What's your favourite 6SN7 tube?

Kentley wrote:Today I took the plunge and tried an old RCA 6SN7 in my ST-120 driver gain hole, using the adaptor discussed above, I really did not expect much, as this RCA had seemed a bit too weak and subdued in the SP-14. I have another Shuguang Treasure on order but I couldn't wait to test the arrangement. And YES - IT'S A WOWIE ZOWIE. There's a sense of depth that is new to me. Bass is way tighter, too.
A highly recommended mod!

The Shuguang Black Treasure is a very nice tube.  Excellent vocals, tight bass, and great bloom on that one.  When new though sounded strange for a week and much better after a month so give it some time.  

When you get a feel for the Black Treasure flip the ST-120 to Triode mode.  You get more of everything good - bass, vocals, width, and depth.

I just stuffed a pair of the Black Treasures into my SP-14. They're still shaking the cobwebs off but, oh my! Agreed, they are slow-starters. You start off with a very good and nuanced bass, but the top end is mud. At about the 20-hour point the tulips start to bloom and you simply stop what you're doing and listen.
They're big SOBs, like power-tube big, so make sure you've room for them. Unless there is some manufacturing defect down the road that pops up these will be my go-to 6SN7s. They're not cheap, ~$100 the pair and price is climbing along with their reputation.
You can lay your hand on the top of the tube after 2 or 3 hours running and feel only warmth, not the sizzling heat of a conventional 6SN7. Cool running, so as long as the vacuum holds out these babies should last forever.

Where are these Black Treasures to be mined? (Mine'd)!

Maybe I could try a pair in my SP14, and one for centre stage among the evil triplets of my ST70.

Tube Nube wrote:Where are these Black Treasures to be mined? (Mine'd)!

Maybe I could try a pair in my SP14, and one for centre stage among the evil triplets of my ST70.

I can't resist responding to one whose sense of wordplay matches mine own. I got my pair here - seems to be a reputable dealer, and pretty fast. Dealers in North America seem to be imposing hefty markups for "premium matched sets" and such. Seems doubtful that it's worth the extra denari. http://www.ebay.com/itm/261818760826?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
I'm in for three of these, as you are planning. So far, even without the final piece in place (driver for ST=120) I'm sold on them.

It seems my seems are bursting at the seams.

It seams so, Kentley!

I am a fan of you very smithly word play, I admit. Good advice to be wary of those who knows they are purveying primo product with these tubes. I'll check around before doing the all-to-easy and impulsive pay pal boogie.

It has been long rumored that some Ebay sellers from the far east sell factory 2nds at fantastic prices.  My first BT CV-181 lasted about 500 hrs and developed mild rushing and an occasional pop or two.  But it sounded really good before it went south.  2nd one hanging tight with hundreds of hours while a 3rd is still in its box.  So buyer beware as you have to be self-insured at these prices.  Be sure and pick up a spare!

Tube Nube wrote:It seams so, Kentley!

I am a fan of you very smithly word play, I admit. Good advice to be wary of those who knows they are purveying primo product with these tubes. I'll check around before doing the all-to-easy and impulsive pay pal boogie.

Don't encourage him, it's unseemly. I figure the ones that come with the mu and whatever penciled right on the tube have probably passed factory muster.

Stop! Stop!! It Hertz!!

Methinks my original thought on having some production trash in the tube that had to burn off may be on the mark. Several hours on the tube now, and it's gotten quieter on quiescence ... Quewl!

Still some residual noise, but certainly not at the level it was. You really gotta have your anal retentive ears on to even notice any more ... which I always do, but that's beside the point, so forget I mentioned it.

"anal retentive ears"

sKiZo wins the Pull-It-Surprise for Best Imagery of 2016. Congrats, and keep it up.

I'd like to thank all the literal people who made this happen ...



That coin base seems to have plateaued for now, which isn't necessarily a bad thing, as it's quite good. Definitely hearing more detail than most any other tube I've been able to cram into the center spot ... to this point anyway. If I had a complaint (and come on already ... you HAD to know I'd come up with something) I'd say it's a bit dark compared to what I'm used to. More fun on the horizon swapping channel drivers ... goody goody!

Is the consensus that these Chung King cv181z are better than vintage 6sn7's like the Sylvanias I'd heard so many good things about? Back before you fickle sons of guns apparently threw them over for this new mysterious, dark and voluptuous stranger in our midst!

Tube Nube wrote:Is the consensus that these Chung King cv181z are better than vintage 6sn7's like the Sylvanias I'd heard so many good things about? Back before you fickle sons of guns apparently threw them over for this new mysterious, dark and voluptuous stranger in our midst!

Well, you have to remember to defrost anything with Chung King on it . . .
I agree with first impressions. Spectacular tube. Question is longevity -- none of us had them long enough to render an opinion. If they crap out after 500 hours I'll go back to my trusty old RCAs and Sylvanias. But if they can hold their mud for 5k-10k hours, which we won't know for a coupla years, they would be my go-to tube.

Well... Maybe my sp 14 deserves a pair for a try out.

The only vintage tubes I can afford are used "test good" pulls.  So I have been off the vintage trail for a while as the very best are scarce and expensive.  But a few in my collection sound very good but are no spring chickens.

The BT CV-181 checks off a lot of boxes in my tube requirements and works well in the ST-120 front end.  I got 500 hrs on my first one several years ago.  It developed mind noise but sounded really good when it fell on the sword.   Then installed its cousin - a Psvane CV-181 - that has over 1,000 hrs and going strong.   The glass globe in the huge tubes barely get warm so should last a while.  With all the noise last week about the Black Treasures I installed a backup so we'll see how long this one lasts.  And the BT CV-181s have gone down in price over that last few years.    

The Psvane CV-181 has a little less bass and more highs than the Black Treasure.  I think I prefer the Black Treasure's smokey hues in my setup and together with the KT-120 output tubes crank out some good bass.  The Psvane would also work very well in the right system.

Both the PSVanes and the Black Treasures make a lot of racket in the driver sections of my Big Bopper M-125s, yet are dead quiet in the line preamp, Don Sachs' iteration of the SP-14. I will cut the Chinese tubes some slack, maybe they are more sensitive to the radiation from the back tubes, rectifiers and iron in the amplifiers, or need some time burning in. It ain't the amps, which run dead quiet with 6H8Cs and RCAs.

Update here ... the original coin base that was making noise in the left channel quieted right down after maybe 10 hours, so I expect it was as I'd originally guessed ... byproduct of manufacturing burning off. The second tube is great right out of the box. No discernable difference between the two, so I now have a good spare, with no plans to roll anything else any time soon.

I also switched over to triode mode ... this tube likes that. Had to kick things up a couple notches, but I've still got plenty of range on the amp to saturate the room ...

I thought by-product, or as in my days we called it "shake," spat and pharted more than just delivering a steady hum. Hmmmmmmmmmmmm.

For those who wish to experiment with 6SN7 in VTA amps as driver: beware cheap adaptors! The first one I purchased on SeeBay was a cheap black plastic with inferior pin clamps. And the 6SN7 would only barely seat itself - half of the pin length remained exposed. Instead, here's a fine model which not only holds the tube much more firmly, but is also nicely gold-plated, with gold tube clamps too. Worth the extra $$$.
http://www.ebay.com/itm/201506915612?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

It appears that the requirements of a 6SN7  used as a driver volt-amp in the VTA amps are quite different from their use in the SP-14 preamp. The difficulty I've run into is that 6SN7s and equivalents are so variable that it's a crap shoot. For example, vintage RCAs vary so greatly in this position that it is impossible to predict the result. Even "identical" tubes sound completely different. 12AU7s, 12BH7s and their mates generally sound consistently similar here. So if you are an experimenter with extra $$$ by all means try the 6SN7 route. My current fave in that hole is an old RCA black plate, fairly common, which I found lacking punch in the SP-14. It's fantastic in the ST-120. Go figure.