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Beta Test: Multitone Loopback Analyzer software

pkane

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This is a software beta-test for IMD and THD aficionados with an intense desire for multi-tone audio testing :)

The start of the documentation and the download website is here: https://distortaudio.org/multitone.html (for 64-bit Windows)

Multi-tone Analyzer (MA) was more of an experiment than a product, but I've been asked to make it available to others, so here it is. With your help and suggestions, this can grow into something bigger! Unlike my other apps, DeltaWave, Distort, etc, I've not spent any significant time testing this myself, just some basic shake-down and verification on a few sound cards and a few computers. Be warned!

1636113488936.png


All the important controls are on the main screen with a few additional settings available if you click the gear icon at the top right.

The red record button is what starts the measurement process, the black stop button next to it aborts it.

Pick the correct audio devices (top is output/DAC, below is input/ADC). Make sure these are configured correctly in Windows, with volume settings set appropriately to 100% and at the desired sample rate, with all DSP/enhancements turned off.

IMPORTANT: DON'T USE THIS WITH YOUR SPEAKERS OR HEADPHONES connected to the loop-back chain! This will hurt your ears and/or damage your equipment due to the wide frequency range and potentially loud sound levels. This is meant for measurements only, not for listening!

Pick the desired test signal. Many are available. What's more, you can change the settings on any of these by just typing in different frequencies or amplitude ratios. For example, you could enter Multitone 10000 and this will attempt to generate a test signal of 10000 tones!

1636114320988.png


Select FFT size. Bigger is better in this case, especially as you increase the number of tones as this increases frequency resolution. The tradeoff is that you'll have to wait longer for the measurement process to finish.

You can select a number of test runs to average, which help lower noise in the measurement.

Frequency from and to selection determines measurement frequency range. MA will always capture the full frequency range up to Nyquist, but will use the specified range for measuring TD+N, IMD, etc.

After capture and processing the results will be displayed on the bottom, below the chart:

1636114558973.png


Frequency response will measure frequency variation based on multi-tone amplitudes, so only works with a larger number of tones (and only multi-tone test signal).

Waveform plot will show the test and captured signals in time domain:

1636114793827.png


I'll be posting more information in follow-up messages. Please take a look, and as always, please respond with all bugs/suggestions/ideas for improvement in this thread.
 
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Blumlein 88

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I'll have to give this a try.
 
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pkane

pkane

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A few notes on v1.0.0 beta:
  • ASIO devices are supported but the same device can't be used for input and output at the same time.
    Either use different ASIO devices, or use one WASAPI and one ASIO, or both WASAPI. Something I know how to fix, but it'll take some time
  • ASIO sampling rate can be configured in settings, under the gear icon
  • WASAPI Shared mode setting should be left turned off in settings for best results
  • IMD result is displayed only for test signals with 5 or fewer tones due to the complexity of computing notch filters for a larger number of tones
  • IMD calculation is different depending on whether the test signal is labeled as SMPTE. All other signals will report DIN-style IMD result.
  • N+D result will be lower with averaging, as long as it's dominated by noise in the loopback chain
  • Clock drift value (assuming different DAC/ADC clocks) is computed with greater accuracy with larger multi-tone signals
  • Delay value is computed from the time the output device starts playing to when the sound is received. This can include delays that may be PC-related, not just those from the DAC/ADC loopback
  • Crest factor is computed for multi-tone signals only. This will be extended to other test signals in future versions
 
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Grooved

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Aaaah, the weekend is saved... ;)
Haha, I have some many things for this weekend, but I may try to cancel a small one to do some tests :)

For now, I get a 2dBFS difference in signal level for each step of 1dBFS Gain setting change, is it normal @pkane ?
Also tried :
one ASIO DAC and one WASAPI ADC : OK
one ASIO DAC and one ASIO ADC (different devices) : freeze. I will try another one later
 
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pkane

pkane

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Haha, I have some many things for this weekend, but I may try to cancel a small one to do some tests :)

For now, I get a 2dBFS difference in signal level for each step of 1dBFS Gain setting change, is it normal @pkane ?
Also tried :
one ASIO DAC and one WASAPI ADC : OK
one ASIO DAC and one ASIO ADC (different devices) : freeze. I will try another one later

2dBFS on 1dB change? That shouldn't happen. Is this with ASIO or WASAPI devices?

I've not had a chance to test two ASIO devices yet, so I wouldn't be surprised if that also doesn't work.
 

Pdxwayne

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This is for EE engineers only or for anyone?
; )

Want my feedbacks?
 

Grooved

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2dBFS on 1dB change? That shouldn't happen. Is this with ASIO or WASAPI devices?

I've not had a chance to test two ASIO devices yet, so I wouldn't be surprised if that also doesn't work.
Yes, but it was with ASIO on DAC, and WASAPI on ADC.
With 0dB Gain, got -4dB level (could increase it on the device but I didn't change anything), then tried with :
-1dB Gain, got -6dB level
-2dB Gain, got -8dB level
-3dB Gain, got -10dB level
...

I will give a quick test on both this thing and two ASIO devices but with another ADC in one hour from now.
 
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pkane

pkane

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Yes, but it was with ASIO on DAC, and WASAPI on ADC.
With 0dB Gain, got -4dB level (could increase it on the device but I didn't change anything), then tried with :
-1dB Gain, got -6dB level
-2dB Gain, got -8dB level
-3dB Gain, got -10dB level
...

I will give a quick test on both this thing and two ASIO devices but with another ADC in one hour from now.

The double change in signal level from gain setting is a bug. Don't worry about chasing it down, I'll fix it, ASAP.
 
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pkane

pkane

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The double change in signal level from gain setting is a bug. Don't worry about chasing it down, I'll fix it, ASAP.

Confirmed -- it's a bug (@Grooved ) . I updated the web page with a fixed version, but didn't change version number. Please uninstall the previous version before installing the new one. This should fix the double signal level change when adjusting gain. Turns out I was applying gain twice, once when generating the signal, and another time when playing it to the DAC :)
 

amirm

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Good work! If you want to replicate my measurements, these are the settings for multitone test:

Sample rate = 192 kHz
FFT size = 256k
Averaging = 8
 

Grooved

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@pkane
Took a moment to test ASIO for ADC (other than Cosmos as it doesn't support ASIO, even if I could try via ASIO4ALL) and I can't get any signal going back to your software. No problem to send signal, but problem to get it back.
I tried with two different devices, on each of their 8 inputs.... nothing, I get the "No sound detected" message, while they worked perfectly in WASAPI.
I have two other devices to test later
 

axyoung9022

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@pkane
It would be much better if you could have options to plot single channel, i.e. L-channel or R-channel besides L+R channels currently available.
 
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pkane

pkane

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@pkane
Took a moment to test ASIO for ADC (other than Cosmos as it doesn't support ASIO, even if I could try via ASIO4ALL) and I can't get any signal going back to your software. No problem to send signal, but problem to get it back.
I tried with two different devices, on each of their 8 inputs.... nothing, I get the "No sound detected" message, while they worked perfectly in WASAPI.
I have two other devices to test later
I did test ASIO for input/ADC and output/DAC separately, using FlexASIO and that did work. But I couldn't get two ASIO devices tested at the same time.
 
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pkane

pkane

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@pkane
It would be much better if you could have options to plot single channel, i.e. L-channel or R-channel besides L+R channels currently available.

Thanks, but the two lines are not both channels, it's actually just the left channel. The spectrum plot shows the captured loopback signal in blue, and just the distortions and noise in white, with the fundamental frequencies notched out. Here's what it looks like when you zoom in around any fundamental frequency:

1636144577631.png
 

jae

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Thank you, will try it out tonight! Would love to eventually see all your tools amalgamated into one application/UI, bonus if it includes a self-updater ;)
 

MC_RME

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And here are the first two (IMHO obvious) wishes:

1. Add buttons to show only blue or white (so one can toggle the view between all three states)
2. Add Auto dBr, so that the highest peak is set to 0 dBr and the scale is also auto adjusted. Makes it much easier to get the values (ratio) of noise floor and harmonics from the screen.

Question - does this one only work with its own signal that it generates? If so, in a synced state, it should be possible to select 'none' in the window choices.

And it crashes on every second measurement when ASIO MADIface USB is output and WASAPI Analog 1/2 is input (using the ADI-2 Pro).
 
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pkane

pkane

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Thank you, will try it out tonight! Would love to eventually see all your tools amalgamated into one application/UI, bonus if it includes a self-updater ;)

Probably will never be a single app, although Multitone was initially built into Distort, and now separated ;)

Self-updater is definitely a possibility, though. I’ll see what I can do.
 
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