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Valve heads


Kevin Dean
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Generally I leave my Trace Elliot V6...at home!

Seriously, after finishing a gig, I would ideally put the amp on standby for a minute before switching it off. Then ideally wait a couple of minutes more before moving it. Get your bass put away, cables put away. If you still have time to spare offer to help the drummer. Then finally move your own (hopefully cooled down valve amp head) off the stage.

 

The reason I leave my V6 at home is with multiband gigs there is often a quick changeover so I might need to move my amp almost immediately after I play or I potentially have to let every bassist on the bill use the amp. Generally, if something goes wrong it will be incredibly expensive to fix (6 power amp tubes). Just not worth it. 

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As @thodrik has said, I used to put mine on standby as I finished the last number.  Walk away off stage or off to the side for a few minutes, go back and power it down but leave it to be the last thing that I moved after all of my other gear was shifted.  If we were the only band on I would even load all of my gear into the car and lifted the head off my cab last thing... I've even been known to have the amp head sitting on the floor to the side of the cabs; I read somewhere that it could 'potentially' prolong valve/amp life if it wasn't sitting on top of a cab which is vibrating for the whole of your gig.  That was never a serious worry but if I thought it was a rough gig I'd sooner not have it up on high.

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Never used a valve bass head, but I owned & used a number of guitar valve amps over the years.

 

As BassmanPaul said, turn it off, move it off stage, load it into the car when you're ready to go. They really aren't as fragile as you might think.

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The valve amp I've got has no fans and a row of six EL34s quite close up to the back grille, so when I pick it up by the top handles with the back facing me (it balances best that way) it ends up at zipper-height and the whole experience is a bit 'Kings of Leon' if I've not let it cool down first. I tend to point my floor fan at the back of it while I'm packing other things away, which speeds the process up acceptably.

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1 hour ago, la bam said:

If you put (the valve amps I've had) it in stand by at the end of the night, it keeps the fans on to assist and speed up the cooling process before switching off and moving.

 

I was under the impression that "Stand By" kept the valve heaters on, which kind of defeats the object. However I've never owned a valve amp with fans.

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There really are  lot of myths surrounding tube amps. Their fragility is one.   Them needing to be cooled to cold before being moved is another. Reasonable care in handling, as befits any quality piece of gear, is all they require. Leaving the amp on Standby. does cool the tubes but not as much as just turning the amp off.

Edited by BassmanPaul
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13 hours ago, la bam said:

If you put (the valve amps I've had) it in stand by at the end of the night, it keeps the fans on to assist and speed up the cooling process before switching off and moving.

Doubtful. Standby is there for the purpose of activating the heater circuits of the valves so they are already hot when the preamp juice hits and the magic happens.

 

I reckon the valves would be a fair bit more cooled down if you turned it off after a minute of fan cooling down from war volume and then the natural convection minus further heating.

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1 hour ago, Downunderwonder said:

 

I reckon the valves would be a fair bit more cooled down if you turned it off after a minute of fan cooling down from war volume and then the natural convection minus further heating.

 

Exactly what I was saying. Dont just turn it straight off, leave it for a minute or two in stand by, then turn off.

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Once you know you have finished playing, I'm not aware of any benefit to putting a valve amp into standby before switching it off. Switching off the mains while in playing mode (i.e. not in standby) does the amp no harm, it just means that the filter caps discharge through the valves as they continue to conduct for a few seconds.

Edited by JapanAxe
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I think the OP may refer to the idea that valve elements are more fragile when at their working temperatures. I simply don't know whether or not that is the case.

 

My amp (valve or otherwise) tends to be one of the last things that I pack away, mainly because I like to get my instruments out of harm's way first, then clear the floor of trip hazards!

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16 hours ago, BassmanPaul said:

Leaving a tube amp on standby with heaters on but no B+ can lead to 'cathode stripping which damages the tubes. :(

That actually causes a different problem but I can’t remember what it is. Cathode stripping in guitar amps is a myth that has been propagated since at least the dawn of the Internet.

 

EDIT: I looked this up and when a cathode is heated but no anode current flows for a long period of time (several hours?), a high-resistance chemical layer can grow between the cathode and its oxide coating. This is known as cathode poisoning.

 

Incidentally, 2 of my 3 gigging valve guitar amps have no standby. The first thing I do when I walk on stage is switch on the amp's power, and by the time I have checked my tuning and pedal settings it is ready to play.

Edited by JapanAxe
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I may well have used the incorrect terminology. it was in the Sixties that I went to school and learned about tubes. The result is basically the same: the tube gets progressively damaged.

 

There ARE a lot of myths, as I said earlier, concerning tube amps. On standby switches, the general consensus appears to be  to use them as little as possible. Some folks even suggest not using them at all.

 

When I'm using an amplifier that has a standby switch I turn the amp on while I put my bass on and then turn the Standby on. Essentially using it as an 'instant on.'

EDIT: Between sets I turn the amp completely off.

 

As regards moving a warm amp, the folks at the NTSB when probing a plane crash look to see if the filament of a lamp is broken. If it is then the lamp was NOT illuminated. If it's in one piece then it WAS illuminated at the time of the crash.  Off topic I know but it does illustrate a point.

 

Edited by BassmanPaul
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More importantly when bringing any electronics into a warm room from a cold outside is to let the electronics get close to room temperature before switching on. Condensation can form on cold components potentially causing electrical shorts.

Edited by Sparky Mark
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