Elrog 300B vs Takatsuki 300B tubes
Charles, I would suggest a resistor at least 20 watts in this position. The heat you are dissipating could be from 6 to 8 watts. For instance the original Joe Roberts WE91a schematic calls for a 50watt resistor in this position. You could also go with two Mills 2.4k 12 watt resistors in parallel. That would give you a 1.2k / 24w resistor. I believe a 10 watt resistor will be burnin hot and too close to its max tolerance. |
Charles1dad, that is great of George to send you another pair of replacement tubes, but why not just ask for a refund? So far you have had 2 separate Elrog 300B tube failures and to date you have been lucky that the failures did not result in any damage to your amps. Why push your luck? If a refund is not available, do you intend to sell the replacement tubes in an attempt to recoup some of your investment? I just crossed Elrog off my Christmas list. |
Excellent comments by Jet just above, regarding the power rating of the replacement resistor(s). And I note in this schematic, which was referenced earlier in the thread, that a 25 watt rating is shown for the present 1K resistor. In general, it is good practice to "derate" a resistor's power rating (i.e., to have the rating exceed the expected actual dissipation) by at least a factor of 2 and preferably more. Rob, thanks for the kind comment :-) Best regards, -- Al |
Jet and Al, Following my earlier post I spoke with George and he also suggested a larger value watt rating resistor would be fine even though the amplifier uses a 10 watt cathode resistor. 20 watts it will be! Thanks gentlemen for valued input. Brf, You make a good point but I am determined to see this through with the resistor suggestion. The Elrog is wonderful sounding and I really enjoy listening to them. If the Elrog fails again despite the resistor swap then that's it for me and I'm back to EML and Takatsuki. If a 5-10 dollar part can prolong the lifespan and reliability of 1500.00 dollar tubes I'm willing to give it a try. I accept the potential risk and will blame no one if things don't work out. Charles, |
