Topics

Direct Audio into the Mac

Craig T. Bailey
 

Well, I'm pleased to say I've got the Morserino piped into my Mac.

In addition, I built a mixing circuit to blend a wired mic input with the line out audio from the Morserino.

This mixer goes into a USB dongle audio card.

Why? you might ask?

When participating in CW Ops Academy, or any other video conferencing system, where you are working with other Morse trainees, its common place to just let the PC's built in mic pick up the code oscilator's side tone over the air.

I'm finding skype was terrible at clipping the keyer, and Zoom wasn't much better. By having it piped direct, the folks on the other end get clean code. Also, by piping it direct, I'm using my headset plugged into the PC (Mac in this case) as the monitor of the side tone.

I suppose this is also precisely what the Mumble app needs as well.

Just one more reason why Morserino is a GREAT educational tool!

Chuck Broadwell, W5UXH
 

On Sun, Aug 4, 2019 at 12:15 PM, Craig T. Bailey wrote:
I suppose this is also precisely what the Mumble app needs as well.
Correct.  Mumble is full duplex so many newcomers to it have problems with the open mic and a speaker.  Turning off the speaker and using headphones makes it usable, but it is far nicer to have a sound card input.  I do not participate in CW training sessions, but still occasionally need to use a mic with newcomers.  On the Mac, a very nice tool is available (unfortunately it costs the same as the M32).  It is LOOPBACK2 from Rogue Amoeba.  It allows you to create virtual audio devices for mixing and pipelining audio between various apps.  I have one virtual device that combines my external sidetone input with the webcam mic when I need to add "voice".  It is also very handy for playing recordings back to someone over Mumble.  I just select the my virtual device that mixes the Audacity output with my input sidetone to select as the input device to Mumble.

Ben Cook
 

That’s pretty cool. I’m starting a CWA session here in a couple weeks and this would be very useful. I do have a Mac program called Audio Hijack from Rogue Ameba which *might* let me pipe the audio in from the built in mic port and a headset into the Zoom conference. I’ll have to give that a try tonight. Else any other details how you accomplished this with your usb mixer?

-- 
  Ben Cook
  ben@...



On Mon, Aug 5, 2019, at 05:49, Chuck Broadwell, W5UXH wrote:
On Sun, Aug 4, 2019 at 12:15 PM, Craig T. Bailey wrote:

I suppose this is also precisely what the Mumble app needs as well.
Correct.  Mumble is full duplex so many newcomers to it have problems with the open mic and a speaker.  Turning off the speaker and using headphones makes it usable, but it is far nicer to have a sound card input.  I do not participate in CW training sessions, but still occasionally need to use a mic with newcomers.  On the Mac, a very nice tool is available (unfortunately it costs the same as the M32).  It is LOOPBACK2 from Rogue Amoeba.  It allows you to create virtual audio devices for mixing and pipelining audio between various apps.  I have one virtual device that combines my external sidetone input with the webcam mic when I need to add "voice".  It is also very handy for playing recordings back to someone over Mumble.  I just select the my virtual device that mixes the Audacity output with my input sidetone to select as the input device to Mumble.

Chuck Broadwell, W5UXH
 

On 8/12/19 11:02 AM, Ben Cook wrote:
I do have a Mac program called Audio Hijack from Rogue Ameba which *might* let me pipe the audio
Ben, I don't think Hijack lets you pipe audio, I think it only lets you capture and record it. The Rogue Amoeba Loopback 2 program works very well for creating virtual audio devices and then piping them. The free trial is a "30 times running" limit, not a 30 day limit, so you could still make use of it without having to purchase the software. At least the last I checked that was the trial policy. Good luck.

Chuck
W5UXH

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



--
_____
Craig Bailey
N1SFT
NH, USA