stereo and mono out jacks, wiring question

[lobsternaut]

I'm building a device which will have stereo output via a 1/4 TRS jack. I also want to include a separate mono out jack for venues with limited inputs, or when stereo is not needed. For the mono out I'm looking at the "Stereo-to-Mono Summing Box" diagram in this excellent Rane article: http://www.rane.com/note109.html

My question is: if I include the above mono out circuit, will it negatively affect the stereo out when mono is not in use? I'm asking only because the L/R channels are connected across the resistor network in the summing circuit.

I guess the alternative would be to build a separate little stereo summing box and bring it when I need mono.

[GGBB]

You could use one of those double-shunted trs jacks like the Switchcraft 14B so that when you insert the stereo plug, the connections from the left and right out to the summing circuit are broken.

[lobsternaut]

Yep, that would solve it. I didn't know those existed. Thanks.

[PRR]

> will it negatively affect the stereo out when mono is not in use?

If the driving unit truly has zero output impedance, than channel separation is not degraded by using this summing box. However, when dealing with real-world units you deal with finite output impedances.....

http://www.rane.com/note109.html

So the question is on you: what is this "device"?

[lobsternaut]

> will it negatively affect the stereo out when mono is not in use?

If the driving unit truly has zero output impedance, than channel separation is not degraded by using this summing box. However, when dealing with real-world units you deal with finite output impedances.....

http://www.rane.com/note109.html

So the question is on you: what is this "device"?

Ah, I missed that section.

It's a 115 year old wooden pump organ that I'm wiring with piezo transducer pickups, one on each side for highs and lows, respectively. The piezos are rated 1kOhm max output impedance, so I suppose there would be significant crosstalk. However, there's lots of acoustical leakage between channels already anyway since they're mounted on opposite ends of the same organ, so it might not make much of a difference.

There is a shop in town that sells Switchcraft parts, so I'll see if they have a 14b in stock. If not I won't worry about it.

[artifus]

harmonium? sweet. lovely sound. tricky to capture. good luck. sounds like an interesting project. ivor cutler ftw!

http://www.youtube.com/watch?v=irKLzbOzUFU

[PRR]

> a 115 year old wooden pump organ

BTDT. Just do it. No electrical "infidelity" can hurt that sound.

[lobsternaut]

harmonium? sweet. lovely sound. tricky to capture. good luck. sounds like an interesting project. ivor cutler ftw!

http://www.youtube.com/watch?v=irKLzbOzUFU

Yeah, it's an 1898 Estey JJ collapsible harmonium built in Brattleboro, VT. The whole thing folds up into a treasure chest-sized box with straps that you can lug around. There's an oak panel in back that screws on, and I'm making a panel of the same size with the pickups and jacks mounted in it to swap out so I can avoid drilling into the original.

I had never heard of Cutler, but I am richer for having watched this video.

> a 115 year old wooden pump organ

BTDT. Just do it. No electrical "infidelity" can hurt that sound.

Agreed! I was asking mostly out of academic curiosity. Gonna wire it up tomorrow and try it out at a show this weekend.