[Amps] 8122,4662,4cx400a,4cx250b,ncl2000

[Dennis12Amplify at aol.com]

That's great information, thanks!

Regards,

Dennis O.


In a message dated 10/3/03 12:12:35 AM Central Daylight Time, gbadger at att.net 
writes:


> The 4662 will replace the 8122 exactly. When I was with Svetlana we 
> retrofitted an ncl2000 with 4cx400a's. The retrofit was straitforwad and it worked 
> well. We chose the 4cx400a for marketing reasons but the 4cx250b would have 
> been a much better choice from a technical point of view beacause the 4cx400a 
> requires jockeying parts around and cutting hard steel  to move the sockets. 
> OTOH the 4cx250b and  socket drops in place easily and few parts need to be 
> moved. Don't worry about the ratings because the cathodes and grids in all 
> these tubes are about the same size. The 8122 and 4662 grid material is soft 
> copper and the others have molly grids which are therefore stronger. The 4cx250b 
> anode size is the same as the 8122 so it is capable of tha same dissipation. 
> and fits in the amplifier with ease. The formal ratings for the 4cx250b are 
> less than the 8122 but it is more rugged because of the grid material.