6SN7 brands

[John Roman]

I'm hoping to do some tube rolling on my Extended Foreplay 3. And as some of you know I've been looking at some 6SN7  and 7N7 tubes. Both those tubes require some changes, most significantly of which is changing out the sockets. Not a major deal to me but I'm curious what other tubes come into play? I rolled some RFT 12AT7's (ECC 81) into my Paramounts a few years back and really liked the difference from the Electro Harmonix tubes. So I'm just, once again, looking for help from the gruppe. Suggestions on tube types and brands would be welcome. At Paully's suggestion I'm currently looking for some Lansdale 7N7's. They're are some available on Ebay and I'm checking that out now. I would also consider an adapter, if they are available, for the 9 pin to 8 pin Loktal sockets.
Thanks,
John

[Paully]

You could convert your pre to 6SN7 and use one of these adapters to try out 7N7:

http://www.ebay.com/itm/Two-adapters-7N7-6SN7-tubes-amplifier-SUB-/250876937414?pt=Vintage_Electronics_R2&hash=item3a696e44c6

I like adapters when comparing tubes as it makes switching around a whole lot easier and less chance of messing something up.

As far as 6SN7 goes, as you would have read in the previous thread I am no expert, I would search the archives on the Tube Asylum over at Audiosylum.com and see what people recommend.  There should be more posts on the topic than you care to read.

Paul

[John Roman]

Thanks Paul,
I appreciate your honest perspective.
John

[Frihed89]

Be careful with the 7N7s, at least the small bottles as they differ a lot in their "internals", even though most were made by Sylvania.  Nu made a round plate version as I recall and the ones I had were very fragile. The 6N7GTs I like the best are Raytheon T plates (with and without support rides), the 6SN7W metal base (all made by Sylvania) and the KenRad black glass.  The "true" Russian 1578 is also an interesting tube, but those recently for sale from the Ukrane are mostly microphonic. They have a plate structure that looks like an erector set with holes and "curley" filament wire inside.  The Tung-Sol 6F8G is also a nice tube and requires an adaptor.  All these tubes are pretty expensive, these days, and many sold as NOS have been well-used, so you have to pay attention.

[Paully]

That is interesting.  Weren't loctals made for high vibration environments?  Odd that the National Union would be fragile.

[Jim R.]

I'll throw in my vote for the russian 6h8c -- but only the ones with the "OTK" marking and/or nickel collar on the base.  These are every bit as wonderful as the 1940s tung sol oval plate black glass tubes, but they don't cost nearly as much.  They may even be a bit more dynamic.

At one time I had many of these 6h8cs but sold all but two pairs, which I'm holding on to for now as they are getting much harder to find.  The other versions of this tube without the OTK label are just ok, nothing special.

-- Jim

[Grainger49]

From what I am reading the OTK indicated a certain quality level is surpassed.  Consider it Russian for Select.  It actually stands for the standard/organization rather than select.

[Laudanum]

My Seduction and FPIII builds have been delayed because one of the dark sides of real life these days smacked us hard in the face last week ... but I will be building the FPIII with Octal sockets for 6SN7's (thanks again Grainger for the advance help).  I've been rolling some into Crack with an adaptor.  I have a couple of the Sylvania 6SN7 / VT-231's that seem to make some of the top 6SN7 lists.  They are really nice sounding tubes.  But so is the brown base Sylvania 6SN7WGTA that I ended up with in a small lot purchase.  And I also like the Sylvania Chrome Dome/Top 6SN7GTB's which can be found pretty readily and labeled for other manufacturers like Baldwin.  I clearly dont have golden ears because I dont find those Chrome domes to lag too far behind the more highly regarded VT-231's.  Of course, this is in Crack, things may be different in the FPIII.  I also have some GE 6SN7's that are interesting although quite different than the Sylvanias.  Im not a tube expert at all so YMMV ... just my 2 cents.

[Lee Hankins]

I have found that usually (there are always exceptions) the tubes from the same manufacturer have similar sound, and as you have discovered the GE you have tried sounds quite different than the Sylvanias.  GE 6SN7GTA/GTB tubes are considered better driver tube than output tubes.

I do not believe that any NOS 6SN7 tube sounds bad, some tubes sound charasteristic traits just seem to mesh or sound better with specific equipment, i.e. the birth of tube rolling.

[Laudanum]

Hi Lee.  Thanks again for your 6SN7 primer a while back. 

[John Roman]

Thanks everyone for the insight!

Jim,
I grabbed a couple 6h8c's off Ebay just to try out. Thanks.

[Lee Hankins]

John, did you get the better ones with the holes in the plate?

[John Roman]

Not sure. They do have the OTK designation though. Holes in the plate? Maybe the holes are in my head lol!

[Lee Hankins]

John here is quote from EWBrown; "OTK stands for "Otdiel Technicheskovo Kontrolya" or Technical Control Bureau. Basically Mil-Spec standards. The "Diamond" is another internationally-recognised "quality" marking."

Pictures of the tube that jrebman was talking about: http://diyparadise.com/forum/index.php?topic=1125.0

[John Roman]

Hey Lee,
So what's the deal with the "holes in the plate" thang?
I just took a look at that link and I'm bettin they are not the same ones I ordered..... ah well, I know better now.
I just checked the bay and found what you're talking about, $170 for a pair. They worth it?