Linlai E 6sn7 tubes

@ram18 -

"I have much to learn."

     Don’t let anyone snow you.

 We’re all (still) on the same curve!

                   Have fun!

@ram18 -

     Brent Jessee mentions having 40’s, VT-231 Ken-Rads in stock.

     I loaned a pair of black glass, to a fellow ’goner, some months ago, "just to try." 

     Haven’t heard from them since.     Guess they liked ’em!

     The bottom-gettered Sylvanias, listed just below the Ken-Rads, are what I’m presently using.   I prefer them to the Ken-Rads, but: still have a couple pair of the VT-231 Rads, for back-up.

                                  Brent Jessee’s website, 6SN7 page:

                                 http://www.audiotubes.com/6sn7.htm

@lowrider57 -

     I don’t even remember buying my pair of two hole, t-plate, bottom-gettered, VT-231 Sylvanias, or: ever having listened to them.

     Must have been when I was going through that 6SN7 comparison from Chimera Labs, and trying everything on it (+), decades back.

     BUT: when I bought Brent Jessee’s last matched pair of round plate Tung-Sols (my fourth pair), a couple years ago and found the Sylvanias hidden in my stash, I tried them in concert in my Cary monoblocks.

     Nothing I’d tried before had given me the organics and sound stage depth of that combo.

                                            They’re still in there!

@ram18 -

     Those are the ones.

     The CKR, bottom-gettering and copper rods (at the top), are a dead giveaway.

      Be very careful about obtaining tubes rigorously tested/guaranteed for low noise, if they're going in a preamp.

After all, this hobby is pretty much about experimenting until you get the right combination of ingredients which sounds right to you. 

     I've always viewed the hobby as an amalgam of science, art and cooking.

     The first always depends on an individual's favorite theories, education and understanding, regarding electricity.

                                  The other two, of course: one's palate.

@ram18 -

     Those figures would indicate tube strength/life and the balance between triode sections.      Nothing, regarding noise.

      There are various ways to test for microphonics/noise*.     My (personal) favorite procedure simply involves a high-gain circuit and earphones.

         *ie: https://tavishdesign.com/pages/audio-tube-noise-measurments

                              and: 

@ram18 -

"Havent felt the bass depth or slam that is often associated with the KRs."

     Has your system, as it now is configured (talking about components, speakers and room) ever produced the kind of Bass depth and slam, that you are attempting to achieve (or: recapture), with your tube changes?

     If you've already discussed that, elsewhere in the thread: my apologies.

"Chill out, you’ve got 4 new tubes installed which require break-in. True NOS Ken Rads need 50-60 hours... ’

                                                              +1

     This is a verbatim quote, from a letter Brent Jessee sends, whenever one buys valves from him:

                   "CARE AND FEEDING OF NEW TUBES: BREAK-IN
     New tubes need a break-in period before they can fully exhibit their true sonic character when used in audio circuits.

     Preamp tubes especially benefit from a good break-in. This period may vary widely, but NOS vintage tubes usually need at least 48 hours of use, sometimes up to 100 hours.

     New current production tubes need 24-48 hours typically.

     Good break-in can be accomplished by either leaving your tube unit turned on in a no-signal condition for 2 days, or you can just enjoy the tubes for several hours each evening and they will be broken in after several weeks.

     New tubes, especially NOS vintage tubes, may sound a bit edgy at first, but after the break-in period will mellow out and sound wonderful."