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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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In Reply to: Tubes - on or off? posted by w9ls on March 11, 2007 at 01:11:50:
...you will be buying new tubes and replacing them more frequently. Their life is measured in hours just like a lite bulb. You should investigate a circuit mod that will allow you to turn off the B+ high voltage but leave the heater on at a slightly reduced voltage and some way of bringing them back up slowly. The thing that burns them out is fast start up and the sudden temp increase especially if one of the filaments is acting as a current limiter and glows very brite on turn on. The heater-filament should come on first then the B+ is applied. When turning off the B+ is turned off first then the filament is either left on or turned off. This was done in heavy industrial transmitters and the government also used this practice in the tube days. Also DC offsets occur on turn on until the circuit stabalizes, so your preamps should be turned on first, wait about 30 seconds, followed by the next preamp or equalizer (if you have one), wait another 30 seconds, followed by the power amp. Otherwise, if your solid state power amp is on all the time and you turn on a preamp a DC offset voltage from your preamp could destroy your speakers. The cones could go all the way forward or all the way back and stay there, the voice coils welded shut! There are relay soft start mods avaliable.
"I take you as you are
And make of you what I will,
Skunk-bear, carcajou, bloodthirsty
Non-survivor.
Lord, let me die but not die out." THE LAST WOLVERINE by James Dickey
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Follow Ups
- If you're serious about leaving tubes on all the time.... - grhughes 07:27:12 03/11/07 (0)
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