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!
This is in part because of the power supply voltage design and transformer design . in some amplifiers it allows several choices for they built it much more rebudt. in a preamplifier look up the Ma for the kt150 voltage draw, you didnot specify your rectifier tube ,let’s say a 5ar4 it may have a different Ma voltage parameter. |
@czarivey "Any tube ... can work as rectifier" I don't know one way or the other if that is factually correct, but I haven't come across any tube amps, DAC,s or preamps that use anything but a tube that is in fact specified as a rectifier tube as a rectifier. And, the manufacturers specify which rectifier is appropriate for the circuit and if there are options. For instance, my Modwright preamp specifies "5AR4, may also use 5U4GB and 5V4GB".
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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 |
