[AndyP[_2_]]

I heard lots of times that a tube microphone will perform better if it has
the chance to "warm up" for a few hours before the recording. But, is there
a limit for how long the mic should be left powered up?

Thanks,
Andy

[Mike Rivers]

On Aug 5, 3:02 pm, "AndyP" wrote:
I heard lots of times that a tube microphone will perform better if it has
the chance to "warm up" for a few hours before the recording. But, is there
a limit for how long the mic should be left powered up? I don't know about modern mics, but mics from the 50s and 60s were powered up all the time - because the whole studio was powered up all the time. I'd say that like anything else, if you know you're not going to use it for a while (your definition of "while") then power it down. If the session isn't over for the day or will continue to the next day, it doesn't hurt to leave everything, including the mics, powered.

Like light bulbs (with filaments), tubes tend to burn out more often
when being switched on than once they're on. Electrolytic capacitors
tend to remain capacitors longer when they have voltage on them.
Things like capsules and very high resistance resistors (like what
feeds the polarization voltage to the capsule) are happier when
they're not damp from humidity or condensation. I suppose if you're
not going to use the mic for a week or more, you might as well turn it
off, but this isn't something that you should let run your life.

Let the anti-global-warming tree huggers listen to their solid state
battery powered MP3 players.

[Scott Dorsey]

AndyP wrote:
I heard lots of times that a tube microphone will perform better if it has
the chance to "warm up" for a few hours before the recording. But, is there
a limit for how long the mic should be left powered up?

That depends on the microphone.

I'd have no qualms about leaving something with a 5840 in it powered up all
the time. If you leave a U47 powered up all the time, it will accelerate the
inevitable deterioration of the PVC diaphragm. If you leave a mike with a
soft-filament start powered up all the time, you aren't reducing turn-on
failures much, but if you leave a B&K 2615 powered up continuously, the thing
will last longer.

Not all tube mikes are the same. In fact, they are all pretty different.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Ty Ford]

On Sun, 5 Aug 2007 15:34:33 -0400, Scott Dorsey wrote
(in article ):

AndyP wrote:
I heard lots of times that a tube microphone will perform better if it has
the chance to "warm up" for a few hours before the recording. But, is there
a limit for how long the mic should be left powered up?

That depends on the microphone.

I'd have no qualms about leaving something with a 5840 in it powered up all
the time. If you leave a U47 powered up all the time, it will accelerate the
inevitable deterioration of the PVC diaphragm. If you leave a mike with a
soft-filament start powered up all the time, you aren't reducing turn-on
failures much, but if you leave a B&K 2615 powered up continuously, the thing
will last longer.

Not all tube mikes are the same. In fact, they are all pretty different.
--scott



leaving a tube guitar amp on seems to decrease the MTBF.

Regards,

Ty Ford


--Audio Equipment Reviews Audio Production Services
Acting and Voiceover Demos http://www.tyford.com
Guitar player?:http://www.youtube.com/watch?v=4RZJ9MptZmU

[Scott Dorsey]

Ty Ford wrote:

leaving a tube guitar amp on seems to decrease the MTBF.

Very different issue, though. The power tubes in a guitar amp are big
and hot. They don't fail the way small signal tubes do; they tear themselves
up with heat. Likewise all that heat bakes the capacitors and resistors.

Most tube mikes use tubes that tend to run cool, and the main failure
mode is filament failure from too many hot/cold cycles for a lot of
those tubes. The U47 is about the only mike you'll see in common use
with heat-related failure issues.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."