Monitor selector. Avoid "click"

[dirty1_1garry]

Hi there!

I need a simple monitor selector.
DA converter > volume controller > monitor selector > few active monitors

So task sound pretty easy: one balanced input, two balanced outputs and DPDT switch between (for one channel only)

But , here is a nuance! When you switch between monitors you hear that molesting “click” sound.
i want to keep my switcher passive, so no relays in it, passive switches only, toggle or rotary.
I’ve tried a couples methods how to avoid that “click”:
- connect 1M resistor between swathing pins of outputs
- connect 4K7 + 2nF between pin 2 and 3 of outputs
- use make before break switch
nothing is happens. Still hear that “click” in the moment when switch goes from one monitor to another.

Is there any real methods?)

 

[ruairioflaherty]

First you need to understand what is causing the click.  Are you getting the click when no audio is playing?  If so you probably have a low level DC offset on the line, check this using a multimeter.

If you are talking about clicks when audio is playing that is unavoidable with such a simple circuit.  You could use FET, opto or VCA  switching to give a crossfade type effect but IMO it's not worth it.

What D/A and monitor controller are you using?

 

[dirty1_1garry]

First you need to understand what is causing the click.  Are you getting the click when no audio is playing?  If so you probably have a low level DC offset on the line, check this using a multimeter.

If you are talking about clicks when audio is playing that is unavoidable with such a simple circuit.  You could use FET, opto or VCA  switching to give a crossfade type effect but IMO it's not worth it.

What D/A and monitor controller are you using?

Looks like I'm getting clicks with and without audio.
So I need measure DC between pin2 and 3 of input XLR and pin1(gnd), right?)

D/A - Apogee DA16
monitor controller - diy one, http://www.proharmonic.com/articles/AT78_OTB.pdf
all ground pins of xlr's interconnected.

 

[ruairioflaherty]

Yes, that's it.  I would expect that the output of the Apogee is AC coupled but who knows.

 

[dirty1_1garry]

I found a funny thing.
Using make-before-break switch with active foster 6301 monitors (switch between left and right channels) there is no any clicks! But if I connect it to ns-10m monitors with crown d-75 amp gives an audible click even if there is no audio.
Looks like that click depends on the output source.

I measured VDC between pins 1 and 2/3 of input source gives = 0.017V (closer to error of voltage meter). VDC between pins 1 and 2/3 of output source gives = 0.022V

 

[nielsk]

You can try 1-5 is meg resistors across the switch contacts, also by using a 4 pole switch wired to connect + & - on the "un-selected" inputs, they will be muted, curing all sorts of potential problems

 

[Chuckles]

Click comes from two places.

If you are switching while audio is playing, the sudden interruption or starting of the signal gives the illusion of a click. This can only be fixed by using opto-resistive couplers to do the switching.

If you are getting clicks when there is no signal then it means there is a DC bias on one or more of the lines. Even 2mV of DC is enough to cause clicking. If your signal is coming from the output of an opamp there may be a couple mV of DC on the line. Use your DMM to look for and DC voltage on the lines. If there is, try connecting a 10K resistor to ground. If the DC voltage does not go away you may have to put a non-polar electrolytic capacitor in series with the line as well s the 10K resistor to ground to stop the DC bias from getting through. A 100µFd 16V capacitor works almost everywhere,

You would be amazed how much gear has some DC on its output or input.