Switching between two PPIMVs

[Leevi]

Has anyone succeeded to prevent popping when switching between two PPIMV?


/Leevi

[shooter]

prevent popping when switching between two PPIMV

short of power down, switch, power on, you might be on a fools errand, but I've ran a few errands like that

[pompeiisneaks]

The popping comes from the buildup of current that has no path, I thought with any popping switch you can resolve the popping by putting in a significantly higher resistor to ground than the normal path, say you have 1M audio pots put in a 20M to ground so when the switch is temporarily 'open' it has a path somewhere until the switch re-engages and then you have a better path again for the signal. 

IN the case of a PPIMV usually its a 220/250k dual pot or some such, so you may do fine with a 1M or so but still even higher is better, meaning the current doesn't want that at all if he PI is in circuit.

~Phil

[Leevi]

The following solution is not optimal but does it pop?


/Leevi

[VMS]

Have you tried it like this:

[kagliostro]

Ciao Risto

Your schematic has something of odd ..... why the MV to be switched are in series and not in parallel ??

also VMS schematic has something strange ......


EDIT:


I don't think this solve pop problems, but will be the way I'll swap between two different PPIMV



the switch is draw as a pair of DPDT (as to semplify the schematic) but use one 4PDT

to solve pop problems, as told, a high value resistor used in parallel to switch contacts

Franco

[VMS]

also VMS schematic has something strange ......

You maybe right, how about my second attempt?

[kagliostro]

A lot better VMS  

But now that I've seen it better, I think that also the  other one will be doable (and only a very small part of the signal will go where you don't want)

Franco

[VMS]

more i think about this more unsure i am on my suggestions 

[kagliostro]

The way I've draw the swap will exclude for sure the unused pots from the signal path

but may be also your circuit is doable without problems .......... or not 

Franco

[Leevi]

Thanks for your proposals guys.


My schematic was not meant to be complete, the idea was just to try prevent pot and keep some kind of usable two-master system.
The basic idea was to disconnect the non-active master by isolating it from ground.
But the setting of the non-active master will still affect to the wholeness since the current partly goes through its pots.


VMS's proposal are not complete either and I see the second one better.


Franco, your proposal seems to be complete since the master are fully separated from each other
but I think it will definitely pop.


/Leevi

[kagliostro]

Ciao Risto

As I told, my schematic is without any shrewdness about preventing pops, it was only to swap completely the unused PPIMV out of the path

to avoid pops you must add resistors in parallel with switch contacts (I think)

Franco

[VMS]

How about pots parallel and switch between wipers with make before break switch

[Leevi]

Do you mean something like this?
I added resistors across the switches to prevent pop.


/leevi

[VMS]

Yes something like that.


I'm just throwing ideas and hoping that the smarter forum members will chime in   

[kagliostro]

I agree, something like that

Remember that connected and switched that way the pots are in parallel, so if you use 1M pot is like you use 500K pots

EDIT: 

Don't know if this will give a different load to the previous stage because here we have AC and no DC

Franco

[Leevi]

Remember that connected and switched that way the pots are in parallel, so if you use 1M pot is like you use 500K pots

Yes, I have noticed that. I think two 500K pots would still work fine since the resistance will be 250K per side.
1M is probably a better choice?


Your proposal is worth to try.


/Leevi

[DummyLoad]

k. nailed it - no interaction between the two dual-gang pots.


use a 22M across all 4 outer poles of the switch.


--pete

[kagliostro]

Ciao Peter

Are you sure ?

I was thinking that if there is a charge on the caps as to avoid pops the resistor must perform a discharge path for the instant on which the switch is acted and the cap is not connected to the wiper of the pot

Something like this



    

Franco

[Leevi]

Thanks guys, now there are many proposals to be tried.


I have noticed that the resistors do not fully prevent the pop especially if you use bigger resistors.
But next time I have double PPIMV case I will try one of those.


/Leevi

[VMS]

i suggest you start with your schem on reply 13.
Less switches less potential pops and you can always double the first caps values if you're loosing to much bass