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billblues
New member
what happens if you accidently send 48v phantom power to a tube mic?
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crankz1
...
Well it kind of depends on what tube mic you are speaking of.
It might accidentally work.
It might accidentally work.
Farview
Well-known member
Most tube mics have a power supply, the phantom goes nowhere.
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crankz1
...
There are some tube mics, such as the Gefell UM900, that are powered via 48v Phantom.
Farview
Well-known member
I think AKG makes one like that as well.
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billblues
New member
I have a groove tube gt66 which i mistakingly sent phantom pwr to for a brief period thru half of my preamp[2 channel]when i thought i was sending phantom pwr to my at 4040 which was on the other channel of my preamp.the gt66 came with no literature.can phantom power destroy the tube in the mic?
evm1024
New member
Tubes are tough
To start with I have no experience with tube microphones. I do have some experience with tubes in the distant past. As I recall tubes themselves are almost indestructable. If you were to bias a tube incorrectly and your plate supply could source enough current you could cause the plate to glow cherry red. The tube would still work after this mistreatment. Can't say how it would sound (fidelity) after that abuse. But the key here is that they do not blow up like semicouductors when you exceed the voltage or current specs. Oh the only way to blow one up that I can think of is to run more voltage throught he filliment supply than needed (12at7, 12au7 etc have a 12 volt filliments and 6au7 a 6 volt filliment). Filliment supplies are usually AC off an individual power transformer winding. (again, my tube experience is outside of mics)
I have not looked at any schematics for a tube microphone but I would suspect that the tubes output is matched to mic out through a transformer. In that case phantom supply would have zero effect.
regards
billblues said:
To start with I have no experience with tube microphones. I do have some experience with tubes in the distant past. As I recall tubes themselves are almost indestructable. If you were to bias a tube incorrectly and your plate supply could source enough current you could cause the plate to glow cherry red. The tube would still work after this mistreatment. Can't say how it would sound (fidelity) after that abuse. But the key here is that they do not blow up like semicouductors when you exceed the voltage or current specs. Oh the only way to blow one up that I can think of is to run more voltage throught he filliment supply than needed (12at7, 12au7 etc have a 12 volt filliments and 6au7 a 6 volt filliment). Filliment supplies are usually AC off an individual power transformer winding. (again, my tube experience is outside of mics)
I have not looked at any schematics for a tube microphone but I would suspect that the tubes output is matched to mic out through a transformer. In that case phantom supply would have zero effect.
regards
Farview
Well-known member
Can 48 volts take out a 12at7? No. 48 volts can't even adequately power a 12at7. The phantom won't get through the power supply.
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billblues
New member
must have been ribbon mics that get destroyed from phantom power?
Farview
Well-known member
That is the rumor. It only applies to really old (or rare) ribbon mics or mis-wired cablesbillblues said:
