Thanks for your information. From my taste, 5751 is my choice than 12AX7. For AU7 or AT7, I want to try but I need more advice on my PAS 3. I do not want to get risky on my preamp. Anyone already tried AU7 or AT7 for 12AX7, let me know the sound
Replacing 12AX7 to 5751 for pre-amp
Does anyone try NOS Sylvania 5751 replacing 12AX7 for preamp? My friend convinced me trying 5751. I did try them for Dynaco PAS 3 and woo sound is warmer, treble is softer special with vocal. Bass is more tighten than before. I want to try more AU7 or AT7. Do they ok to try? I know that we can replace any 12AX7 with other lower current.