better suited in one application or usable in both. All tubes were used at the input amplifier stage of the amp since this seems to be where most people develop their perceptions of how good a pre-amp tube is.
What Makes A Good Tube?
The musical detail or ability to reproduce the sound of the instrument is a key factor in assessing a tube for guitar amplifiers. There is no perfect tube available. Each one has strengths, weaknesses and certain factors that contribute to its overall ratings. Usually a compromise is arrived at in the search for premium tone.
All tubes will exhibit some degree of microphonics. Microphonics do not mean that a tube is unusable. You just have to screen them a little closer and determine where they are best suited for use. Input pre-amps are the most sensitive areas of the amplifier. When used in this application most tubes will generate some noise if you tap on them with a pencil during operation. Keep in mind that doing so can actually damage the tube and make it more microphonic or cause it to fail if you hit it real hard. Although they are screened prior to shipment a tube is an electromechanical device and can be damaged during shipment. A microphonic tube will ring, howl or produce general feedback problems. It will be more noticeable at louder volumes or when used in close proximity to a speaker, typically in combo amps. If the tube has good tone at lower volumes and is free from unwanted noise, you use it in a less sensitive part of the circuit, such as tone recovery or phase inverter applications.
Noise is more of a problem than microphonics. A noisy tube will make random popping noises, crackle occasionally or just hum. All tubes have a certain noise floor; this is the inherent background noise that the tube makes in operation. Typically, you will notice this as a soft hiss or "white noise". Tubes designed for high gain can exhibit more background noise. Other components can cause noise problems that may be blamed on a bad tube. Plate resistors are notorious for causing hiss and crackling as they age and begin to fail. A new tube may better amplify these defects, so try substituting another new tube to be sure of the source of the noise.
If you're not sure if your tubes are bad, we have some great trouble-shooting tips to help you find out. You won't need a tube tester either, so you can try these suggestions right at home. You'll find more info in our blog article, "How To Tell If Your Tube Is Bad".
The Complete Reviews
Samples have been tested in our audio reference equipment and in the amplifiers of working musicians that have logged many hours and many miles. It’s the feedback from these testers that tell the tale. No failures of any kind have occurred under the most demanding conditions and, in round table discussions and blind testing in the studio, players consistently preferred the Northern Electric over any pre-amp tube we currently offer.
The Northern Electric 12AX7 is made with the highest quality materials. Everything is designed to give you unsurpassed audio quality. This tube has very large smooth plates. This design is much like a Telefunken smooth plate but a bit shorter. This design provides plenty of gain while maintaining an extremely low noise floor. Like any large plate tube, tapping on the bottle with the volume turned up will generate some mechanical noise, but the Northern Electric is not in any way prone to microphonics. It has been torture tested in a JTM 45, a Deluxe Reverb, an Orange 50 watt combo and Bandmaster Reverb, with no failures or noise problems after hundreds of hours in clubs or in the studio. It doesn’t matter if you use an American or British design, this tube works.
In our listening tests it was easy to hear that the tube did not change the voice of the amplifier as some pre-amps do. The Northern Electric enhances the sound across the entire spectrum. Our testers have reported no noticeable spikes or weakness in the lows, mids, or high end. The highs are very smooth with a balanced midrange response and warm, full bottom end. If you notice any frequency anomalies you should have a look at your speaker of choice as that is likely where the problem is. As you drive your guitar amp harder you will notice that this tube is passing both the fundamental note and beautiful spectrum of harmonics to the power amp. The resulting overdriven signal is warm and complex but never gets confused or mushy sounding. It is absolutely the best 12AX7 that we can offer you.
At $59.95 it is not cheap, but if you want uncompromised tone this is the one for you.
High gain enthusiasts will appreciate the lack of microphonics (despite the fairly large plates) and quiet operation, along with their thick yet precise tone. There is nothing cold or sterile to be found here.
If you want an upgrade from your amp's stock preamp tubes and aren't quite sure where to start, you can't go wrong with the Preferred Series 12AX7.
It is very smooth and pleasing to the ear. I attribute this to the broad midrange response. In audio or guitar equipment, grating highs and booming lows will give you listening fatigue or make you think your amp just sucks. The Gold Lion's voicing is such that the midrange response seems full, while the highs and lows are nicely controlled. This tube would be great if you are retubing one of those classic old radio consoles. It would also be great in a Marshall JCM800 series amp to tame the bright channel and cut some of the crazy high end.
The best news with the Gold Lion ECC83/B759 is that I could not get one to feed back at major sound pressure levels in a combo guitar amp. Finally.
This tube in your first gain stage will deliver a most pleasant reproduction of your audio source or make your guitar amp sound warm with real creamy drive when pushed with hotter pickups.
NOTE: For those of you that love to take a pencil and whack hot tubes, you will be rewarded with a satisfying, loud, "PING". It's the nature of the beast with any large plate dual triode used in V1. If you get uncontrolled squealing at higher volume levels or if touching the amp causes a ringing noise you probably have a genuine microphonics problem. If you like to tap your tubes all the time to see if they are microphonic, you will likely cause a genuine microphonics problem.
Tube construction is quite rugged with very thick glass that’s formed into the typical “fat bottle” construction that I’ve come to expect. It’s quite attractive with the gold pins and very nice gold screening on the bottle.
Structurally this tube is familiar to the eye with the wide ribbed plate design, rounded bottle top and a single round getter with dual support rods. Nothing fragile about this tube. The pins are medium thickness and gold plated to prevent oxidization. Alignment of the internal elements, pin straightness and alignment of the internal plate structure are excellent. It looks like they put a little more care into the construction.
Sonically I find these tubes to have a lot of punch. More gain than a JJ ECC83S and less gain than a Shuguang 12AX7. Noise is extremely low and microphonics are almost non-existent. I attribute that to the overall build quality. The high end on these tubes may be described as silky. Lots of definition and sparkle without a hint of harshness. The bottom end is not as pronounced as I had expected. Not an issue in a guitar amp and they certainly worked well in my tube pre-amp.
This tube should work well in all applications due to its excellent construction and balanced sonic profile.
The smaller plate reduces noise. They are dead quiet both electrically and mechanically. Nice thick bottles and well aligned internals also help. If you currently like the Tungsol 12AX7 you will love this tube. The gain is similar but overall it is quieter and a bit warmer to my ears.
I've had some samples that were tried in various amp stages. Pre-amps, tone stacks and phase inverters, a winner in every location, although I like to use a 12AT7 for reverb circuit drivers due to their lower gain rating (just a personal preference of mine). I have used the EH to successfully tame amps that defied all other attempts to kill microphonics and unwanted feedback. This tube is a winner, buy 'em and try 'em, they may be just the piece you've been looking for.
How about the sound? Well they are advertising this as a 7025. Back in the day this meant something. To be specific, it should indicate this tube as having been designed for extra low noise and microphonics. EH has obviously used this as their main design criteria and really hit the mark. It’s quiet and I could find no trace of microphonics in a couple demanding guitar amps and my tube phono stage.
Tonally they are balanced and smooth. No harshness in the top end. To my ears these tubes seem to have a bit less gain than a Tung-Sol 12AX7 or the JJ Frame Grid.
Guitar amps is where these guys will shine. Regardless of your taste, from high-gain to folk, these will be great in your amp. Almost no background noise allows the high gain user to really drive the amp hard and be assured that the only feedback will be by design. At more reasonable gain levels you will find these to be warm and detailed.
Only time will tell how these perform after a few hundred hours of use, but out of the box they seem to be an excellent tube at a good price.
They don't have the best sound in this type, being prone to the occasional pop or tick. The sound quality lacked any real character but was acceptable. If the budget is tight, their affordability will be attractive. Also, keep in mind that many amp designers design the equipment to sound best with the tubes they will use in production. I have a friend that claims his amp only sounds right using Chinese pre-amp tubes, but your mileage may vary on this issue. If you like the Sovteks then go for it, particularly if you will use them in high gain applications with lots of effects.
JAN-Philips 12AX7WA - If you really want NOS (New Old Stock) tubes, this is one of the best buys out there. The Philips tube is well built and should be long lasting. The tubes I tested had lots of gain while still maintaining very good noise levels and good tolerance for microphonics. The tone was solid in the midrange with very wide dynamic response. If you're not careful with your setup, you can get these tubes to be boomy in the bottom end and shrill in the high end. I found that they were great with the tone controls set flat. Great in both combo amps and monster stacks.
JAN-Philips 5751 - Now here's a surprise, and a good one at that. The 5751 is typically referred to as the lower gain 12AX7. The fact is they are just dual triodes with the same pin-out as others in the 12AX7 family. This particular batch of NOS 5751 fails to perform as most 5751 tubes. It's not lower gain, it's not darker. These JAN-Philips 5751 tubes are one of the best dual triode tubes I've ever heard. They have nearly 12AX7 gain, extremely low noise, and frequency response that covers any audio application. They sound good in everything I've tried them in but particularly shine in single ended, simple amp circuits. Good examples would be a Fender Champ, tweed Princeton, Gibson GA-5 or any amp that has a preamp, power tube and rectifier. One of the best deals available in an NOS 12AX7, is actually a 5751!
These are vintage all the way. The bottles are the correct size with a fairly flat top with 4 seems that you can detect. Large grey ribbed plates topped off with a large round getter ring supported from both sides of the plate structure. The Mica supports are medium thickness with a dozen contact spots around the bottle. There are dual support rods between the top and bottom supports to minimize microphonics.
The vintage Tungsram tubes are not bright and sparkly tubes. I find them to be a bit darker than most current production tubes, but not deficient in any way. There’s plenty of high end, it’s just not as aggressive as many are these days. At the other end of the sonic spectrum the tube has great bass definition, very solid and focused. This was very apparent when using them in my phono amp where the soundstage seemed to open up with depth and clarity. The midrange was nicely balanced and I couldn’t detect any hot spots when listening to a variety of material. Due to the large plates there’s lots of gain on tap.
If you really wanted NOS Mullard but can’t find/afford it, these would be an excellent substitute. Beautiful, balanced reproduction in an old school design that’s still available if you want it.
Ei 12AX7 - This tube should win an award for best and worst in class. The first one I tried squealed in the combo amp and produced a ringing sound in the half-stack. (Remember these were not from the pre-screened tubes that thetubestore.com sells.) The second one I tried was fantastic. There were no microphonics problems with this second tube. The scores for microphonics (2 and 4) are for each individual tube that was tested. A few phone calls to another tech confirmed my suspicion: there is a high failure rate when initially screening these tubes for microphonics. The ones that do pass testing are wonderful; they are very musical sounding with lots of gain and a very low noise floor. When playing the guitar you could really get the benefit of their dynamic range. They can reproduce soft passages accentuated with a sharp punch and you don't have to go near the volume controls. I'm keeping the test tube for some long term testing. These would be great tubes for home audio applications. Due to the microphonics problem, I'm unsure as to their roadworthiness. At home or in the studio, they will deliver great results. The only caveats are; make sure they are carefully screened and don't think about using them in high gain combo's unless they are tested in a similar amp first.