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Old 12th January 2009, 09:29 PM   #1
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Default Tube Care for Prolonged Life

I was wondering if anyone had tips for a beginner to try to get the longest life possible out of my tubes. My S-5 kit uses 5670 and 6005 tubes, and I'm just wondering what the best way is to get the longest life out of my tubes.

I know keeping them well ventilated is important, but how long could I expect these tubes to last? At least a few thousand hours is reasonable right?

In terms of turning the system on and off, is it a bad idea to start putting a signal through them before they've completely warmed up? Should I be careful about turning it on and off frequently?

What about cleaning contacts and things?

Any advice about good tube care would be wonderful, thanks in advance.
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Old 13th January 2009, 01:18 AM   #2
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The voltage and thermal cycling probably puts a bit of stress on the tubes, especially at power up. A soft start circuit, or a CL90/CL110 thermistor may help ease things up to operation.

Otherwise lifespan depends on how often and how long you use the amp.

Vibration could be a factor, but that's probably more an issue with guitar amps like the Ampeg SVT-VR and not little HiFi amps.

When you can pick up a sleeve of 6005/6aq5's for about ten USD, I would just stock up on tubes and forget about lifespan.
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Old 13th January 2009, 02:38 AM   #3
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Most pertinent param I have found (given that we're not flogging the device in guitar-type service) is heater voltage.  I saw a test performed statistically by GE back in the day that showed that running a 6.3v tube at 6.5 or so volts shortened the average lifetime by, like, 30-40%, while operating the heaters at 6.1-6.2v gave a statistical 200% lifetime in large test samples.

I operate all my heaters at the 6.1-6.2v level, and (aside from a very rare catastrophic failure) am getting 30,000-40,000 hours from outputs and essentially indefinite lifetime from small-signal devices (I have never, in hundreds of thousands of hours of operation, had one 'wear out').  This in hi-fi use.

One geek's data point.

Aloha,

Poinz
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Old 13th January 2009, 02:43 AM   #4
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Default Heater voltages

The biggest killer of tubes can be too much heater voltage and or inrush current.
If a tube typically requires 6.3V, I give em 6 volts instead.. if you use ac for heaters you can place a small value high wattage (I use at least 20W) say .1 or .15r on each leg of the heater to trim voltage and in turn limit inrush current. Ventilation is good too.. I have small fans running off say a 6.3 volt tapping of tranny rectified with some capacitance.. a 12v dc fan will run at 7.5 V in this setup and if it is small wont make much noise at all.. I do this for the internals of my amps to keep resistors/caps cool.
Heat is thine enemy... Understand it, embrase it and then conquer it!!!!
or like whitelabrat says ignore it all and buy a boatload of tubes to stockpile!!!
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Old 13th January 2009, 05:24 AM   #5
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Running tubes close to their maximum cathode current will shorten their lives. If there's a choice between high voltage and low current or low voltage and high current, I'd go for the former.
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Old 13th January 2009, 12:41 PM   #6
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Quote:
In terms of turning the system on and off, is it a bad idea to start putting a signal through them before they've completely warmed up? Should I be careful about turning it on and off frequently?
Yes, give them a minute to warm up before you start hammering on them. Dont turn them on and off a lot, Id leave it on unless its going to sit idle more than say an hour.

Line voltage can be an issue for some users. This is especially the case if your sitting at the end of a long lightly loaded transmission line (rural).

Quote:
What about cleaning contacts and things?
Cleanliness is good, but beware of pulling the tubes a lot, strain on tubes and sockets.
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