G2 distorted audio using TRS and standard mic input

[echo_india]

Hi all,

My G2 has developed an issue lately where my TX audio is very distorted when I plug my microphone directly into the TRS or the standard mic input sockets. It actually sounds like rf getting into the audio even though I know this is not due to RFI and I suspect this is something with the radio itself.
Its like as if the G2 is not able to drive the microphones and goes into distortion.

Line input from my external audio rack seems fine and I hear no distortion on the audio running it this way.

Thanks.

Leslie EI5GJB

[echo_india]

Just to add. My microphones are dynamic - RE20 and SM7B.

[laurencebarker]

Have you run the audiotest app? that records a short piece of microphone audio then plays it back to you with no RF involved at all. It is there for exactly this kind of purpose.

[Roger GT]

Do you also have these problems with the dummy load?

[echo_india]

Distortion is the same when transmitting into dummy load also, and gets worse with power increase.

I took a few pictures to explain better. With bias disabled on the mic inputs I see a voltage on the mic tip and mic ring terminals which seems kind of weird.

Depending on Hardware Options -> Selecting either Tip or Ring voltage will be either at 3.2v at the tip and 1.6+ at the ring terminal of the standard mic input.

Flipping to Ring radio button -> Voltage of 3.2 will be on the ring termina and 1.6+ will be on the mic Tip.

[w-u-2-o]

While there is some anecdotal evidence that the rear balanced mic input is more sensitive to RFI than the front panel unbalanced input, nevertheless 99% of all RFI problems are due to one or more of the following three problem areas:

Poor station grounding and bonding practices--example: viewtopic.php?f=48&t=4784

RFI coming in other cables/poorly shielded cables--example: viewtopic.php?f=48&t=4799

Mic wiring mistakes--example: viewtopic.php?f=48&t=4827

In this particular case, first things first: if you can tell us EXACTLY how your mic cables are built, i.e. pin x goes to pin y, that might offer some important clues. For the rear panel balanced input you should be using a standard XLR to TRS balanced mic cable. For the front panel input you need to be using an balanced XLR to unbalanced TRS cable with the non-standard TRS wiring that these radios require.

[echo_india]

While there is some anecdotal evidence that the rear balanced mic input is more sensitive to RFI than the front panel unbalanced input, nevertheless 99% of all RFI problems are due to one or more of the following three problem areas:

Poor station grounding and bonding practices--example: viewtopic.php?f=48&t=4784

RFI coming in other cables/poorly shielded cables--example: viewtopic.php?f=48&t=4799

Mic wiring mistakes--example: viewtopic.php?f=48&t=4827

In this particular case, first things first: if you can tell us EXACTLY how your mic cables are built, i.e. pin x goes to pin y, that might offer some important clues. For the rear panel balanced input you should be using a standard XLR to TRS balanced mic cable. For the front panel input you need to be using an balanced XLR to unbalanced TRS cable with the non-standard TRS wiring that these radios require.

Thanks Scott for your input. This is not an RFI issue by any means I can assure you that. I should not have any voltage on both tip and ring at the same time and this is especially true when Mic Bias is disabled.

See image from Saturn schematic for mic bias - 5v is supplied to either TIP or RING and not split. The issue is on the board and not external to the G2.

In any case XLR wiring from RE20 microphone
XLR TRS
Pin 1 -> TRS -> Shield
Pin 2 -> TRS -> TIP/HOT
Pin 3 -> TRS -> RING/COLD

[w-u-2-o]

I should not have any voltage on both tip and ring at the same time and this is especially true when Mic Bias is disabled.

I can't explain your voltage readings. Where they measured with or without the mic connected?

If PTT is enabled you should see 3.3VDC pull-up voltage on whatever pin is not selected for the front panel mic.

If bias is enabled you should see approx. 2.5VDC bias voltage on whatever pin is selected for the front panel mic.

See image from Saturn schematic for mic bias - 5v is supplied to either TIP or RING and not split. The issue is on the board and not external to the G2.

Front panel mic bias voltage comes from U2. It is 3/4 of AVDD. U28 is merely a switch.

In any case XLR wiring from RE20 microphone
XLR TRS
Pin 1 -> TRS -> Shield
Pin 2 -> TRS -> TIP/HOT
Pin 3 -> TRS -> RING/COLD

As suspected, that represents a mic wiring error if you intend to use the front panel mic input.

This wiring is, however, perfect for the rear panel balanced input. Note that some people have reported that tip and ring are reversed on that rear panel balanced input so you might try swapping hot and cold (+ and -) if you are not obtaining good performance from that input with this cable. Note also that there is no provision for mic bias or phantom power on the rear panel balanced mic input so you should not detect any.

To use your balanced output mic's with the front panel mic input see this topic: viewtopic.php?f=12&t=2790&p=5387

[echo_india]

Thanks Scott.

No mic was connected when taking voltage readings. My G2 is the non-display version, so no mic inputs on the front panel.

Just on your point where noted that some people have reported that tip and ring are reversed on that rear panel balanced input I will check this out. However, even if it were the case that the TRS hot and cold were reversed, it still would not account for the distorted audio on the standard mic input.

[w-u-2-o]

Thanks Scott.

...

However, even if it were the case that the TRS hot and cold were reversed, it still would not account for the distorted audio on the standard mic input.

But the cable you are using with the standard input could easily account for this. You need to build the correct cable per the link posted.

[DL8LAQ]

Note that some people have reported that tip and ring are reversed on that rear panel balanced input so you might try swapping hot and cold (+ and -) if you are not obtaining good performance from that input with this cable.

This is a note Laurance sent me:
"The tip and ring connectors on the front panel 3.5mm jack and rear panel 3.5mm jack are swapped over. That may be the issue with your mic connectors. It can be corrected by modifying an internal cable. The "tip and ring" settings in software are correct for the rear panel input."

[echo_india]

Hi all, I appreciate the feedback for this issue but I am not closer to resolving by just focusing on mic cables and the like. The issue is solely with the G2. It is unable to provided clean audio amplification when plugging in a Dynamic Microphone into the TRS socket directly or into the standard mic 3.5mm socket currently.

What works:

RE20 -> Mic Preamp -> isolation transformer -> G2 back panel TRS input. In this scenario the 20db mic boost is disabled on Thetis and using minimal mic gain on Thetis also produces Clean audio.

RE20 -> Mic Preamp -> isolation transformer -> 3.5mm standard mic input. In this scenario the 20db mic boost is disabled on Thetis and using minimal mic gain on Thetis also produces Clean audio.

What does not work due to complete audio distortion.

RE20 -> G2 back panel TRS input. In this scenario the 20db mic boost is enabled or disabled on Thetis and adjusting mic gain to get a clean audio response which is impossible to get due to distortion. The G2 is unable to cleanly drive the Microphone.

RE20 -> 3.5mm standard mic input. In this scenario the 20db mic boost is enabled or disabled on Thetis and adjusting mic gain to get a clean audio response which is impossible to get due to distortion. The G2 is unable to cleanly drive the Microphone.

This will need to be looked into by Apache labs or someone reputable in the EU by Apache.

[w-u-2-o]

Unless and until you publish what mic cable wiring you used for these tests all bets are off. AFAIK you are the only person having this difficulty and you've already documented an incorrect cable build for the front and rear "standard" mic inputs (not to be confused with the rear balanced input).

Note that it doesn't matter which standard mic input you test, they are wired in parallel.

With professional type balanced microphones the best answer is to use the balanced mic input on the rear (probably marked "XLR"). This will provide the best performance and eliminates any requirement for special cables, just use a standard XLR to TRS balanced mic cable. You already appear to have one. Why haven't you tried this?

[echo_india]

Unless and until you publish what mic cable wiring you used for these tests all bets are off. AFAIK you are the only person having this difficulty and you've already documented an incorrect cable build for the front and rear "standard" mic inputs (not to be confused with the rear balanced input).

Note that it doesn't matter which standard mic input you test, they are wired in parallel.

With professional type balanced microphones the best answer is to use the balanced mic input on the rear (probably marked "XLR"). This will provide the best performance and eliminates any requirement for special cables, just use a standard XLR to TRS balanced mic cable. You already appear to have one. Why haven't you tried this?

Are you serious I mean what is not clear in my explanations? I don't have a G2 with display on the front. I told you already my wire cabling xlr to TRS. whats not to get. Microphone to TRS balanced input produces distorted audio - Simple. Do you even own an G2 cause it seems you did not look at the pictures I attached here to see the type of G2 I have.

[w-u-2-o]

My bad on missing the TRS in your post, sorry

Perhaps your G2 needs to be returned for service. It would not be the first one with problems out of the box.

[administrator]

Hi,

1. Have you tried the audio test app available with the rig? this is probably the easiest method of testing your audio.
2. Try using an alternate mic to see if you still get the distorted audio
3. If you are getting clean audio using the isolation transformer the CODEC Mic input is working as intended.

refer page 23 of the manual for the audio test app.

https://apache-labs.com/download_file.php?downloads_id=1023

Regards,

Tony

Hi all, I appreciate the feedback for this issue but I am not closer to resolving by just focusing on mic cables and the like. The issue is solely with the G2. It is unable to provided clean audio amplification when plugging in a Dynamic Microphone into the TRS socket directly or into the standard mic 3.5mm socket currently.

What works:

RE20 -> Mic Preamp -> isolation transformer -> G2 back panel TRS input. In this scenario the 20db mic boost is disabled on Thetis and using minimal mic gain on Thetis also produces Clean audio.

RE20 -> Mic Preamp -> isolation transformer -> 3.5mm standard mic input. In this scenario the 20db mic boost is disabled on Thetis and using minimal mic gain on Thetis also produces Clean audio.

What does not work due to complete audio distortion.

RE20 -> G2 back panel TRS input. In this scenario the 20db mic boost is enabled or disabled on Thetis and adjusting mic gain to get a clean audio response which is impossible to get due to distortion. The G2 is unable to cleanly drive the Microphone.

RE20 -> 3.5mm standard mic input. In this scenario the 20db mic boost is enabled or disabled on Thetis and adjusting mic gain to get a clean audio response which is impossible to get due to distortion. The G2 is unable to cleanly drive the Microphone.

This will need to be looked into by Apache labs or someone reputable in the EU by Apache.

[qst]

Hello,
I have 3 days of G2 without display and I have to confirm that it is impossible to use the TRS input. I feed the balanced microphone signal from the Apollo Twin X and the signal is distorted and there is a lot of noise. When connected to a line or microphone input, the modulation is clear without distortion and there is no hum. Something is wrong with the microphone system. Slawomir

[laurencebarker]

In any case XLR wiring from RE20 microphone
XLR TRS
Pin 1 -> TRS -> Shield
Pin 2 -> TRS -> TIP/HOT
Pin 3 -> TRS -> RING/COLD

Those connections cannot work into the front or rear panel 3.5mm jack inputs. This is what Scott reported a while ago.

The "tip" connection can be selected to be microphone or PTT; the "ring" can be selected to be PTT or microphone.

To use a balanced microphone connected to the 3.5mm jack inputs you would need:

XLR TRS
Pin 1 -> TRS -> Shield
Pin 2 -> TRS -> Shield
Pin 3 -> TRS -> Tip


In other words: one side of your "balanced" microphone input would need to be grounded.


The rear panel **6.3mm** jack socket will accept a balanced input.

[w-u-2-o]

You might have misunderstood Slawomir, Laurence. The way I understood Slawomir's post is that the unbalanced mic and line inputs are working fine but that the balanced mic input is not. Maybe he'll reply and clarify.

Unfortunately there have now been quite a few reports in this forum of the G2 balanced mic input not working properly. The two major themes have been RFI/echo and distorted audio.

Have you or anyone at Apache further investigated this issue? I'd be happy to do it, alas I do not have a G2 to do it with.

[laurencebarker]

Mine was actually a reply to Echo India's post; which was a balanced microphone being connected to an unbalanced input. I wasn't sure which input Slawomir used, but I did see it was another balanced microphone.

I have seen the reports of issues with RF sensitivity on the balanced microphone input. I'm not aware of any non-RF issues with that input; and one of the people reporting a problem with that input had observed it working correctly with no RF present using the "audiotest" app.... which really ought to be an indicator that RF *is* part of his issue. With a dynamic microphone connected to the input, and Audiotest recording the audio with no RF present, the balanced input works fine. I have mentioned the issue to Abhi. As of a few weeks ago I do now have the same build standard as is being shipped.

[laurencebarker]

Hello,
I have 3 days of G2 without display and I have to confirm that it is impossible to use the TRS input. I feed the balanced microphone signal from the Apollo Twin X and the signal is distorted and there is a lot of noise. When connected to a line or microphone input, the modulation is clear without distortion and there is no hum. Something is wrong with the microphone system. Slawomir

Hi Slawomir please use the "Audiotest" app that is described in the manual. That will record and replay audio through any of the mic inputs and allow you to choose the bias and 20dB gain setting.

[w-u-2-o]

Mine was actually a reply to Echo India's post; which was a balanced microphone being connected to an unbalanced input. I wasn't sure which input Slawomir used, but I did see it was another balanced microphone.

My bad, Laurence, sorry. I did not read your post carefully and missed who you quoted. My apologies.

I have seen the reports of issues with RF sensitivity on the balanced microphone input. I'm not aware of any non-RF issues with that input; and one of the people reporting a problem with that input had observed it working correctly with no RF present using the "audiotest" app.... which really ought to be an indicator that RF *is* part of his issue. With a dynamic microphone connected to the input, and Audiotest recording the audio with no RF present, the balanced input works fine. I have mentioned the issue to Abhi. As of a few weeks ago I do now have the same build standard as is being shipped.

There certainly seems to be a high sensitivity to RF on the balanced input.

I wonder if anyone is using the balanced mic input successfully?

[qst]

Hi,
I didn't do an audio test. I have an EV RE27ND dynamic microphone. I use an Apollo Twin X Audio interface and this interface has a symmetrical TRS output which I connected to the TRS input on the G2. The signal was littered with heavy noise and communication was impossible. I tested the G2 microphone input and am currently working on the "LINE" input because the Apollo Twin X also has a line output. Now the modulation is clean. I can adjust the gain level in Apollo in/out and select the level so as not to exceed half of the ALC scale. I will test it again and write whether it can be used with the TRS input. I think we will slowly solve the problem.
73!
Slawomir

[w-u-2-o]

I use an Apollo Twin X Audio interface and this interface has a symmetrical TRS output which I connected to the TRS input on the G2.

You can't do that. The balanced input on the G2 is a microphone preamp input. You are badly overdriving it with the output of the Apollo. This is why

The signal was littered with heavy noise and communication was impossible

Moving on...

am currently working on the "LINE" input because the Apollo Twin X also has a line output. Now the modulation is clean. I can adjust the gain level in Apollo in/out and select the level so as not to exceed half of the ALC scale.

Of course that works. A line output to a line input is proper and permissible.

I will test it again and write whether it can be used with the TRS input. I think we will slowly solve the problem.

If by "TRS" you mean the balanced mic input, then the problem is already solved. You cannot take the output of the Apollo and put it into a mic preamp input.

You could try the RE27 directly into the G2 balanced mic input by itself.

Or you could connect the Apollo Thunderbolt interface to your PC and use the new cmASIO feature of Thetis.

[qst]

Hi,
I do not agree with the opinion that the output from Apollo must necessarily be connected to the G2 line socket. In Apollo and DAW there is an adjustment of audio signal levels. Yesterday I connected the signal from Apollo to the "mic" input and after setting the microphone signal level, the signal was clean without distortion and noise. The TRS socket should work the same way. The question arises whether the input resistance is correct to connect a microphone signal there. If I turn on PTT on TX and the power is set to "0", the noise produced is not the result of RF transmitting to the microphone amplifier. A common case is a problem with the mass of the system. A potential difference may arise and therefore a hum occurs. I will do some experiments and write about the effects.
Slawomir

[laurencebarker]

There is substantial gain in the balanced TRS input compared with the other mic inputs. That makes it the most sensitive input.

I ask again: please use Audiotest. It will help you to answer a lot of questions.

[W7GES]

I just tested the Balanced mic input with my G2 w/front panel display.

I used an amplifier and transmitted 1000 watts, listening through a kiwisdr.

I could not hear any distortion on my signal. I used a Sennheiser HMD-280 microphone headset with the balanced mic input.

My normal SO2R setup uses a Heil 781 fed through a YCCC SO2R box into the G2 back panel TRS jack.

I also tried my "normal" audio with the 781 and back panel TRS input and the audio was clean with no distortion as well.

73,

George / W7GES

[MW0XDT]

Not sure if any solution was actually found to this issue, reading the above?…However what is clear is that Laurence suggests using the audiocheck app (more than once) and so as I’m experiencing very distorted audio, I’d like to start here.

…only problem is I can’t get the script listed in the manual to run… cd github/Saturn/sw projects/audiotest …brings up bash: cd: too many arguments, I think due to the two spaces used. Apologies as I am new to Linux (but enjoying the challenge) Please point out the ridiculous error of my ways, I won’t be offended!

Best 73 Rich MW0XDT

[n1gp]

Hi Rich,

It's the space in the directory name that is causing the issue.
Try either escaping the space by putting a slash in front of it:
cd github/Saturn/sw\ projects/audiotest

or putting quotes around the line:
cd "github/Saturn/sw projects/audiotest"

73

-Rick / N1GP

[MW0XDT]

Thanks Rick,

I’ve tried with both techniques which is now accepting as a command, but telling me there’s ‘no such file or directory’
Double and triple checked the script, still no go?

Then noticed in the directories there should be an underscore after sw_projects etc …the underscore is hidden as the whole script is underlined in the manual. Entered this and it’s accepted, next step is listed as ./audiotest ….typed this in and I’m back to ‘no such file or directory’ although I know it’s there?

On the plus side, I’ve got a great ‘receiver’

Thanks again for the help.

73 Rich