I'm looking for advice on building a passive mixer that combines multiple stereo line signals into a single output channel to connect to my custom stereo amplifier. I've already got my circuits and designs laid out, but I'm feeling pretty worn out and need some help with the math. My plan is to let various devices like computers, CD players, and radios play through the same speakers by switching certain input channels on or off. From what I've researched, I've seen that a 1k resistor per input channel is commonly suggested for protection, and that 100k logarithmic pots are typically used for volume adjustments. It sounds straightforward, but I want to make sure I'm not missing any critical issues. Am I on the right track here, or are there any potential pitfalls I should be aware of?
1 Answer
Have you considered making an active mixer instead of a passive one? Using op-amps can significantly improve the audio quality. You'll find plenty of schematics online, and a couple of TL074 op-amps should suffice for this kind of project.
That makes sense! Just make sure to check the output impedance of your mixer to match your amp, and you should be good to go!
I appreciate the suggestion, but I designed this mixer to work with my custom stereo amp, which outputs about 100 watts per channel. I’m mainly looking to mix line-level signals from my devices, and I don’t need any extra amplification.