Tube amp question


I am a novice tube amp owner. I have had my Black Ice Audio Fusion F22 for not quite a year. I want to understand plate voltage and how it impacts tubes or vice versa. I want to roll the tubes to the KT150's which Black Ice has said can be used without issue. The plate voltage of the amp is 500v. In other posts, someone said that KT150's require a minimum of 600v at the plate. Since Black Ice says their amp can use them, does this rating depend on the circuit? I have some basic understanding of electronic circuits and I googled plate voltage but I'm still not clear on what it is exactly. Can someone knowledgeable with tube amps help me understand this? Thanks!

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Showing 5 responses by daveyf

@atmasphere If you place a KT150 on a tube tester, it will not get to spec unless 600 volts is available. As a result, there are few tube testers that can actually test this tube.

@atmasphere While I agree with you that a tester that cannot properly test a KT150- shows the limits of the tester, ( BTW, yours- nor any Hickok- I am aware of can test these tubes--and your KT88 spec is no good for them) it also points to the fact that they need more voltage than 400 volts to come to spec, IMHO.

So now we hear that the OP and one other member has had the same problem when running KT120's. The amp went into protection mode. I would think if it does that with KT120's...nothing good can happen when you roll in KT150's.

OP, I would ask Mr. Allen to confirm that there will be no damage to his transformers by running the KT150’s...and maybe have him put that in writing. While the amp may supply ’enough’ voltage for the KT150’s to work, as russ69 pointed out above, you will not get all the power that the tube can produce.

Personally, I would be more concerned about using a transformer that was not originally designed for this tube, but if the manufacturer is ok with that..so be it.

KT150's require 600 volts at the plate. If you are not able to supply that voltage, i cannot believe you would be getting the best SQ from this tube. Bigger question is whether the transformers on your amp will suffer?