I have been playing with a lot of a KT-88 or 6550 cathode followers and for some time have been enjoying the Triode connected 6550EH output tubes as duty in my headphone Amp as an output stage.
Some time ago I read an article in Tube CAD about pentode based cathode followers and so I wanted to investigate this further and since only simple rewire is all it required to go from triode to pentode on the same platform I could evaluate the sound and performance differences between the (2) two. So far the only measurements I did was noise and the pentode connection reduced that from 2.2 mV to 0,7 mV Hum was totally gone in pentode mode yet was noticeable in triode mode however a regulated power supply would have made both quiet. Maybe?
I thought I would share this with you. The attached schematic shows actual measured voltages with the 6550EH tubes with about 500 Hours on them.
Some time ago I read an article in Tube CAD about pentode based cathode followers and so I wanted to investigate this further and since only simple rewire is all it required to go from triode to pentode on the same platform I could evaluate the sound and performance differences between the (2) two. So far the only measurements I did was noise and the pentode connection reduced that from 2.2 mV to 0,7 mV Hum was totally gone in pentode mode yet was noticeable in triode mode however a regulated power supply would have made both quiet. Maybe?
I thought I would share this with you. The attached schematic shows actual measured voltages with the 6550EH tubes with about 500 Hours on them.
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