best tube source as far as burn in?

[iknowjohnny]

I normally buy from tube depot, but since changing my cathode biased amp to fixed i'm noticing the tubes i've gotten there have drifted a lot even those i've used very little. My favs, the EH EL34's have drifted to 10 MA apart, and yes, i swapped sockets and the readings followed the tubes. So i assume they don't burn them in. Who does and reliably?

[jelle]

Lord Valve (NBS Electronics) burns them in and tests for mechanical stability while at working temperature and voltage.

[iknowjohnny]

Thats great and all, but i went to his site and theres nothing there about buying tubes or prices...nothing ! Theres just a phone # which is not very convenient, especially from my home phone which cannot dial out of state. Anyone else?

[jjman]

The Lord does work in mysterious ways. If I wanted new tubes with the most assurance of burn in I would buy them from him. Mostly since he's been advocating for that service for many years. All sets I bought from him were truly matched and didn't drift.

[selloutrr]

you can buy winged C's pre burned in at tubesandmore.com

try eurotubes they may offer that service aswell.

[David Root]

To get Lord Valve's catalogs, pull up his e-mail link and put SPAM ME in the subject line and hit send. He will e-mail you his lists and prices.

[iknowjohnny]

Yeah i did that already. haven't got it yet, but anyone know what the EH 34's run per pair at LV?

[Tinkerer]

Try this place:
http://www.dougstubes.com/
Doug is very good with both price and service. I have no hesitation in buying from him, and I live in Australia!
Have a read in his 'services' section to see what he does with tubes prior to selling.

Tinkerer

[iknowjohnny]

Ahhh, yes ! i forgot about doug's tubes. Thanks !

EDIT: geez, another weird site ! how do you even see the tubes he sells?! Well, shite....guess it's back to tubedepot for a pair that will drift to 10 Ma apart.

[vibratoking]

I asked the Lord to SPAM ME 3 times in the past 3 months. Nothing, nada...So I agree, the Lord does work in mysterious ways. The only thing that is not a mystery is that I won't give my money to a guy that can't even be bothered to send me his price list. Joker in my book.

[Structo]

Yeah, I never have gotten anything from him.
Is his business still in operation?

[krash]

had a friend who had an amp in his shop for like 1-2 YEARS with basically no update on progress or anything. he did get the amp back eventually, but dude, this is even worse than my turn around!

[selloutrr]

Buy a maxiburn and burn your tubes in yourself! Just buy your tubes in bulk and a maximatcher so you can match them after they drift

[Phil_S]

IMO, you're just poking fun, but the real truth is that you can match tubes in fixed bias amp without much effort. If you want to match just for mA draw, you get that when you bias the tubes. If you want to match for transconductance. you'll need to make sure you can get enough voltage range on the grid bias circuit so you can get a couple of decent readings that are far enough apart to give you a decent calculation.

It is probably true that a matching rig will hold bias voltage constant and vary plate voltage to obtain a transconductance number. But the calculation will work either way. The main thing is to get the numbers at appropriate, real life, operating voltages.

As I understand it, transconductance tells you/us the expected rate of change in bias over a range of operating conditions. IOW, do they stay matched as you drive them harder?

You wouldn't want to match 100 tubes this way, but it should work fine to pick a pair from a smaller batch, maybe 10-12 tubes.

There is also a school of thought that says some mismatch is not only OK bue a good thing in a guitar amp. I don't know one way or the other on this point, but I've heard decent tone from tubes that aren't matched.

When all is said and done, if you want match pairs, quads, whatever, pay the piper and buy them from someone who will not only do the dirty work, but stand behind it.

I've exchanged comments with Lord Valve over at alt.guitar.amps, where he spends a lot of time expounding on his view of national and world politics. The group is not moderated and you can read it on Google if you don't have a news server. He seems to have a grip on tubes, but isn't the only one out there. Doug is a new listing for me. Over at 18watt.com, they seem to like "the Sarge" Terry Kilgore. I've done business with Jim McShane/Citation Amps (just Google for him). There's also Mike at KCA, whose name I run across sometimes. There's no shortage of people who know tubes. Life is short. Pick someone and see if they live up to your expectations. If not, move on.

[krash]

There is also a school of thought that says some mismatch is not only OK bue a good thing in a guitar amp.

That's my alma mater!

You only get 2nd order distortion component if the tubes are mismatched or there is some other reason to get asymmetric clipping. There are many ways to achieve asymmetric clipping but imbalance of tubes will do it.