Measuring and adjusting virtual audio levels between PowerSDR/Thetis and other app's

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w-u-2-o
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Measuring and adjusting virtual audio levels between PowerSDR/Thetis and other app's

Postby w-u-2-o » Sat Oct 17, 2020 3:59 pm

In the Windows audio system, an audio level of 0dB, or 100%, represents the maximum audio level possible in a digital audio stream or channel. At levels above that clipping of the audio waveform will occur, as obviously when all the bits of the digital word representing the audio are set to "1" there is no more dynamic range available.

There are a great many places within the Windows sound system where audio gain of a device or channel can be adjusted. At the most basic, device level, this would be in the device driver, if the device has a driver that allows such adjustments. This is rarely the case for more conventional devices. However, if you are using something a bit more capable, for example an ASIO sound interface like a Behringer or Focusrite product, the driver may come with a separate control panel that allows audio gain adjustment.

Another, very basic, device level place where audio gain can be adjusted is in the Windows Sound Control Panel. At the bottom, under advanced sound options, you will find a mixer that can be adjusted for applications that support the Windows Sound Mixer.


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However, the new, Windows 10 Sound Control Panel still does not replicate the device level controls that are found in the legacy Windows Sound Control Panel, which can be reached from the new sound control panel by clicking on "Sound Control Panel" in the upper right hand corner. Confusing? You bet! But it is critical to go into the old style control panel and check the levels assigned to each device. Fun tip: you can right click the numerical readout and change it between percent and decibel readings.


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Initial settings:

1. Set all levels to 0dB or 100% across the board--the importance of this first step cannot be overstated!

- PowerSDR or Thetis RX1 AF 100%
- PowerSDR or Thetis VAC RX Gain 0dB
- PowerSDR or Thetis VAC TX Gain 0dB
- Windows new Sound Control Panel audio mixer--any app you care about that appears on mixer list 100%
- Windows old Sound Control Panel--all devices you are using, including any virtual devices, set level to 100% or 0dB; this includes both recording and playback devices
- If you are using Voicemeeter set all sliders to 0dB

Performing step 1 above substantially simplifies your work flow. With every part and path through the system set to maximum gain, this maximizes the dynamic range of every part of the system and reduces the number and location of final adjustments to just two. For those of you used to making level adjustments on analog audio systems do not fear this approach. There is no penalty for leaving everything set to maximum gain because digital data transfer does not add noise to the signal, there is no amplifier noise like there is in an analog audio system.

2. Choose one place and one place only to change the TX audio level. My recommendation would be to change this is in the digi mode app if possible. That way you don't have to mess with PowerSDR/Thetis when using different app's. This is not always possible, but it is possible in most of the popular app's like Fldigi and WSJT-X.

3. Choose one place and one place only to change the RX audio level. My recommendation would be to change this using the RX1 AF control on the main PowerSDR/Thetis console. That way it is completely obvious where your level is at and you never have a situation where you "forgot" that you changed it somewhere out of sight, out of mind, like the VAC control panel or Windows mixer. If this messes with your listening levels use Master AF to make up for that, or use an external speaker or headphone amp with its own volume knob.

Note that the RX1 AF control is linear, not logarithmic, in its scaling. At 100% your are at 0dB. At 50% you are at -6dB. At 25% your are at -12dB.

As you get more comfortable, practiced and sophisticated in your operations you can, of course, start making adjustments elsewhere.

Debugging your RX levels:

- Install the free Orban Loudness Meter app.
- Connect the Orban app to Thetis using your favorite virtual cable software.
- Ensure that VAC RX gain is 0dB.
- Turn on MON.
- Assert TUN.

The resulting tone should show a level of -1dB (peak, PPM and VU) in Orban.

If it does not show -1dB, then there is a problem in your virtual cable or in Windows. As discussed above, check the Windows Sound control panel (new one), all the way at the bottom, under Advanced Sound Options. Check also the old Windows Sound control panel and the levels set for your virtual cable devices.

Once you've eliminated the virtual cable and/or Windows, then you need to take a look at your receiver setup. Are you using DIGU? Is RX1 AF set properly? Where is your AGC Gain set to?

Debugging your TX levels:

- Set VAX TX gain to 0dB,
- Select DIGU mode,
- Set any of the common app's like Fldigi or WSJT-X to 0dB (maximum) output, then use their "tune" or "test" function.

You should see 0dB on the mic meter in Thetis. If you don't, then there is some problem in your virtual cable or in Windows.
NN3RP
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Re: Measuring and adjusting virtual audio levels between PowerSDR/Thetis and other app's

Postby NN3RP » Sun Oct 18, 2020 10:35 pm

I followed this post and set the sounds per the instructions. While trying to debug the RX levels, and after I installed the Orban software, I cannot find the Orban





The instructions said to connect Orban to Thethis using the VAC cable. When I assert Tune, I do not see anything displayed on the Orban meter.


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Debugging your RX levels:

- Install the free Orban Loudness Meter app.
- Connect the Orban app to Thetis using your favorite virtual cable software.
- Ensure that VAC RX gain is 0dB.
- Turn on MON.
- Assert TUN.
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Re: Measuring and adjusting virtual audio levels between PowerSDR/Thetis and other app's

Postby w-u-2-o » Mon Oct 19, 2020 1:17 am

NN3RP wrote: The instructions said to connect Orban to Thethis using the VAC cable. When I assert Tune, I do not see anything displayed on the Orban meter.
It appears you have started the Orban app since the screenshot shows the little on/off button at the bottom gold in color. However, just to be safe, set the autostart option in Orban to ON.

It is not clear that you have properly connected Orban. You only presented a screen shot of Orban settings, not the Thetis VAC settings.

With MON on, do you hear a tone in your speakers/headphones when asserting TUN?
NN3RP
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Re: Measuring and adjusting virtual audio levels between PowerSDR/Thetis and other app's

Postby NN3RP » Mon Oct 19, 2020 2:42 pm

Thanks for your assistance:


It appears you have started the Orban app since the screenshot shows the little on/off button at the bottom gold in color. However, just to be safe, set the autostart option in Orban to ON.

* I set the autosart option in Orban to ON and restarted the PC

[i]It is not clear that you have properly connected Orban. You only presented a screen shot of Orban settings, not the Thetis VAC settings.
[/i]

Thetis VAC1:
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[i]With MON on, do you hear a tone in your speakers/headphones when asserting TUN?[/i]

I do hear the tone when asserting TUN but there is nothing displayed on the Orban:

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Orban Settings:

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TX Settings display properly with Mic enable on Thetis: 0 Db

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Rafael / NN3RP
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w-u-2-o
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Re: Measuring and adjusting virtual audio levels between PowerSDR/Thetis and other app's

Postby w-u-2-o » Mon Oct 19, 2020 4:22 pm

NN3RP wrote:I do hear the tone when asserting TUN but there is nothing displayed on the Orban
Screenshots are worth a million words...

Your virtual cabling is messed up. You have assigned your Thetis VAC1 output to "Line Out (Virtual Cable 1), and your Orban input to "Line 2 (Virtual Audio Cable)". Get that sorted out properly (probably best to change it on the Orban end) and you should be working.
NN3RP
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Re: Measuring and adjusting virtual audio levels between PowerSDR/Thetis and other app's

Postby NN3RP » Mon Oct 19, 2020 7:36 pm

Changing the setting on Orban does not make any difference. I'll keep it the way it is.
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Re: Measuring and adjusting virtual audio levels between PowerSDR/Thetis and other app's

Postby ea3aqr » Mon Oct 19, 2020 9:08 pm

One question:

On " Windows old Sound Control Panel--all devices you are using, including any virtual devices, set level to 100% or 0dB; this includes both recording and playback devices"

When I set my recording level to 100% (Using a Sound Blaster X AE5 and ASIO drivers) it equals to +9db gain. To set it to 0db, my audio gain should be 69%.

What is the correct setting?
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Re: Measuring and adjusting virtual audio levels between PowerSDR/Thetis and other app's

Postby w-u-2-o » Tue Oct 20, 2020 12:18 am

ea3aqr wrote:When I set my recording level to 100% (Using a Sound Blaster X AE5 and ASIO drivers) it equals to +9db gain.
Measured where, and how? Without that context it is impossible to answer or understand your question.
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Re: Measuring and adjusting virtual audio levels between PowerSDR/Thetis and other app's

Postby ea3aqr » Tue Oct 20, 2020 6:36 am

w-u-2-o wrote:
ea3aqr wrote:When I set my recording level to 100% (Using a Sound Blaster X AE5 and ASIO drivers) it equals to +9db gain.
Measured where, and how? Without that context it is impossible to answer or understand your question.


If I set recording gain level to 100% in windows old sound control panel and then switch to db reading (right click) it shows me a gain of +9db
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Re: Measuring and adjusting virtual audio levels between PowerSDR/Thetis and other app's

Postby w-u-2-o » Tue Oct 20, 2020 3:19 pm

Now I understand. Going back to your original question...

ea3aqr wrote:One question:

On " Windows old Sound Control Panel--all devices you are using, including any virtual devices, set level to 100% or 0dB; this includes both recording and playback devices"

When I set my recording level to 100% (Using a Sound Blaster X AE5 and ASIO drivers) it equals to +9db gain. To set it to 0db, my audio gain should be 69%.

What is the correct setting?
My guide above is intended for making connections between software applications, not hardware devices. Nevertheless, the correct setting for recording (mic) gain on your Sound Blaster card is whatever it takes to achieve consistent Thetis mic level readings near, but not over, 0dB. It's better to err on the side of too little than too much. Unlike making connections between software applications where the output levels are very predictable and repeatable, the levels coming out of a microphone will vary substantially based on a speaker's voice, distance from the microphone, and the microphone itself. Therefore the strict 0dB/100% gain rule does not apply to microphone inputs.

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