Parallel 2nd stage, kinda

[Smokebreak]

I could use some extra sets of eyes on this.
My goals are:

1: Standard 1987(besides the omission of the Lo input on the 820r input)
2: Standard 1987 Jumpering capability
3: Extra lil' gain stage in front of either Treble input
4: 2 + 3

I think this will work, but my concerns are(when running "4"):

A: having signal run through 2 gain stages on one side, and 1 on the other, before it hits the mixer. I'm not even exactly sure why it's bothering me
B: essentially connecting the grids via the switch, with what will be probably a 10K stopper. I'll shield that, but besides that, I'm not sure why that's bothering me either!
More than 1 wire from that input grid just seems like a bad idea. I've done the same switching with single input amps with success, but I always take the switching signal from before the first 68K

Thoughts?

[martin manning]

If you jumper the inputs and go through two gain stages on one side and only one on the other you will have phase cancellation.

[Smokebreak]

Ah yes. I could put to use the unused triode upfront in the 820r channel, but then I've got consecutive parallel stages. How does that sound?

[Smokebreak]

Ok I think this will work. It basically doesn't allow the 820r triode to pass signal when in higher gain mode, but still allows normal operation of both channels, and (via the treble jack..) added stage and parallel option

[Smokebreak]

For posterity's sake, this switching works well to accomplish parallel/jumpered input and added gainstage to a Marshall type, while maintaining standard treble/bass inputs. I also added a split/shared cathode switch for v1

However, I goofed and forgot to drill a hole for the other gain pot. So, I used a dual gang. The only problem I'm having is that when running the input stages paralleled, I can tell that if I did have 2 pots for the gains, I'd be running the bass channel around 5 when the treble channel is on 10.

I'm trying to find an elegant solution to accomplish this. So far, a 150K from wiper to ground, on the bass gain pot is getting me close, but of course that affects the bass channel when running it straight up, as well.

I'm wide open to any suggestions.

[surfsup]

Correct me if I'm wrong, but with parallel and the second dpdt in the down position, your treble channel will be out of phase at the mixing point, yes?

Might it be better to run a triple pole switch, and combine the two switches into one to prevent this? That extra hole will get you a location for the extra pot you want if a pot fits where the single pole was.

[Smokebreak]

I don't believe so. When in parallel mode , and the dpdt in the down position, the inputs are basically jumpered, and the signal sees the same number of stages at the mixer. The added gain stage is also grounded in this position.
If you are in parallel mode and flick the dpdt up(added stage), all inputs are grounded, basically preventing the user from ever achieving an out of phase signal.