Help-with unwanted TX reverb using electret mic PC audio

G3ZQH
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Help-with unwanted TX reverb using electret mic PC audio

Postby G3ZQH » Tue Oct 25, 2022 3:27 pm

200D, Protocol 2 v1.9, Thetis 2.9.06 4/23/22
Windows 10 PC
Voicemeeter Potato
Koss SB45 electret headset
Audio routed through PC mic/phone sockets

Problem recently with a strange reverb type effect on TX audio reported when in QSO. The audio has a slightly digital/robotic sound to it with an obvious reverb/echo. I have checked for obvious RF feedback but this is not the problem (4W out or 400W shows same effect). I have completely reset my audio set up using the excellent guide by Rob W1AEX and all seems as it should be. I use PureSignal but the reverb is there with or without it engaged.

The reverb is not present with mic plugged in directly to the rig. Unfortunately, I have a fault with the mic socket on the 200D leading to noise/tones inserted into the mic audio. This makes it even worse audio than with the reverb.

I think this reverb effect has been reported before but I could not find a solution. Has anyone had this effect and, if so, is there some simple setting that I have wrong? I've not had this effect previously in 5 years use of my 200D, but with many Thetis and Windows updates in recent years there might be some bad interactions in the audio chain.

I've attached a recording of the reverb audio made by another ham during QSO so that you can hear the effect.

If anyone has any ideas about this please let me know. I've spent several days trying to solve what I thought would be a simple problem but with no positive results so far.

73 Dave G3ZQH
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w-u-2-o
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby w-u-2-o » Tue Oct 25, 2022 3:59 pm

Assuming this is truly not an RFI problem, then it is a virtual audio configuration problem and this discussion belongs in and will ultimately be moved to the virtual audio sub-forum.

You did not successfully attach your audio file.

We need to see screen shots of your entire Voicemeeter window, your Thetis VAC setup window, and the Advanced tab of each relevant Windows Sound Control Panel device. At a minimum that means the two Voicemeeter virtual devices and the microphone device. An example of this particular window/tab is shown below.

The reverb is not present with mic plugged in directly to the rig. Unfortunately, I have a fault with the mic socket on the 200D leading to noise/tones inserted into the mic audio. This makes it even worse audio than with the reverb.

Is this problem the same or similar to that described in viewtopic.php?f=12&t=4384 ???

Example of Windows Sound Control Panel advanced settings tab. All of the relevant devices MUST be set to 48KHz, stereo if possible, 16 or 24 bit.

Capture.JPG
Capture.JPG (101.99 KiB) Viewed 5826 times
G3ZQH
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby G3ZQH » Tue Oct 25, 2022 4:36 pm

Hi Scott
Thanks for the quick response.

Here is further information attached:

Audio file of reverb TX- sorry a bit long but you get the idea
VM screenshot
Thetis VAC settings
Windows Mic
Windows VM Input
Windows VM output

Yes, the problem with rig mic audio is very similar to that described in the topic. Actually I have had this problem for several years but moved to PC audio to avoid it. Now I have a problem with rig and PC audio so need to fix one of them (or even better both...!)

73 Dave G3ZQH
Attachments
2022_10_20_15_16_38dave g3zqh.mp3
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VM Output Windows.pdf
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VM Input Windows.pdf
(42.65 KiB) Downloaded 111 times
VM screen PC SSB G3ZQH 25.10.22.pdf
(132.34 KiB) Downloaded 109 times
Thetis VAC PC SSB settings G3ZQH.pdf
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Mic Windows SCP settings.pdf
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w-u-2-o
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby w-u-2-o » Tue Oct 25, 2022 5:09 pm

The good news is nothing appears grossly wrong. I neglected to ask for the Realtek output advanced tab but I can see Voicemeeter reports it being 48KHz.

A few things catch my eye:

1. Since your Realtek audio interface is not ASIO you should not use ASIO in Thetis VAC. Try changing that to MME.

2. You've got the A1 hardware out in Voicemeeter set to the Realtek interface, which is good and necessary for Voicemeeter to work properly. However you can see it has negotiated a buffer size of 512. Therefore you should match this in Thetis VAC, so change the main buffer size there from 256 to 512.

3. 10dB of TX gain in Thetis VAC is a lot. If your mic level into Thetis VAC from Voicemeeter is low then check mic level in the Windows sound control panel and bump it if you can, and/or bump it on the A1 channel in Voicemeeter.

It does not appear that you use Voicemeeter for anything but patching the Realtek audio to Thetis. If that's all you use it for you can dispense with Voicemeeter and assign the Realtek devices directly in Thetis VAC. Again, use 512 buffer size and MME drivers.

Give those things a shot and let us know how you make out.

P.S. Posting PDFs is a horrible way to post screen shots. Make them jpg files and then you can use the "place inline" attachment button to embed them in your post so that they can be seen without a lot of downloading/opening/etc.
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby G3ZQH » Tue Oct 25, 2022 7:02 pm

Thanks Scott, that's all useful. My knowledge of the details of these audio pathways is sketchy at best. I'll implement those changes and it will take a day or two to do some on-air tests. I have a few other questions below.

1. Since your Realtek audio interface is not ASIO you should not use ASIO in Thetis VAC. Try changing that to MME.


In Thetis VAC I can set up ASIO driver and can see Realtek ASIO In/out. I was able to use this setting successfully (without checking audio quality) but it was unstable in Windows when plugging in/unplugging my headset so I left it. I may be wrong, but doesn't this suggest that my PC does have Realtek ASIO drivers?

Thetis VAC Realtek ASIO.jpg
Thetis VAC Realtek ASIO.jpg (180.7 KiB) Viewed 5789 times


In my (admittedly trial and error) experiments I found that MME gave a significantly worse delay in TX audio monitoring compared with the ASIO setting. ASIO was almost real time but MME had several hundred 100s milliseconds delay. I have never achieved a totally stable resampler (dropouts and runaways happen regularly) but my observation was also that the ASIO VAC setting was more stable.

I use my PC for multiple tasks, not just radio, and often use Voicemeeter to help with re-directing audio as needed- probably rather inexpertly.

73 Dave G3ZQH
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w-u-2-o
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby w-u-2-o » Tue Oct 25, 2022 7:46 pm

My apologies. It seems that your Realtek interface is ASIO capable with a good ASIO driver. So by all means ignore that part of my advice! :D

However, with that said, can you confirm that you selected the ASIO driver for the Realtek Speaker device in Voicemeeter for Hardware Output A1?

Please post a screenshot of what pops up when you select Menu > System settings/Options in Voicemeeter.

And, of all the things I suggested, the very first thing you should probably try is to change the VAC buffer size to 512 to match the Realtek buffer size shown in Voicemeeter.

You are correct, MME is dog slow. WDM-KS is pretty fast, almost as fast as ASIO. But ASIO is the king for low latency.

Great job on posting that screenshot with a jpg! :)
G3ZQH
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby G3ZQH » Tue Oct 25, 2022 10:23 pm

Please post a screenshot of what pops up when you select Menu > System settings/Options in Voicemeeter.


VM settins options ASIO.jpg
VM settins options ASIO.jpg (184.24 KiB) Viewed 5767 times

I don't think I have ever changed the defaults in this part of VM because it presents warnings about 'specific expertise' needed to make changes of many of the parameters.

I feel I am making slow but steady progress now in understanding what's happening in VM with your input. Not had a chance yet to check TX audio.

73 Dave G3ZQH
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w-u-2-o
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby w-u-2-o » Tue Oct 25, 2022 11:20 pm

If the Realtek ASIO drivers are properly installed, you can see in that latest screenshot that you did not select the Realtek ASIO instances of the mic and speaker devices when you assigned inputs and outputs in Voicemeeter.

Try reassigning them.
G3ZQH
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby G3ZQH » Wed Oct 26, 2022 6:59 pm

If the Realtek ASIO drivers are properly installed, you can see in that latest screenshot that you did not select the Realtek ASIO instances of the mic and speaker devices when you assigned inputs and outputs in Voicemeeter.

Try reassigning them.


I tried this but could see the Realtek ASIO only in the VM OUT tab and not in the VM IN. See screenshots below. This doesn't seem right. Is this an ASIO problem? If it is, how do I find the correct ASIO drivers?

VM out list.jpg
VM out list.jpg (60.16 KiB) Viewed 5720 times
VM in list.jpg
VM in list.jpg (27.91 KiB) Viewed 5720 times
VM settings ASIO.jpg
VM settings ASIO.jpg (303.9 KiB) Viewed 5720 times


Scott, thanks for persevering with this problem. I did not realise it was going to be so complicated! (for me anyway...).

73 Dave G3ZQH
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby w-u-2-o » Wed Oct 26, 2022 9:49 pm

Dave,

My first thought on that was to do a Google search on "Realtek ASIO Voicemeeter". The very first hit was a 5 page thread on the VB Audio forum about how the Realtek ASIO driver doesn't work well or reliably with Voicemeeter. Then I found a similar thread on the Steinberg forum.

Not using Realtek myself I've got little more to offer in that department. I'd suggest you consider a more serious audio interface. There are many good ones. I like the Behringer UMC202HD, but it only has fully balanced I/O for mic and speakers. However it is quite inexpensive, works very well, and the Behringer ASIO drivers are second to none.

At any rate, at this point I can only recommend going back to either MME or WDM across the board, adjust the VAC buffer to match what Voicemeeter reports, and let us know how you make out.

One more thought: is there any sort of Realtek control panel or app you can bring up? If so, what do the settings there look like (i.e. post a screen shot).

73,

Scott
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby G3ZQH » Thu Oct 27, 2022 9:55 am

Yes, you are right Scott, I have become distracted from the reverb problem by trying to get the ASIO drivers working. There is a free Realtek control app but, unfortunately, it won't download from Microsoft store (don't know why). From your search (thanks for doing that...) I can see that the combination of Realtek ASIO and Voicemeeter may not be viable.

However, one final request- I tried this patching within Voicemeeter to allow the mic ASIO input as well as the output. It seems to work and has been stable so far. Just want to check that this is a viable set up with VM. If so, I may give that a try as a last resort before going back to MME.
VM settings ASIO Input patch.jpg
VM settings ASIO Input patch.jpg (292.52 KiB) Viewed 5675 times


73 Dave G3ZQH
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby w-u-2-o » Thu Oct 27, 2022 2:40 pm

G3ZQH wrote:Yes, you are right Scott, I have become distracted from the reverb problem by trying to get the ASIO drivers working.

You were right to be distracted, Dave, because...

I tried this patching within Voicemeeter to allow the mic ASIO input as well as the output. It seems to work and has been stable so far. Just want to check that this is a viable set up with VM. If so, I may give that a try as a last resort before going back to MME.VM settings ASIO Input.

Brilliant! I should have thought of that myself. Great job, that should work fine for full ASIO!

Now the one sketchy thing that is going on is that the Realtek ASIO driver is negotiating a buffer size of 160 with Voicemeeter. How is that working out for you in terms of sound quality? What Thetis VAC buffer setting is working for you? If the answer is "none are working well" there are still more things that can be fiddled with.
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby G3ZQH » Thu Oct 27, 2022 5:07 pm

Now the one sketchy thing that is going on is that the Realtek ASIO driver is negotiating a buffer size of 160 with Voicemeeter. How is that working out for you in terms of sound quality? What Thetis VAC buffer setting is working for you? If the answer is "none are working well" there are still more things that can be fiddled with.


I noticed the buffer size change to 160. I have tried 512 and also 256 and both seem stable but at 64 it was unstable. I'm on 256 now. However, the bad reverb is still there in the audio just like it was before so there is still a problem. It is hard to see what else could be going wrong with the audio chain, so now I'm also going back to look at possible RF feedback and maybe try to source another headset just in case mine has a fault. I have an old Heil HC4 headset (broken) which I can repair just to check out the audio.

If there are any other ASIO tweaks that can be tried please let me know. This has turned out to be a far more difficult problem to solve than I originally thought...

73 Dave G3ZQH
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby w-u-2-o » Thu Oct 27, 2022 5:26 pm

This topic started out with you writing that there was no RFI problem. My very first thought was "No, it's an RFI problem." But I answered with "Assuming it is truly not an RFI problem..." Clearly we've managed to eliminate pretty much all of your digital audio configuration issues. The only thing left to check is whether or not the Realtek audio interface has some sort of monitoring path that needs to be turned off. But that seems unlikely.

Meanwhile, reverb (or echo) on transmit is a classic sign of SDR RFI. Because of the 100ms or so of latency between the mic and the antenna in an SDR, give or take depending on how the SDR and audio processing are set up, anything getting back into the mic from the antenna sounds exactly like reverb or outright echo.

Does this reverb occur when you are working into a dummy load or at very low output power? Where is the antenna relative to the PC?

Have you tried the simple expedient of a few ferrites on the mic cable? Have you tried a different microphone?

What sort of grounding and bonding work have you done on the station? Is the PC itself properly connected to the station ground?
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby G3ZQH » Thu Oct 27, 2022 7:49 pm

Does this reverb occur when you are working into a dummy load or at very low output power? Where is the antenna relative to the PC?

Have you tried the simple expedient of a few ferrites on the mic cable? Have you tried a different microphone?

What sort of grounding and bonding work have you done on the station? Is the PC itself properly connected to the station ground?


As you say, if pretty much everything else has been eliminated then I really need to look again at RFI. Seems like I am going round in circles! My antenna is about 30m/100ft from my shack PC and I have occasionally suffered RFI when operating at full power. However, reducing power from 400W to 4W did not affect the audio reverb. This is what made me think originally that it was definitely not RFI. I have a big ferrite on the headset lead and plenty of other ferrites around the shack. Rig, PC etc are all bonded to the same ground but, because my shack is in an upstairs room, there is no station ground as such apart from that provided by antennas and the grid supply.

I find it impossible to monitor my own audio on TX by monitoring (audio delay). Recording my TX audio from Thetis has been unsuccessful so far (need to try this again) and Web SDRs seem to have very poor audio quality. It could be the mic so I am currently reviving an old headset with broken mic lead and damaged boom.

I'll keep you updated with progress...

73 Dave G3ZQH
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby w-u-2-o » Thu Oct 27, 2022 8:14 pm

G3ZQH wrote:I find it impossible to monitor my own audio on TX by monitoring (audio delay).

You should be able to monitor it well enough to detect any reverb or the like. It is usually quite obvious. It certainly was in your recording. It only take a few short transmissions.

Another option would be to use the recording feature of Voicemeeter to record the output of Thetis with MON activated and play that back for inspection.
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby oe3ide » Thu Oct 27, 2022 8:39 pm

Hi,

I also had this reverb effect.. two times.

First it was a misconfiguration. Before I switched to 100% USB-audio, I had a hardware mixer in the chain. And there I had a line back from the output to the input :oops: => easy fix

2nd was RFI on 17m at high-power. But the reverb was different, it was not as "consistant" as the first issue. Also some sizzle on the tx-audio.
Reason was: I had turned down the mic-input on the mic-preamp way too much. The 0db gain was reached by pumping up the small input-signal. So a small portion of RFI was enough to get this bad audio => some more ferrites + adjusting input-mic-gain was the solution.
(and of course now problems with mic direct to the usb-audio interface).

My experience, in case someone searches for reverb audio/RFI

73 Ernst
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby G3ZQH » Sun Oct 30, 2022 8:17 pm

Reverb problem now finally solved! I thought it would be any easy fix but that was not the case. After looking at the PC/Thetis audio chains I found a few small problems but none of these were responsible for the reverb effect. I looked for RF feedback and added more ferrites. Again, no perceptible improvement.

Finally, I decided to reset the Thetis database back to my last 'good' version from about 9 months ago. I went through and checked/amended all the settings (not just the audio). At the same time I improved my PC grounding and added yet more ferrites. I temporarily eliminated Voicemeeter Potato from the audio VAC set up just in case there was a hidden problem there.

After all that I finally got good sounding audio when monitoring my own signal and the thumbs up from several helpful NA hams in QSOs. When I re-introduced Voicemeeter for VAC it worked well and the audio was good. No reverb.

So, in the end I am not sure what caused the problem because I changed a lot of things at the same time. My feeling is that the problem was caused by my Thetis database becoming corrupted but I do not have any firm evidence for this.

I hope this thread will be useful for anyone who has a similar problem. Thanks to Scott and Ernst for expert input.

73 Dave G3ZQH

Note: this solution was good for PC audio but did not resolve my 'audio birdies' problem when I use the rig mic input on my 200D.
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby w-u-2-o » Sun Oct 30, 2022 9:13 pm

I'm betting it was the grounding. There's nothing in the code that can introduce reverb.
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Re: Help-with unwanted TX reverb using electret mic PC audio

Postby dondb1 » Tue Nov 01, 2022 6:33 pm

I've been fighting reverb and RFI ever since I received the radio a few month's back .I tried everything conceivable in the shack....actually i'm surprised there are still torroids out there as i thing i bought them all! Just yesterday i put a Balun design choke right after my balun......and the RFI is all gone. I'm running a full loop 520 feet long with 192 ' of open feed line to a 4:1 Balun Design and now a choke , 6 feet of coaxial to the back of my tuner. I was working with a few other Anan owners and we were all scratching our heads with internal settings, patch cords, feed line lentghs, external audio setups and so on. Thought i'd throw this fix out there in the event it could help someone.
Don

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