Crucial TUBE question
I placed a KT 150 power tube into a Prima Luna Evo 300 preamp rectifier slot. I know. But what happened was surprising. The sound was, well, magnificent glorious. Nothing burned out. No smoke. No arc lights. I asked Upscale Audio to advise me as to what damage I may have done or could have done to the PL. They only said they would not advise placing anything but the original tubes in the slot. They would not commit to whether or not that power tube could be used in place of a rectifier to tube. So, is it an absolute or not? If so, why? I’d appreciate feedback (please, no slams) from anyone having any experience with this. Thanks!
Accident is sometimes the mother of invention. that said, I doubt this is a great discovery but you never know. Upscale audio's response is predictable legal CYA when they have no idea what the technical answer is. Hope someone who actually knows what happens when a power tube goes into a rectifier socket replies. Jerry |
OK I pulled up the pinout for both tubes. Nothing shorts out (obviously based on your experience). The heater will not have current in a KT150 so I don't see how it works well if at all. Pin 4 is a grid in one tube and a plate in the other. Other pins aren't used in both. Makes me think there is another rectifier in the PL. Perhaps the tube is just for show. Jerry |
@mulveling has confirmed my read that the heater would not be hooked up. (needs both pins to have a circuit). So KT150 would not light up and would not produce any current. At this point I don't think we need someone with tube knowlegde, we need someone with a primaluna schematic to figure this out. We all agree you should not have done any damage. We don't understand why you got music. One other thing to check, follow your cables and make sure the preamp is actually in the signal path. I assume it is as you must be using it for volume control if nothing else, but you could be using your DAC or Roon. Jerry |
Sounds like @dogearedaudio found the connection between pins 7 and 8 that allowed it to work. I also agree with his recommendation of the Mullard GZ34. Jerry |
