Vacuum tube ! And Warnings

I would never buy tubes off eBay. That was the first mistake.  

I've bought all kinds of Valves from eBay. A good visual, and a way to check is the only way a valve goes in my units, ANYWAY. I don't care who sold it... It has to get to you somehow, THAT alone is a reason to check it.. Normally, no problem, but there is that 20 foot slide across the the UPS, FEDX, USPS, trailer floor, into the brake lining being transported on the same trailer.. That's also had lawnmowers, condoms, and laddies brasseres (some men too) all on the same cargo run...SQUASH comes to mind....I've had a bad one or two, all signal valves though no power valves...just cheap, burn out before you could blink an eye stuff, with power valves.. 6L6 stuff usually.. Solvex is pretty good for the most part..
I like um...I just don't trust um....

Regards

You know I though about what you did. That can't work their wired different, I don't think you can swap that valve. I'm not an EL34 guy.
Where's the bass?? But really, I don't think it's interchangeable.. Two different animals all together.. A guy told he could do it with VTL, from KT90, to EL34, with a flip of a switch, and of course a rebios (maybe he had some type of auto bios). My VTLs no switch, 6550, Kt88 or 90s no EL34 for sure..They are wired different...No plug and play....

Regards..

Yeah EL34's seem not same league  as 90/88's/6550's. Seems altogether dif design. Its like a  minature 90.

I know there are quite a  few audiogoners who havea  negative bias on buying tubes from ebay sellers.
I've bought quitea  few lately and have no issues. 
Nearly all test as seller states.
The reputable dealers prices are out my budget, ebay offers a  opportunity to purchase these fine NOS tubes. Test strong is OK with me. Sonics on a strong tube will be identical  with a  NOS. 

eBay is a marketplace, a good one, with information about sellers and feedback. Bad sellers don’t last long there. Sellers selling tubes are like any other sellers, they are subject to the discipline and the systems in that marketplace.

Buying tubes in a marketplace like eBay requires knowledge of what you are buying and what types of risk it entails. It requires understanding how tubes are tested and how they may fail and what happens to the equipment if a failure occurs. For example a power tube failure in a high power tube amp can damage the amp, whereas a noisy or bad small signal tube will just give you some noise in your buffer or preamp.   It is also important to understand the limits of tube testing and how it is imperfect it can be in terms of determining the health and proper operation of the tube under real load.  Furthermore, we are dealing with fragile miniature glass devices here, some 50 years old with microscopic metal wound wires, then being shipped through postal or courier services.  Sometimes issues will arise even if the sellers are honest and conscientious.

Bad sh*t happens when newbies don’t take time to learn and understand in depth what they are dealing with with vacuum tubes and try to buy tubes off eBay to save a few bucks and get burned, figuratively and literally.

I have bought thousands of dollars of tubes, old stock and new stuff, from eBay and my problem rate is very very low.

I've recently learned of low microphonics and testing.  Does anyone have experience buying matched tubes that also have low microphonics?