Question about Summing inputs

I am debating two options for intercom in the 10. I have decided that an audio panel isn't necessary.

Option 1 is to use an intercom with no unswitched inputs. In this scenario, I would need to sum three 500 ohm inputs with 220 ohm resistors (2 comms and EFIS) into the primary Comm intercom input.

Option 2 is to use an intercom with unswitched inputs to avoid summing.

Option 1 is preferred as that intercom has 2 music sources and a crew mode. This will be going in a ten, so care about back seat passengers. That said, I don't want to have any issues, such as reduced volume by summing inputs.

Is option 1 doable without any problems or hassles?

Larry

RV-10 intercom

On my RV-10 flights with backseat pax, being able to isolate rear pax conversations was useful for pilot and rear seat pax. 4 people chatting can be bad when ATC calls and they don't know to be quiet. After briefing that if the rear needed me to tap me on a shoulder, I often isolated the pax so they could be in their own little world.

I did something similar in an RV-3 recently with two radios and no intercom. The AeroElectric PDF suggested 150 ohm, 1/2 watt resistors in this setup and it worked well. A toggle switch (ACS p/n 11-04237) was installed to switch between radios for MIC and PTT.

You could roll your own Pax isolation as well with appropriate switching.

Vern said:

On my RV-10 flights with backseat pax, being able to isolate rear pax conversations was useful for pilot and rear seat pax. 4 people chatting can be bad when ATC calls and they don't know to be quiet. After briefing that if the rear needed me to tap me on a shoulder, I often isolated the pax so they could be in their own little world.

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Good advice and this is why I like the 6 passenger intercom. I can isolate just the passengers or isolate them and the co-pilot. However, it doesn't have the unswitched audio ports for monitoring my second comm.

Larry

Raymo said:

I did something similar in an RV-3 recently with two radios and no intercom. The AeroElectric PDF suggested 150 ohm, 1/2 watt resistors in this setup and it worked well. A toggle switch (ACS p/n 11-04237) was installed to switch between radios for MIC and PTT.

You could make roll your own Pax isolation as well.

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This is helpfull, but still curious if the three connections that I am planning would push it too far.

Larry

Unlikely to be a problem, but you can get a summing amp from many sources if you want to guarantee success.

Vern said:

On my RV-10 flights with backseat pax, being able to isolate rear pax conversations was useful for pilot and rear seat pax. 4 people chatting can be bad when ATC calls and they don't know to be quiet. After briefing that if the rear needed me to tap me on a shoulder, I often isolated the pax so they could be in their own little world.

Click to expand...

Also handy for when my wife wants to sleep and not be bothered with ATC calls.