Replacing The Stock EH 6SN7 Tubes For Cary SLP 05

The notes an info on this page, have proven very accurate, in my experience: (http://www.dehavillandhifi.com/6sn7_vt.htm) I've tried every tube in the top 10, on this listing, in the last few years. The National Union(VT-231), RCA(VY-231) and CBS/Hytron(6SN7GT) were the warmest(in that order). The bottom gettered tubes, from the 40's and 50's, are the best sounding of the NOS 6SN7 family. The exception to that is the Sylvania, tall bottle 6SN7W, but- That one definitely does NOT fit your desire for a warmer sound. BTW: Nothing currently produced will match the presentation of NOS tubes.

If you want a warm sound; the Tung-Sol round plate is not your cup-o-tea anyway. It's my fav, because of it's very clean, non-euphonic(my taste) presentation. I'm using them as drivers, with Sylvania 6SN7W's, as phase splitters(another very uncolored tube), in my mains monoblocks. The Brimars would represent the other end of the temp spectrum. Brit valves, like Mullard(ECC33) and Brimar(CV1988/6SN7GT), tend to be much warmer than those European or American manufactured, and well worth seeking out. BTW: don't skip finding a Mullard(Blackburn plant)GZ34 rectifier, as that will also transform your unit, in a very pleasant way. Matter of fact; I'd probably start with that position and tube.

A circuit using a pair of tubes(one per channel), in any stage(gain/splitter/buffer), will have better balance if the tubes are matched. Whether you can discern the difference or not(numerous variables), is another matter. Of course if you have a number of stages, and each has mismatched tubes; the effect would be cumulative.

Most of the 6SN7 family tubes that I've purchased, have been in matched pairs. They are worth the wait and cost. Avoid any, that claim to be matched, but are not the exact same tube(internal appearance). A difference in presentation, between your channels, is almost certain to result. I've bought pairs that were identical in appearance/internal structure, but labeled differently(ie: Sylvania 6SN7W/6SN7A), and had differing date codes, but were perfectly matched in sound and electrical measurement. The 5% figure is a good one. Also, the triode to triode balance should be close, for each tube. Buying loose tubes, from different people would be a crapshoot, given that few tube sellers will have the same tube tester, and if they did; how close would the calibration be between them?