Leaving tubes hot for extended periods?

spl84

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Just curious if it hurts preamp tubes to leave tubes on for like 24+hours? I'm asking this with regard to a Project tube box s2 phono preamp. Twice now I have forgotten to turn off the preamp and left the tubes hot for 24 hours. No music was playing but the unit was powered on and generating alot of heat(as it does) I'm not sure why they didn't include some sort of auto off feature or at least a standby mode like tube driven guitar amps. Anyways, did I ruin them or damage them? From now on I will put some kind of reminder for me to remember to switch it off but do I need to order new tubes?
 

Revolutions

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You can do lots of damage like that. If nothing is wrong, don’t fret about it. Just try not to do it regularly.

Standby on a guitar amp will still wear out the tubes, so not a total solution there either.
 

Vincent Kars

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Project tube box s2 phono preamp.
A little bit of Google will tell you that the lifespan of a tube in a pre-amp is about 10.000 hours. By leaving it on for 24 hours, you now have 9976 hours left....

 
Just curious if it hurts preamp tubes to leave tubes on for like 24+hours? I'm asking this with regard to a Project tube box s2 phono preamp. Twice now I have forgotten to turn off the preamp and left the tubes hot for 24 hours. No music was playing but the unit was powered on and generating alot of heat(as it does) I'm not sure why they didn't include some sort of auto off feature or at least a standby mode like tube driven guitar amps. Anyways, did I ruin them or damage them? From now on I will put some kind of reminder for me to remember to switch it off but do I need to order new tubes?
In that use, I’d have thought it’s no different to leaving a light bulb on. It’s a waste of electricity and will eat into its total lifespan, but no harm should arise.

You could maybe use a simple plug-in time switch, as it’s a low current item. I’d not be so keen if it were a power amp, but for a few watts it’ll save you forgetting.

Does the handbook carry any relevant cautions or advice? A call to Henley the importers might be worth trying.
 
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My2Cents

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The tubes in a low voltage device such as the PT S2 are no more than 'window dressing'. They run a plate voltage of 18V DC. To get any tone from an ECC83/12AX7 they would need to be powered at around 100- 300 volts (which is common when used in guitar amps and high end hi-fi amps).
The tone from the S2 is actually coming from the IC's quad Op Amps.
You are unlikely to do any damage to the tubes by leaving the unit on for long periods of time due to the extremely low voltage.
It has a standby switch, but doesn't appear to be automatic.
So no, you don't need to replace them (12AX7's are pretty cheap anyway at around 20 bucks for a JJ or Electro Harmonix).
You could probably pull them out and notice no difference in sound.
 
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spl84

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The tubes in a low voltage device such as the PT S2 are no more than 'window dressing'. They run a plate voltage of 18V DC. To get any tone from an ECC83/12AX7 they would need to be powered at around 100- 300 volts (which is common when used in guitar amps and high end hi-fi amps).
The tone from the S2 is actually coming from the IC's quad Op Amps.
You are unlikely to do any damage to the tubes by leaving the unit on for long periods of time due to the extremely low voltage.
It has a standby switch, but doesn't appear to be automatic.
So no, you don't need to replace them (12AX7's are pretty cheap anyway at around 20 bucks for a JJ or Electro Harmonix).
You could probably pull them out and notice no difference in sound.
So basically what you're saying is that there's no point spending money on high end tubes for such a device?
 

My2Cents

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I wasn't referring to phono pre amps. I think they all use some kind of DC/DC boost module, usually ups the voltage to around 40. This may be enough to make the tube work but most of the amplification of the signal is being done by transistors as a 12AX7 can only increase the signal by x100 and a phono pre has to increase the signal more like x1000.
Like I said, it's mostly window dressing, but to some ears it may add a little warmth. IMHO the Cons outweight the Pros. The only 'Pro' is perhaps a slight increase in warmth, everything else is a negative (when to switch it on and off, not knowing if the tube is still good etc.) Turning it on and off frequently is not good fot the tube and the tube needs to be heated for 10 - 15 minutes to get the best from it. And leaving it on too long compromises the life of the tube! What a hassle. A high end solid state pre seems to be a much simpler option... and it will always sound the same.
 
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