Preamp Deal of the Century

Jewel - *I* liked the KenRad Black Glass tubes and I like the Tung-Sol Round Plates. They are both very good choices. Honestly, the stock 6Sn7's sound a bit like a cross between both tubes - somewhat closer to the Tung-Sol but less harmonically complex.

The Tung-Sol Round Plates are sweeter, more open, and have less midrange bloom than the Ken Rads.

Ultimately, the tubes you choose as "best" will depend 100% on your listening preference and the rest of your system. No-one can tell you what is best for YOU.

It is good to attempt to determine what character your system needs before seeking out tubes. I don't know what the rest of your system is so its difficult for me to determine (guess) its sonic signature. Even if I did know what your system consisted of, odds are your listening preference is different than mine to some respects and my choice in tubes would not be correct for you.

So.. that said, with the stock tubes in your Supratek, what elements do you think would be beneficial to your system?

Be cautious when buying "names/model numbers" of tubes vs. construction of tubes. Often times a tube will carry a specific number yet the internal construction may be different. The Tung-Sol Round Plate referrs to a specific construction or type of Tung-Sol 6SN7GT which is to my knowledge MUCH different sounding than the more common "black glass" Tung-Sol 6SN7GT.

Vingage is also important. Tubes can sound different from one another, even on a month-to-month basis in some cases - ie; January manufacture sounds different than February. To me, a matched manufacture date is VERY important otherwise the tubes, however identical in appearance, can sound somewhat different. Also... matching the electrical ouput is important because the L/R channels on the Supratek cannot be biased. A severely mis-matched pair of tubes could result in a soundstage that leans to one side or the other because the gain on one channel is greater than the other.

Likewise - just because a tube is a "6F6G" doesn't mean its THE 6F6G that everyone is talking about. THE 6F6G you want, I believe is the Sylvania 6F6G - clear glass - green print or the somewhat different - National Union black glass 6F6G. Ebay is a GREAT place to research tubes and to get more familiar with the internal construction. For an example, go do a search on Ebay for "6F6G" and see how many different versions there are.

Hello Gang.I have been out of town, just catching up on the thread. Swampwalker, hope your progressing on your troubleshooting.... These things can be frustrating, but persevere there brother as you will indeed be rewarded. Jewel.... regarding microphonic 6sn7's??? As bwhite correctly pointed out, many 6sn7's tend to be microphonic in the supratek,noteably the Kenrads, however...your dealer states that: "all nos 6sn7's tend to be microphonic" That is a rather profound statement to be sure, and nothing but total pile of BS.Perhaps it is just because of the sad supply of kenrads in his inventory.Yes, the Kenrads can be microphonic in the supratek but certainly not all of them.They need to be cherry picked. I had to go through a dozen of mine to find a pair that were quiet. The least microphonic and quietest of any 6sn7 types are the rca 5692 [red base].Personally.... I preferr the sonics of the Kenrad vt-231gt's[navy version] or the tung-sol rounds in my rig. That said: any strong testing RCA redbase 5692 will simply stomp the modern chineese or russian 6sn7.These have more air and extension up top and are a little leaner in the bass, but the bass is nice and tight,very fast and has very good resolution.Does not have quite the atmasphere or bloom in the midrange like of the kens or the tung sol rounds but good examples of this tube are very smooth and non-fatiguing.Very system dependent here with regards to tone and synergy. A good example or a case in point: I have a MFA luminescence B that employs a 6sn7 for gain in its line stage... The Lumi tends to be a shade on the dark side of nuetral. Both the Kenrads and tungsol rounds would be my "least" favorite 6sn7 when employed in the Lumi, while the rca 5692 is "far and away" the best 6sn7 type tube in the lumi.The sylvania 6sn7wgt vt231 metals are very similar tonally to the rca 5692 however,these tubes also tend be microphonic in the Supratek and also need to be cherry picked per sey. The tung sol round is an all around great performer in the supratek, as well as the much more common 1930's rca grey glass 6sn7gt's. The RCA's can be sourced just about anywhere as there were more of these manufactured than any other tube ever made. The RCA gt's are tungsol roundish sounding[read sweet] in the supratek, traditionally much easier to source and easier on the pocket book as well. Again... system "synergy" is the key word here. Personally... I find the Tungsol round just a little too "tubey" or sweet sounding in my rig. Your mileage may very of course. Suggestion here: It may be a good idea to acquire a batch of say a dozen of the same 6sn7 type and then cherry pick the best pair and sell off the rest.I know... can get a little costly,but they are pretty easy to sell on ebay or right here on the gon. Slowhand and tubegrover... Sure happy to hear you guys liked the 6f6g's for regulator duty[amazing huh].A great alternative from the insanely priced we 350b.To be candid: I am always a little aprehensive about recommending anything in a public forum as we all have different rooms,amplifiers,rigs and ears. PS: For those sourcing early bottle type 6f6g's for regulation duty in the supratek....these can also be substituted with a 1611 or 1621 tube. These tubes are physically about the size of the we 350's with similiar internals. Cheers David.

Hi guys

I am getting VERY curious with this 6F6g thing. I am willing to try a pair in my Chardonnay. But what about the brands? Any suggestion? Tung-Sol, Ken-Rad, Sylvania...

Best,
Lisbon

Do Tung Sol Round plate tubes come in both clear and black glass? Do they say round plate on them or just tung Sol SN7GT?

Hi Slowhand, Here are some pictures of the Tung Sol Round Plate tubes grouped with some other tubes:

Photo One

Photo Two

The images are not terribly high resolution but might give you some idea of what to look for. Look closesly at the tops of the tubes to see the U shaped plates which are visible in Photo Two - at the very top of the tube - above the Mica spacers.