Rookie tube mistake

[The Dude]

So I went into my media room were I have my 2 channel setup in, you know the one I never listen to. Well couple reason I don't listen to it, is one the room is a mess and needs to be recognized, 2 the pre amp doesn't have a phono input, 3 my power amp needs serviced which I discovered last time I wen to listen to music. The mistake you may ask, well I turned on the pre to let it warm up, and when I turned on the power amp I herd a hum so I shut the power amp off. Now thinking I just fired up this tubed pre amp and don't want to turn it on turn it off kind of thing. So I walk a way and forget about, which I know isn't safe luckily these tubes don't generate that much heat so *** wasn't to warm over there. But know you ask how long, well that's the question I really don't know, I would say at least a month but I know I have had it on and off after the 4th of July so no more then 2 months OUCH.

I don't know what kind of damage was done and won't until I have the cash to take the power amp in for service, at which time I was going to have the pre amp looked at.

[Guest " "]

if you have solid state rectified power supply in the pre amp....leaving it on for an extended times is not a big deal if it is in normal working order....the pre tubes last 5 times longer than the power amp output tubes. If you have tube rectified power supply....leaving it on keeps the clock ticking on remaining useful hours on the rectifier tube.

[JBryan]

1-2 months..impressive!. Its OK...you should be fine since most preamp tubes don't operate under much strain. I know friends that keep their preamps powered up for days at a time and back in the day, the military kept their gear running 24/7 - of course, they had plenty of replacement tubes on hand...still do. I generally keep my tube gear powered only while I'm listening but I have walked off and left the preamp on over the weekend on occasion without damaging the tubes. I have a Scott 222c that I picked up from a gent who bought it back in 1961, used it sparingly for the next 35 years and had left it unused and collecting dust in the cabinet for over 15 years when he sold it to me. In my excitement, I foolishly plugged it in and turned it on...and it worked (WHEW!). I used it daily for the next 10 years and every so often I'd leave it on overnight or the weekend and to my relief, it always seemed to soldier on. Then one morning, I turned it on and was treated to an amazing light show from the rectifier. Rather than just replacing the 5AR4, I sent it off to Terry DeWick for repairs and a check up - I figured it was time. Aside form the bad solenoid cap in the power supply (the culprit) and now defunct rectifier, Terry said it was operating within spec. I had him upgrade some caps and replace the 7189 power tubes (one was at 40%, the others were above 80%) with EL-84Ms and its been working like a charm ever since.

I would be a bit wary and pay close attention when you fire up the preamp next as that tends to be the most likely time for tubes to fail - especially the rectifier. Have fun.

[sunnysal]

I think your worst case scenario is that you have used up some of the useful life of the tubes, in tube preamps the useful life can be arguably decades. I would not anticipate any damage done by leaving the preamp on for a long period per se. Since we don´t know make and model of preamp and amp, nor type of tubes it is hard to give a more specific opinion. do have a set of replacement tubes on hand just in case, which is a good policy anyway for tube amp owners. let us know what happens the next time you fire it up (forgive the pun!) and listen. regards, tony

[The Dude]

Thanks for the reinsurance that everything will be ok. For the record, the pre amp is a Tubes4hifi sp6. It uses two 12ax7s for pre, and I think 12x4 for the rectifier.