1. There is the standard 845 tubes
2. There is the 845B tubes which are supposed to sound better than the standard 845 tubes
3. There is the 845M or metal plate. It seems the production of these may have stopped till modifications are made. Be careful when using these tubes as the current requirements are different and some amps may not be able to handle without modifications. In the Dehavs they have to be biased a whole division lower on the scale.
4. 845 NOS Tubes. They cost a fortune and sound a bit better than the chinese 845s.
2. There is the 845B tubes which are supposed to sound better than the standard 845 tubes
3. There is the 845M or metal plate. It seems the production of these may have stopped till modifications are made. Be careful when using these tubes as the current requirements are different and some amps may not be able to handle without modifications. In the Dehavs they have to be biased a whole division lower on the scale.
4. 845 NOS Tubes. They cost a fortune and sound a bit better than the chinese 845s.