HarmonicTHD
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How reassuring.
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Stereophile's Jim Austin disagrees w Atkinson; says tubes have something that can't be measured
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fpitas
Master Contributor
Exactly. No transistor can offer piece of mind like that.
HarmonicTHD
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Peace. (I mean no bombs)
If a power/output transistor is shorted it will put the amp into protection mode or blow the fuse. If the output transistor is partially bad they usually make some slight crackling and fuzz sounds as in distortion. If the BIAS is off it may be checked with a millivolt meter across the emitter resistors and adjust the BIAS control small pot that should be on the amp PCB near the output transistors. To get the proper voltage across the resistor consult the service manual for that number and then calibrate the BIAS via that small potentiometer that I mentioned.
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As for more 'durable', a lot depends on what is meant! If you 'abuse' a semiconductor, its hatched. Not so with a tube- they can be quite 'durable' (forgiving) in that regard. If you mean in terms of service life no-one argues that- that is after all why tube gear has the tubes mounted in sockets
I expect in our class D stuff the service life will be quite long since the operating temperatures are lower than often seen in class AB stuff.
FWIW, in case its not obvious by now, I'm pretty literal/specific which can complicate exchanges like this.
Those drug-store (emissions) testers were terrible- they might pass a bad tube and reject a good one. So not much has changed except the tubes now perform worse and are less reliable than 50-60 years ago. You still have to try a different tube in the suspect location and see what happens just like 60 years ago.
Don't tubes have applications in radar and broadcasting? I don't know and am just asking.
tungsten carbide drills, you say?
sadly, i was going to link the monty python sketch, but this is the best i can find
ok find something slightly better, but i don't use twitter....
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English present perfect. An action that began in the past and continues into the present.
Your tense may vary.
EDIT:
Actually, I wasn't sure if they (or anyone else, for that matter) were still making any Nuvistor amps (preamps) -- and, characteristically, I was also too lazy to check!
i think the original proximity fused anti air craft shells used a very small tube. no idea how they survived the g forces when fired. i know the Japanese were amazed by how good a shot american naval aa guns were....Don't tubes have applications in radar and broadcasting? I don't know and am just asking.
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that's hysterical -- and I don't remember this sketch?!?tungsten carbide drills, you say?
sadly, i was going to link the monty python sketch, but this is the best i can find
Sort of like the four Yorkshiremen's alternate universe.
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Well -- microwave ovens.Don't tubes have applications in radar and broadcasting? I don't know and am just asking.
I have to assume that the really big "border blaster" transmitters (if there are any still extant) are still using water cooled tubes as the finals. But, heck, maybe there are 100 kW power transistors now??? Maybe even ICs, for all I know!
320A Vacuum Tube
The 320A Vacuum tube is a 3 element water cooled tube designed for use
as an oscillator, modulator, or amplifier at the higher power levels
and high frequencies.
Filament ratings: 35 volts at 435 amperes
Average thermionic emission: 90 amperes
Characteristics at 18 kV plate voltage and 8 amperes plate current:
Amplification factor: 30
Plate resistance: 965 ohms
Transconductance: 31,100 micromhos
Maximum plate ratings:
maximum plate voltages: 12.5 kV modulated
18 kV non modulated
20 kV rms AC
current: 15 amps DC
dissipation: 150 kilowatts
Maximum grid dissipation: 2 kilowatts
source: http://j-hawkins.com/mexblast.shtml
Oh, yeah!
The drug store testers ("U-Test-M" in my area) were simple emission testers. A competent tube tester measures a tube's transconductance, which is a measure the ratio of how much plate current swing a given input voltage swing could cause. That is a better measure of the tube's actual performance, although that was not perfect either, because the tester did not apply high plate voltages & currents to the DUTs (Device Under Test), similar to what they would see in actual use. Tube could pass U-Test-M but crap out in the application. Still, the tester did catch a lot of duds, though.
computer-audiophile
Major Contributor
Philips 1kW tuber amp from 1955
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Based on the many merits that -based on this discussion- tubes supposedly have over semi tech, you'd think that tubes are still extensively used in aircraft radars, self-driving cars, the 5G infrastructure, power grid... etc. Guess what - they aren't. Even high power and high frequency isn't a tube domain. Not that consumer audio falls into any of those categories compared to other far more critical applications. Nor would I pitch micro-oven design as an exercise in utmost accuracy that I'd like to see revisited in my audio gear, but hey, that's just my "uneducated opinion". :-D
No one tells the marines to keep using arquebuses because they were so ground-breaking back in the 1400s. :-D
No one tells the marines to keep using arquebuses because they were so ground-breaking back in the 1400s. :-D
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MAB
Major Contributor
Yes, I heard that the testers were imperfect, they seemed to work for my family when I was a kid. I'm not suggesting that the local drug store tester would support audiophile tube rolling.
But none of the culture that supported tube use exists anymore. And I see audiophiles struggling with their tube gear without a proper community.i need one of these so badly its untrue.Well -- microwave ovens.
I have to assume that the really big "border blaster" transmitters (if there are any still extant) are still using water cooled tubes as the finals. But, heck, maybe there are 100 kW power transistors now??? Maybe even ICs, for all I know!
View attachment 286142
320A Vacuum Tube
The 320A Vacuum tube is a 3 element water cooled tube designed for use
as an oscillator, modulator, or amplifier at the higher power levels
and high frequencies.
Filament ratings: 35 volts at 435 amperes
Average thermionic emission: 90 amperes
Characteristics at 18 kV plate voltage and 8 amperes plate current:
Amplification factor: 30
Plate resistance: 965 ohms
Transconductance: 31,100 micromhos
Maximum plate ratings:
maximum plate voltages: 12.5 kV modulated
18 kV non modulated
20 kV rms AC
current: 15 amps DC
dissipation: 150 kilowatts
Maximum grid dissipation: 2 kilowatts
source: http://j-hawkins.com/mexblast.shtml
Oh, yeah!
fpitas
Master Contributor
Not much anymore. Banks of transistorized RF modules have replaced them, for the most part. They sum the outputs together to get the required total power. If a module breaks, you can remove it and your transmitter is still functional, albeit at slightly reduced power output.Don't tubes have applications in radar and broadcasting? I don't know and am just asking.
Galliardist
Major Contributor
They’d have to start using arquebuses because they were formed later.
Anyway, the analogy you are actually looking for is pouring boiling oil from castle walls - so much warmer and more organic!
they were used in the 15th century....ala the 1400s
theREALdotnet
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I for one have experienced at least some of the history of electronics, mostly consciously I think.
I’ve had lucid moments between electrocution incidents, too (I believe).
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