Cathode Follower Switching

[Zenabi]

I am trying to switch a cathode follower in and out of the circuit. Please see attached pic for reference.

The left side is taken from Merlin's dccf page.
The right side is what I'm replacing the starred resistor with.

A dpdt switch will be used. One side will connect/disconnect 100ohm resistor. The other side will connect tonestack to either plate or cathode. (A 3pdt could also be used to change the slope resistor in the tonestack as well.)

When in cathode follower mode, the switch will connect the 100ohm resistor to bypass the 1M resistor. The tonestack will be connected as usual.

When in plate driven mode, the switch will short the 100ohm resistor and connect V2 to ground. The tonestack will disconnect from the cathode and be connected to the CR on the bottom.

Will this work?
Am I overcomplicating this, is there a simpler way to do this?

Thanks.

[Zenabi]

Bump

[Zenabi]

Bump

[ghostinthescope]

Can you post a more detailed schematic of the switching scheme you are proposing?

And... this thread may be of interest to you?

https://el34world.com/Forum/index.php?topic=31546.0

[sluckey]

Your goal is to switch between plate driven and cathode driven tonestack? There is no need to switch anything between the tubes. I would do this...

[Zenabi]

Can you post a more detailed schematic of the switching scheme you are proposing?

And... this thread may be of interest to you?

https://el34world.com/Forum/index.php?topic=31546.0

Thanks for the link. Long read. But I learnt a lot and it helped me.

[Zenabi]

Your goal is to switch between plate driven and cathode driven tonestack? There is no need to switch anything between the tubes. I would do this...

Thank you.
Yes that's exactly what I want to do, and was my first instinct.

My own version is actually similar, except that when in plate driven mode, the DC coupling is through a 1M resistor. I could just break the connection here, but somehow feel the 1M would be safer (?).

The reason why I'm going through this trouble is that, I think the CF affects the gain stage it's coupled to. I know it at least steals some current from it. What tonal effects I'm not sure.

To be clear, I want to do it as you've shown (I'd probably add resistors off the coupling caps to ground). As it's simple and there's no DC on the switch.

[Merlin]

My own version is actually similar, except that when in plate driven mode, the DC coupling is through a 1M resistor.

A series 1M resistor would give you a terrible loss and crappy response from the tone stack

[Zenabi]

A series 1M resistor would give you a terrible loss and crappy response from the tone stack

Thanks for the reply. Sorry, my diagram was unclear. I redid my diagram using Sluckey's. See Fig1.

I guess my question really is whether breaking the connection between the CF and plate of gain stage has any effect. See Fig2.
If leaving the cathode follower connected has no tonal effect when I'm plate driving my tonestack, I'm just doing exactly what sluckey showed.

[Merlin]

I guess my question really is whether breaking the connection between the CF and plate of gain stage has any effect. See Fig2.

If there's a 1Meg resistor in series with the CF grid, then leaving the CF connected won't have much effect. But with 100ohms it may have some clipping influence if you leave it connected.

[Zenabi]

If there's a 1Meg resistor in series with the CF grid, then leaving the CF connected won't have much effect. But with 100ohms it may have some clipping influence if you leave it connected.

Thanks, Merlin.

I suspected there to be an influence and thought that a break in the connection was needed.