[SOLVED!] 12AX7 Vs. 12AX7A


Nowadays, once it comes to vacuum tubes that have high voltage gain, the winner in 12AX7 vs. 12AX7A is a hotly discussed topic. Even though their names sound somewhat similar, 12AX7 and 12AX7A have unique characteristics. You have difficulty choosing between 12AX7 and 12AX7A for your guitar tube amplifier? In that case, this article could help you out. 

A Comparison Of The Tubes 


Regarding series and parallel circuit support, significant differences exist between 12AX7 and 12AX7A. In the case of 12AX7, it only supported parallel circuits when it was introduced. Released years after 12AX7, 12AX7A was able to support parallel as well as series circuits from the get-go. Because of that, 12AX7A came out on top in 12AX7 vs. 12AX7A if compatibility is concerned. 


All in all, 12AX7 has a long lifespan: it’s going to last up to five years and beyond. About 12AX7A, it could hold together for quite some time. For most of the time, in terms of durability, 12AX7A is superior to 12AX7.


If you place gain above all else, you should know that quite a few factors affect the amount of gains. In ideal conditions, 12AX7 and 12AX7A each deliver around 100 Mu which is sufficient for standard guitar tube amplifiers. As a result, once it comes to gain, there is no clear winner in 12AX7 vs. 12AX7A. 

Microphone Noise

All vacuum tubes including 12AX7 and 12AX7A could detect vibrations then recreate them as signals (microphony). Because the 12AX7 is a high-gain tube, the impact is usually more noticeable. On the other hand, thanks to the short plate structure, 12AX7A manages to keep the microphone to the minimum in use. Needless to say, in the eyes of people who like to regulate microphone noise, 12AX7A outmatches 12AX7. 


Both the 12AX7 and 12AX7A offer a smooth and clear tone which improves the sound across the full spectrum as well. Depending on the situation, the tubes could produce a well-balanced middle tone, a warm and rich low tone and a smooth high tone. That being said, once again, 12AX7A is the winner as it’s capable of generating extremely low audio.

A Summary Of 12AX7 Vs. 12AX7A 

CompatibilityParallel filament circuitsBoth parallel and series filament circuits
Durability1-5 years4-6 years
Gain100 mu100 mu
Microphone noiseMore noiseLess noise
ToneHigh, mid and lowHigh, mid, low and lower

Is It Possible To Use 12AX7 And 12AU7 Interchangeably? 

Totally yes, but you will need to pay close attention to the circuit diagram and look up instructions. Switching from 12AX7 to 12AU7 for your amp will not technically damage it but it’s best to exercise caution nonetheless. 

Which 12AX7 Should I Pick For Metal Songs? 

The best 12AX7 tube for metal is JJ ECC83S since it can produce a darker rhythm. You could think of JJ ECC83S as an upgrade from the ECC803S. 

Is It Required To Match 12AX7 Tubes? 

Even though matching the preamp tubes is a good idea, it is quite unnecessary. However, if you still insist on doing so, you can expect an equitable gain from both tubes. One of the most recommended tubes to match with the 12AX7 is the 6DJ8 type.

How Can I Know If My 12ax7 Tube Is In Bad Condition Or Not? 

You will be able to determine the stage of your tube through sound since it is possible to hear strange or heavily distorted sounds sometimes. Another symptom is the sporadic power loss.

Where Are 12ax7 Tubes Produced? 

Currently, there are four manufacturers that produce 12AX7 tubes. The first one is the New Sensor located in Russia. The next supplier is situated in Slovakia under the name JJ Electronic. The last two suppliers come from China and they are Shuguang, and Quanzhen.

Can I Use 12at7 Rather Than 12ax7? 

The 12AT7 tubes differ vastly from 12AX7 in terms of gain. Specifically, 12AX7’s gain is 100 mu, while that of the 12AT7 is just 60. That means 12AT7 supports more headroom but it falls behind 12AX7 in terms of sound, performance, …. 

Is It Safe To Touch The Vacuum Tubes? 

The mechanism of the vacuum tubes resembles that of the light bulbs: a glass envelope that generates heat while working. Thus, it’s ill-advised to handle vacuum tubes all the time but it is alright to touch them occasionally. 

Which Amp Uses 12ax7? 

12AX7 is a common sight in the hi-fi, professional line and microphone preamps. Nowadays, you should be able to come across 12AX7 in guitars made by Fender, Marshall, Boogie, Soldano, …

Should I Keep The Preamp On All The Time? 

For power amp and preamp, it is wise to leave them on all the time for improved sound and longer lifespan. 

Which One Can Be Found Easier, 12ax7 Or 12ax7a? 

Since the 12AX7A is an upgraded version of the 12AX7, you should have an easy time getting your hands on 12AX7A.