I ordered a matched pair of Psvane 6sn7 gain tubes for my diy preamp. Told to expect 40-60 hours for break in. What's the easiest & quickest way to do this without playing the full system for a couple of days? Like: I run the tuner through the pre for 8 or 10 hours at a time with the amp turned off. If so, should the volume knobs be up? Or something else?
Thanks
Thanks
I just put new tubes in and listen as I always do. I haven't noticed much burn in with indirect heated tubes like yours, in the case of DHTs there may be some stabilization of parameters over the first couple of dozen hours.
There may be some shift in operating point during warm up but this occurs every single time you turn the equipment on.
I think the tube, and wire burn in thing is mostly audiophile mythology with the exception noted above.
There may be some shift in operating point during warm up but this occurs every single time you turn the equipment on.
I think the tube, and wire burn in thing is mostly audiophile mythology with the exception noted above.
funny but the tube manufacturers of old never mentioned tube burning in that i know of,
Kevin, do you know of any RCA publication that mentioned this?
i built two 2A3 set amps and they sounded just fine right after construction and testing...
Kevin, do you know of any RCA publication that mentioned this?
i built two 2A3 set amps and they sounded just fine right after construction and testing...
I have found some NOS tubes to be noisy and hum, which usually goes away after some hours of use. Just use them as normal...
That's because the manufactures did it for you. Everything made was burned in at the factory as standard practice before quality testing and shipment. But with today's questionable quality control who knows how much burn in they get other then the bare minimum to make then function. I've always believed this "burning in" was really a matter of burning in your brain to accept the supposed or imagined new sound. And this goes triple for passive parts. Unfortunately I know people in our New Jersey Audio Society that think even fuses need burning in. 🙄
i for one like that 1/2 second of "real loud" just when a fuse is done "burning in"! 
aren't tubes just a long protracted burn in period...isn't that what thermionic emission is? 😎
aren't tubes just a long protracted burn in period...isn't that what thermionic emission is? 😎
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Do we have any solid evidence of this? It's an oft-heard statement, and I've always accepted it at face value, but I can't say I've ever seen or heard any objective evidence that this is true. Nor am I entirely sure that the current manufacturers partially or totally skip this step..
That said, there's a tube vendor who I've known & worked with for years. He has some interesting insights on burn-in, and I dare say his knowledge is reflected in the quality of his work.
One thing that is clear, though, is that +gas+ is an issue, particularly with old-stock tubes, used and new. Giving them time to 'burn off' the gas can have a significant effect on noise, Gm and DC operating points - the latter, particularly, in the case of power tubes.
Oh I don't doubt there's a whole lot of that kind of thing involved - the whole spectrum of human beliefs & biases.
tube cathode deteriorate with time, each time you power a tube up, it dies a little
until such a time its transconductance has degenerated rendering tubes useless...
this the reason why sockets are used, they are meant to be replaced...
so this is a very good advice...
until such a time its transconductance has degenerated rendering tubes useless...
this the reason why sockets are used, they are meant to be replaced...
so this is a very good advice...
NOS valves which have sat on a shelf unused for 50 years may need a few hours to settle down: get gas out of the metal and into the getter. They don't care whether there is any signal present, just heater and anode current.
Modern valves: who knows? They may have a poor vacuum or dirty metal surfaces so could get better or worse in the first few hours use.
Some degree of 'burn-in' necessarily takes place at the factory as the cathode surface is activated by severely overrunning the heater for a while.
40-60 hours burn-in is more likely to be your ears getting used to the slightly changed sound caused by sample variations from the previous valves.
Modern valves: who knows? They may have a poor vacuum or dirty metal surfaces so could get better or worse in the first few hours use.
Some degree of 'burn-in' necessarily takes place at the factory as the cathode surface is activated by severely overrunning the heater for a while.
40-60 hours burn-in is more likely to be your ears getting used to the slightly changed sound caused by sample variations from the previous valves.
my experience with NOS tubes, if they are no good, they are no good,
right at the start, so i just toss them....
right at the start, so i just toss them....
Depending on the type of tube it takes around four hours for the cathode emission to stabilise. After that you can test for "matched pairs".
One simple way to switch on and let them heat up.... than switch off and let them cold down. Than repeat this several times (at minimum 10..20 times).
For this purpose I purchased my KT120 at Cryoset Online Store where the treatment is done. I noticed on the KT120 a much lower idle noise current. Just my experiences...
Or simple read there about "Cryoset Deep Cryogenic Treatment"
Hp
Nope, and that's because as previously pointed out this was done as part of QC. There are papers RCA published about tube life and parametric stability as part of the process of improving reliability in the early 1920s. I have them somewhere and if I can find them I'll share.
I see some measurable parametric shifts with modern DHTs in the first hours of use, both with inexpensive 300Bs, GM70s and a few other types.
Edit: Something to note is that almost all of my designs use fixed bias, I suspect these shifts would be obscured to some extent in applications with cathode bias.
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