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Re: UPDATE

209.20.170.147

Primary Z of the OT in the Wright 2A3 amp is 3K. I should know, George 'borrowed' the idea of using it from me (MagneQuest TFA-204).
I don't know that the impedance issue is so severe that 5K need be used. KR publishes a plate resistance of 700 ohms at 250Vp and 50 mA. Note that this is lower than a biplate 2A3, not higher. The gain is also a bit lower than a stock 2A3 and with 5k it would be really low. I would suggest instead increasing the current, which will pull the Rp of the KR down a bit and take away the strained sound. This is what we do in our amps, you get a different cathode resistor to use with the KR tube, one that increases the current draw a bit.
A thought just occured to me, that with the TFA-204 you might not get quite the full effect of the greater bass punch of the KR2A3, as the TFA-204 has a relatively lower inductance than some larger SE trannies.
My comparisons of biplates vs. the KR2A3 on Galantes was done with a parafeed amp with about triple the output inductance and a primary Z of 2.5K.
Once again I will say take any tube rolling experience with a grain of salt. Any tube needs its operating environment optimized, and every system will show a different balance of strengths and weaknesses from a given component. I find the KRs are quite good for systems with lower sensitivity speaks, and the Chinese 2A3s are nice with high sensitivity systems like Galantes, but there may be certain equipment combos where the opposite is true..

Meantime bring on some Sovtek monoplate 6B4s and give me DC fils!


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