paralleled SE output tubes

[Colas LeGrippa]

Hi,

I'd like to add an output tube to my new SE build. Can I just run wires straight from the first tube to the other ?

Colas

[RicharD]

You can parallel SE output tubes but your Zout goes down by 1/2.  Assuming cathode bias, you either need separate cathode resistors or 1/2 that too.

[Colas LeGrippa]

I gotta check the filament supply current to see if it can feed another power tube though.
What about the grid stopper and coupling caps? Is it better to use 2 coup^ling caps or just one ?

Thanx

Colas

[RicharD]

Individual grid stoppers so you form a summing network is how I've done it in the past. 

[Colas LeGrippa]

thanx

regards

[HotBluePlates]

Depending on what you're already using, the grid reference resistor ( from grid to ground) may need to be lowered. This is more an issue in fixed-bias amps than cathode bias. In such a case, you might halve the resistor and double the coupling cap value.

[tubeswell]

FWIW here is the schematic of a parallel SE I did at the beginning of the year. I used a switchable 470R in parallel to change the bias. The amp can also run 1 x 6L6 etc