Balanced Passive Monitor Controller Stereo/Mono switching

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Praqtice

Member
Joined
May 23, 2009
Messages
14
Hello

Attempting to build a balanced passive monitor controller using a 10k 4-pole 24 step attenuator with a 4PDT on-off-on switch for input selection/mute and a 4PDT On-On switch for output selection.

Source impedance from DAC is about 100R and monitor amp input impedance is 30K. Both balanced connections. I intend to connect speakers from controller with 5m xlr cables and DAC to controller input with 1m xlr cables.

However I’m having a bit of trouble working out how to implement a Stereo/Mono switch into the design. From what I gather there’s many ways to do this but ideally I’d like to do it with a toggle or rotary switch.

If I were to use a 4PDT switch for instance, could I use a design like this drawing (attached) of the 4PDT 3x4 pin arrangement? Apologies for scribbliness. If so what resistor value would be recommended? 1k?

Or would a design like this rotary switch pin arrangement from a well known passive monitor control design work better/worse?

http://www.audiotechnology.com.au/wp/wp-content/uploads/2014/04/m-s-r-switch-575x201.jpg

I understand this design contains no resistors so presumably the output will jump up 6dB when in mono position. Is there any way I could implement some resistors into this design to account for this?

Many thanks in advance
 

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Matt C

Well-known member
Joined
Apr 29, 2012
Messages
235
Location
Saint Paul, MN, USA
in my passive monitor controller I used the method you linked to (on the audio technology website), and it seems to work fine. Just a DPDT toggle connecting L to R.  I don't think there's any significant level increase using this method
 

Praqtice

Member
Joined
May 23, 2009
Messages
14
Thanks Matt, I might just pick up a Lorlin and give that a whirl. Do get much clicking/popping when using it?
 
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