Punit I have always liked the CBS/Hytron 5692 better than the RCA. It's very worth getting.
I squirrel, you must have a bad or near end of life TS VT-231. Your other tube comments sound pretty consistent with what most people hear, but not with the TS, especially the sibilant and harsh part. I've never found this, myself. It DOES have less bass weight than the RCA or KenRad tubes, though.
I read over at Tube maze that someone had similar issues with the TS RP, it was recommended that it be put on extended burn in as per the following comment
'The TS RP often need some extended usage to “wake up” the cathode and strip off the oxidized layer of barium on the cathode to get down to the strongly emitting layers of cathode emulsion. Before an extended “burn in” or “wake up” period, the roundplate 6SN7s are a little bit sluggish-sounding, and sound a little bit muddled/muddy, and in particular do not have good treble extrension or “air” in the high frequencies. But.. oh, WOW, when these legendary roundplate TungSol 6SN7s DO wake up after some burn in time… they will absolutely blow you away.'
Accordingly I did so and the sound improved markedly.
I then did a marathon 6SN7 tube comparison last night which yielded the following results:
Studio Six
Test of 6SN7’s Valves - 21/09/14
Tube 1 - RCA Red Base 5692 1950’s
Valve is quiet, nice colouring, 1st up noticed sounds thicker, maybe more texture
vocals are smooth, texture, maybe more centred image, nice rhythm, feels smoky with everything being intimate.
T4 = starts very delicate, music coming from a black background, no noise, no sibilance, snare drum sounds tight, good layering of the instruments, at end of track good cymbals decay
T5 = guitar image in far right, vocal is dead centre, aware of a nice drum kick around 2.00 great emotion and no brightness at all! very relaxing to listen to, great sound
I feel as though i can hear everything in its right place, nothing is too emphasised.
T6 aware the shaker at 1.00 can hear detail in bass guitar, no sibilance or brightness
T5 no sibilance or brightness, good rendition of space
Overall sound is warm, thick and lush with plenty of unforced detail, maybe not the last word in resolution
Tube 2 - RCA 6SN7-GT 1940’s half grey glass
T4 tonal balance is brighter, seems very clear, no sibilance, not as much colour, doesn’t sound as thick or textural
T5 wide soundstage, impression is its clearer or just lighter, not as much bloom drum kick not as well pronounced
T6 sounds thinner I think, shaker is there but not quite as textural, music is not as layered
Tube 3 - RCA 6SN7-GT Grey Glass 1940’s
T3 better than valve 2 little more texture, better depth to soundstage not as thin, bass guitar line is easier to follow.
T4 warmer, better separation, quiet, snare drums are not pronounced not quite as as thick or full bodied as V1
T5 more texture, val is clear with emotion, not as warm, no sibilance, 1.51 little bit shouts , good emotion, orchestra in background not a layered as in V1 but netter than V2
Tube 4 - Ken Rad Staggered Plates 6SN7GT/ VT-231 JAN CKR
T3 a little grudge not a smooth or liquid as V1 or V3, bit shimmery on cymbals, could be a touch dirty, not smooth or liquid, bit shrill
T4 vocal a little coarse, soundstage is shallow, instruments sound a bit plain and thin, boring
T5 attention wandered, vocals seems to be covered in a sheen, missing rich texture of V1 or V3
Tube 5 - Tung Sol Round Plates Black Glass 6SN7GT/VT-231
T3 clarity and delicacy, goals are more alive, best so far nice layering, i cancer everything that is going on, heard reverb for the 1st time at end of track
T4 nice reverb, vocals are crystal clear, none of the grunge apparent in V4
T5 guitar very nice harmonics, not trying to stand out, instruments behind layered well, very clear and clean sound. Great emotion mid track. Best of all worlds here, everything just sounds right!
Conclusion:
Tube 5 - Tung Sol Round Plates Black Glass is the winner followed by
Tube 1 - RCA Red Base
