[rosgr63]

Jose they have a B4 type base.
They are actually more rare than the 45's and I am hoping to have an amp built for them, or another variant I came across just as rare.
There is also a black plate version.

 

[kiertijai]

@rosgr63  : Are they Marconi  P250?  Are they similar to 2a3/45?
How can we use them as : drivers or power tubes?
How do they sound?

 

[RiDeC58]

Apologies if this was covered earlier in this thread, but what do people think of the new 6AS7 from Sophia?

 

[rosgr63]

Kiertijai I have only tried the 6SN7 A.M. tubes, not the Marconi yet.
They are P250 for output duty.
 
 

 

[Xcalibur255]

I bought a little grab bag of 6 single 6SN7 tubes off eBay and they just arrived today.  From the pictures I could only identify a couple of them, an RCA and GE GTB mainly, so it was mostly a $35 gamble just for the heck of it.  I didn't have many tubes for my single 6SN7 operated OTL amp so I figured it'd be fun.  All 6 of the tubes carried interesting re-brand names on them, such as DeForest and Corvair which was part of the intrigue that got me to buy them.
 
They came today, and some very pleasant surprises were in store for me.  I was right about the first two, though the RCA GTB is a style I haven't seen before, I'm not even sure it is RCA but it's definitely american.  Tube 3 is an early 50's RCA GT with offset plates, basically the grey glass tube without the grey glass.  No excitement there since I know this tube and personally am not a big fan.  Tube 4 was a much nicer surprise.  The Corvair turned out to be a NOS Hytron 6SN7GT t-plate.  This is the only american tube brand I haven't heard so I was really happy to see this one, and the tube is pristine.  Tube 5 got even more interesting.  The DeForest ended up being a Japanese black plate Hitachi 6SN7GTB.  I've really wanted to hear one of these too so score #2.  Best surprise came last: the tube marked Eico ended up being Italian made, though exactly who made it I do not know.  It is a GTB tube with offset grey ladder plates and very clear micas.  So no huge score like a Fivre or Marconi in disguise, but I'm still excited to find out what it sounds like.
 
Listening to them all will be a good time for sure.  There is definitely more than $35 worth of tubes here so I think I did pretty well.

 

[dminches]

Well done.
 
If you could post pictures that would be great.  That's the only way we can learn!
 

 

[Xcalibur255]

I'll definitely do that at some point.  I just cleaned them all today so I'm not really up for digging all six out of their boxes again right now.
 
I started off with the 50's RCA GT in the amp; figured I'd build my way up to the best of the bunch.  It sounds pretty nice actually.  I had a Brimar GTY clearglass in just before and the two actually sound pretty similar to my ears.  The Brimar sounds a bit faster and edgier, more extended on top and has slightly better bass definition.  Both tubes excel at bringing out the texture of midrange tones.  This has that classic thickness in the lower midrange that I don't care for in RCA tubes though.  I suspect the GTB RCA will be the same only less refined more or less.  I have no expectations for the other four tubes and those are the ones I'm excited about.

 

[rosgr63]

Well done Xcalibur!
 
Tube #5 is likely to be a SICTE or an ATES (Italian RCA), if the micas are transparent.
 
 
 

 

[Xcalibur255]

It matches the SICTE tube exactly, only branded as EICO.  Do they have a good reputation?  Thanks for the help with the ID rosgr.

 

[rosgr63]

SICTE have a good reputation.
There are a few versions some with completely smooth flat plates others with flat ladder type plates and so on.
 
One of my favorites has black type plates as shown here.
 

 
 
 

 

[Audio-Omega]

Is there a particularly good tube for movie scores ?  I want music to be fast, tight, clear and with good resolution.  Sylvania 6SN7GT is my favourite so far.  

 

[musicman59]

Quote:

Is there a particularly good tube for movie scores ?  I want music to be fast, tight, clear and with good resolution.  Sylvania 6SN7GT is my favourite so far.  

I love my Sylvania 6SN7WGT brown base and chrome top.
 
 

 

[rosgr63]

If you like the Sylvania sound I would also recommend the 6SN7W Short Bottle, Black Base, with the lower mica inside the base.
 
I don't know if it will fulfill all your expectations, but it's a tube worth trying.

 

[Skylab]

All of those Sylvanias are very nice.  I am using 6SN7WGTs in my Cary SLP-05, and they sound terrific.  Sylvania made some really nice tubes.

 

[dminches]

Rob, does those have a brown base and silver top?