DCAudioDIY.com

Grover used a 6N7 as an input tube for multiple amps, I'm sure he could provide some good info.

Administrator/Moderator/Almighty one, is Grover subscribed here?

Not to the best of my knowledge...

Roscoe

_________________
I can explain it to you, but I can’t understand it for you.

Okay, here we go! Thanks, Roscoe.

Parallel 6N7 is a great tube, gain of 35, Rp around 22K I think. Very musical. Check out Thomas Mayer's blog:

http://vinylsavor.blogspot.com

He has a "Tube of the Month" feature and some of these are inexpensive high-gain tubes that have been overlooked by the hobbyists. You might find something you like there.

Oh, as for the 6N7 as a differential amp, it's great. Again, gain of around 35. Don't know the Rp for the individual sections. There is a well-known vintage amp that used this as a differential phase splitter but I can't recall which one it was. I think you would typically use about 47K plate load per section running at bout 3 ma each.

It's the same as 6A6 and 53, electrically.

Here's a Tong-Sol data sheet for the 6A6, courtesy of Frank's Electron tube Pages:

http://tubedata.tubes.se/sheets/127/6/6A6.pdf

OK, sorry, that one's for Power Duty, not small-signal use.
Here's the set of curves we're looking for....

http://tubedata.tubes.se/sheets/021/6/6A6.pdf

Oh, excellent, thanks!

How about a 1633 as a replacement for one of the 6SN7s? It's a special grade with tightly matched sections.
It's for military radios, so it has a 25V heater, but otherwise it's just a 6SN7 with matched sections.
Yes it's Octal....
Yes, you can borrow a couple if you want to test them....

http://frank.pocnet.net/sheets/049/1/1631.pdf

FerdinandII,

Interesting choice - I've not heard about that one! Let me stir it into the mix and see what drops out. The heater doesn't throw me. As you say, it looks like another 6SN7/6J7 but with a difference heater requirement. It also looks like the plate ti reduced to 300V from 450V, and plate dissipation drops from 7.5W to 2.5W. Grid-to-Plate capacitance is a little lower, and you say the sections are better matched. Let's see if I can determine how much head room I have with these.

_________________
- Guy

Guy,

Sorry for any confusion, but I meant to recommend it to Stuart, since he's gone all DIFF AMP on me......

Nothing that would prevent you from using it, but NOS choice is limited and they can be pricey.