Rumbling audio,,,,again

[Trucker]

Latest version of Thetis. Yesterday evening I started getting a rumbling sound in the audio when the volume is turned up much at all. I had this problem previously and determined at that time, it was a Display Port to HDMI adapter I was using. Getting a Display Port monitor seemed to fix the problem. Until yesterday evening. The rumbling came back. Nothing had been changed. I tried several things and configurations to resolve it. I was about to switch to my backup pc when, on a whim, I clicked on the SNB button. The rumbling went completely away! Even at full volume it's not there. Turning off SNB, the Noise comes back.
I then tested it on my backup pc. Got the rumbling again. Clicked on the SNB button and gone!
None of my other radios including my Flex 6600M have this problem. I can run SmartSDR on either pc as well. And no rumbling. Switch to Thetis and leave off the SNB and it's back.
I cannot imagine what is causing this to happen. It appears to be something in Thetis itself. Maybe a setting somewhere that needs to be changed. But, what, I have no idea.
Any suggestions would be appreciated.
James
WD5GWY

[w-u-2-o]

James--since you are the only person to ever report this problem that makes it very difficult to debug.

Have you tried both VAC and "regular" audio? Does it do this on both?

[Trucker]

Scott,
Thanks for replying. I haven't tried direct audio connections from the 8000DLE. It is sitting several feet away from my operating desk and pc. So,I have only used VAC.
I did try MME and Direct Sound to see if it might be a driver issue. I did have a problem with the audio going completely away when I was testing SDR Console with my 8000DLE. It ended up affecting both SDR Console and Thetis. I had to update several drivers, including the Realtek driver. That brought the audio back for Thetis and SDR Console. Maybe the updated driver changed something in Windows 11. I will have to dig deeper and see.
James
WD5GWY

[Trucker]

Adjusting EQ seems to help a lot. Along with lowering AGC to 40. At that point, it is barely noticeable. If I change AGC back up to 60 or so, it's back again. And needs the SNB button to get rid of it. Maybe one of my neighbors has fired up something that is causing this.
If it is, I find it odd that SmartSDR doesn't hear it. ( SmartSDR doesn't use VAC for audio between the radio and pc. )
I will keep experimenting and hopefully track this down.
James
WD5GWY

[Warren_NR0V]

James,

That's a most interesting situation. It would seem that something is distorting segments of the signal waveform and SNB is then correcting that distortion when it's turned on. SNB has the seemingly magical ability to correct/replace entire segments of a waveform. If you're not familiar with that and have interest in seeing any more, you can look here:
<https://openhpsdr.org/videos/Friedrichshaven2016/NR0V.mp4>

Unfortunately, I don't know the source of the original distortion. Possible causes: (1) Received interference ... as you point out, the fact that your Flex doesn't see that would seem to eliminate that possibility; however, antenna and ground cables and connections could vary, (2) a problem with the radio hardware ... possible, but, my guess would be unlikely ... but there could be a firmware issue if you're using P2 firmware, (3) Windows/Network connection between radio and PC ... I'd be suspicious there, (4) Compute problem in PC ... I think you tried two computers; so, this doesn't seem too likely, (5) Software issue in Thetis ... I somewhat doubt it since others aren't seeing it ... also seems unlikely since EQ and AGC settings as well as SNB can improve the situation.

I don't have the answer for you but perhaps these thoughts might help with the troubleshooting.

Warren NR0V

[Trucker]

Warren, thank you for the information. It gives me a lot to think about.
My radio is an 8000DLE using P2. Other than the time I mentioned in the past, everything has worked very well. I will rearrange some things and try direct connection to the headphone output ( front panel) and see if the problem exists in the audio from that source. It could be hardware related if it still happens.
James
WD5GWY

By the way, thank you for sharing WDSP. It is an amazing package that makes everything else I have used pale in comparison.

[Trucker]

Update: hooked my Tannoy powered studio monitors directly to the headphones output on the front of my 8000DLE. No distortion at all. SNB and NR2 both off, and nothing but background static. Maybe something in the new Realtek audio driver is causing the problem.
I may just leave the speakers connected to the headphones jack. I might have to do rearranging to make it work. I am not sure how close to the 8000DLE I can safely put the speakers and not have RFI issues.
James
WD5GWY

[w-u-2-o]

It seems like you've got some VAC related issues.

What happens if you do something like install Voicemeeter and route the audio through that?

[Trucker]

Scott, I'm going to show my ignorance here. I was under the impression that VoiceMeeter was for connecting microphones and speakers with external hardware devices using ASIO.
I will give it a try if you think it would make a difference.
James
WD5GWY

[w-u-2-o]

Voicemeeter is an all-purpose, software audio mixing board.

I'm curious what would happen if you used it in between your normal sound hardware devices and drivers and Thetis VAC.

[Trucker]

Just downloaded Voicemeeter Potato and installed it. Shutdown the 8000DLE and my pc. Connected powered speakers back up to the pc's audio line out. After a bit of fumbling, I seem to have VMP working. Running Thetis and selecting VMP for audio and a few other settings, I now have audio and with NR2 and SNB both off, no rumbling!
Talk about controlling the audio, it seems like the few controls I have tried in VMP really do have a good effect on the audio. I downloaded the manual. It looks like a lot of reading and experimenting is in my future.
Scott, I do wonder what could be the difference between using Voicemeeter Potato and the VAC settings I had been using?
James
WD5GWY

[w-u-2-o]

I'm glad that experiment worked. It proves that there is nothing intrinsically wrong anywhere.

These results indicate that there is something about your chosen VAC settings that don't play well directly with your sound interface but is perfectly happy with Voicemeeter.

Have you played much with the VAC settings?

[Trucker]

I installed Voicemeeter Potato on my main pc and the backup pc. It worked fine on the backup pc. But, on my main pc I had problems getting it to work properly.
On a whim, I decided to rollback the Realtek audio driver on the main pc. And just like when I started having problems after installing SDR Console, no audio output at all! So, I completely removed the Realtek driver and then downloaded ( Windows Update) the new Realtek driver. Audio is back. And, no more rumbling! I can use Direct Sound or Windows MME and everything is working correctly.
I don't know what SDR Console did during installation, but it is gone from my main pc and isn't coming back. I did install it on a laptop I use with my Hermes lite 2 and it works fine and didn't corrupt the audio driver.
I am hopeful this issue is fixed. I appreciate all the help I was given. I don't have a lot of hair left. So this prevented me from pulling out any more!
James
WD5GWY

[Trucker]

One more update.........hopefully the final update to this saga.
The rumbling came back. In desperation, I decided to just bite the bullet and use the headphones output on the front of the radio. I installed my studio monitors on a upper shelf above the 8000DLE. It seemed to be working. Then, I started hearing the rumbling again, but at a much higher volume in order to hear it. And just like before, the Spectral Noise Blanker would knock it out.
I decided that if I had to use the SNB to get rid of the rumbling, that I would rather have the speakers in front of me instead of off to the side like I had to do to directly connect them to the 8000DLE. So, I put them back where I have had them all along, on the raised shelf on each side of my monitor. Connected them back to the computer and rumbling was back in all it's glory.
A bit of background information. I am nearly totally deaf in my left ear. And have something like 70% hearing in my right ear. I wear hearing aids. The left one just sends sound from my left side to the right side hearing aid. They are pretty fancy. I have an app on my cellphone that allows me to make several adjustments. ( plus several presets from the Audiologist that I cannot change) These hearing aids have really made a difference in my life.
Back to the rumbling sound. I brought up the EQ in Thetis which I have been using all along since it helped me hear things better when listening to a qso. I made some adjustments to the LOW audio frequencies while listening to just the band noise with the rumbling present. Adjusting the low frequencies eliminated the rumbling without having to use the SNB at a!l !
And, listening to a qso, everything was clear and easy to understand.
I don't recall having made any EQ changes in quite a while. But, something was different.
So, in the end,it wasn't VAC ,RFI or anything like that. It was my EQ settings causing the problem.
Again, thanks to Scott and Warren for offering suggestions on what may have been going on.
James
WD5GWY

[Trucker]

I have changed computers, network cables, coax and even a different power supply in an attempt to isolate the source of the rumbling I hear with my 8000DLE.
If I increase the AGC very much past 45 it becomes apparent. And the only way to suppress it, is to engage the SNB. That works very well. But, it suppresses the low frequencies in the receive audio. Nothing objectionable, but it is noticeable.
After doing a lot more reading here in the Thetis forum, about AGC, I found a post about using the Step Attenuator. As an experiment, I set the Step Attenuator to 15, ( with the SNB off) and the rumbling disappeared. I can increase the AGC up to 100 and still no rumbling that I can hear. And best of all, it doesn't effect the low frequency audio in the receive signal like the SNB does. Everything just sounds great.
I am hoping this isn't just a bandaid that is masking an underlying problem. Because if it is, my next choice would have to be sending my radio to Doug to find out if the problem is actually hardware related.
Living in a big city like Fort Worth, Texas l, it could easily be something nearby causing the problem. In the past we had a neighbor whose A/C system would wipe out 80 and 40 meters when it cycled on. It finally died and the owner of the house had to buy a new system. After that, no more problems with 80 and 40 meters. Given the long streak of hot weather we have been experiencing, it is possible someone else in the neighborhood is having problems that are behind the issue I have been experiencing.
At least the Step Attenuator seems to be doing a great job of eliminating the rumbling.
James
WD5GWY

[w-u-2-o]

Given that the rumbling you perceive goes away with ridiculously small AGC gains, and ridiculously high attenuation, it's very possible that the rumbling you perceive has something to do with how your hearing deficit and/or hearing aids interact with the normal noise floor output of the receiver.

It would be very helpful if you could post a high quality audio/video recording of an instance of rumbling to see if any of the rest of us perceive the sound the same way you do.

For this recording I suggest the following settings:

- AGC gain approx. 10dB above the displayed average noise level on the panadapter
- AGC medium
- Receiver passband 100 to 2900 Hz
- All NR, EQ and NB disabled.

OBS is an excellent tool for producing high quality audio/video recordings. You can make a direct audio connection to OBS via Voicemeeter. Make sure audio levels are set to achieve near 0dB peaks in OBS.

[Trucker]

Scott,
Here's a link to a short video using the settings you asked for. I hope this works. I have never used OBS Studio before.
https://youtu.be/WK7VpA-2c4A

[w-u-2-o]

Scott,
Here's a link to a short video using the settings you asked for. I hope this works. I have never used OBS Studio before.
https://youtu.be/WK7VpA-2c4A

Unfortunately the video is currently set to "private" so I can not access it. Please change the video to public.

[Trucker]

Sorry about that. It " should " work now.

[K1LSB]

Trucker,

That rumbling is normal, I hear it on my setup all the time. If you click on any active QSO in your panadapter the rumbling will disappear and will stay gone after that.

Mark

[Trucker]

Trucker,

That rumbling is normal, I hear it on my setup all the time. If you click on any active QSO in your panadapter the rumbling will disappear and will stay gone after that.

Mark

Mark,
At least you have proven I am not losing my mind and hearing things!
There was a time when I did not hear the rumbling sound. I wasn't sure if I had inadvertently changed something and caused it to happen. Or, there was a hardware problem or RFI from something in my neighborhood.
It is odd that I never noticed it till recently.
Thanks for responding.
James
WD5GWY

[KI4P]

Trucker,

That rumbling is normal, I hear it on my setup all the time. If you click on any active QSO in your panadapter the rumbling will disappear and will stay gone after that.

Mark

Mark,
At least you have proven I am not losing my mind and hearing things!
There was a time when I did not hear the rumbling sound. I wasn't sure if I had inadvertently changed something and caused it to happen. Or, there was a hardware problem or RFI from something in my neighborhood.
It is odd that I never noticed it till recently.
Thanks for responding.
James
WD5GWY

Interesting! kinda sounded to me like some of the settings on rec EQ were set to high, I have done that and figured it out, but see you dont have that on. Strange.
Richard

[w-u-2-o]

First of all, it's not you, it's really there

Second, I disagree that it is normal. I don't experience that on my 100D or my 8000. If you watch numerous videos on YouTube that demonstrate reception in Thetis/Apache setups there is no rumbling.

Third, changing the S-ATT does not eliminate the rumbling, it is still in the audio. It can be clearly heard at all times. It's just that making that adjustment tends to lower the overall audio output across all frequencies. The same is true of lowing AGC gain.

SNB apparently rolls off the audio starting around 300 or 400 Hz. Thus it should have the same effect as raising the low edge of your passband up to 300 Hz (you might try this to confirm my statement is correct).

Using the same test conditions that you used, I put the audio output of my 8000 into a spectrum analyzer. Without SNB I get this:

Capture3.JPG (180.21 KiB) Viewed 2499 times

With SNB activated I get this:

Capture4.JPG (179.66 KiB) Viewed 2499 times

No rumbling in either case.

Now compare this to your recording, first without SNB:

Capture1.JPG (197.26 KiB) Viewed 2499 times

And then with SNB activated:

Capture2.JPG (194.23 KiB) Viewed 2499 times

Something is creating those bizarre humps centered at about 140 and 280 Hz. And isn't it interesting that they have that harmonic relationship?

I'd suggest a follow up experiment in order to eliminate anything having to do with the Windows sound system, sound drivers, or sound card. Plug some headphones into the ANAN and listen there instead of with VAC. See if the rumbling is also present in that audio path and let us know.

[W4WMT]

Hi All,
How do we know the rumbling sound wasn't actually a signal on the band?
His panadapter is zoomed out so far, I can't squint hard enough to see if the rumble is actually within the receiver passband or not.
73,
Bryan W4WMT

[K1LSB]

Did anyone bother to try the suggestion I posted? If you click on any QSO in the panadapter where human speech is present, the rumble will go away and stay away.

Mark

[K1LSB]

In my experience, whenever I first start a Thetis session in SSB mode and am listening to a portion of band that has nothing but noise floor, there is a distinct rumble. But as soon as any voice appears in the passband the rumble goes away and never returns even after the voice is gone.

So I've never paid it any mind. I just tune to any QSO and the rumble goes away and stays gone after that.

Mark

[Trucker]

Scott,
I tried headphones as you asked. With the same settings as you originally asked me to try. The rumbling isn't present until I click on NR2. It's either not present with standard NR, or because of my hearing, I cannot hear it at all. I have not attempted to change any of the default NR2 settings as I wasn't sure if that would help or make a difference.
I can lower the AGC as when using my powered speakers and once around 40 to 45 it goes away. I am beginning to wonder if I should contact Doug and see if he thinks it could be a hardware problem.
I appreciate all the advice and input from everyone that has responded. I am also glad, in a way, to know it's not all in my head!
James
WD5GWY

[K1LSB]

Scott,
.
.
The rumbling isn't present until I click on NR2.
.
.
James
WD5GWY

Thanks for mentioning that, I had forgotten that I'm always running NR2.

Mark

[w-u-2-o]

Scott,
I tried headphones as you asked. With the same settings as you originally asked me to try. The rumbling isn't present until I click on NR2.

Apples and oranges. NR2 will generate some artifacts from time to time, including a low frequency rumble. If you let it run for more than a few seconds the rumble will often disappear.

More importantly: with headphones plugged into the ANAN you don't get the rumble. This then points a really big finger at the Windows sound system, Windows sound drivers, and/or sound card settings. Post a screen shot of your sound card settings in Windows > Control Panel > Sound > Playback, in particular any tab that is labeled "Enhancements". Or, if you have a special control panel provided by the sound card manufacturer, post that, too. What sound card are you using with VAC?

It's either not present with standard NR, or because of my hearing, I cannot hear it at all. I have not attempted to change any of the default NR2 settings as I wasn't sure if that would help or make a difference.

You want to make sure these are set to Pre-AGC and Gamma. Make that change and listen again.

I can lower the AGC as when using my powered speakers and once around 40 to 45 it goes away.

I'm pretty sure it doesn't go away. The volume of the noise signal just becomes low enough that you can hear it with your ears.

I am beginning to wonder if I should contact Doug and see if he thinks it could be a hardware problem.

By doing this experiment and not hearing it in the headphones plugged into the ANAN you just proved it is NOT a hardware problem.

When I have some time this evening I'll grab some screen shots of the noise audio spectrum with and without NR2 so you can see the NR2 "rumble" and observe how it is completely different from your original problem.

[Trucker]

I think you hit the nail on the head. I am using Windows 11 PRO. It took a while, but I had to look under Settings/System/Sound. Then in the Advanced section, All Sound Devices/Properties, there is a section for Audio Enhancements and Spatial Sound. I turned both of those off and, so far, no rumbling that I can detect.
I tried to go back through the above steps to photograph them, but for some reason, I cannot get to the exact place where I was able to turn those settings off. Earlier versions of Windows seemed to be easier to navigate ( at times) than Windows 11.
I will keep trying to find where I actually made the changes and document them. The directions you gave are fine on my Windows 7 computer. But, are different on Windows 11.
Thanks for your help.
James
WD5GWY

Forgot to mention, I have the AGC set at 65 with no rumbling. So huge improvement!