Electro-Harmonix 7025 is a new 12AX7 tube featuring very low noise.
In a guitar amp, 7025EH sounds similar to TungSol 12AX7, with an excellent mid-range and a tad more smoothness when pushed.
Like TungSol 12AX7, the tone of 7025EH is well balanced. 7025EH does not accentuate or cut off any particular frequency range like some of the other 12AX7 tubes.
The tone of 7025EH is not too dark and not too bright, making it an easy drop-in for any music style you play and instrument/pickup you use.
If you are trying to tame a very high gain guitar amp, 7025EH makes it easy. 7025EH eliminates the worries for microphonic feedback while smoothing out the tone of the beast.
In audiophile application, 7025EH is the go-to for phono amps.
Microphonic audio issues are very distracting when present but are often intermittent and difficult to solve. We often put these O-rings on preamp tubes, but the O-rings just change the resonance. O-rings may reduce microphonic noise, but they do not eliminate it.
7025EH, on the other hand, eliminates microphonic noise at the source. All these worries and hassles go away, and you can throw out those unsightly O-rings too!