Finally started on my 6L6 amp. Need tube suggestions.

[lazzer408]

About to start on my 6L6 PP amp but I thought I'd ask for opinions on a few things.

I have the following to play with.

400v B+
12AU7
12AX7
6SN7
6EU7
6L6

I'm quite happy with the floating paraphase inverter I used on my 6V6 PP amp but it could use a little more gain. I do like the cathodyne PI too. Any suggestions using drivers after a PI or should I just drive the 6L6s with the PI?

 

[multi]

Are you going to run the 6L6 as Pentodes, Ultralinear or Triode?
Phil

 

[lazzer408]

Pentodes for now. At the moment I don't have UL OPTs for it.

Class of operation will be AB.

 

[Parafeed813]

My 6l6 amps were inspired by the 6L6 AB2 thread here.
It has an LTP splitter (5814a) into an LTP driver (6SN7) and a MOSFET buffer for the AB2 grid current.
The 6L6GCs run at 440V in triode mode, no NFB.
Plenty of power and I like the sound.

 

[artosalo]

...I do like the cathodyne PI too. Any suggestions using drivers after a PI or should I just drive the 6L6s with the PI?

Cathodyne works very well and no drivers are needed.

Here is one version of 6L6 PP I have done:

An externally hosted image should be here but it was not working when we last tested it.

 

[dirkwright]

Yeah, with the outputs in pentode mode, they are sensitive enough not to need a driver stage. You would have to modify it unless you want to provide a negative supply.

 

[lazzer408]

Cathodyne works very well and no drivers are needed.

Here is one version of 6L6 PP I have done:

Would a 6SN7 work in place of the 6SL7. Gain is much lower. Or 12AT7?

 

[artosalo]

The sensitivity would be quite poor with 6SN7.
If you want to use 12AT7, 6SN7, etc. then a LTP phase inverter with one voltage amplifying stage is better topology.

Something like this:

An externally hosted image should be here but it was not working when we last tested it.

 

[lazzer408]

I got one channel done. Wired a 12AX7 as a floating paraphase. With only one channel wired, B+ sits at 420v with screen supply at 400v. What should the screen voltage be? Datasheet calls for 400v B+, 300v screen.

 

[artosalo]

400 V for screen and anode voltage is fully OK.
Adjust the cathode current to some 50...55 mA/tube.

 

[lazzer408]

Will do.