12AX7 is often used in the first stages of amps due to its high gain. The first stages of the amp affects the sonics the most. If you are looking to upgrade the tubes in your amp, first stage is where you want to start.
There are many 12AX7 on the market today. And they all sound different in subtle yet distinguishable ways. This makes making the choice a little complicated.
This guide intends to help you select the right 12AX7 for your application.
See our 12AX7 Page for full listing
Best 12AX7 For Guitar and Bass Amps
TungSol 12AX7 is our go-to tubes 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 is a long plate design that has fuller sound. The build quality is tight, making microphony a non-issue. Mullard 12AX7 has good amount of gain. Coupled with fuller tone, Mullard 12AX7 works well for adding fuller mids to your tone.
Chinese 12AX7B "Silver Dragon" is the favorite amongst metal musicians. This tube is used by amp manufacturers like Mesa as their OEM 12AX7. If high gain sound is what you are after, this tube will do very well.
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.
12AX7 and Microphonics
High gain of 12AX7 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 a microphone.
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 is tubes that are very microphonic, causing ringing sound or feedback.
We screen all our 12AX7 for excessive microphonic noise. We also offer extra noise screening for an extra cost. We recommend low noise option if your equipment is sensitive to microphony.