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Tube Mic / Tube Pre sounds better after warming up for extended period of time 24hrs Condenser Microphones
Old 31st December 2016
  #1
Tube Mic / Tube Pre sounds better after warming up for extended period of time 24hrs

Accidently left my tube mic on overnight + a few days on two separate occasions. I am thinking leaving a tube mic or preamp on for an extended period of time before use makes it sound better.

The first time i recorded with it after leaving it on for a few days straight, i was pretty shocked at the quality increase. Recording vocals everything sounded warmer and more detailed at the same time. A win win. Great texture and definition.

I thought it may just be a placebo effect though, as I recorded a few days later and let the mic warm up for like 15min and it still sounded good. But, turns out it's not, I think theres something to it now: I accidentally left the mic on for a few days again and recorded something. Sure enough, same warm detailed sound I remember from when I left it on the first time, noticeably better than when I let the mic warm up for 15min.

I also noticed this when I had a tube preamp before I had my tube mic. I accidently left it on for an extended period of time. I made a thread about it a while back: Ideal time to warm a tube preamp before recording I honestly think there's something to this.

They say your supposed to let a tube mic / preamp warm up for about 30 min before recording, but I've had one warm up for a few hours and haven't heard much of a difference between that, and when I turn it right on and record. Leaving it on overnight seems to make a very noticeable difference, at least in headphones. Anyone know whats going on?
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Old 31st December 2016
  #2
I don't want to name names, but I've had one of the worlds best mic techs tell me that more than 20mins or so is pointless. I don't ever recall leaving a mic on that long in one burst, so maybe you're right. But I've also not had any issues doing it my way
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Old 31st December 2016
  #3
I've always thought anything class A or high voltage tube can benefit from being on at least a couple hours since I heard my first hi end piece around '96.
It's not night and day but it's there IME.
Dave Hill confirmed this to me over ten years ago (he said leave on an hour minimum) and he is a Jedi/Zen master of audio design, so yes. If anything it's good practice just for consistency, from the beginning to the end of the session.
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Old 31st December 2016
  #4
Quote:
Originally Posted by psycho_monkey View Post
I don't want to name names, but I've had one of the worlds best mic techs tell me that more than 20mins or so is pointless. I don't ever recall leaving a mic on that long in one burst, so maybe you're right. But I've also not had any issues doing it my way
I read that too, although I am hearing a pretty obvious difference. Maybe its the electricity in my studio? It is in a 100 year old house. Not sure if that matters. Try it yourself if you get a chance. The Mic i tried is a Telefunken Cu 29 copperhead tube mic. I also had the same sort of effect using a blue robbie tube preamp on a blue kiwi solid state mic. Sounds like the tube is fully warmed up or something after an extended period of time, really sounds nice.

Quote:
Originally Posted by NathanEldred View Post
I've always thought anything class A or high voltage tube can benefit from being on at least a couple hours since I heard my first hi end piece around '96.
It's not night and day but it's there IME.
Dave Hill confirmed this to me over ten years ago (he said leave on an hour minimum) and he is a Jedi/Zen master of audio design, so yes. If anything it's good practice just for consistency, from the beginning to the end of the session.
Yes I noticed this. Thanks for the info. Maybe there is something to it
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Old 31st December 2016
  #5
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When you have a marginal tube that has a little higher noise emissions, when you have it on for an extended time, the emissions can often drop to nothing and it becomes perfectly silent.

I'm sort of convinced that in that same longer time frame for warm up, that perfect/near perfect tubes also wind up benefitting.

Also, when the heat of every part inside of a piece of gear has reached the full peak operating temperature, the sound seems to focus.
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Old 31st December 2016
  #6
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Very hard to quantify.... I suspect it is totally placebo. So many factors that u can't eliminate from your experiment. I convinced myself once of the opposite. I thought that my tube mic sounded worse after leaving it on for a while. It turns out that the theory was bunk. I must have just sung better those times or had luck in that direction somehow. I suggest to leave it on for an hour, record into it and then do the same thing after being on for a whole day. Do this 10 times over a few weeks and put all the audio files into a track. Close ur eyes and see if u can pick the difference each time. If u can't reliably tell the difference, it is placebo. Even better, get an assistant, or friend or someone to turn it on the night before sometimes and sometimes not. That way, it is double blind. If u can tell the difference under those conditions then u have discovered something extremely strange and very interesting.
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Old 31st December 2016
  #7
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Maybe the tube affected the room temperature a fraction of a degree and balanced the moisture levels giving the artist slightly increased comfort levels thus enhancing the performance.
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Old 31st December 2016
  #8
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Quote:
Originally Posted by Moondog007 View Post
Very hard to quantify.... I suspect it is totally placebo. So many factors that u can't eliminate from your experiment. I convinced myself once of the opposite. I thought that my tube mic sounded worse after leaving it on for a while. It turns out that the theory was bunk. I must have just sung better those times or had luck in that direction somehow. I suggest to leave it on for an hour, record into it and then do the same thing after being on for a whole day. Do this 10 times over a few weeks and put all the audio files into a track. Close ur eyes and see if u can pick the difference each time. If u can't reliably tell the difference, it is placebo. Even better, get an assistant, or friend or someone to turn it on the night before sometimes and sometimes not. That way, it is double blind. If u can tell the difference under those conditions then u have discovered something extremely strange and very interesting.
No, it is literally measurable.
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Old 31st December 2016
  #9
Gear Nut
well, guitar players know about that... they leave their tuve amps warming up at least a half hour before play.

And tubes is and old technology... People decades ago always kept warming up ALL their equipment before using it... they said always they equipment worked better after warm up (not only in the audio area), it was an obliged step...
Old 31st December 2016
  #10
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lobsterinn's Avatar
Seems easy enough to test.

Record some repeatable things both ways, like a reamped guitar part (after warming up amp the same amount of time), a piece of music through speakers, a keyboard part through solid state amp, etc.

Then set up a blind A/B test and see if there's a preference.
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Old 1st January 2017
  #11
Quote:
Originally Posted by kangking View Post
I read that too, although I am hearing a pretty obvious difference. Maybe its the electricity in my studio? It is in a 100 year old house. Not sure if that matters. Try it yourself if you get a chance. The Mic i tried is a Telefunken Cu 29 copperhead tube mic. I also had the same sort of effect using a blue robbie tube preamp on a blue kiwi solid state mic. Sounds like the tube is fully warmed up or something after an extended period of time, really sounds nice.
I have no idea how you'd go about doing a fair test on this though? Are you just doing vocal takes after 24hrs? How are you removing the other variables?

I'm not saying it DOESN'T make a difference (although the guys designing the gear might not agree), but I just don't know how you could do a fair test.

Maybe set a speaker up with a pre-recorded signal, and "re-record" that straight away, after a minute, 10 minutes, an hour, 2hrs, 24hrs and see what the differences are?

Our 67s occasionally pop a bit during the warmup phase of a few minutes, but then stabilise. I've not noticed any difference between doing vocal takes at the start of the day vs the end. Well - not with the mics anyway, the performances obviously vary!
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Old 1st January 2017
  #12
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I try to make it a practice to let everything warm up for at least two hours. I have heard from others that 24 hours, or even "leave it all on throughout the entire duration of a project" works well for them, but in my case, I usually shut everything off at the end of a day. Sometimes though I will leave things on for two or three days during times of intense work, then I don't have to warm it up all over again. YMMV. I would tend to believe what the OP has observed.

Last edited by edva; 1st January 2017 at 05:57 AM.. Reason: +
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Old 1st January 2017
  #13
Quote:
Originally Posted by edva View Post
I would tend to believe what the OP has observed.
Whilst I'm perfectly willing to be openminded, there doesn't seem to be much scientific method involved, nor do the manufacturers support this long term viewpoint.

From a practical point of view, most working studios can't set up and leave stuff on the night before. I tend to leave preamps on but turn off tube mics (actually I don't think I have any tube pres..). The extra hours on a U47's tube isn't worth a possible improvement I don't feel.
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Old 1st January 2017
  #14
Gear Guru
 

Quote:
Originally Posted by toledo3 View Post
When you have a marginal tube that has a little higher noise emissions, when you have it on for an extended time, the emissions can often drop to nothing and it becomes perfectly silent.

I'm sort of convinced that in that same longer time frame for warm up, that perfect/near perfect tubes also wind up benefitting.

Also, when the heat of every part inside of a piece of gear has reached the full peak operating temperature, the sound seems to focus.
Which is why tube gear has vents and the Sony C800g has a radiator - oh, wait...
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Old 1st January 2017
  #15
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bgood's Avatar
I was always told preheat for about 30 minutes... You're just burning hours of life from the gear leaving it on for hours before you track...don't do it baby
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Old 1st January 2017
  #16
Quote:
Originally Posted by psycho_monkey View Post
I have no idea how you'd go about doing a fair test on this though? Are you just doing vocal takes after 24hrs? How are you removing the other variables?

I'm not saying it DOESN'T make a difference (although the guys designing the gear might not agree), but I just don't know how you could do a fair test.

Maybe set a speaker up with a pre-recorded signal, and "re-record" that straight away, after a minute, 10 minutes, an hour, 2hrs, 24hrs and see what the differences are?

Our 67s occasionally pop a bit during the warmup phase of a few minutes, but then stabilise. I've not noticed any difference between doing vocal takes at the start of the day vs the end. Well - not with the mics anyway, the performances obviously vary!
Yes just vocal takes. But its very noticeable. Like enough to post on here 2 times about it. I'm definitely noticing something.

Quote:
Originally Posted by edva View Post
I try to make it a practice to let everything warm up for at least two hours. I have heard from others that 24 hours, or even "leave it all on throughout the entire duration of a project" works well for them, but in my case, I usually shut everything off at the end of a day. Sometimes though I will leave things on for two or three days during times of intense work, then I don't have to warm it up all over again. YMMV. I would tend to believe what the OP has observed.
Old 1st January 2017
  #17
Quote:
Originally Posted by kangking View Post
Yes just vocal takes. But its very noticeable. Like enough to post on here 2 times about it. I'm definitely noticing something.
Got some examples to share?

But seriously...try the test I suggest. Try it with music, try it with a reproduced source, try it with a white or pink noise source and get some real results. Not just "I'm noticing something".

You could be right, or you could be killing your tube gear needlessly.
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Old 1st January 2017
  #18
Gear Nut
Quote:
Originally Posted by psycho_monkey View Post
Got some examples to share?

But seriously...try the test I suggest. Try it with music, try it with a reproduced source, try it with a white or pink noise source and get some real results. Not just "I'm noticing something".

You could be right, or you could be killing your tube gear needlessly.
Your ears may be telling the truth.

But rather than stumbling upon a great secret of audio, you may have simply identified a need for maintenance (actually, that's also a great secret of audio). There is no reason that anything more than 20 minutes or so should make any difference if everything is ship shape inside. But if you have failing tubes, bad solder joints, aging capacitors or iffy resistors, the slow heating of every component might well make a difference. Perhaps its time for a check up?
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Old 1st January 2017
  #19
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Quote:
Originally Posted by joeq View Post
Which is why tube gear has vents and the Sony C800g has a radiator - oh, wait...
I didn't say that tube gear needs to get super hot or anything.

WHAT I SAID IS THAT THE SOUND CHANGES UNTIL ALL PARTS REACH THEIR OPERATING TEMP.

There is a decent amount of literature on this from back in the hay day of valves, if anyone wants to go hunting. I don't have links on hand, but it's out there.

Last edited by toledo3; 1st January 2017 at 05:36 PM.. Reason: removed a mild expletive
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Old 1st January 2017
  #20
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toledo3's Avatar
 

Quote:
Originally Posted by psycho_monkey View Post
I have no idea how you'd go about doing a fair test on this though? Are you just doing vocal takes after 24hrs? How are you removing the other variables?

I'm not saying it DOESN'T make a difference (although the guys designing the gear might not agree), but I just don't know how you could do a fair test.
You can do a spectral analysis on the noise floor. You will probably see slightly less noise overall, basically.

I don't think it makes a big difference or anything, most times. But you can see the signature of the self noise of a piece of tube gear shift over time. The sonics when recording change in measurable ways as well, but I have never tested that personally (have tested the self noise/emissions).
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Old 1st January 2017
  #21
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Quote:
Originally Posted by kangking View Post
Accidently left my tube mic on overnight + a few days on two separate occasions. I am thinking leaving a tube mic or preamp on for an extended period of time before use makes it sound better.

The first time i recorded with it after leaving it on for a few days straight, i was pretty shocked at the quality increase. Recording vocals everything sounded warmer and more detailed at the same time. A win win. Great texture and definition.

I thought it may just be a placebo effect though, as I recorded a few days later and let the mic warm up for like 15min and it still sounded good. But, turns out it's not, I think theres something to it now: I accidentally left the mic on for a few days again and recorded something. Sure enough, same warm detailed sound I remember from when I left it on the first time, noticeably better than when I let the mic warm up for 15min.

I also noticed this when I had a tube preamp before I had my tube mic. I accidently left it on for an extended period of time. I made a thread about it a while back: Ideal time to warm a tube preamp before recording I honestly think there's something to this.

They say your supposed to let a tube mic / preamp warm up for about 30 min before recording, but I've had one warm up for a few hours and haven't heard much of a difference between that, and when I turn it right on and record. Leaving it on overnight seems to make a very noticeable difference, at least in headphones. Anyone know whats going on?
usually that is observed within the 100 hours of using tubes that have been in storage.
you see, over time the cathode will polarize by oxidization from the trace air that is in the vacuum tube. This causes a low emissions from the cathode until the oxidization is cooked off the cathode.
Old 1st January 2017
  #22
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edva's Avatar
Quote:
Originally Posted by drtechno View Post
usually that is observed within the 100 hours of using tubes that have been in storage.
you see, over time the cathode will polarize by oxidization from the trace air that is in the vacuum tube. This causes a low emissions from the cathode until the oxidization is cooked off the cathode.
could heat evaporation of moisture, most likely on the diaphragm, also be one factor?
Old 1st January 2017
  #23
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monkeyxx's Avatar
"It sounded like I remembered" that's a pretty low quality testing procedure. As others have already pointed out several times.

Personally 15 minutes to half an hour has been plenty enough for me. I don't want my tubes cooking all night long either way. The gear goes to sleep when I do. Not to mention the wasting of precious electricity.
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Old 1st January 2017
  #24
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Muser's Avatar
I've even heard some solid state gear perform the same. 15 to 30 minutes until the temp stabilises.
Old 1st January 2017
  #25
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Quote:
Originally Posted by edva View Post
could heat evaporation of moisture, most likely on the diaphragm, also be one factor?
I wouldn't think as much considering the internal temp that mic runs.

nos tubes are really bad at doing this. But its standard operation to run the tubes without plate voltages before selling so you can get the tube to test good again. So when you buy one from a dealer or the bay usually they have been cooked long enough (unless you are buying someone's replacement tube service caddy/box).

so you won't really see this usually unless you have tubes laying around for years.
Old 1st January 2017
  #26
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but I have heard stories about the big blue cap on the backside of the mic board: They have a special oven that they place a bunch of caps in a test fixture and hand selecting the cap for certain esr and capacitance properties at a temp that is supposed to duplicate the operating temp inside this mic.

so that is probably why the warm up notice in post #19 . the tube circuit itself is ready to go in 5 minutes, but the rest of the mic has to warm up to temp.
Old 1st January 2017
  #27
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toledo3's Avatar
 

Quote:
Originally Posted by drtechno View Post
usually that is observed within the 100 hours of using tubes that have been in storage.
you see, over time the cathode will polarize by oxidization from the trace air that is in the vacuum tube. This causes a low emissions from the cathode until the oxidization is cooked off the cathode.
Old 1st January 2017
  #28
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kennybro's Avatar
Most likely that your ears or the source sound quality changed in 24 hours. 20 to 30 minutes of warming up a tube mic gets it to where it's going to go.
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Old 1st January 2017
  #29
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edva's Avatar
there is a school of thought that tubes last a lot longer if never turned off. I have seen this in practice, but only once, since almost nobody does this. But, I did have a buddy with a studio who left his tube equipment on constantly, for years and years, with no apparent issues.
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Old 2nd January 2017
  #30
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I forget which threads, but someone was posting links to kemper profiling sessions where after coming back from lunch breaks, the Guitar Amps sounded different to the pre lunch break profile tests. I call that Pizza Ear syndrome.
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