Digital transmit audio handling without processing

Not everyone cares to process their transmit audio.  Hams wanting to transport their transmit and receive audio without any processing in the audio chain may want to use a scheme like the one described below:

 

Overall scheme:

(1)  Unlike the schemes described elsewhere on this website, no software based digital audio processing is utilized to tailor transmit audio.

(2) The scheme presented in this article describes a methodology for routing USB microphone output directly to a Kenwood TS-590SG  (or TS-590S) via a separate USB cable. 

(3)  Alternatively, Appendix A provides a guide for setting up up a conventional (analog) XLR microphone together with an outboard USB audio interface in lieu of a USB microphone.

(4) Perhaps you prefer to first experiment with a  USB microphone without any software processing.  If so, follow the guidelines presented in Appendix B.

(5) Some hams may prefer a purely analog hardware based approach to audio processing.  Appendix A  below describes a simple, inexpensive and hightly effective scheme that can be implemented for about $200.

 

 How this scheme works

A. Digital audio output from the Rode NT-USB microphone is routed to the computer via a type A/B USB cable.  Note:  Type A/B USB cable is a standard issue USB 2.0 cable. This is the most common A to B Male/Male type peripheral cable, the kind that's usually used for printers.

B.  Your computer then routes digital transmit audio output from the microphone onward to the transceiver via Type A/B USB cable.  Finally, it is converted from digital to analog and transmitted.

C.  Received audio from the Kenwood 590SG is transported from the PC to a pair of near-field monitor speakers.  Alternatively, receive audio can be routed from the 590SG's rear panel speaker output jack direct to the speaker.

D. 55 watts RF output from TS-590SG transceiver is routed  to the linear.

E. 700 watts RF output from the ACOM 1010 linear is routed to the tuner.

F. 700 watts RF output from Palstar AT1500BAL is sent to a horizontal loop antenna via 450 ohm ladder line.

Settings

Using only a USB microphone without the benefit of any software processing of the transmit audio

Carefully perform the following steps to set up your microphone for direct transmission without any software based audio processing being necessary:

1. Enter windows sound manager utility and select the “recording” tab.

  • Select your Microphone from the list and make it the default device. 
  • Double-click the device to open the  Properties drop-down window.
  • Select the “listen” tab and check the box adjacent to “Listen to this device.”  Then, enter your “USB audio CODEC”  playback device from the drop-down box.
  • Select the “Levels” tab and set the slider to 30 as a starting point to minimize the microphone’s pickup of ambient noise.   Adjust as necessary. (see below monitoring steps)
  • Select the “Advanced” tab and select 2 channel, 16bit, 4800 Hz or whatever your Microphone is cable of producing.  Un-select Exclusive Mode.

2. To playback the 590's receive audio from a pair of  near field monitors (preferably), make sure that  the “recording” tab is still selected.

  • Select "USB Audio CODEC" from the list and make it the default communication device. 
  • Double-click the device to open the  Properties drop-down window.
  • Select the “listen” tab and check the box adjacent to “Listen to this device.”  Then, enter your “USB audio CODEC”  playback device from the drop-down box.
  • Select the “Levels” tab and set the slider to 70 as a starting point to adjusting the audio output  from your speakers.   Adjust as necessary. 
  • Select the “Advanced” tab and select 2 channel, 16bit, 4800 Hz or whatever your Microphone is cable of producing.  Un-select Exclusive Mode.

3. Now, select the "Playback" tab"

  • Select your USB mic from the list and make it the default device.
  • Double-click the device to open the Properties drop-down window.
  • Select the “Levels” tab and set the slider to 30 as a starting point.   Adjust as necessary. (see below monitoring steps)
  • Select the “Advanced” tab and select 2 channel, 16bit, 4800 Hz.  Un-select Exclusive Mode.

4. To further set up this scheme and monitor your output:

  • Enter Windows Device Manager to determine which port is designated for the UART and make certain that the 590sg is set up to reflect the correct port, baud rate (preferably 115200).
  • To keep things simple, use VOX to key the rig by setting menu 69 to “USB,” menu 70 to “rear,”  menu 71 to “3”, menu 76 to “on,” menu 77 to “15”,  and menu 78 to “4”.  (adjust settings as necessary)
  • To monitor your transmit output, first turn on the 590’s monitor by double pressing the “power” button on the front panel.  Turn the multi-knob initially set the monitor level to “14”. 
  • Plug in your headphone to the 590’s front panel and speak into the microphone.  You should hear yourself transmitting.  If not, repeat the preceding steps.  If you do hear yourself, adjust the "Recording" and "Playback" tab levels as necessary to achieve a slight deflection of ALC on voice peaks with minimal background noise and no distortion in your transmit audio. 

Notes:

  1. Depending on which USB microphone is used, you may be able to make other level adjustments on the microphone itself.
  2. Although not recommended, you may want to try setting menu 36 set to “Hb1” which may help cleaning up the low end should that  be necessary. Listen to yourself in the 590's monitor to evaluate the results.  Perhaps you want to further utilize the transceiver to fine-tune your transmit audio.  If so, try creating your own personalized user “U” defined tx EQ settings with the Kenwood ARCP-590G software.  Again, listen to yourself on the monitor as you tweak your settings.  K4QKY believes that utilizing software based processing techniques as described elsewhere in this website is a more effective alternative than relying on the transceiver's built-in processing tools.  Try both alternatives and decide for yourself.
  3. Although some hams will disagree, K4QKY recommends keeping the rig's internal speech processor off (except in weak signal conditions).  Adjust microphone gain for only a slight ALC meter deflection on voice peaks.    

Appendix A

XLR microphone together with a USB audio interface in lieu of a USB microphone

Hams often already own one or more conventional microphones and may understandably be reluctant to spend the extra dollars on a USB microphone.  Assuming that they also desire to transport digital transmit audio, they may want to consider integrating their microphone as discussed in this article.

Pros and cons 

  • USB mics are less complicated to set up. 
  • XLR mics require an audio interface.
  • XLR mics are typically more sophisticated in design.
  • USB mics are preferable for portable radio operations with a laptop.

Choosing an audio interface

The webpage at https://www.sweetwater.com/insync/audio-interface-buying-guide/#io provides a useful buying guide for hams who elect to purchase an audio interface to use with their favorite conventional XLR microphone.  

 

K4QKY's USB audio interface choice is A Behringer U-Phoria UMC202HD.  You can learn more about it by watching the video at https://www.youtube.com/watch?v=7hr0CnElTug snd purchase one at https://www.sweetwater.com/insync/audio-interface-buying-guide/#io or from another vendor of your choice. 

 

 

Setup 

  1. Download and install the driver for the interface from https://www.musictri.be/Categories/Behringer/Computer-Audio/Audio-Interfaces/UMC202HD/p/P0BJZ/downloads.
  2. Connect an XLR cable between mic and front panel of the interface.
  3. Hookup a Type A/B USB cable between your PC and the rear panel of the interface.
  4. Restart your PC and enter your PC's windows sound manager.  Setup the recording and playback devices to conform to the instructions below.

Recording tab - Set the interface as the default device.  Select the “listen” tab and check the box adjacent to “Listen to this device.”  Then, enter your “USB audio CODEC”  playback device from the drop-down box.  Select the “Levels” tab and set the slider to 30 as a starting point to minimize the microphone’s pickup of ambient noise.   Adjust as necessary. Select the “Advanced” tab and select 2 channel, 16bit, 4800 Hz or whatever your Microphone is cable of producing.  Un-select Exclusive Mode.

Playback tab - Select your USB mic from the list and make it the default device.  Double-click the device to open the Properties drop-down window.  Select the “Levels” tab and set the slider to 30 as a starting point.   Adjust as necessary.  Select the “Advanced” tab and select 2 channel, 16bit, 4800 Hz.  Un-select Exclusive Mode.