heymisterk Posted January 14, 2012 Share Posted January 14, 2012 Basic, practical question: How long do you/should you leave your tube amp on "Standby" versus just turning the whole amp off? There are times when I will play, then go do something for a half hour or an hour, then come back and play some more. It's times like those that I can't decide what to do. Advice? Jeff Link to comment Share on other sites More sharing options...
surfpup Posted January 14, 2012 Share Posted January 14, 2012 I'm sure someone can explain the tech side better than I can, but I don't think it matters much either way. As I understand it the standby feature allows tubes to build current more slowly before powering up and dissipate current more slowly when powering down, thus increasing tube life. (Someone feel free to correct me here). So as long as you use the standby when powering up and powering off, it won't matter if you power down for those half-hour breaks. Nor will it matter if you just use standby. On the more practical side, I always power off (after a brief standby) for those little half-hour breaks because I know I'm likely to get sidetracked and forget I left the amp on! Link to comment Share on other sites More sharing options...
Twiz Posted January 14, 2012 Share Posted January 14, 2012 I don't think you're hurting anything leaving it on standby for 30 minutes. Maybe wasting electricity a little, but I don't think it will hurt the amp. I usually try to leave my amps on standby for maybe 3-5 minutes before I turn them off. Link to comment Share on other sites More sharing options...
saturn Posted January 14, 2012 Share Posted January 14, 2012 My Carvin tube amp really only gets played at gigs. It's too loud to play in the house. I leave it on Standby during our set breaks. When we're done I usually switch it to Standby while I unplug my cords and cables...about 3-5 minutes then I shut the Power down and unplug it. I try not to move it until just about everything else has been packed up, and even then it's usually still hot! Link to comment Share on other sites More sharing options...
dbreslauer Posted January 14, 2012 Share Posted January 14, 2012 In tube amps, the standby switch physically interrupts the B+ (DC) voltage from the rest of the circuit, between the rectifier and the power filter capacitors: essentially blocking the high voltage DC from the rest of the amp stages. When powering up an amp with standby on, the lower "heater" voltage warms up the tubes, without that high DC voltage also present. And, just a warning I feel compelled to make: Even when the standby is ON, power filter caps can hold a high voltage charge, for a very long time. do not interpret standby ON as DC not present! Actually, don't interpret an unplugged and turned OFF amp as not having a DC Charge for that matter. hope this helps! Don Link to comment Share on other sites More sharing options...
daveinspain Posted January 14, 2012 Share Posted January 14, 2012 Good thread, I always wondered that myself... I have forgotten to turn off my amp a few times and left it on all night. I imagine that's not so good for the amp but i wonder how much it affects tube life... Link to comment Share on other sites More sharing options...
heymisterk Posted January 14, 2012 Author Share Posted January 14, 2012 Okay...I think I get it. Thanks! Link to comment Share on other sites More sharing options...
L5Larry Posted January 14, 2012 Share Posted January 14, 2012 Think about your standby switch on your amp as the gear shifter in your car. It is the difference between "Idle" and "Drive". You wouldn't start your car with the transmission in "Drive", and you wouldn't turn the engine off with it in gear either. You would put it in "Park" or "Neutral" for either of these operations. Same with warm-up. When you start your car you shouldn't just slam in into gear and race off, you let it warm-up a little. If you're driving down the road on the way to the grocery store and realize you forgot your list, you may let it idle in the driveway for the short period of time you're in the house looking for your list, but you wouldn't leave the engine running, even in "Park", for the hour or so you are in the store shopping. Letting your car idle for long periods of time (no load on the engine and transmission), may not put any major wear and tear on your engine, but it does consume energy and adds to the engine use "hours", neither of which is generally a good thing. So......... Treat your guitars like your wife..... and treat your amps like your car, and you will get many miles of pleasure from all of them. Link to comment Share on other sites More sharing options...
KL Posted January 14, 2012 Share Posted January 14, 2012 The standby switch on most amplifiers is not that important really. The advice I got from Dr Z was to put it on standby for a few minutes when switching on, but just turn both the power and standby switch off at the same time when you are finished. If you are playing live you can leave it in standby mode when you are off stage. If you don't use the standby facility it will reduce the life of your tubes but only by a very small amount. Link to comment Share on other sites More sharing options...
charlie brown Posted January 14, 2012 Share Posted January 14, 2012 Well, my Blues Jr. has NO standby switch. So, I just power it up, 5-10 minutes, before (Bar) gig time, and use my tuner, as a "standby" switch during breaks. Works well, and when I power off, after the gig, I let it sit until everything else is packed and/or put away, then put on the cover, and pack it, last. So far, so good! CB Link to comment Share on other sites More sharing options...
Tim Plains Posted January 14, 2012 Share Posted January 14, 2012 I know everyone has their own way of doing things but I don't see how keeping the amp in standby before shutting it off is of any benefit. Even the user's manuals I've read say it doesn't matter. This is from my Tone King's manual. "When turning off the amp, turn both the POWER and STANDBY switches. The order that you turn them off is not important." At home, I let the tubes warm up for a minute or two before I start playing and I'll play at lower volumes for the first few minutes before turning it up. When I play with the guys, I let the tubes warm up for up to 10 minutes. If I plan on using the amp again within 15 - 20 minutes, I leave it in standby. Link to comment Share on other sites More sharing options...
CaptainNemo68 Posted January 14, 2012 Share Posted January 14, 2012 Actually, I seem to remember having an issue one time at a gig where I used stand-by and did not turn the amp completely off between sets. By the last set it seemed like the tubes were so hot it was affecting my sound, causing an overload of saturation and distortion. I believe it only happened once and I don't think I had to change out any tubes. Link to comment Share on other sites More sharing options...
stein Posted January 14, 2012 Share Posted January 14, 2012 There are 2 things at play. Tubes need to be heated to work, and they need to be up to temperature to have the proper characteristics they were designed for. The standby prevents the high voltage signal from entering before the tube has the proper ability to take them. Depending on the amp, it may matter a little or a lot or none at all. But usually, it only takes about 10 seconds initially to heat up the heaters. The other issue overall is heat. Tubes wear because the metal in them breaks down from heat. But the metal also takes a beating being turned on and off, as the metal has to contract and expand every time this happens. It would be impossible to be able to say which causes more or less wear for each tube, because they are all different. But for sure, turning an amp off and on causes more wear then leaving it on for like a half hour. So, in that way standby can be your friend, as a way off turning it "off" without having to let it cool down and heat it up again. Link to comment Share on other sites More sharing options...
ZuWa Posted January 14, 2012 Share Posted January 14, 2012 I leave my '76 JMP MKII on standby for hours sometimes. A major cause of electronic component failure is stress caused to metal parts by them expanding and contracting due to temperature changes. The fewer heating/cooling cycles something like a tube has to experience the better. The same goes for caps, resistors, diodes, etc. Also, different metals expand and contract at different rates and at different temps. So, don't keep turning your tube amp on and off! Someone else mentioned this earlier in the thread: Do not move your tube amp for 10 minutes or longer after turning it off. You want the tubes to cool before subjecting their internals to any shock whatsoever. Also, tube amps with tube rectifiers don't generally need a standby switch. The brief time it takes for the rectifier tube to start doing its thing is enough time for the input and output tubes to safely "turn on" without risk of damage. One more thing: Class A/B output sections draw max current under no signal conditions, so make sure you use your standby switch when not playing if your amp is push/pull. There are also parasitic oscillations that can occur when internal amp parts go bad - your amp will be working hard cranking out sounds you cannot hear. Your amp in both cases would really be working hard even though you wouldn't be hearing anything. Link to comment Share on other sites More sharing options...
bonzoboy Posted January 14, 2012 Share Posted January 14, 2012 I always use the "Standby" mode for at least 5 minutes whether powering up or down and haven't changed the tubes in my 1983 JCM 800 2204 Model since 1997 and my 1984 JCM 800 4210 Model since I bought it used in 1992.Using Standby makes a substantial difference in tube life from what I have found. Link to comment Share on other sites More sharing options...
codename Posted January 14, 2012 Share Posted January 14, 2012 I read somewhere,probably Guitar World magazine, that you should not power off while in standby but can't remember the reason given.I think it was that it is bad for the caps. Link to comment Share on other sites More sharing options...
Rich W Posted January 15, 2012 Share Posted January 15, 2012 I read somewhere,probably Guitar World magazine, that you should not power off while in standby but can't remember the reason given.I think it was that it is bad for the caps. In some (but NOT all) modern amps, if you power off without going into standby, the caps will self-discharge. I've tried this with a couple of my amps and measured across the caps. It works. If you're going to open your amp up to do some service, then leaving her on for awhile and then powering off without standby is the way to go. On the other hand, some amp experts like Dave Hunter (writes good tech articles for Gibson.com) claim that leaving her in standby for a minute or two before powering off may help to prolong output tube life. Link to comment Share on other sites More sharing options...
canon_mutant Posted January 15, 2012 Share Posted January 15, 2012 Mine will stay on all evening sometimes. Got a degenerative joint problem now so can't play as long each time as I used to so I let it warm up in stand by, power it on and play as long as my fingers/wrists can stand it, back to stand by, lather, rinse, and repeat. It is much better on it than to go cold, hot, cold, hot, cold. Link to comment Share on other sites More sharing options...
daveinspain Posted January 15, 2012 Share Posted January 15, 2012 I also use the stand by switch every time I put down the guitar so it doesn't start feeding back and or make noises... Link to comment Share on other sites More sharing options...
djroge1 Posted January 15, 2012 Share Posted January 15, 2012 If I am at a gig I will leave it on standby between sets. If I am at home I will usually turn both off because I may get side tracked before getting back to the amp. If I have just finished building the amp I will leave it turned on with the volume down just to let current run through all the caps/resistors to break them in. As for the standby switch - when I turn off the amp I always turn it to standby first because it drains the electro caps. That way if I have to open her up and play inside the dc voltages are gone. Link to comment Share on other sites More sharing options...
ZuWa Posted January 15, 2012 Share Posted January 15, 2012 WOW - this is interesting. There are two opposite comments in this thread, one says to turn it off first to drain the filter caps, the other says to put it in standby first to drain the caps. I always put mine into standby first, wait a bit, then flip it off, but it's interesting to read how and why other folks do what they do. Link to comment Share on other sites More sharing options...
djroge1 Posted January 15, 2012 Share Posted January 15, 2012 WOW - this is interesting. There are two opposite comments in this thread, one says to turn it off first to drain the filter caps, the other says to put it in standby first to drain the caps. If you are only an end user - you only use the amp and never do repairs or builds then go ahead and turn both off at the same time as it really doesn't matter. However, just turning the power off on the amp does not dissipate the electricity stored in the electrolytic caps; well actually they do drain just very very very slowly and it could take days for the electricity to drain. Link to comment Share on other sites More sharing options...
L5Larry Posted January 15, 2012 Share Posted January 15, 2012 As for the standby switch - when I turn off the amp I always turn it to standby first because it drains the electro caps. That way if I have to open her up and play inside the dc voltages are gone. This is REALLY good information, and probably why I've never been ZAPPED while digging around inside tube amps! Anyone who has an inkling to stick their hands inside their amp chassis TAKE NOTE! Link to comment Share on other sites More sharing options...
ZuWa Posted January 15, 2012 Share Posted January 15, 2012 If you're going to open your amp up to do some service, then leaving her on for awhile and then powering off without standby is the way to go. As for the standby switch - when I turn off the amp I always turn it to standby first because it drains the electro caps. That way if I have to open her up and play inside the dc voltages are gone. I only bring this up because it's a safety issue and the two posts state opposite things. The only way I know of to thoroughly discharge your filter caps is to ground them to the chassis. You can ground pin 1 of a 12AX7 preamp tube or ground the "+" side of the filter caps to ground through a wire, preferably with a resistor in series (10k to 20k or so) to slow the rapid discharge down and prevent any loud pops or cracks. I don't believe the order you flip the on/off or standby switches drains the filter caps. Be careful out there! Link to comment Share on other sites More sharing options...
djroge1 Posted January 15, 2012 Share Posted January 15, 2012 I only bring this up because it's a safety issue and the two posts state opposite things. The only way I know of to thoroughly discharge your filter caps is to ground them to the chassis. You can ground pin 1 of a 12AX7 preamp tube or ground the "+" side of the filter caps to ground through a wire, preferably with a resistor in series (10k to 20k or so) to slow the rapid discharge down and prevent any loud pops or cracks. I don't believe the order you flip the on/off or standby switches drains the filter caps. Be careful out there! Try it out and see what happens. 1. Turn the amp on in play mode. 2. Turn both play/standby off. 3. Measure one of the electro caps. You will see the volts drain. This tells us that there is a charge and the rate at which the multimeter is draining the caps. Next: 1. Turn the amp on in play mode. 2. Place the amp in Standby mode for a minute. 3. Power off the amp completely. 4. Measure one of the electro caps. Post the results. I didn't completely believe what I was reading in Dave Funks Tube Amp Workbook Vol. 1. So I put it to the test. Link to comment Share on other sites More sharing options...
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