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Monitor switching

Postby Random Guitarist » Wed Apr 29, 2020 5:05 pm

I'm setting up a small secondary workspace and need monitor swithcing.

At the moment I'm thinking about a 4 pole double throw switch in a tin with balanced connections. (I do have an old mpatch that could be used but the switches can be crackly and I suspect it may slightly degrade the sound.) I'm assuming a switch in a shielded box is about as good as things can be for this application?

Am I missing anything?

Should I be using high value resistors across the switch to prevent clicks and pops when switching?

Thanks,

Grant.
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Re: Monitor switching

Postby Hugh Robjohns » Wed Apr 29, 2020 5:13 pm

Random Guitarist wrote:I'm setting up a small secondary workspace and need monitor swithcing.

I assume we are talking about monitor loudspeakers here, and balanced line level signal switching?

At the moment I'm thinking about a 4 pole double throw switch in a tin with balanced connections ... I'm assuming a switch in a shielded box is about as good as things can be for this application?

Yes, that would do it. There are (arguably) better ways of doing it, but that is the simplest by far.

Should I be using high value resistors across the switch to prevent clicks and pops when switching?

You could... It would potentially help to prevent the unused monitor picking up nasties. Wire 100k Ohms to ground on each leg of the outgoing lines. Ideally they should be closely matched 1% or better to avoid unbalancing the lines.
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Re: Monitor switching

Postby Random Guitarist » Wed Apr 29, 2020 5:29 pm

Thanks for the rapid reply.

Yes, balanced speakers, interface will be an Audient ID22. Probably using 1/4" TRS jacks for the box.

For the resistors I'd assumed higher would be better and was thinking 1M, is there a particular reason why 100k is prefereable?
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Re: Monitor switching

Postby ef37a » Wed Apr 29, 2020 6:01 pm

Random Guitarist wrote:Thanks for the rapid reply.

Yes, balanced speakers, interface will be an Audient ID22. Probably using 1/4" TRS jacks for the box.

For the resistors I'd assumed higher would be better and was thinking 1M, is there a particular reason why 100k is prefereable?

If I may Hugh? The idea of the resistors is to drain any residual current from the output coupling capacitors* in the source equipment. GOOD design dictates this should be done anyway but, 't'appen.
The resistor and the associated capacitor will form a 'time constant' and you want that to be a quick as possible so that the charge does not stay long on the output. That indicates a low value of resistance but that might load the source unduly and cause signal loss or/and even distortion so, as is usual in this world we compromise! 100K is a pretty common value for this purpose.

*How TF we carry on with the latest fashion for DC coupled outputs with fekking VOLTS on them I cannot say! I DO hope all monitor amps are suitable protected but since these voltages can be + or - of chassis I foresee problems? I doubt many monitors amplifiers have non-polarized input caps? (Wil, am i being paranoid here?)

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Re: Monitor switching

Postby Kwackman » Wed Apr 29, 2020 6:46 pm

Random Guitarist wrote: interface will be an Audient ID22. Probably using 1/4" TRS jacks for the box.

The iD22 has two pairs of speaker outs built in, you can switch between them by setting up the "F" buttons....
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Re: Monitor switching

Postby Hugh Robjohns » Wed Apr 29, 2020 6:59 pm

ef37a wrote: The idea of the resistors is to drain any residual current from the output coupling capacitors* in the source equipment. GOOD design dictates this should be done anyway but, 't'appen.

I'd assumed the souce device's output would already have their own drain-down resistors anyway. But you are right in that it is a requirement.... However, I was actually more concerned about not leaving the unselected speaker with open-ended inputs!

As for the suggestion of 100k? It needs to be high enough not to drag the speaker's input impedance down too far, but low enough to pull the unused input lines down effectively.
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Re: Monitor switching

Postby Random Guitarist » Wed Apr 29, 2020 8:56 pm

Kwackman wrote:
Random Guitarist wrote: interface will be an Audient ID22. Probably using 1/4" TRS jacks for the box.

The iD22 has two pairs of speaker outs built in, you can switch between them by setting up the "F" buttons....

It does, but the second outputs are already spoken for. :)

Thanks,

Grant.
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Re: Monitor switching

Postby Kwackman » Wed Apr 29, 2020 9:05 pm

Random Guitarist wrote:
Kwackman wrote:
Random Guitarist wrote: interface will be an Audient ID22. Probably using 1/4" TRS jacks for the box.

The iD22 has two pairs of speaker outs built in, you can switch between them by setting up the "F" buttons....

It does, but the second outputs are already spoken for. :)

Thanks,

Grant.

Ah. I should have known it couldn't be that easy!
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