6922 vs 6SN7

[Rodango]

What I'd like to know is the voltage swing capabilities of the 6DJ8 vs. the 6SN7. I have heard that the 12AX7 is incapable of the required voltage swing to drive KT88s to their full ability and that 6SN7s are preferred for the job. But how about 6DJ8's? Can they adequately drive KT88 grids?

My favorite 6DJ8 became obvious to me when I was rolling tubes through my CD player. When I put the USN 7308s in, the sonic quality was so impressive that stopped right there. They are amazing.

[Geek]

Hi,

Originally posted by dsavitsk
How are you using these?

They don't like the fancy stuff. Straight resistors, maybe a bypass cap on the cathode (unless you're doing a LTP of course) and they sound fine. Think old school with these

Cheers!

[Shoog]

I use PCC88's in a FVP5 variant (of my own design), it took a few years to evolve the design and now it is better than the CCS loaded 5687 preamp I built. It came out favourite in a DIY meet shoot out. No hint of bright tizz, but it took a lot of fine adjustment to get it to that.
As others have said, its how you use these valves that makes the difference, and generalisations are less than useful.

Shoog

[kmtang]

I bought a couple of the TFK PCC88 and use them in my clone Audio Research SP-10. It sound so good.

My friend Albert use the same in his Audio Note DAC's SRPP buffer stage. He just loves it.

For 6SN7's, I collected couple boxes of them. I found the Loctal base ones 7N7 has much more open sound than the 6SN7. Possibly the Loctal version were designed for high frequency operation that has lower inter grids capacitance.


Johnny

[refference]

Hi all ,

Just in time , one more opinion , Morgan Jones wrote on his book , Valve Amplifiers :

" A total of 529 valves was tested , and the results show that
the reputation of the 6SN7 / 7N7 is well justified .
..... valves from the 6SN7 / 7N7 family are likely to produce the
lowest distortion .
Valves with B9A bases are significantly poorer"

What do you think about that ??

Regards ,

Carlos

[Miles Prower]

Originally posted by refference
"A total of 529 valves was tested , and the results show that
the reputation of the 6SN7 / 7N7 is well justified .
..... valves from the 6SN7 / 7N7 family are likely to produce the
lowest distortion .
Valves with B9A bases are significantly poorer"

What do you think about that ??

I've used 6SN7s and 6CG7s mainly as cathode followers. I also used a 6J5 (like 1/2 of a 6SN7) as a gain stage without cathode resistor bypassing, and I certainly don't have any complaints as to how they work.

[Original Burnedfingers]

I'm fixing to build a tube line stage and have some 6922's(Siemens CCa) and nos 6sn7's and would like to know which tube is best for this application in terms of sonic quality?

I would recommend building Franks line stage that you can find doing a search. I would also build a 6922 that I'm sure somone could provide a schematic for.

Make them both and then evaluate and keep the one you like.

[the_manta]

Hi Folks !
6SN7/7N7/6CG7/6FQ7 can sound quite OK. But only when operated properly ! Menas over 200V Ua and about 10mA current. Then they operate very linear. Sound is typical triode like and not with an exaggerated midrange as a ECC83.

My favorites are high gm pentodes like E55L, E810F, E280F, 12HG7, 12GN7, EL802 etc. I like pentode sound much more than triode sound. More dynamics and natural.

Regards, Simon

[john]

I would also suggest that you should build both line stage. And be happy with the one that will suit your ears.

Boy oh boy! Plenty of 6sn7s' tube rolling sessions will be undertaken since you haven't mentioned what particular brand of 6sn7 you'll be plugging in on your linestage amp. Each make of 6sn7 tube got it's own unique sonic imprint on every circuit design. And same thing goes with the 6922 tubes.

[Miles Prower]

Originally posted by the_manta
Hi Folks !
6SN7/7N7/6CG7/6FQ7 can sound quite OK. But only when operated properly ! Menas over 200V Ua and about 10mA current. Then they operate very linear.

That's not necessary. Here's a loadline I did for the 6J5. As you can see, this is quite linear with an estimated THD of 0.008%. As this stage was actually used, it would be even better since the gain was a bit too high, and so the cathode bias resistor wasn't bypassed. As this was the first voltage amp, the required output swing wasn't anywhere near the max possible, so that would make the THD even less than the estimate, based on max swing. That also made for a convenient gNFB summing node.

Works just great.

Drawing a heavy current like that would only be necessary if you were using it as a cathode follower driver for Class AB2 grids. (And then you'd be better off using a MOSFET source follower to get that Zo even lower than that of any hollow state device.)