Hello all. I'm attempting to build a passive audio mixer from multiple sources to a single stereo headset. It's based off of this design here: http://www.epanorama.net/circuits/linemix.gif
I had originally intended to include the stereo potentiometers, but their price is such that I'll just live with controlling the volume at the source. I'll have much more than two inputs. However, I'm a ham radio operator, and all of my rigs output audio in mono rather than stereo. I'd like to hear their sound through both ears so I plan to include a stereo to mono switch on some of my inputs so when the radios are plugged in, I can throw the switch and get audio out of both speakers on the headset. However, I'm stuck on how exactly to wire the switch in. I understand that I should have some "isolation" resistors to isolate the various inputs from each other. I also figure that I can't just short the Left and Right channels together without bad things happening. Here's a rough MS Paint schematic of a single input and its relationship to the output: http://i226.photobucket.com/albums/dd230/Zatnikitelman/monostereooptions_zpse1afaf37.jpg
The left diagram has a 5.6k resistor in series with a SPST switch before the 10k isolation resistors. The right diagram (should say input "stage" not "state") excludes the resistor. The other design I'm considering, are those two designs depicted, but the switch and/or series resistor are after the isolation resistors, but "before" the connection from the other inputs. This last solution has been suggested to me, but it doesn't seem right. Wouldn't that bridge all the inputs and make the entire unit output mono audio? I'd like to have the radios output to my headphones through both speakers, while still playing a game on my computer where having stereo audio is imperative. What's the better solution here? Or is there another solution entirely? I've seen designs using active op-amps and such, but I'd like to keep this as simple as possible for now and not need to get power to this.
In my various searchings, I've found the recommended "Why Not Wye" link that others have recommended for similar problems, but the circuit that looks most similar to my situation (Figure 3), looks like it's for either mono or stereo, but that everything would go from stereo to mono, and not selectively like I need.
Thanks for any advice you can provide on what my solution needs to be.
Matt
I had originally intended to include the stereo potentiometers, but their price is such that I'll just live with controlling the volume at the source. I'll have much more than two inputs. However, I'm a ham radio operator, and all of my rigs output audio in mono rather than stereo. I'd like to hear their sound through both ears so I plan to include a stereo to mono switch on some of my inputs so when the radios are plugged in, I can throw the switch and get audio out of both speakers on the headset. However, I'm stuck on how exactly to wire the switch in. I understand that I should have some "isolation" resistors to isolate the various inputs from each other. I also figure that I can't just short the Left and Right channels together without bad things happening. Here's a rough MS Paint schematic of a single input and its relationship to the output: http://i226.photobucket.com/albums/dd230/Zatnikitelman/monostereooptions_zpse1afaf37.jpg
The left diagram has a 5.6k resistor in series with a SPST switch before the 10k isolation resistors. The right diagram (should say input "stage" not "state") excludes the resistor. The other design I'm considering, are those two designs depicted, but the switch and/or series resistor are after the isolation resistors, but "before" the connection from the other inputs. This last solution has been suggested to me, but it doesn't seem right. Wouldn't that bridge all the inputs and make the entire unit output mono audio? I'd like to have the radios output to my headphones through both speakers, while still playing a game on my computer where having stereo audio is imperative. What's the better solution here? Or is there another solution entirely? I've seen designs using active op-amps and such, but I'd like to keep this as simple as possible for now and not need to get power to this.
In my various searchings, I've found the recommended "Why Not Wye" link that others have recommended for similar problems, but the circuit that looks most similar to my situation (Figure 3), looks like it's for either mono or stereo, but that everything would go from stereo to mono, and not selectively like I need.
Thanks for any advice you can provide on what my solution needs to be.
Matt