Popping again.....Cap across channel switch?

[pedro]

I decided to change my amp back to indiv clean and OD masters as I prefer the flexibilty - however I am back to my problem of getting loud pop when switching channels. In single overall master topology I simply dont have this problem - there is no pop at all.

Rather than rewire and revert bacl AGAIN to overall master is there anything I can try to get rid of the problem ?

I've checked and rechecked all my switch wiring so I'm sure its not that causing the problem

All I can think is that its a problem with the switch shutting off the signal momentarily and then a spike when the contacts close. Or some sort of contact bounce from the relay. But as I say it doesnt do this in single master topology.

My wiring for the channel switching is exactly as per this schem attached.

Does a cap across the relay or switch work - if so what values ?

Thnaks in anticipation of a problem cured - I really do prefer seperate masters.

cheers
pedro.

[Normster]

Cap across the switch worked for me (and Bob-I as well). 0.1uF/100V should be all you need.

[pedro]

stuck a .1uf 450v across the panel switch which switches the DC supply in and out - and still same problem.

Is it something going on with the signal not the supply ?

This has me stumped - does anyne else have ame popping issues - I think someone reported same problem for a few other builders - Tommy maybe ?

I think I will go back to overall Master and sep clean and OD levels feeding the Master. Frustrating...............Oh Well...........

Pedro

[Tdale]

I haven't come as far as to actually making a Dumble yet..although I have started now.

I asked about the poping relays, just to be sure what to do when I get to the switch wiring..

I got a schematic for optocoupler switching, but I think it would be easier to use relays..if they are quiet..

Tommy

[BobW]

Pedro, initially Try a 1M across the switch contacts from the V1a .047uf contact to the wiper of the HRM OD level pot. If this doesn't work, try a lower value, but don't go below 250k, it may adversely affect the tone/bandwidth. HTH BobW

[Tdale]

Pedro..

What's the difference between OD master and global master? The clean master I know, it's right before the OD/Clean switch. But what's the difference between OD master and Overal master... Where are the two pots placed, in each case?

Tommy

[pedro]

Hi Tommy

if you compare the Hybrid A schem with the others in the file section - say the TR Emerald posting - you will see the difference - either 2 sep vol controls for clean and OD before the PI - or an OD section that then goes to a global master ( which also acts as clean master in CL mode. )
then onto the PI .

cheers
Pete

[pedro]

Normster/Guys,

Have i been thick here ?

Cap across the switch worked for me (and Bob-I as well). 0.1uF/100V should be all you need.

...do you mean put the cap across the relevant relay contacts - not the DC panel switch or footswitch which is what I have been trying ?

pedro

[Tdale]

Is the OD master the same pot at the Level pot in the OD section?

I see the clean master, and I see the global master (in the hybrid A) But the OD master....?

Tommy

[pedro]

The OD "master" is the "OD level" pot on the Hybrid A schem...

cheers
Pedro

[pedro]

Guys,
I've just been reading about popping effects pedals when switching. Seems the solution is to prevent a dc imbalance across the coupling cap feeding the switched signal using a resistor to ground on the output side of the DC blocking coupling cap.

Would a large resistor pulling the output side of the 0.047uF CL2 coupling cap to ground work here ? If so what sort of values - 1M ? Obviously I dont want to lose any AC signal to ground or impair the tone.

??

pedro

[Normster]

I'm just guessing, but the circuits I've seen that switch between caps used a 4M7 to ground.

[pedro]

heres what I tried at "lunch" today working from home....

1) 4.7M resistor strapped from CL2 coupling cap to ground ( before the relay ) result - still get a loud pop when switching

2) so, then tried the 4.7M resistor placed between input leg of PI input cap and ground - result still get a large pop.

3) back to overall master volume relay wiring - Zero popping !!!!

4) back to sep masters - popping !!!!!!!!

HELP !!

pedro

[BobW]

Pedro, Did you try the 1M as suggested on the earlier post?

[pedro]

Bob - not yet - forgot !!! - will try that tonight
cheers
Pete