Tube rolling in Hagerman Trumpet MC

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.

My most recent experience if Tube Rolling 6SN7 using the KR VT231 Black Glass, as the tube to be compared to as the Base Tube, ended with a unexpected outcome.

In my circuit, two Valves from different Brands, but similar production era's to the KR, showed the KR's as having a artificial bloated bass and not competitive in any way the Bass that was on offer from the other two Valves. The KR fell way short in being able to create the impression the other two Valves were capable of in the Mid's and Highs.

A stated in my circuit on my Power Amp's.    

@drekow 15v