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Mixer resistor values

Discussion in 'General Electronics Discussion' started by helpful55, Aug 2, 2016.

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  1. helpful55

    helpful55

    3
    0
    Dec 28, 2012
    In addition to inside I run my pc audio music stream to a sound system in my shop. I like to be able to just move one of the shops stereo system speakers outside when I am working there with a longer wire. The problem is that some of the music has mixing where the vocals or part of the music is not the best with one channel. So I am making a passive mixer for the shop setup. I would like to find an appropriate resistor value that won’t attenuate the signal any more than I have to. If this circuit does cause some input mixing that is not really a problem as I can disconnect the mixer when it is not needed so I won’t be diminishing my stereo effect in the house when I listen there. I have seen 10K recommended, but that was for general audio equipment and I don’t know if a pc output would need similar, I wouldn’t want to harm my pc sound circuits. What would anyone recommend for resistor values for this mixer? I can experiment if there is a range I should try, I would just like to have a good starting point if so. And since I am obviously driving two stereo systems (the main one will probably still be on, I don’t want to be flipping a switch back and forth) should I be using some type of impedance adjustment for that part of this? Thanks for any help.
     
  2. Sunnysky

    Sunnysky

    470
    118
    Jul 15, 2016
    mixing not the best? or amplifier distortion? or bad speaker?
    No idea what you have for speakers, cable or amp or output signal quality.
     
  3. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Any problem simply setting up a secondary sound output on the computer?
    Problem with passive is that the signal WILL attenuate, by a noticeable amount
     
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  4. helpful55

    helpful55

    3
    0
    Dec 28, 2012
    Yes that sounds like the way to go so I don’t have to modify my normal sound output system at all. I have a USB sound device that I got set up and it seems to be working fine. I will run it’s output to the shop and if I think it is deficient I will go to a better USB device. Do you think that I could just directly connect the stereo outputs on this device without ruining it or should I still use a mixing resistors? I can use low resistance resistors because for the shop sound I would like the channels mixed as well as possible anyway. I have tried it with 1K resistors and the drop was not too bad. I have a pretty decent wattage sound system it is on and if I would have to I can go bigger. I can turn it up the volume, but I am never into that if possible I'd rather keep my input level up. An experiment is not really a big deal if I fry it as it’s an inexpensive device. Hadn’t got back to this earlier as I had been real busy with other projects in the summer. Thanks for your help.
     
    Last edited: Dec 18, 2016
  5. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Not a problem.
    1K is a decent value to work with, go for it.
    You may also be able to find a setting in the sound properties of you computer to actually set the output as 'Mono' for a select device. Some music players also have a 'DSP' section allowing you to customise things like Down-mixing Stereo to Mono and other effects.
    So you could continue to do this in software, or build your Stereo to Mono passive Mixer.

    I do apologise actually about my earlier reply. Your desire wasn't to simply output two different media streams, but to down-mix to Mono when you decide to play audio outside with a single speaker.
    In this case, I would suggest your original approach of a passive mixer to mix your Left/Right into a single Mono Channel, or see if you can run the outdoor stereo in 'Bridge mode' or Mono.
    (As long as your indoor stereo is connected to the audio-out of the PC *before* your resistor mixer, you will still get stereo in the house although you may get a slight mono mix in the house. This effect will be more pronounced with smaller value resistors. A second audio device either built-in or USB will avoid this)
     
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  6. helpful55

    helpful55

    3
    0
    Dec 28, 2012
    Ok I got the circuit set up and it does what I want. This is great now, both channels from my one outside speaker with adjustable inside volume and no degradation of my house stereo sound. My settings don’t have a mono setting. I guess windows is too smart and maybe it recognizes the speakers as stereo! What I am calling a sound system is just a simple Logitech Z623 pc speaker system so no settings on it either. I had to do a little wiring anyway as I also inserted a pot in the channel that is for the inside speaker I need to lower once I raise the total volume for outside use. The 1K resistors do some reduction but a pretty small amount, I barely have to raise the volume. I get kind of crazy on things that aren’t quite right and although this setup can make plenty of noise to annoy neighbors I may get a hair and build a low power active mixer. Like I say not needed though.

    I was having my usual “setting” problems with windows and plugging into a front case usb allowed the audio, but the rear mobo jacks wouldn’t so I got a “potentially” better usb device and same problem. I have been through some of these windows sound settings before and it has been a pain. I ultimately found that I had to set the stereo mix in recording for listening to that device then it worked off the rear port. I hope I don’t run into the no stereo mix difficulty like I did one time. That is a pain and I think required a downgrade in driver to get that, although I have done some of the updates and they haven’t deleted it so I don’t know. Thanks for all of your help. On to my other always ongoing problems/projects.
     
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