Some initial thoughts on these Tungsrams after 5 hours of burn in but first the technical differences are thus..
1T4: Vf 1.4 Volts / If: 0.05 Ampere
1T4T: Vf 1.4 Volts / If: 0.025 Ampere
Voltage is the same but the amperage is half.
Now I am about as remote in technical knowledge is as tuktoyaktuk is to urban density! So if anyone with knowledge cares to chime in then please do! Having said that, even though it has half the amp's the volume is not effected. I find my volume settings on my test tracks to be the same for the 1T4T as for the 1T4 so it seems better battery life does not come at a cost of power with these which is good news!
I can also report zero ill effects using these in place of the recommended tubes.
The sound so far is quite remarkable actually. They have a great deal of air around the notes, decay of a note seems to go on forever and these beat the Lorenz's in terms of detail retrieval by quite a margin, quite a margin! It is like suddenly there is more texture in instruments and voices. Strings on a violin have that extra bit of waxiness and there is zero grain, zero!
I was listening to an HDTT recording of Beethoven's Violin Concerto in D, it is a 24/96 transfer from 4 track tape. The artists are Alfredo Campoli and the RPO. This is a vintage recording and all the better for it. I simply have not heard a violin portrayed on my system with such startling clarity and realism before, heck,I have not heard it to this level on many other systems! I was really impressed with it with the Lorenz's but the Tungsrams take the realism of the performance to a very different level.
The other thing they do is throw a wider, deeper soundstage, not an unbelievable one, just very real, it allows the orchestra to be seen very clearly, placement of instruments is pinpoint.
The creamy, airy treble and mid range does not come at the expense of weight or depth either. I would put them on par with the Lorenz and Mullards for weight. The Banging of the guitar body on Krushevo feels so real, it is deep and one can feel the echo in the body of the instrument, not out of it but in it!
You all know how much I love my Lorenz's but with the reservation that these tubes have some more burn in to go I would have to say hand on heart these are the better tube and I do not know if that is down to the make or the lower amperage.
The ting noises on the Ken Rad/Sylvania's soon burned off and the Tungsrams slight tinging disappeared within an hour. I tried them with my Heaven S's which are 16 Ohm at 112 db and my Piano Fortes which are 16Ohm at 108db and could hear no hiss whatsoever even with the volume knob turned up fully.
I must say even though my initial thoughts of the dealer I got these and the Sylvania/Ken Rad's from was less than glowing I have to say he knows his onions when it comes to tubes if my experience is anything to go by. Both pairs have proved first rate in sound quality and in terms of being very quiet tubes. The were both packaged perfectly and delivery was fast so I feel confident in recommending him. His prices are good, and the tubes are tested before shipping and he was very proactive in dealing with my initial complaint about the first set not being what they were advertised. Everyone makes mistakes, its how they deal with them that matters and I have no complaints with Robert, this is his website..