12AX7 is a high gain tube often used in the first stages of tube amps. Tube amps use multiple tubes, and the first position is referred to as V1.
Because of the high gain, 12AX7 in V1 has a lot of effect on amp sonics. If you are looking to upgrade the tubes in your amp, 12AX7 in V1 is where you want to start.
There are many 12AX7 on the market today. These 12AX7 perform similarly, but they sound different in subtle yet distinguishable ways. Because of the number of choices available, making a choice seems daunting at first. Well, fear not. We hope this guide helps you select the right 12AX7 for your application by cutting right to the chase.
Best 12AX7 For Guitar and Bass Amps
TungSol 12AX7 is our go-to tube for guitar amps. Tung-Sol 12AX7 delivers good gain without washing out the fine details and textures. It has good balance and good crunch. TungSol 12AX7 handles everything from vintage rock sound to modern high gain tone.
Mullard 12AX7 has a bit more fullness to the sound. Mullard 12AX7 is a long plate design, with excellent build quality. Mullard 12AX7 also has good amounts of gain. Coupled with fuller tone and good gain, Mullard 12AX7 works well for rhythm guitar duties as well as producing wailing solos.
Chinese 12AX7B "Silver Dragon" is the favorite amongst metal musicians. This tube is often used by amp manufacturers as their OEM 12AX7. If high gain sound is what you are after, this tube will do very well. We take even greater care in testing and rejecting these tubes as we know they will be used with volume side opened. Once we toss all the duds, we refer to the remaining punch-packing12AX7B as the "Silver Dragon".
Want to try them all? Try our 12AX7 Sampler Set of all three tubes above.
We carry many more on our 12AX7 Page
Best 12AX7 For Audio
Genalex Gold Lion ECC83/B749 is a long plate design. Gold Lion ECC83 delivers full sonic range with excellent articulation. Like all Gold Lion Tubes, Gold Lion ECC83 is built with meticulous quality. Gold Lion ECC83/B749 with gold pin is ideal as the premium upgrade for any audio 12AX7 application.
Mullard 12AX7 is also a long plate design. Mullard 12AX7 become the go-to standard for audio. Mullard 12AX7 provides good balance, good resolution and pleasant low-mids. Mullard 12AX7 is a good choice for upgrading factory installed 12AX7.
TungSol ECC803S GOLD is a short plate design. ECC803S Gold delivers extended response with smooth mids. ECC803S Gold is low in microphony also. This makes ECC803S Gold well suited for phono application.
12AX7 and the Gain
A 12AX7 is a high gain tube. Various 12AX7s tends to be a few points higher or lower on the gain. Due to the nature of vacuum tube circuit, this doesn't mean one will be louder than the other. Instead, the gain affects the tone and noise floor. Higher gain doesn't always mean better tone, so we encourage you to try different 12AX7 and see how they work for you.
12AX7 and Microphonics
High gain of 12AX7 also means there are more chances for microphonic noise. Microphony is caused by the tube picking up mechanical vibration and amplifying it. This is just like how a microphone works.
Some amount of microphony is normal. For example, if you tap a vacuum tube, you can hear it on the amp output. What we want to avoid are tubes that causing ringing or feedback. When a tube is really microphonic, it can pick up and amplify sound from the speakers, forming a feed back loop.
We screen all our 12AX7 for excessive microphonic noise. We also offer extra noise screening for an extra cost. We recommend low noise screening option if your equipment is sensitive to microphony.