Tube rolling in Hagerman Trumpet MC

@lewm Yes, I thought it made some sense that the buffer stage would have less impact than the gain stage and less consequence of a microphonic tube. I found that very difference in the EH Gold Pins when I used them in each position. 

In my set up, I find the 6SN7's to be very quiet tubes, in that even at a very high volume, there is no audible tube rush. The opposite is true in my Cary phone preamp, which uses 12AX and 12AU7's or their variants. There is very notable tube rush at higher volume until the music starts, then it is inaudible. I believe it is a different design than the SLP 98, as I've read that all gain is from the tubes. Maybe that means that something else provides at least some of the gain in the 98 preamp. I don't really understand all this but I don't have to either. I don't plan to build or even rebuild these components. I trust the manufacturers to that. 

In the old Cary PH301 phono stage, it came with some very cheap Chinese and Yugoslavian tubes. I described them as "ringy". Even with them, I could tell that the Cary was a step up from the old phono stages that I had used before. I also had recently switched to LOMC from MM and I know that made a difference as well but got hooked on tubes in pre stages in this way. My humble beginnings. :)

I get that the 6SN7 has the larger glass surface but what about the really large tubes like KT88's (I think that's what they are). Seems a lot of folks are in love with them and the old 300B amps?????????? I"d love to hear them sometime but probably never will. Anyway, sorry to gab so much. This stuff is all very interesting to me, at least from a listener's standpoint. 

@lewm 

Thanks for all of the information and conversation.  I have stayed out of it by and large because my system is much more humble.  I just can’t resist though.

My favorite 6sn7 variant is the Melz metal base 7 hole plate version 6n8s from the early 60’s.  When I bought mine, they hadn’t been discovered yet, so they were comparatively cheap.  I have two pair and a pair of Sylvania black base VT231 as well.  The 6sl7’s are the old red/brown base Brimars GTY version, rectifiers are Mullard 5ar4.  And the 300B pair are Takatsuki though I have a pair of EML mesh plate as well.  It is probably obvious that this is a low watt SET system (8 wpc).

I don’t even remember all of the preamp tubes I rolled through, it has been about two decades.  I know various RCA, and possibly some Sylvania or maybe Westinghouse?  
 

The most unusual find were the USSR tubes, I didn’t expect them to be that good, but they seem to balance out the warmth of my set up and add some speed and extension.  I don’t like terms like “air” or “sparkle” but there you have it.  I could see where they would be way too bright or edgy I a different system.

Oh and btw.  No issues with microphonic in the preamp.  Just the phono stage.  The ax7’s can really take off in the initial gain stage pre riaa.  That running is pretty amazing to experience.  My favorites I. The v1 of the trumpet mc are a pair of Siemens Ecc83 with 19mm plates, they are microphonic somewhat, and just wonderful.  I did find out about a trick that while a bit risky is worth a try.  It did help for noise and actually the tubes are less microphonic as well.  Take the tubes and holding them firmly, rap them on a table a few times on their sides.  Then turn them upright and more gently tap them on the table, or use a pencil to tap the side of the tube. The theory is that at times a bit of the plate coating (or other material) can dislodge and get stuck in the grid area and this let that fall to the bottom of the tube where it is less likely to cause a problem.  It worked and I can still use my favorite tubes.  Most of you probably knew this, but I thought I would share it for those who don’t.

Lastly if anyone has thoughts about “better” 6sn7 or 6sl7 that aren’t crazy expensive, I would love to hear about them.

For those of you who feed your Hagerman Trumpet with an SBooster power supply, what voltage do you use? Thanks for the help.