Which tubes to roll

For whatever power tubes you decide on: Upscale Audio's quality and customer service are hard to beat. Check out Kevin's procedures and offerings: (http://www.upscaleaudio.com/view_category.asp?cat=85) Both power and driver tubes have a major impact on your presentation. Try some NOS 6SN7GT/VT-231 (Sylvania or Ken-Rad)bottom getters from the 40's for a real treat: (http://shop.ebay.com/?_from=R40&_trksid=m38&_nkw=vt-231&_sacat=See-All-Categories) Neither are expensive right now, and both provide an expansive sound stage, excellent imaging, accurate timbre and frequency response. Here are some comments on what to expect with some of the different brands available: (http://home.att.net/~chimeraone/6sn7sound.html) I've purchased quite a few tubes on the "Bay" over the past few years, and only had one bad experience.

That's a good link(thanks)!! His observations on chinese business ethics(there's a stretch) and manufacturing, mirror mine. BTW: If you like transparency, nice freq. extension in both directions, and liquid mids- The Winged 'C' 6550C's(latest iteration/St Petersburg plant) that Kevin sells are working very nicely in my Cary monoblocks. I was a hardcore NOS tube addict, until the cost of matched quads/octets of anything decent in power pentodes became unrealistic(Dom Perignon taste/grain alcohol budget). Uncle Kev came through, in style. You could say I'm a happy customer. Does it show? (http://www.upscaleaudio.com/SED-quotWinged-Cquot-6550C_p_16.html)

The big difference between the tubes you mention is "power dissipation", or the maximum output that the tube is designed to produce at a certain plate voltage. ie: The average KT-88 will be designed to output about 35W, while the EL-34 is more between 17 and 20W. The Telefunken EL-34 was designed to output about 25W, which is high for it's type. The KT-90 and EL-34 tubes are at the opposite ends of the power output spectrum in your list, with the others falling between. There are also differences between tubes within one type, ie: the original 6L6 was a 19w tube while the 6L6GC is usually rated at 30w. A lot depends on the plate voltage the tube is manufactured to handle, and whether it's a tetrode or pentode being run as such or as a triode. Even a pair of EL-34s can output 90w with 800V on their plates. The differences in presentation/sound between all those tubes would be ridiculous to even approach, given the multitude of variables. ie: Manufacturers, amp designs, variations in bias/plate voltage, again- are they being run in triode mode, etc. There are also a plethora of personal tastes involved in the analysis of tube "sound". Again- Kevin has a vast amount of experience with various equipment and tube designs. Tell him your tastes and he can direct you to the tubes that can best satisfy them.