6sn7 and 5u4 tubes

If you can find some CV1988 Brimars....one of the best usually go for around 100 a piece.

A good place to start would be to find a NOS pair of Sylvania or Ken-Rad VT-231 bottom getters from the 40's. That's IF you enjoy a very accurate and transparent presentation. This is what to look for: (http://cgi.ebay.com/Pair-Sylvania-6SN7-GT-VT-231-Preamp-tubes_W0QQitemZ170271128352QQcmdZViewItem?hash=item170271128352&_trkparms=72%3A570%7C39%3A1%7C66%3A2%7C65%3A12%7C240%3A1318&_trksid=p3286.c0.m14) (http://cgi.ebay.com/Ken-Rad-Vt-231-6sn7-1940s-Matched-Pair_W0QQitemZ220293427549QQcmdZViewItem?hash=item220293427549&_trkparms=72%3A1205%7C39%3A1%7C66%3A2%7C65%3A12%7C240%3A1318&_trksid=p3286.c0.m14)The top getter Sylvania "Bad Boys" don't even compare(EXCEPT for the 6SN7W/JAN CHS, tall bottle). If you like a "warmer"(British- Brimar/Mullard) coloration: Try RCA, Raytheon or National Union VT-231's(again- bottom getters) from the same era. They all deliver great timbre, tone, frequency extention, wonderful soundstage and imaging(if the rest of the system/room is up to it. I've never purchased from those sellers on eBay, so- I can't vouch for them.

I don't have your amp, but you might want to check with Brent Jesse - http://www.audiotubes.com/6sn7.htm; good selection, good prices ,honest advice - not afflated other than as a satisfied customer

go to the tubeseller.com website for a description of 6SN7 tube sounds.
Larry

My intro to tube rolling began seven years ago when I bought a Blue Circle BC21 preamp.

I was pretty shocked by the transformation when I replaced the stock 6SN7s with WWII era VT-231s.

My favorites for the BC21 are the ones Rodman99999 suggests, the Sylvania and Ken-Rad VT-231s. Both tubes convey an enormous sense of scale while also imparting the positive qualities of this era of tubes. Refinement, dimensionality and a great midrange.

I feel the Sylvania is a bit more neutral, while the Ken-Rad seems more organic. I should say I have a preference for the black glass Ken-Rad over the clear glass version. In my set up, the black glass sounds, bigger, bolder and richer.

Godd luck!