Hi!
I use the 6X4 as a rectifier in a hybrid bridge (with two BY 127 Si-diodes) in the power supply of my preamp, who takes about 50 mA at 300V. Rectifier input voltage is 450 V AC. From the tube's cathode, there goes a NTC resistor (ca. 300 Ohm cold, a few ohms hot, to reduce startup current) to a 50 uf electrolytic, a 5 H choke, another 50 uf cap, and then into the first regulator tube, a PL 84. Voltage reference is a TAA 550 temperature-compensated precision zener voltage source (33 V).
I built this amp in the late 80's, and at the moment where I am writing this posting, it has run 22,869 hours.... (I have a counter in the PSU....
), always with the same tubes.... This also applies to the PL 84 / PL 95 / PCF 802 in the 2-stage regulated power supply....
So far I don't see any signs of weakening of the tube(s)....
Don't know how much you'd charge the tube, but with the above data you easily could expect about 8 years of 8 h daily service.... (23,000 : 8 : 365)
Uli
I use the 6X4 as a rectifier in a hybrid bridge (with two BY 127 Si-diodes) in the power supply of my preamp, who takes about 50 mA at 300V. Rectifier input voltage is 450 V AC. From the tube's cathode, there goes a NTC resistor (ca. 300 Ohm cold, a few ohms hot, to reduce startup current) to a 50 uf electrolytic, a 5 H choke, another 50 uf cap, and then into the first regulator tube, a PL 84. Voltage reference is a TAA 550 temperature-compensated precision zener voltage source (33 V).
I built this amp in the late 80's, and at the moment where I am writing this posting, it has run 22,869 hours.... (I have a counter in the PSU....
), always with the same tubes.... This also applies to the PL 84 / PL 95 / PCF 802 in the 2-stage regulated power supply....So far I don't see any signs of weakening of the tube(s)....
Don't know how much you'd charge the tube, but with the above data you easily could expect about 8 years of 8 h daily service.... (23,000 : 8 : 365)
Uli
IMO, that's too much for a 6X4. 70 mA. is "normal". Look at the data sheet. While I wouldn't worry if the draw is 75 mA., a switch to the 6CA4/EZ81 is indicated, if 100 mA. of B+ are really needed.
Re: How much current
indeed, like Eli said, this even exceeds the ratings of the next bigger tube in this row, the EZ 80. (rated for 90 mA max.). And I prefer running the tubes not at their limits, especially not rectifier tubes. Forward drop increases quite much when running them close to their limits. So indeed take a EZ 81, or, if you can provide for a separate 5 V heater supply, the GZ 34 (5 V, 1.9 A heater (connected to cathode), EZ 81 is 6.3 V, 1 A, heater isolated from cathode) and has at 100mA only a few volts forward drop. EZ 81 has 15 V there, GZ 34 only 8 V.
Uli
SINGLEENDED said:The pre amp. consume 250vdc @ 100ma.
indeed, like Eli said, this even exceeds the ratings of the next bigger tube in this row, the EZ 80. (rated for 90 mA max.). And I prefer running the tubes not at their limits, especially not rectifier tubes. Forward drop increases quite much when running them close to their limits. So indeed take a EZ 81, or, if you can provide for a separate 5 V heater supply, the GZ 34 (5 V, 1.9 A heater (connected to cathode), EZ 81 is 6.3 V, 1 A, heater isolated from cathode) and has at 100mA only a few volts forward drop. EZ 81 has 15 V there, GZ 34 only 8 V.
Uli
Re: Re: How much current
I have a couple of EZ81 brand ultron ,3pcs of GZ 34 rca , 6X4 tungsol , 6X4 raytheon , 6X4 ge, and trying to get my hands on Haltron if you can help.
Why 6X4 ge and at their peak limits. 1, it is very quiet . 2, it is not pushy compare to others, 3, open soundstage. .
Btw the preamp is feed from oil bath trans supply.
ulibub said:
I have a couple of EZ81 brand ultron ,3pcs of GZ 34 rca , 6X4 tungsol , 6X4 raytheon , 6X4 ge, and trying to get my hands on Haltron if you can help.
Why 6X4 ge and at their peak limits. 1, it is very quiet . 2, it is not pushy compare to others, 3, open soundstage. .
Btw the preamp is feed from oil bath trans supply.
I can recommend the tubes of actual production from www.jj-electronic.sk. They habe both EZ 81 and GZ 34 in production. But brand doesn't really matter with rectifier tubes as long as they are quality products.
But for what do you need an oilbath transformer for your preamp???? Is it fed directly from a high-voltage line????
But for what do you need an oilbath transformer for your preamp???? Is it fed directly from a high-voltage line????
Brands.
Brand does not make the sound.
Different manufacturer make their tube differently.
I like GE & Haltron they sound open and warm.
JJ is not so good I have a few pieces.small sig.
Yes it is feed directly from the high voltage line.
And yes it really make the whole set up sound different. Very quiet i should say.
Brand does not make the sound.
Different manufacturer make their tube differently.
I like GE & Haltron they sound open and warm.
JJ is not so good I have a few pieces.small sig.
Yes it is feed directly from the high voltage line.
And yes it really make the whole set up sound different. Very quiet i should say.
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