The RAM tube is a short plate construction which is very low in microphonics. If you've had problems with microphonics this is the tube to try.
The 12AX7LPS Sovtek is the closest to the large plate European construction. This Russian 12AX7 works well in a traditional circuit.
Our Low Noise tubes are a superior tube especially tested for today’s quality line stages. Only 30% of the tubes we test perform well enough to be considered Low Noise.