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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
Shuguang 12AX7A (Discontinued)
Shuguang 12AX7B
Svetlana 12AX7
Tung-Sol 12AX7 (reissue)
Electro-Harmonix 12AX7-EH
Electro-Harmonix 7025-EH
Sovtek 12AX7-WA, 12AX7-WB
Sovtek 12AX7-LPS
Sovtek 5751 (Discontinued)
JAN-Philips 12AX7WA
JAN-GE 5751
JAN-Philips 5751
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

Review Notes

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.

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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".

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The Complete Reviews

Northern Electric 12AX7 It’s not often that something truly special comes along. The Northern Electric 12AX7 is brand new and exclusive to thetubestore. This is not something that came along overnight. We have been developing and testing this product for almost 2 years to ensure that you will be buying a product that stands up against anything on the market, new or old. To do this we have traveled to the manufacturer to observe production and quality control methods, and obtain pre-release samples that have been in the field for over a year now. Our hard work and close relationship with the manufacturer have paid off.

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.

Preferred Series 12AX7 This 12AX7 is a versatile, quiet tube that will be at home in just about anyone's guitar or HIFI rig. In a Fender Champ they displayed no microphonics or rattling, and had a warm, smooth character that can still get rowdy when driven. The detail is all there as well.

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.

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Preferred Series 7025 / 12AX7 A great sounding 12AX7 tube type that reminds me a little more of the ECC83 that EI made in the old days. That's a pretty nice compliment. I compared this tube against an old EI and Telefunken smooth plate and there was very little difference. Lots of gain with a rather low noise floor. No microphonics issues at all. Very good considering the large plate size. Spot welding may be better for microphonics than crimped plates. I tried it in all the standard guitar amp duties and it was fine. Fabulous in Blackface Fender amps. We tried this 7025 in a 66 Vibrolux reverb 2x10 combo and the tones were all there. Light and shimmering or really aggressive, it's all good.

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Tung-Sol 12AX7 - There are only so many ways to describe tube tone and most have become cliches. The Tung-Sol 12AX7 has the gain and drive of a Chinese 12AX7 and the pure tone of a Mullard or Brimar from the U.K. I've had two people come to me recently with amps they thought were in need of complete overhauls. In both cases, careful examination revealed no serious problems and all the tubes "tested" as good. At the end of the day, I replaced the NOS Mullard and RCA pre-amps (one in each amp) with a reissue Tung-Sol 12AX7. In both cases the owners were very impressed and thought that their amps had been restored to full health. Believe it or Not.

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Gold Lion ECC83 / B759 - Yet another great tube from Russia and another in the line of large plate dual triodes. By my count we have the Sovtek 5751, Sovtek 12AX7 LPS, Mullard and now the Gold Lion brand. A quick glance and you might think they were all the same but careful inspection reveals physical differences in construction and plate coatings. Listening to these tubes reveals even greater differences.

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.

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Gold Lion CV4004 / 12AX7 - The Genalex brand has earned a reputation as the premium tube coming out of Russia. The CV4004 is a fine example of why they got there.

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.

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Mullard CV4004 / 12AX7 Reissue - This tube looks nothing like Mullard tubes of old but it has a lot to offer. This is a small plate design more suited to high gain amps. Old Mullard with large plate structures are sought after for audio systems because of their gain and detail. Those same attributes are the last thing you want in your Marshall stack.

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.

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Mullard 12AX7 / ECC83 Reissue - This is a nice tube but in my opinion better suited to home audio than guitar amps. The tubes have well balanced triode pairs and a very even flat response. Compared to a Tung Sol it sounds a bit flat, but so does a NOS Mullard. Microphonics is not an issue despite the larger that average plate structure. The transconductance on my sample was the same as two NOS samples I measured. Not really high gain at all, but a real good noise floor and a nice smooth tone that doesn't encourage ear fatigue the way some preamps can be. The Tung-Sol 12AX7 is my favorite preamp for guitars because it accentuates highs and lows. The Mullard adds virtually no tone coloring and is smoother sounding to my ear than a JJ ECC83S. For hi-fi gear the Mullard will likely be a winner but there are better choices for guitar amps for less money.

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Electro-Harmonix 12AX7 - These are not relabelled Sovtek 12AX7-LPS tubes. There is a marked difference in construction and performance. The 12AX7 EH has a nice balanced sound, fairly low noise floor and excellent performance in terms of microphonics. The lack of microphonics may be in part from the return of the shorter plate structure or materials.

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.

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Electro-Harmonix 7025EH - Here’s something completely different from Russia. Electro Harmonix has released the all-new 7025 model and it’s quite a departure from their previous offering. Clearly this was new from the ground up and not a re-working of something else. The only thing that carries over from their other designs is the rather tubby bottle they fit into. This is a dual triode with very short plates, in fact the plates are open at both ends so you can see the cathodes and control grids quite easily. There has been a lot of effort to shield the triode sections, including a full plate between them to prevent interference and added support across the two triodes to cut down on vibration. A single overhead getter bridged across the triodes tops it off. The micas are not extra thick but they are clean and well aligned to hold the structure. Overall the tube is well built with good alignment of the internal structures.

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.

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Shuguang 12AX7A (Discontinued) - When the tube stockpiles dried up in the 80’s, and before modern tube production ramped up, there was little available on the market except the Shuguang 12AX7. These have been in production for decades, and while the factory has changed locations over time the tubes have remained unchanged. Many amp companies have made this tube a stock component, two of the biggest companies were Peavey and Mesa Engineering. The design is interesting and unique. Two small dual triodes separated by an isolation plate and held in place with 3 mica spacers. These little tubes are notable for their high gain. They tend to be a bit gritty and bright with a little more background noise than most. It’s the price for high gain. Most frequently used by hard rock and metal lovers for all of the reasons listed above.

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Shuguang 12AX7B - Although this tube is listed as a variant of the 12AX7A there is really very little difference to discuss. For all intent and purpose this is a 12AX7A that has high gain and low noise. Shuguang discontinued the 12AX7-A vacuum tubes in recent years. One thing that I will say about both the A and B, is that they really sound good for rock and roll. If you are having noise and microphonics issues with the A variant but want to keep the gritty attitude, then you should try the 12AX7B before you move on.

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Sovtek 12AX7-WA, 12AX7-WB - I've grouped these two together because they have essentially the same sound. The only noticeable difference between the two was a bit more gain from the WB model. These tubes are rugged little brutes, and that's probably why they are OEM components for many major amp makers. Both tubes could be whacked with a stick at full volume and not show much in the way of microphonics - but DON'T DO THIS AT HOME, as it is often a destructive test for tubes.

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.

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Sovtek 12AX7-LPS - This is an entirely new design from Sovtek and a great step up in sound quality. They have very large ribbed plates and great sound reproduction. I found them very smooth and well balanced in terms of bass, mids and treble response. The large plates make them more prone to microphonics and in combo amps, so they can be a problem if you like to run things wide open. It is still the best thing Sovtek has produced in a 12AX7, with very good gain and low noise. I would advise against using them in compact high-powered combo amps where they will be subjected to lots of vibration. One other note about the construction of these tubes is they have filaments that are almost completely encased in the plate structure. They often don't "light up" when working properly. This is not a problem, it's normal for the LPS.

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JAN-GE 12AX7WA - If you have a Fender amp from the 60’s this tube was often used as original equipment. This is a classic and you won’t find a better replacement for your Fender. Pure American tone. Excellent gain with no microphonics and great harmonic detail. It’s not uncommon for these tubes to last decades under normal use. The plate structure is very tough, featuring smaller ribbed plates with a thick glass bottle and nice steel pins. An all-time favourite of both players and techs, these tubes are hard to beat.

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JAN-GE 5751 - While not really a 12AX7, it shares the same pin-out arrangement and is designed for less gain in favor of lower noise and microphonics. It worked well in both test amps and can be used to advantage if your amp has too much grind. One of these should calm things down a bit. The 5751 is an affordable alternative to the 12AY7 used in original Fender tweed amps and can be subbed for a 12AT7 like a reverb driver tube. In this application, you will get good gain with a warmer sound than the 12AT7. The even balancing makes them a nice phase inverter and allows you push the front end of the amp a little harder.

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Sovtek 5751 - The Sovtek 5751 is an affordable alternative to the 12AY7 used in original Fender tweed amps and can be subbed for a 12AT7 reverb driver tube. In this application, you will get good gain with a warmer sound than the 12AT7. The even balancing makes them a nice phase inverter and allows you push the front end of the amp a little harder. If you wish to use a 5751 in a 12AX7 position to reduce gain we recommend you use the JAN-Philips 5751 tube.

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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.

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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!

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Svetlana 12AX7 - For several years the original Svetlana 12AX7 tube from St. Petersburg (Winged "C"/SED) tried to develop a good 12AX7 and mostly failed. The current production Svetlana is a New Sensor product and is a member of 12AX7-EH and Tung-Sol 12AX7 family. All three of these tubes is virtually identical. The biggest difference seems to be in plate coating, gain and sound quality. I find the tube to sound a bit smoother than the EH and it has less gain than the Tung Sol. If you are not inspired by the Electro Harmonix and also find the Tungsol too grainy then this is the tube you want to give a chance. It has everything you want in a good pre-amp. Low noise, no Microphonics issues and very clear and open without being too bright. The construction is on par with the more expensive Tungsol. The price point on this 12AX7 tube is great because it will hold its own with more expensive options. Samples seem very reliable. If you like the JJ ECC83S but want something with a litter more glimmer this is where you should put your money.

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JJ ECC83-S / 12AX7 - This tube sports a different plate design than found in most 12AX7's. When you look at them you can't help but think that they must be rugged and good for the musician on the road. The compact plate structure does nothing to dampen their sound or dynamic response. I find them to be well balanced. While not as harmonically rich as others I tested, they do provide high gain without the usual noise and microphonic problems you would expect. This is great sound for your dollar. If you're using a combo amp and find the Philips a little rich sounding, the JJ ECC83 may be your solution.

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JJ ECC803-S / 12AX7 - This JJ offering has huge plates in its triode sections giving it a real punch with lots of gain. The larger plates combined with crimped construction may contribute to the background noise it produces. While not actually bad, it’s enough that in some high gain amps you may want to avoid using it in the #1 preamp position. This tube is really well built. The large dual triode assembly is impressive and well aligned within the bottle. I’ve had great success using it in the cathode follower circuit that many great amps use to drive their tone controls.

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JJ ECC83-MG / 12AX7 - The ECC83 MG is a fine sounding tube. I was unable to notice a loudness reduction compared to the standard JJ ECC83S tube. The tonal characteristics were easier to hear. Compared to the JJ ECC83-S this tube sounds a little more eager to hit the midrange. I’m not sure how that will work in all audio applications, but in a guitar amp it’s great. It can take a bit of wooliness out of a standard Fender tone stack by taming the bass response. Bottom end is ample but not enhanced. The smaller plate structure helps keep microphonics under control, making it great for combo amps. The way it sounds makes me think it will be a winner in Marshalls when replacing the Chinese tubes people like to run. Boogies will boogie and Fenders will be fine. If you are looking for some affordable experimentation, this should be on your short list.

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JJ E83CC / 12AX7 - Everything special about this tube is under the hood. It looks like the JJ ECC83S and if it wasn’t for the screening you couldn’t tell them apart. So why a different model number? Back in the day many companies switched the order of numbers to indicate that this tube was better than the standard model. JJ has continued that tradition and produced a tube that recreates a vintage Tesla tube with the same model number. What the two tubes share is the short box plates and frame grid. I have read that this same design was pioneered by Amperex. The short plates can be easily seen and they’re standard issue on many JJ tubes. The frame grid is the special sauce. Normally the grid wire is wound around two vertical support rods on opposite sides of the cathode. The frame grid tube has a rigid frame that almost looks like a ladder and the wire is wrapped around that. This improves the quality and consistency of the grid winding and reduces vibrations that could cause microphonics. The tube sounds very good and it’s extremely quiet. Spiral filament winding does seem to have an effect. The noise floor is better than the standard ECC83S. Frequency response is excellent. In the lower register of guitar it produces a nice thump. Great for palm muting, drop tunings and percussive rhythm. Mids are upfront but not honkey and there’s no issue with highs. When I slammed the front end of my amp with a boost pedal the overdrive was quite musical and focused. I didn’t get heavy mush. I also ran a pair of these tubes in my phono stage with good results. I’d have no problem recommending for use in studio rack gear or other audio applications.

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JJ 5751 - This is an excellent 5751 and does exactly what you want from a tube with this designation. It has a very low noise floor and no tendency toward microphonics. It is a very quiet, low noise alternative to the 12AX7 with slightly reduced gain. The trade off, is that to my ears it has less harmonic content and detail compared to the GE 5751 or a good 12AX7. The physical construction is similar to many 9 pin miniatures from JJ, with small plates and great build quality.

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RFT ECC83 - A blast from the past. I haven’t seen these tubes in about 30 years. At first glance you may confuse this tube with a 12AT7. It has very small plates and the mica support wafers are very light. There is a musical quality in this tube and the light construction may be part of the recipe. It has great harmonic content and detail that many current production tubes seem to miss. These are great in classic Marshall and Fender designs and have a noise floor more in line with a 5751. Although expensive, there won’t be any more once the supply runs dry. Audiophiles should put these on the list of tubes to try while they can.

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Tungsram ECC83 / 12AX7 - When I first looked at these tubes I thought of vintage Mullards. I don’t know if they were using the old Mullard equipment to build them or if they were just trying to copy the look and feel.

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.

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Ei 12AX7 (Discontinued) - 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.

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