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Post by OtisGreying on Jul 25, 2020 23:53:56 GMT -6
I have a flea 47 and I tend to turn it on and off sometimes with only an hour in between switching it back on, I guess in effort to try and preserve the tube. Is there anything wrong with turning this style of mic on and off frequently?
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Post by Ward on Jul 26, 2020 5:50:11 GMT -6
Every time you turn on a tube powered piece of gear, there's a tiny power surge to the tube(s). Some have argued that it uses more energy and causes more harm than leaving said gear on for 24 hours. I've always thought that was an exaggeration but perhaps there is some truth to it.
The rule for all studios I've worked at or owned was: leave the gear on if you're going to use it again within 12 hours.
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Post by EmRR on Jul 26, 2020 7:28:05 GMT -6
This system is perhaps more sensitive to problems than most, with the way the tube is heated. I probably wouldn’t power down for a break of less than 8-10 hours. Overnight, yes.
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Post by craigmorris74 on Jul 26, 2020 9:25:40 GMT -6
This system is perhaps more sensitive to problems than most, with the way the tube is heated. I probably wouldn’t power down for a break of less than 8-10 hours. Overnight, yes. What about tube gear in general, Doug? I'm always unsure what to do when I take a studio break. |
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Post by svart on Jul 26, 2020 9:50:54 GMT -6
Tubes are no different than incandescent lightbulbs. Turning them on and off wears out the filament a little faster with surge currents, but probably offset by the time the filaments are off.
I found a study a long time ago when I was working on designing a halogen lamp driver that came to the conclusion that it's pretty much up to the lamp build quality that determines it's lifespan and all the fancy tricks like PWM, constant current and underpowering are really just exploiting the fact that most of these lamps are built to only last a small amount of time at their specified ratings and could actually could have been built to last indefinitely.. things like the halogen gas purity and the thickness of the filaments matter. The hot filaments are degraded by any residual oxygen and wear thinner, increasing the chance that the physical shock of being instantly heated will break them.
Anyway, I went with the new (15 years ago) high powered LED modules that were coming out at the time and never experimented further with halogen.
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Post by mulmany on Jul 26, 2020 9:51:18 GMT -6
My understanding is that the warming up period is the hardest part for tube gear.
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Post by christopher on Jul 26, 2020 12:12:26 GMT -6
Reminds me when I was trying to learn about this topic I discovered this: en.m.wikipedia.org/wiki/Centennial_LightI leave on and turn off when done for the day. For mics they do warm up and that might affect its behavior. Cold and hot sound a little different. Not enough for me to care IMO. However when it’s cold and warming up is when I might get little tube clicks and zipper sounds. |
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Post by EmRR on Jul 26, 2020 12:12:48 GMT -6
Put perspective on it:
Lots of capacitors are rated for 10,000 hours use.
Lots of pots are rated for 10,000 rotations.
Most tube filaments are rated for 10,000 hours use.
Temper that with the availability of the replacement. The importance of the thing remaining original in every possible way. Etc
I have seen some caps and some tubes from 1930’s broadcast gear that have run 400,000 hours without replacement, still fine. Something will always defy the odds.
In 22 years of running a lot of tube gear, I’ve yet to see a filament fail on power up. I've seen filaments in guitar amps fail when the amp fell out of the van or off the stage, and I've also seen amps fall over many times without killing a tube. I’ve certainly replaced power tubes that have worn down, yet others were heavily used when I got them and still going strong. Last year I went through my Gates SA-70 rack checking tubes (10). All have been in use at least 20 years. Took a lot of measurements. No worse performance than any NOS tube I tried for comparison. Slightly lower current draw was the only sign of use, and well within spec.
We can talk about the weakest moments for tubes, but the practical reality has to be parsed. Generally I’m more concerned with long term ongoing use, so the frequency dictates the power cycling.
If it’s thunderstorm season, I’m not leaving anything on and unattended, period.
If it’s winter and I have a multi-day block booking, I may leave it on 24/7. But maybe not anything with really expensive tubes. Temper that with warm-up time, will I have a half hour at least for warm up before we start again?
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Post by drbill on Jul 26, 2020 13:43:52 GMT -6
^^^^. Good advice Doug EmRR ! |
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kcatthedog
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Post by kcatthedog on Jul 26, 2020 14:55:10 GMT -6
Tube rule of thumb: at least 30 minute warm up to stabilize ?
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Post by EmRR on Jul 26, 2020 15:10:07 GMT -6
Tube rule of thumb: at least 30 minute warm up to stabilize ? I've never IMAGINED a difference after 30. Something super critical (punch ins) an hour might be better, sometimes gain just barely increases over a longer time until everything gets up to temp, but you also might not notice that either. Usually tube startup noise calms down completely within 5-10 minutes, important with mics. |
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kcatthedog
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Post by kcatthedog on Jul 26, 2020 15:18:02 GMT -6
Thx!
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Post by OtisGreying on Jul 26, 2020 15:33:24 GMT -6
Got it. So I won't power it off unless I know I won't be using it for the next 8-12+ hours. Thx guys
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Post by bluegrassdan on Jul 27, 2020 16:47:33 GMT -6
I suspect a lifespan shortener of tubes is PSU voltages creeping upward with out-of-tolerance resistors, and non-regulated supplies combined with higher wall voltages these days. Just measured mine at 124V at the wall outlet. That's a 12.72% increase from 110v.
Accounting for the wall voltage alone, a 6.3v heater tap would be spitting out 7.1v. A U47 PSU would increase from 105v to 118v. An out-of-spec resistor could increase it quite a bit more.
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Post by EmRR on Jul 27, 2020 17:07:22 GMT -6
I suspect a lifespan shortener of tubes is PSU voltages creeping upward with out-of-tolerance resistors, and non-regulated supplies combined with higher wall voltages these days. Just measured mine at 124V at the wall outlet. That's a 12.72% increase from 110v. Accounting for the wall voltage alone, a 6.3v heater tap would be spitting out 7.1v. A U47 PSU would increase from 105v to 118v. An out-of-spec resistor could increase it quite a bit more. The filament resistor in a U47 is wire wound, so that won't go out of spec, it'll just go open and the mic will go silent. Unless it's been replaced! with who knows what. Though generally carbon resistors go high rather than low if they creep. |
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Post by bluegrassdan on Jul 27, 2020 17:30:04 GMT -6
What about filter caps aging?
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Post by EmRR on Jul 27, 2020 19:28:12 GMT -6
What about filter caps aging? The only way they'll affect voltage is when they short and it goes to zero. |
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Post by Ward on Jul 28, 2020 19:50:27 GMT -6
What about filter caps aging? Oil in paper? |
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