12AX7 Comparison of Current Made Tubes
A Comparison of Current Made 12AX7 Tube Types
| Part Number |
Gain | Noise | Guitarist Description |
| JJ Electronic T-12AX7-S-JJ |
Medium |
Medium |
This tube has a well balanced, colorful tone with strongly defined lows, mids, and smooth highs. It allows for more clean head-room than higher gain 12AX7s. In overdrive, it is smooth and strong with well-defined lows and mids. |
| JJ Electronic T-12AX7-GOLD-JJ |
High | Low | This Slovakian tube is full bodied and bright with lots of depth and color. It's like the 12AX7-S-JJ on steroids, keeping the definition and adding a lot of bite and brightness. In overdrive, it keeps its well-defined bite and brings out the highs. |
| JJ Electronic T-ECC803-JJ |
High | High | This Slovakian tube is full-bodied with a straightforward presentation and emphasis on the highs. It packs some bite with its higher than normal gain. In overdrive, it is not quite as defined as the 12AX7-GOLD, but if offers more crunchy fizz. |
| Tube Amp Doctor T-12AX7-PS-TAD |
High | Medium |
This is the ubiquitous Chinese 12AX7 with "premium" selection. The gain is high and the German "Tube Amp Doctor" must be filtering out the noisiest ones. |
| Ruby T-12AX7A-C5 |
High | Medium |
This is the ubiquitous Chinese 12AX7 with added selection. The gain is high and the American "Ruby Tubes" must be filtering out the noisiest ones. |
| Groove Tubes T-12AX7-C-GT |
High | High |
This is the ubiquitous Chinese 12AX7 with added selection. The gain is high and the American "Groove Tubes" must be filtering out the noisiest ones, but a few seem to have still gotten through. |
| T-5751M-GT |
Very Low |
High |
With an amplification factor of 70, this tube is supposed to have much less gain than a standard 12AX7. It has a straightforward, thin and bright sound. In overdrive, it offers a lot of crunchy fizz and mid to high frequency bite. |
| T-12AX7B-CHINA | High | High |
The Chinese 12AX7B is very similar in tone to its standard Chinese cousin, but the 'B's seem to average in at slightly lower gain and noise |
| T-12AX7-CHINA | High | High |
This ubiquitous Chinese tube is straightforward and bright. Its high gain gives it some bite too. In overdrive, it brings out the highs and offers easy access to harmonic sustain. |
| Electro-Harmonix T-12AX7-EH |
High |
High |
This Russian tube is full bodied and bright with a more straightforward presentation. It packs a lot of bite with its higher than normal gain. In overdrive, it offers a lot of crunchy fizz. |
| Sovtek T-12AX7LPS-SOVT |
High | Medium |
This Russian tube is full bodied and well-balanced. It has a high gain with a very smooth presentation. In overdrive, it is not quite as defined as the 12AX7-S-JJ, but it offers more crunchy fizz. |
| Sovtek T-12AX7WA-SOVT |
Medium |
Medium |
This Russian tube has strong lows and bright highs. Its lows demand attention when playing full bar chords. In overdrive, it offers a lot of crunchy fizz. |
| Fender T-12AX7-FND |
Low |
Low |
This is the Russian Sovtek 12AX7WC. It is very similar sounding to the 12AX7WA but not quite as powerful. |
| Peavey T-12AX7-PV |
Medium /High |
Medium |
Peavey is currently using both T-12AX7-S-JJ and T-12AX7-EH |
| RCA, GE, Sylvania T-12AX7-A |
Medium |
Medium |
These are NOS American tubes. They tend to fall right in the middle of the road with a straightforward and well-balanced tone. In overdrive, the RCA was easy on the highs while still offering easy access to harmonic sustain. |
Graph Interpretation
All 12AX7s have an amplification factor (µ) of 100 ("high-mu"). Ideally every 12AX7 should yield the same gain when placed in the same circuit. However, in reality there are comparative gain differences among 12AX7s.This graph is based on the average gain and noise measured from different tube brands, using the same number of samples for each brand. It should not be assumed that every single 12AX7 from a specific brand will exactly match its place on this graph.
The gain rating is only a relative reference (e.g. a rating of "10" does not mean ten times louder than a "1").
Numbers in parenthesis represent the average gain rating over the entire audio frequency range (Low, Mid, and High)| Voltage Gain Rating | Noise Rating |
| 10 = High Gain 1 = Low Gain |
10 = High Noise / Microphonics 1 = Low Noise / Microphonics |
