I've been running 6SN7's for just under a week now, and ready to post my initial feedback.
I'm coming to the conclusion that the signal tube selection is all down to personal taste and system synergy. My system comprises Salk HT3's, I consider these to be extremely neutral and capable of fast deep bass, neutral midrange and an open/airy top end - not perfect but no speaker is (for example I find the soundstage is too flat). My amp is a highly modified Musical Fidelity KW500, the mods have deepened the bass, improved the mid-range and smoothed out the top end (not restricted it), all this means is I can go louder without realizing it. To put this in perspective others, that have compared my amp, find it warmer than the Modwright house sound. So I'm not looking for any mid-range warming in my system but looking for a tube that doesn't change the bass or mids and possibly extends the top end detail, as this is my personal preference and the smoothness of the amp/neutrality of the speakers can accommodate it.
What does this mean - I like 6N1P's/6N6P's and have turned my back on 6H30 DR's, unfortunately I found the 6N1P's a touch on the hard side with the 6N6P's having similar detail and potentially less harsh? Enter the EML, which added an organic element, and I was sitting back enjoying the EML/6N6P combination and going to give it a few weeks to get my long term reaction to it. This was not to be, enter the 6SN7's
Putting in a pair of new production Tung Sol 6SN7 I noticed something different, maybe a more dimensional soundstage (lacking with my HT3's) and it didn't appear to lose the 6N6P detail but did sound a little coarse and unrefined. Jumping next to the Tung Sol round plate 6SN7's, they have the same family sound as the new production version without the coarseness, the difference isn't huge, but is significant. I think I could actually live with the new one in the short/medium term, but based on past experience, the round plate should possibly be less fatiguing over the long term.
Today - I've warmed up and tried 6N1P/6N6P/6SN7's.
The 6N6P's have been eliminated, on the basis of not being as detailed as 6N1P's or 6SN7's.
It's now a choice between the 6N1P's and the Tung Sol round plate 6SN7's, at the moment I feel the 6SN7's are going to be better to live with long term. I need to give them a few more days/weeks. I should also add that the 6N1P's are not the ones Dan sends but are the older version that cfchew referred to in his first post, these are slightly superior to the new ones (not the same night and day as moving from the 6H30's to the 6H30DR's, but enough to notice a difference).
My findings differ slightly from those already posted, again I feel this goes back to synergy/personal preference I inferred to at the beginning of this post. In my system, the EML rectifier tube has had more impact than the 6SN7's, the 6SN7's are more of a fine tuning.
At this stage I reserve the right to change my opinion! These are my initial reactions after 6 days, I normally allow a couple of weeks before making a final judgment on tubes.
After all this the MWTP is a phenomenal source, the tube rolling just allows us to fine tune it and support the global economy.
Phil
