Rumbling audio,,,,again

[w-u-2-o]

...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.

That's indeed where I was headed with that line of questioning. It makes perfect sense that you had "rumbling" with those settings turned on.

Don't forget to set NR2 to Pre-AGC and Gamma.

No need for more spectrum analyzer plots now

[Trucker]

Scott, it's been purring like a kitten all evening. I can run the AGC all the way up and still no rumbling. It's amazing how a couple of settings like that can cause so much havoc.
Thanks again for your help.
James
WD5GWY

[K1LSB]

Hmm, I've got Audio Enhancements and Spatial Sound turned off for all of my devices but still have the rumble.

Mark

[w-u-2-o]

Glad we got it on the first page, James

BREAK

Mark, try doing the same experiments I suggested to James. Again, settings are as follows:

- AGC gain approx. 10dB above the displayed average noise level on the panadapter
- AGC medium
- No attenuation
- Receiver passband 100 to 2900 Hz
- All NR, EQ and NB disabled.

Listen via VAC, then listen via the headphone jack on the ANAN.

[K1LSB]

Scott,

I'll try that this evening, thanks. With that said, please be aware that I don't normally use VAC for receive, I'm usually listening to the 1/4" speaker jacks on the rear panel of the 7000DLE MKII (of course I can enable VAC for RX).

Mark

[Trucker]

Mark, if I understand correctly, the rumbling you hear has always been present, correct?
One of the things that Scott suggested to me was to listen to my audio connected to the headphones connection on my radio. I used the front panel connection. I could not hear any rumbling at any AGC setting.
You might want to try that first. But, disconnect your rear speakers first. If you don't hear the rumbling, I would suspect one or both of your rear speaker connectors may have a wiring issue.
There are several posts about a wiring issue for the rear speakers on the 7000/8000 that could cause problems if the connectors ( TRS if I remember correctly) are wired incorrectly.
You may want to check that out.
James
WD5GWY

[w-u-2-o]

Those TRS speaker jacks are indeed tricky. They are a very non-standard implementation. The voice coil of an unpowered speaker must be wired across the tip and ring. Do not use a powered speaker. Do not connect anything to the shield.

[K1LSB]

The rear speaker jacks are tricky, I use a pair of screw terminal plugs to connect a line-out converter that reduces the output power to line-level that's then fed into my MOTU M4 that feeds a pair of powered speakers through VM Potato.

https://www.amazon.com/gp/product/B07M6 ... UTF8&psc=1

https://www.amazon.com/gp/product/B001E ... =UTF8&th=1

Mark

[K1LSB]

Trucker,

The rumbling originates somewhere in software, it isn't caused by the speakers or jacks. The rumble is only present when first pulling up a Thetis session. As soon as I click on any active QSO the rumble disappears and never returns.

Mark

[Trucker]

Trucker,

The rumbling originates somewhere in software, it isn't caused by the speakers or jacks. The rumble is only present when first pulling up a Thetis session. As soon as I click on any active QSO the rumble disappears and never returns.

Mark

Ok, this is probably above my pay grade. Hopefully, Scott can help you figure it out.
James
WD5GWY

[K1LSB]

Glad we got it on the first page, James

BREAK

Mark, try doing the same experiments I suggested to James. Again, settings are as follows:

- AGC gain approx. 10dB above the displayed average noise level on the panadapter
- AGC medium
- No attenuation
- Receiver passband 100 to 2900 Hz
- All NR, EQ and NB disabled.

Listen via VAC, then listen via the headphone jack on the ANAN.

I performed your experiment, the rumble is present if NR2 is enabled regardless of configuration settings or output device.

Mark

[S_Car_Go]

My radio does the exact same thing. Often when one of those frequency sweeps happen the rumbling will either start or stop. I just assumed it was an issue in the algorithm or some sort of artifact.

[Trucker]

So far, after running all day today, not a single rumble. I can set the AGC as high as it will go. And no rumbling in the audio at all. I didn't have the problem until recently. I suspected many things. But, Scott's line of questions pointed me in the right direction.
In my case, using VAC for audio in and out had been working well. Something changed and the Audio Enhancements and Spatial Sound was turned on. I don't recall changing those settings. I am thinking that it is possible that Windows Update turned them on. That, or when I updated the Realtek audio driver.
Either way, rumbling isn't " normal " if things are working together properly. As an experiment, maybe, making things simple would help track down the problem. Use VAC with powered speakers connected to the computer. And see if the problem exists at that point. ( no Audio Enhancements or Spatial Sound turned on) use Scott's basic settings and see if the rumbling is evident. If not, then add back any external hardware that had been previously used. And see at what point the rumbling returns.
Just some thoughts that occurred to me.
James
WD5GWY

[w-u-2-o]

I performed your experiment, the rumble is present if NR2 is enabled regardless of configuration settings or output device

That's a whole different kettle of fish. Not at all the same problem as James.

Any NR algorithm is going to have some audible artifacts. Perhaps you are extra sensitive to those from NR2. I routinely set my receive passband low end at 50Hz and I can only notice the slightest rumbling if I place my AGC gain line very close to the displayed average noise level (DANL) on the panadapter. When the AGC gain line is (a more reasonable IMHO) 10dB above the DANL any rumbling is almost inaudible.

I recommend that the NR2 setting be Pre-AGC and Gamma but otherwise use the default settings. Are those the settings you are using?

[K1LSB]

Yes sir, my NR2 settings are Pre-AGC and Gamma.

The rumble I typically hear is distinct, not subtle or subdued. Kinda like a waterfall, but not so loud that you're standing close enough to get wet.

I did notice that when I was adjusting the low-cut point on RX audio per your suggestion there was no discernible reduction in rumble until I was passing the 140-150 range, at which point the rumble became suppressed, which suggests I'm probably hearing the same 140 Hz node you were observing on your spectrum analyzer.

Just passing along my observations.

Mark

[w-u-2-o]

This morning I made some measurements here using some pretty challenging conditions:

- RX passband 50-3500Hz
- AGC gain line set right on top of the noise floor.

With NR2 activated I got the following noise spectra:

Capture.JPG (191.19 KiB) Viewed 1663 times

There's certainly a little content down around 140Hz, and this can certainly be characterized as a "rumble". I did find that I could distinguish that content by ear but it is by no means distinctive or objectionable (to me). And it's completely inaudible to my ears with an actual signal in the passband.

Even with that little artifact it seems far preferable to no noise reduction at all:

Capture2.JPG (173.69 KiB) Viewed 1663 times