Re: Direct Audio into the Mac

Craig T. Bailey
 

Hi Ben,

CW Ops Academy is precisely why i've been working on getting CW piped directly into my computer.

I've done several classes where students will "send" from their oscillator, and Zoom, or Skype, would simply pick up the code through the internal microphone on the computer.
Let me tell you - its an awful experience!
Half the time the zoom client will clip the audio when a dit is sent first, the other half the time some other person has their microphone open, so you hear yoru own code echoed back over zoom because people don't know how to mute their computer mics.

So, I'm trying to come up with a simple way to pipe this all in.

Chuck's point is a good one - an internal sound mixer app with virtual devices will work. Although I fear the technical level of most "students" in these morse code classes will prevent that from happening.

On the Mac, i've had some good success with an external USB sound card (dongle) but, I needed a custom built audio summing circuit, and a wired mic to pipe the morserino and my mic together. Then in the mac... the OS has a built in app called "midi" that will let you build "aggregate" devices. The midi app doesn't sum/mix the audio channels, though.

The ultimate tool would look like this:


box that will let you plug in:
1. a 4-conductor TRRS line from the morserino (for audio into morserino and audio out of morserino)
2. a 4-conductor TRRS wired headset (for mic into the zoom app, audio out of the zoom app, AND a monitor of the morserino output)
3. a 4-conductor TRRS output back to the PC/Mac to carry audio into and out of zoom.

On a 2012+ mac book, the headphone port is actually a TRRS for phones & mic.
I have a dell precision that also has a TRRS port for onboard sound and mic.

Can someone help me with the circuit design? The box should have gain control to reduce or increase the volume of each input and probably a master output?

I have built the summing circuit that I found at Rane.com https://www.rane.com/note109.html
And it works pretty good, although there is potential for some ground looping. (I've used this in my car to pipe together my 2-meter radio and a MP3 player into the car's aux jack)
But I think the added complexity of the TRRS (4-conductor) ports AND the concept of audio input & output qill require a better design.

I'd be interested in working with someone to develop this circuit and a Bill of Materials, because I think the Morse-Learning community has fully adopted video conferencing, but the audio NEEDS to be piped into the system. I can handle soldering, and reading schematics, but I've never designed a circuit from scratch.

Thanks very much



--
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Craig Bailey
N1SFT
NH, USA

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