Building a stupid simple monitor switcher

[samguaiana]

Hi there!

I would love to build a painfully simple, yet very high quality monitor switch. I don’t need volume and it can be fully passive. I would do either two or three sets of monitors. Are there any solid schematics for something like this?

Thanks!

 

[Dylan W]

Sure, I have one in my current setup. It works great. All you need is a 4-pole switch. Wiring is pretty self-explanatory: L+, L-, R+, and R- each get their own pole. Input for each leg goes to the common of each pole, and outputs from the positions. All pin 1 go to chassis, or you can get a 6-pole switch and switch the shields.

I used an aluminum Hammond pedal enclosure with a switch like this:

https://www.ebay.com/itm/374323229933
Unless you’re talking about speaker-level switching, which is much the same, you just have to make sure the switch is adequately rated. In that case, both legs of the unbalanced speaker signal would need to stay floating.

 

[Brian Roth]

Hi there!

I would love to build a painfully simple, yet very high quality monitor switch. I don’t need volume and it can be fully passive. I would do either two or three sets of monitors. Are there any solid schematics for something like this?

Thanks!

I'm assuming line level audio from a desk or converter output. Balanced signal from the source? Balanced inputs into powered speakers?

Bri

 

[samguaiana]

I'm assuming line level audio from a desk or converter output. Balanced signal from the source? Balanced inputs into powered speakers?

Bri

Yes, all of the above. Basically trying to solve the problem of keeping my sub active while switching speakers but keeping the Apollo as my monitor controller for volume/talkback

 

[Whoops]

"I guess just an enclosure with a 2 pole 3 position rotary switch would do what you want to achieve"

EDITED: it needs 4 pole 3 positions. The 4 poles allow to switch 2 balanced signals (Left and Right)

 

[MicMaven]

I guess just an enclosure with a 2 pole 3 position rotary switch would do what you want to achieve

Yes. I use either rotary or simple toggle switches for this sort of thing - and ... um ... errrrr ... ahem ... (just thinking aloud) it seems I always use break-before-make switches - not the make-before-break type. Or, am I conn-fused? My road to Heck is well paved with all of my good intentions! Anonymous ...

 

[Whoops]

Break before Make is what makes sense to me

 

[scott2000]

it seems I always use break-before-make switches - not the make-before-break type.

yes...a.k.a. non-shorting

 

[RCAguy]

Another consideration is avoiding ground loop hum. If the monitor selection is internal to say a mixer, single pole switching of the (unbalanced) signal is fine; if an assortment of external sources, it's best to switch both the signal and shield (signal return).

 

[ccaudle]

it's best to switch both the signal and shield (signal return)

It is best to switch differential signals so the shield is not also the signal return.

 

[RCAguy]

It is best to switch differential signals so the shield is not also the signal return.

Obvious if balanced - I was referring to unbalanced wiring (as implied by the above "2-pole" suggestions).

 

[ccaudle]

as implied by the above "2-pole" suggestions

Yeah, those earlier suggestions really should have been 4-pole switches since the OP clarified that this is for balanced signals.

Switching the shield always makes me squeamish, it basically defeats the purpose of using the outer conductor as a shield when you treat it that way. It would be like taking a coax cable and cutting a chunk out of the middle and replacing with just a couple of wires.

 

[Whoops]

maybe I'm missing something but as far as I see it for Balanced signals only 2 poles are needed, one pole for signal + and another pole for Signal -
Or 3 poles if you want to switch the shields/ground also

I don't see why 4 poles are needed, but as I said, maybe I'm missing something so let me know

 

[ccaudle]

I don't see why 4 poles are needed

Presumably the OP is not working with a mono monitoring system.

 

[Whoops]

Presumably the OP is not working with a mono monitoring system.

Ohh Yeah

I was sure I was missing something really basic, and I was actually, sorry for my mental blockage.

Thanks mate

 

[scott2000]

Posted this 3 way Alps switch earlier with a drawing made from something sitting here but it had errors...
Hopefully this doesn't have any and makes some sense...

https://www.mouser.com/ProductDetail/Alps-Alpine/SRRN134300?qs=4QwOlnKYOEtv3KD8fG0jiA==

 

[RCAguy]

Yeah, those earlier suggestions really should have been 4-pole switches since the OP clarified that this is for balanced signals.

Switching the shield always makes me squeamish, it basically defeats the purpose of using the outer conductor as a shield when you treat it that way. It would be like taking a coax cable and cutting a chunk out of the middle and replacing with just a couple of wires.

Agree. For balanced, I leave shields solid at the source, and open at the destination (or through 20nF in a high RF environment), then switch both legs of audio inputs to preserve CMRR.

 

[studiog]

Not extremely simple and now obsolete but the old ssm2404 logic controlled switches were great. I made a studio main monitor circuit, balanced and totally click less using these and a simple logic control with push switches.

 

[zzzzz]

I’ve built several A/B switchers using these old KENTEK data switch boxes found at swap meets for pennies and among ewaste. Switches are thru-hole solder tabs, have plenty of poles, feel good, and are nice looking enclosure (paint em something cool!) only annoying part is removing all of the original wiring from the switch.

The ones I have used were for switching parallel ports for printers. Punch out the back panel for XLR jacks and you’re good to go.

https://www.ebay.com/itm/145254662675

 

[nsalis]

When I hear about the need for a monitor switcher, SPL products always come to mind.

https://spl.audio/en/spl-produkt/control-one/