Elrog 300B vs Takatsuki 300B tubes

Ok, here is the information that George emailed me.
Hi Joe,
You can post this data. Be sure to mention that customers of these amplifiers test their AC line voltages(AC Voltmeter). Over 122V AC is a game changer for these or any other 300B tubes. Ideally, in their home they should be have voltages in the 114-122V range. If they have excessive voltage, they should purchase a "variac" as a means of protection for their equipment.

Best,

George

Hello Joe,
Here it is the recent data taken from Friday's testing......

Takatsuki 300B 474V plate 33 watt dissipation
84 V across cathode

Elrog 300B 484V plate 32 watt dissipation
79V across cathode

EML 300BXLS 486V plate 31 watt dissipation
75V across cathode

Psvane 300B 484V plate 30 watt dissipation
74V across cathode

Line voltage 119.4VAC

Cathode resistor value 1.025K ohms

Best,

George

I hope this helps,
Joe

Excellent info, Joe (& George). That all seems very comfortable relative to the specified "limiting operating conditions for safe operation" of the Elrog tube. (79V/1.025K = 77 ma). And the plate dissipation which can be calculated from those numbers is actually closer to 31 watts rather than 32.

Enjoy! Best regards,
-- Al

Hi Al,
In your opinion given the values that George measured, do you feel these represent a high stress level on the 300b tube or more of a moderate level? The heat dissipation levels measured by George are higher than the 26 watts that Israel cited for the amplifier. Although 31 W seems well off the maximum of 39 or 40 W dissipation for the 300b. Is the plate voltage similar to your VAC Renaisance?
Thanks,
Charles,

Charles, George said I should have no problem using the tubes in my amps. Yours are older then mine, make sure the cathode resistors are the same and the rest of the values didn't change.

Best,
Joe

Hi Charles,

My only knowledge of the 300B operating parameters in my VAC Renaissance 70/70MkIII consists of the values Raquel provided in the thread I quoted from earlier. In which he said that the plate-to-cathode voltage is approximately 430 volts (compared with 484-79 = 405 for the Elrog in this case), with an idle current of approximately 85 to 90 ma (compared with 77 ma for the Elrog in this case). Also, based on those numbers for my amp, 90 ma x 430 volts = 38.7 watts plate dissipation.

The numbers George measured for the Elrog seem to me to be moderate.

Best regards,
-- Al