opinions on this channel routing arrangement

[Dimitree]

In my DIY console that I'm currently building, for the routing of the channels to the buses, I'd like to have three push switches that route the signal to their corresponding bus #1 #2 or #3. If no switch is pressed, then the signal goes to the main Mix bus. Of course as soon as one of the switch is pressed, the connection to the main Mix bus is broken. So you either route the signal to the main Mix, or to one of the buses.
For all the buses, the summing is done with virtual earth summing, and the "rbus" resistor values is yet to be determined.

Do you see any downside in this arrangement that I drawn?
I see those two aspects to consider:
1) there is a priority in the routing, ie pressing both #2 and #3, signal goes to #2. That does not bother me.
2) bus resistors are left floating when the signal is switched off from their bus. I don't know how much this could be an issue, considering that the switches would be placed really close between them and between the buses, on the PCB

what do you think? is there something I didn't consider?
thank you

 

[dogears]

i'd suggest paralleling the switches so you can select any or all. the "permissive" arrangement is kind of counterintuitive to me, plus there is no way to un-assign the channel from the bus.

i'd also suggest flipping the switch arrangement if youre using VE summing. the old school way is to toggle the bus from the signal or to ground through the resistor. meaning, the signal flow is signal to normally open, common to resistor to bus, and normally closed to ground. engaging the switch ties the signal to the bus through the resistor. that makes the gain on the bus constant, but you don't get any noise benefit from turning a channel off.

if you flip the arrangement so that it is signal tied to bus resistor then switch common, and the switch selects from tying the resistor to the bus or ground, you reduce the gain and noise as you turn channels off.

 

[Dimitree]

thanks! yes I'm following your advice and adding another switch for the main mix bus. I'm also reading that this configuration could lend to bad crosstalk performance at higher frequencies.

Do you think the two approaches can coexist? The idea is to have passive mixing (Neve 1272) on the main mix bus, and virtual earth summing on the other buses. For the virtual earth summing I flipped the switches/resistors as suggested, instead on the passive mixing bus, the bus resistors gets grounded when not used.
Do you see issues in this?

 

[dogears]

i don't see why that would be a problem or that this would inherently generate crosstalk. i think that would be more a function of layout than anything else.

with this approach, calculate the parallel impedance with everything turned on, and make sure that it is high enough that your driving amps aren't sad.