[sdgserv]

I have been reading many threads on this forum about tubes. Can't seem to find the answer.
I have a Dared VP 16 and a Mad Ear Hd and have been doing a bit of tube rolling.
I was just wondering how long to stick with a tube before giving up on it.

 

[Cool_Torpedo]

IMHO 50 hours. That's the point where most tubes get their working point stabilized. After that what they do is ageing and losing performance. Of course you might like better the sound of an aged tube, but that's more than what I'd consider burn-in.
If you're swapping tubes on a quite new amp, you can hear the burn-in time of other components which take longer to be fully burnt-in like capacitors or even trannies. Some caps need up to 400 hours to get fully burn-in. So my advice is not to swap tubes -specially if they're expensive NOS ones- on a newish amp, unless you want to get wrong conclussions. Keep the stock tubes until the unit is at least 500 hours old, then start swapping tubes.

Rgrds

 

[sdgserv]

Thank you..I have had both amps for almost a year, but I understand about changing parts to soon.
If I keep the amp on with the new tubes for about 3 days with music playing..but with very low volume so I can't hear until I am ready to evaluate. Would this be away to go?. (that was a bad sentence structure)

 

[Cool_Torpedo]

Quote:

Originally Posted by sdgserv /img/forum/go_quote.gif Thank you..I have had both amps for almost a year, but I understand about changing parts to soon. If I keep the amp on with the new tubes for about 3 days with music playing..but with very low volume so I can't hear until I am ready to evaluate. Would this be away to go?. (that was a bad sentence structure)

If the amp is a pure class A design, it would "cook" the tubes even without a signal passing throughout the output tubes, so using a low volume will work very fine. At least this was what an amplifier maker told me.

If it's a class AB or B design, then some signal is needed and it'd be better that the volume were set at normal listening levels, though low volume can work too, however burn-in time could be a bit longer.

In any case three days, it is 72 hours, of continuous use using a signal to make the amp work, should be more than enough to have the tubes at their optimum and stable working point. You could expect them to last at it for several hundred hours if they're big power tubes, or even thousands if they're small signal ones of the double-triode kind.

Rgrds

 

[Uncle Erik]

Quote:

Originally Posted by sdgserv /img/forum/go_quote.gif Thank you..I have had both amps for almost a year, but I understand about changing parts to soon. If I keep the amp on with the new tubes for about 3 days with music playing..but with very low volume so I can't hear until I am ready to evaluate. Would this be away to go?. (that was a bad sentence structure)

It's generally not a good idea to leave an amp on for three days. They get awfully hot and do fail. When they fail, fire is a possibility.

Even if not, when it gets hot and doesn't cool off, that's when transformers could melt and short part of the winding, electrolytics fail, and similar.

I don't think burn-in is worth the risk. There's some change in burn-in, but I think it's become way too overblown here. You can listen to brand new gear and thoroughly enjoy it without having to run it for hundreds of hours first. That's just ridiculous.

I'm not arguing that it doesn't happen, but I am saying that it's not worth it, especially considering the risks.

 

[sdgserv]

Ok..I am new to tubes and their needs. Although I have had a couple amps I have never done anything to them.
This what I have done..My Dared VP 16 came with Chinese tubes. They sounded fine until someone said "hey try these tubes" so I bought 4 matched Electro-Harmonix 6V6GT and 2 tung-sol 6SL7. I have not dropped them in yet, just wanted to ge some info

 

[Cool_Torpedo]

Quote:

Originally Posted by Uncle Erik /img/forum/go_quote.gif It's generally not a good idea to leave an amp on for three days. They get awfully hot and do fail. When they fail, fire is a possibility. Even if not, when it gets hot and doesn't cool off, that's when transformers could melt and short part of the winding, electrolytics fail, and similar. I don't think burn-in is worth the risk. There's some change in burn-in, but I think it's become way too overblown here. You can listen to brand new gear and thoroughly enjoy it without having to run it for hundreds of hours first. That's just ridiculous. I'm not arguing that it doesn't happen, but I am saying that it's not worth it, especially considering the risks.

Hi Unle Erik,

Not to start a comfrontation, but just to clarify to avoid panic. If a tube amp is properly built, and I'm speaking of big tube amps to drive speakers delivering 30wpc and more, there's no problem leaving it on 3 days or a week for that matter. Sometimes I've left my power amps -for speakers- on for a couple of days without the slightest hint of a problem. Not a bit hotter than when being used for a couple of hours.

Regarding small amps for headphones, things are even less dangerous since the small double triodes usually mounted in them don't get a fraction of the dissipated heat of the big EL34, 6550, KT88, etc based amps. Some manufacturers of tube preamps and phono units recommend leaving them always on, provided they use 12AX7, 12AT7... which don't generate much heat and have expectable lives over 7-8000 hours. Some units, like X-Cans V2, not even have an on-off switch, they expect you to leave it always on, and that unit is specially not suitable for that since the tubes are really enclosed into they metal cylinder and has no vent holes.

OTOH I mostly agree with you, there's no need to hurry up things, one can learn a lot just listening how sound changes with burn-in, and obviously any device will suffer more stress if left always, or more time than needed, on. No need to age tubes and caps if not enjoying of their useful life.

Rgrds

 

[sacd lover]

Quote:

Originally Posted by Uncle Erik /img/forum/go_quote.gif I don't think burn-in is worth the risk. There's some change in burn-in, but I think it's become way too overblown here. You can listen to brand new gear and thoroughly enjoy it without having to run it for hundreds of hours first. That's just ridiculous.

X2

Burn in IS so ridiculously overdone here. I use tubes constantly in eleven headamps and one integrated amp, around 35 or so different types; not to mention the different brands. With most, if not all new tubes, I hear a slight glare that disappears after just a few hours along with a small increase in dimensionality. After that initial startup, I dont think I could tell the new tube with a few hours use from an identical tube with hundreds of hours use.

 

[tomb]

Well in DIY, we often bias our own tubes. Because of that, the "burn-in" is measurable. However, it's not burn-in in the sense that's its discussed around here, so I agree with Uncle Erik in principle.

What happens is that NOS tubes have gas infiltration that occurs from sitting unused on the shelf over the last 40-50 years. Sometimes it takes several days for the getter to catalyze all of those gas molecules. The bias will change and must be re-adjusted constantly while that's occurring.

New tubes - similarly, the heaters undergo some break-in as they are heated up and cooled down - expansion/contraction, iow. The consistency of the heaters/cathodes and how they release electrons to the plates determines the performance of the tube.

I would number that in days, too -perhaps a week in extreme cases. However, the cool-down is just as important as running at temperature. So, leaving it on constantly is not going to be optimum. Use it, listen and enjoy it. When you're not doing that, turn it off.

 

[sdgserv]

All of you know a heck of a lot more than me..I am going to drop them in and play normally. I will see what changes..

 

[zipdisk]

Quote:

Originally Posted by sdgserv /img/forum/go_quote.gif ...I am going to drop them in and play normally. I will see what changes..

That's a good idea. Then you can see for yourself whether tubes change, to what extent they change, and over how long a period change takes place.

 

[jamato8]

I find that for most tubes a few hours with some requiring around 25 hours of use to settle. I am listening to some 6DE7's right now that sounded ok but took more hours to settle in than normal but like noted above, often a few hours is all that is needed. They hit their peak, plateau and then spiral into a long slow death, but hey, don't we all? :^)

 

[sdgserv]

When they die will they see a bright light?

 

[jamato8]

Sometimes but don't let them go towards it. It's hard though because they are hot to follow it. Some just whimper and wine, hiss and growl, not a pleasant thing at all but in the end there is no return and down the road to the promised land, the land fill, they go. Oh sorry, were we talking about people or tubes? Pretty much the same though.

 

[sdgserv]

OMG... Humor at Head-Fi .. You know they are going to come for us at night with pitch forks and torches. Haa!

I actually did get to see a tube die, quite the light show