|Originally posted by markl
I'm not so sure about this. 6922 and 7308 are rated to handle more power than 6dj8. I believe the Melos manual is explicit about the need for 6922's. Most likely result would be reduced life of any 6dj8's you use at a minimum, who knows what else at most (arc'ed tube bursting?). Don't want to be an alarmist, just adding a word of under-informed caution.
Ah! I knew you could move up from the 6dj8 without problems, but I didn't think about going the other way.
I thought that the main difference in the tubes was tighter specifications. From one website I have the following descriptions:
This is one of two premium versions of the 6DJ8 tube. First of all, it is the same tube as the 6DJ8, and will work wherever a 6DJ8 is needed. It has premium features such as low noise, low microphonics, and usually a longer lifespan.
This is probably the ultra 6DJ8 type tube. It has all of the features of the 6922, but the triode sections are also matched to each other, and the tubes all fit within very tight specifications. Therefore, any 7308 should match any other 7308 within the same brand.
I'm am not saying that there is not a different power handling capability, only that this particular website did not mention it. Perhaps the Melos requires the better quality & longer life tube to perform up to specs??
Larry in Dallas