Jet City Retrovalves

[MrBeasty]

Has anyone tried these 12AX7 substitutes, yet?

RetroValves are 100% analog vacuum tube replacement devices offering the warm, fat, punchy sound traditionally associated with only glass vacuum tubes. RetroValves are pin-for-pin compatible with 12AX7 tubes in nearly any guitar amplifier, offering instant modification of preamp gain characteristics. Blue RetroValves are significantly lower gain, effectively “cooling off” the preamp gain.. RetroValves arevery low noise and have no potential for the microphonics sometimes characteristic of vacuum tubes. And because RetroValves operate with much less heat and consume less power, they reduce stress on the amplifier’s electronics. Use RetroValves alongside vacuum tubes, or replace vacuum tubes in any “cocktail” combination. They operate in any 12AX7 socket, in nearly any guitar amplifier. RetroValves are so cool and advanced, they’re protected by US patents: 7,286,060; 7,408,401; and 7,482,863; as provided under license from ROBERTS AUDIO TECHNOLOGIES. And, they’re so robust, JCA warrants RetroValves to be free from defects in material and workmanship affecting form, fit, and function for the lifetime of the product. RetroValves are only recommended and warranted for use in guitar amplifier products.

http://www.jetcityamplification.com/retrovalves/

[djd100]

I tried an amber (medium gain) RetroValve in a buffer stage in a custom 50W RM2 (2 X Egnater/Randall MTS), and it did fine (not in a distortion stage). It stiffened the amp's feel a little and made it a little harsher in the mids and upper mids. The best thing was that it was about 4 db quieter noise wise than my quietest 12AX7 in that spot, so they can be useful IMO.

They also lower your heater current so if you're on the ragged edge they can help you there too (they're powered by the heater supply). Ultimately tone-wise I prefer the real deal.