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SSB audio distortion #qmx #SSB Firmware beta 1_01_003 release #qmx #ssb

 

Well, I bit the bullet and installed the 003 FW.
Update of FW went all fine, no issue there.
I wired up a electret mic I found in my junk box.
Tested the mic on pc and sounded fine.
I made an adapter using the electret mic and a foot switch for ptt.
The Mic and ppt switch works. But...
Testing SSB TX with QMX on dummy load and listening on my ICOM 7300, the audio is badly distorted before calibration and even worse post calibration. So much so that the speech is unintelligible.
The audio sounds like the QMX is only picking up the peak signals from my voice.
Most of the calibration plots look nothing like the example ones from the release notes. And only a few mildly resemble the examples.
Adjusting mic gain to about 70 seems to improve the audio. However, every time I key up,? there is now an awful lot of noise before I even start speaking. Once I start speaking the audio is ok'ish with a load of background noise.
I tried messing about with other SSB settings with no improvements.
I did find a second electret mic that gave me similar results.
I have now set it back to factory default and seeking advice.
Any suggestions?
?
Mel. M0KMD.
 

HI Mel,
?
See my earlier message with a similar issue.
?
I had that distortion and then turned off predistortion etc. and it improved.
I re-ran the calibration and then is was OK ( for a bit ) and now have distortion again.
?
I don't have time to perform more rigorous testing/recording conditions, but I will post again when I do.
?
72 Simon G0FOZ
 

Make sure you are not getting feedback between QMX and IC7300. I had lots of feedback and distortion until I backed the audio way down on my receiving QMX+. I made two QSOs with good signal reports.

Mike Krieger


On Thu, Mar 27, 2025 at 6:23?AM Mehmet Dinch via <msdinch=[email protected]> wrote:
Well, I bit the bullet and installed the 003 FW.
Update of FW went all fine, no issue there.
I wired up a electret mic I found in my junk box.
Tested the mic on pc and sounded fine.
I made an adapter using the electret mic and a foot switch for ptt.
The Mic and ppt switch works. But...
Testing SSB TX with QMX on dummy load and listening on my ICOM 7300, the audio is badly distorted before calibration and even worse post calibration. So much so that the speech is unintelligible.
The audio sounds like the QMX is only picking up the peak signals from my voice.
Most of the calibration plots look nothing like the example ones from the release notes. And only a few mildly resemble the examples.
Adjusting mic gain to about 70 seems to improve the audio. However, every time I key up,? there is now an awful lot of noise before I even start speaking. Once I start speaking the audio is ok'ish with a load of background noise.
I tried messing about with other SSB settings with no improvements.
I did find a second electret mic that gave me similar results.
I have now set it back to factory default and seeking advice.
Any suggestions?
?
Mel. M0KMD.
 

Hi Mel

It's possible the microphone isn't sensitive enough. Turning up the gain increases the audio but also the noise (if the mic SNR isn't enough)

73 Hans G0UPL


On Thu, Mar 27, 2025, 13:23 Mehmet Dinch via <msdinch=[email protected]> wrote:
Well, I bit the bullet and installed the 003 FW.
Update of FW went all fine, no issue there.
I wired up a electret mic I found in my junk box.
Tested the mic on pc and sounded fine.
I made an adapter using the electret mic and a foot switch for ptt.
The Mic and ppt switch works. But...
Testing SSB TX with QMX on dummy load and listening on my ICOM 7300, the audio is badly distorted before calibration and even worse post calibration. So much so that the speech is unintelligible.
The audio sounds like the QMX is only picking up the peak signals from my voice.
Most of the calibration plots look nothing like the example ones from the release notes. And only a few mildly resemble the examples.
Adjusting mic gain to about 70 seems to improve the audio. However, every time I key up,? there is now an awful lot of noise before I even start speaking. Once I start speaking the audio is ok'ish with a load of background noise.
I tried messing about with other SSB settings with no improvements.
I did find a second electret mic that gave me similar results.
I have now set it back to factory default and seeking advice.
Any suggestions?
?
Mel. M0KMD.
 

Yep, done that one. I was using headphones on the IC 7300 whilst testing TX on QMX.
?
Cheers.
?
Mel, M0KMD
 

Did you leave predistortion off during calibration?
?
Let me give that a go..
?
Cheers,
?
Mel. M0KMD
 

Hi Hans,
?
Yep, that did cross my mind..
?
In fact my first attempt was to use a PC gaming headset with mic. The audio gain was very low from the headset compared to the electret mic's I found in my junk box.
?
These electrets seemed to work quite well on my PC. I would have thought they would work equally as well on the QMX...
?
I forgot the mention, I also removed an electret mic from a Baofeng speaker mic to use on the QMX. That gave the same results as the other electret mic's.
?
Could you remind me of the mic that you used please?
?
Cheers.
?
Mel. M0KMD
 

Hans' suggestion of microphone can be found on the beta page: under the heading Microphone Choice.? Though I suspect this microphone is more sensitive than needed for HF radio transmission.
?
I had a similar issue with the noise you describe when not speaking.? I found it was caused by having the Mic. gain set a little to high.? The sweet spot for me was to actually transmit silence and dial the gain down until that noise disappeared.
?
My Mic. gain is set at 75, with Mic. compression set at 14, and Transmit EQ. Global gain set at -8.? Just for reference as all Mics. are different...
 

Hi Myles,
?
Yep, I tried the dial back as well. I eventually settled on mic gain of 65 but the audio was still rough without background noise.
?
Thanks for sharing your settings.
?
Are these setting post calibration?
?
Cheers,
?
Mel. M0KMD.
 

I just found another mic capsule on an Arduino MAX9814 board. Took that off to try again.
?
Without calibrated, much better audio! Adjusted mic gain and compression. I set the noise gate to 30 and everything else as default. Still not perfect but very much improved and very usable!
?
Ran the calibration through and left every thing else as it was and the audio is very rough.
?
I'm going to factory reset it again and dial in the setting I was happy with and leave it at that, unless anyone has any suggestions to improve calibration results to improve the audio.
?
Note that there is a lot of merit in what Hans says. Not every electret mic are the same. This last one that I found on an Arduino board seems to work nicely.
?
Cheers,
?
Mel. M0KMD
?
 

Hi
strangely I had the same problem.
I was using a uhf/vhf handhelds mike.
after I found out that there was a LED connected inside the mike case
I took it out
now it is perfect
73 DE muhsin TA1MHS
 

Muhsin bey, selamlar :-)
?
Thanks for the tip. I'm using the electret capsule removed from other hand mics or other scrap pcb's. No LED's on any of these.
?
I wonder how significant it is that my plots are nothing like the examples in the documentation?
?
Another interesting observation:-
I set my QMX back to factory default and dialed in what I found to be workable and tested with dummy load (without calibration).
With my antenna plugged in (20m dipole, monoband, good SWR 1.2), on TX, the audio was badly distorted again. I also noticed that there was hardly any power going out. The power meter needle didn't even move.
?
Working through calibration again as I type this to try again...
?
Saygilar ve hormetler.
?
Mehmet (AKA Mel) M0KMD
 

Mehmet,? I used the band configuration menus to move the band edges closer to the legal band edges, and then set the band center to 14.175.? Then set the mic levels carefully, then did calibration one page at a time using O. I managed to get nicer looking graphs that way. I'm not sure how to interpret them, but I also noticed PEP my output levels came up close to my tune levels at that point, and the audio seems to sound good.?
--
73, Dan - W2DLC
 

Hi Daniel,
?
Thanks for your suggestion.
?
I have set the band edges and center frequency as recommended. The plot doesnt look any better..
?
?
Mel. M0KMD.
?
?
 

I forgot to add the band config screen.
 

Your band configuration page looks very different from mine. I can see all of the bands at once.
--
73, Dan - W2DLC
 

As I said, I can't judge whether that plot looks good or bad. Some of Hans's plots looked similar. Everyone's radio will likely have different looking plots as the hardware has variations.
--
73, Dan - W2DLC
 

Yeah, I just took a snippet of the 20m band. :-)
 

Hello Mehmet and all,
?
if you need significant more than 55 dB audio gain the micro is not sensitive enough for QMX use. You will find something about this on page QMX QMX_plus SSB settings from QRP Labs Wiki.
?
73 Ludwig
 

On Thu, Mar 27, 2025 at 11:23 AM, Mehmet Dinch wrote:
The audio sounds like the QMX is only picking up the peak signals from my voice.
...
Adjusting mic gain to about 70 seems to improve the audio. However, every time I key up,? there is now an awful lot of noise before I even start speaking. Once I start speaking the audio is ok'ish with a load of background noise.
Mehmet, the reason for this is described also on page QMX QMX_plus SSB settings (see Noise gate).
?
73 Ludwig

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