Beta Test: Multitone Loopback Analyzer software

[Sokel]

Something must be off with IMD:

normal



now

I tried older version and it works fine, different DAC too.
Does the same with CCIF.

 

[Sokel]

Something must be off with IMD:

View attachment 442731

normal



now

I tried older version and it works fine, different DAC too.
Does the same with CCIF.

Nope, it's ok now,forget the above.

 

[walge]

Hello,

Yesterday I start to play with this sw.
I have a FOcusrite 2.2i
It seems to have bad freq. response.
I am trying to understand if there is a procedure to calibrate .
Or it is better to search a very good sound card?
I have a AP system 2 as referecw in my lab but something portable for tests will be good.

Many thanks

Some things done in the past:

Storia

Finale Stereo Single Ended con 2A3 ed alimentazione a valvola raddrizzatrice GZ34 (Presentato su Audio Review) Amplificatori monof...

milleniumaudiolab.blogspot.com

Walter

 

[walge]

Hi Walter,

Don't know what you're measuring or how, so can't comment on what might be wrong. The basic idea is to run a Match on the original digital file as the reference compared to the loopback recording. You'll want to use music to do this, and record about 1-2 minutes, at least. Turn off any non-linear EQ settings, and use these options:

View attachment 448865

If you are using an interface with DAC/AD built-in or have the two clock-synchronized, then you can omit the Correct clock drift option to speed things up.

Hi

thx for answer.


I would like to measure some electronic with my friend.
With REW we have calibrated the freq. answer and now it is flat.
Even is the 2i2 seems to be not so good.


Walter

 

[pkane]

Hi

thx for answer.


I would like to measure some electronic with my friend.
With REW we have calibrated the freq. answer and now it is flat.
Even is the 2i2 seems to be not so good.


Walter

You can use the same calibration file in Multitone, or create a new one using a Log-Chirp and then exporting the result using Export Measurement->Export Frequency Response as Text menu. You can select calibration file from settings:

 

[BKDad]

This is probably an obvious question, but even with a thread search I couldn't find the answer. So, here goes...

In the Capture Plot window, there is an option to Add Settings Values to the plot. Perfect!

Next to the checkbox, there is a window to presumably customize what's displayed. Normally, the box just says "default". How do I customize this? I'd like to add Crest, for one. Is there a reference to this somewhere?

Thank you, as always. Great work.

 

[pkane]

This is probably an obvious question, but even with a thread search I couldn't find the answer. So, here goes...

In the Capture Plot window, there is an option to Add Settings Values to the plot. Perfect!

Next to the checkbox, there is a window to presumably customize what's displayed. Normally, the box just says "default". How do I customize this? I'd like to add Crest, for one. Is there a reference to this somewhere?

Thank you, as always. Great work.

Not that obvious, apparently

The default value will add some standard values to the bottom of the plot, such as Fin/Fout, FFT size, etc. Something like this:

Instead of accepting the default, you can create any information text you want using Multitone variables expression.
For example, to display rms, crest factor and peak levels, you could enter the following:

RMS={levelRMS}dBFS Crest Factor={crest}dB Peak={level}dBFS

The resulting text under the plot will then show the desired values:

Any text you use for the plot will be remembered and shown in the drop-down list so you can use it at a later time.

Hope this helps!

 

[BKDad]

Not that obvious, apparently

The default value will add some standard values to the bottom of the plot, such as Fin/Fout, FFT size, etc. Something like this:

View attachment 454629

Instead of accepting the default, you can create any information text you want using Multitone variables expression.
For example, to display rms, crest factor and peak levels, you could enter the following:

RMS={levelRMS}dBFS Crest Factor={crest}dB Peak={level}dBFS

The resulting text under the plot will then show the desired values:

View attachment 454631

Any text you use for the plot will be remembered and shown in the drop-down list so you can use it at a later time.

Hope this helps!

Perfect.

I didn't know about that Variable Support Document. Dumb on my part.

Thanks!

Oops - One detail - isn't crest factor a linear term, not dB? (1.41 for a sine wave)

 

[pkane]

Oops - One detail - isn't crest factor a linear term, not dB? (1.41 for a sine wave)

Yes, of course. So, to fix this, just omit the dB label from the text, which I typed by mistake. The power of variable expressions is that you can enter any text you like, including using the wrong units

RMS={levelRMS}dBFS Crest Factor={crest} Peak={level}dBFS

And if you really do want to display CF in dB, you can use this, instead:

RMS={levelRMS}dBFS Crest Factor={Log10(crest)*20}dB Peak={level}dBFS

 

[BKDad]

Yes, of course. So, to fix this, just omit the dB label from the text, which I typed by mistake. The power of variable expressions is that you can enter any text you like, including using the wrong units

RMS={levelRMS}dBFS Crest Factor={crest} Peak={level}dBFS

And if you really do want to display CF in dB, you can use this, instead:

RMS={levelRMS}dBFS Crest Factor={Log10(crest)*20}dB Peak={level}dBFS

I already have a new Note expression saved. Thanks!

My list is a little lengthy, so I had to add a bunch of spaces in the middle to avoid the Frequency legend. No problem, of course.

 

[BKDad]

Time for another probably obvious question or two.

I exported a wav file from REW of the NID multitone test sequence. Actually, two - one with crest factor reduction enable and one without.

Then, I dragged each of the files onto the MT window. Got the analysis and exported each into a csv file. From there, I got the exact frequencies used for the NID sequence generated in REW.

I then added a custom test signal MT with those tones at those frequencies. I then exported that as a wav file. Did the same with crest factor optimization on and off.

OK, so far?

I then dragged the MT generated file onto the MT window and exported the resulting analysis to a csv file.

I learned a couple things. Remember, no actual audio test hardware was involved.

First, there was no difference between crest factor optimization being on or off with the files generated by MT. None. Does this feature only work with certain test signals?

Second, the phases reported for each tone of the MT generated test signal were either 0 degrees or 180 degrees. But, you know that. Is there any way to customize these phase values?

Third, the two REW generated files had quite different phase values for each tone. What was kind of odd is that crest factor reduction being on or off made some difference, but not much.

The crest factors for the two REW generated files was around 3.3 - one was very slightly different by a tenth of a dB. The crest factor for the MT generated test signal was about 5.8.

The goofy thing is that I tried comparing the two through my actual hardware of a Topping E50 DAC (balanced) > E1DA Cosmos Scaler > E1DA Cosmos ADCiso. I used Audacity to play each of the files as an external generator to eliminate some variables. The measured level of both signals was set to .710 Vrms as measured with a Fluke 97 RMS AC voltmeter, so that was not a variable.

The distortion for both test signals was really low but you could see additional IM tones popping up out of the noise floor with the REW generated test signal, even though that test signal has a lower crest factor. I'd have thought the opposite. Go figure.

The results were identical whether using REW or MT as the analyzer. Amazingly so, in fact.

Any ideas about this one? I'd presume that if I could set the same phase values for the test tones as the tones created by REW, I'd get identical results there, too.

 

[pkane]

First, there was no difference between crest factor optimization being on or off with the files generated by MT. None. Does this feature only work with certain test signals?

Yes, crest factor optimization works only with multitone signals in MT. Custom test signals are not optimized.

Second, the phases reported for each tone of the MT generated test signal were either 0 degrees or 180 degrees. But, you know that. Is there any way to customize these phase values?

For a custom test signal, enter the frequency followed by @75 to change phase to 75 degrees. Something like this:

test 1k@75/2k@85/3k@95

This will place 1k sine at 75 degrees, 2k at 85, and 3k at 95.

Not sure about the differences in crest factors between REW and MT.

For me, 10 tone Multitone in MTA produces CF of 3.5 when optimized, and 3.8 when not.

 

[BKDad]

Yes, crest factor optimization works only with multitone signals in MT. Custom test signals are not optimized.

View attachment 454962


For a custom test signal, enter the frequency followed by @75 to change phase to 75 degrees. Something like this:

test 1k@75/2k@85/3k@95

This will place 1k sine at 75 degrees, 2k at 85, and 3k at 95.

Not sure about the differences in crest factors between REW and MT.

For me, 10 tone Multitone in MTA produces CF of 3.5 when optimized, and 3.8 when not.

Excellent! I will give this a try.

I am only trying to correlate results between the two packages. Some guys I know don't want to replace all the expensive test gear they bought that runs on 32 bit Windows and doesn't now in 64 bit Windows 10/11 because of a lack of proper drivers.

The particular test signal I am referring to is this one:

My real intent/desire is to be able to use Jon Risch's Spectral Contamination Test just because it's used in some quarters by some people. (see above) Easy to do in MT, of course. But, generally, I just want to understand all this better.


Thanks very much!

 

[BKDad]

Update: After adjusting the phase relationships, guess what! The test signal files produced by REW and MT give pretty close to the same results in terms of peak value, crest factor (of course) and so on. Not exact; there's a tenth or two of a dB difference. That could be due to any of a number of slight differences I missed between settings in REW and MT.

Thanks again for the help.

 

[DrCWO]

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

Just installed v1.2.9 and like it

One thing I don't unterstand or maybe I haven't found the right setting yet.
Please let me explain.

I use the test signal 1000Hz sine and 128 (ore other number) of repeats for averaging.

If my the output of my DAC (ADI-2 pro) is 0dB and I connect analog out to analog in I also see 0dB in the display of the ADC during measurement process.
Also the diagram show a 1kHz peak at 0dB and reducing noise at each iteration.

If I decrease the DAC output to -10dB with same loopback connection as above I see -10dB in the display of the ADC during measurement process.
Also the diagram shows the 1kHz peak at -10dB and reducing noise at each iteration.

But at the end of the measurement the measured curve jumped up to 0dB instead of staying at the -10dB I saw during measurement.

Any ideas how this can be prevented?

Thanks' DrCWO

 

[Sokel]

Just installed v1.2.9 and like it

One thing I don't unterstand or maybe I haven't found the right setting yet.
Please let me explain.

I use the test signal 1000Hz sine and 128 (ore other number) of repeats for averaging.

If my the output of my DAC (ADI-2 pro) is 0dB and I connect analog out to analog in I also see 0dB in the display of the ADC during measurement process.
Also the diagram show a 1kHz peak at 0dB and reducing noise at each iteration.

If I decrease the DAC output to -10dB with same loopback connection as above I see -10dB in the display of the ADC during measurement process.
Also the diagram shows the 1kHz peak at -10dB and reducing noise at each iteration.

But at the end of the measurement the measured curve jumped up to 0dB instead of staying at the -10dB I saw during measurement.

Any ideas how this can be prevented?

Thanks' DrCWO

Jump where? At the chart?
Just change the vertigal units to dBFS.

 

[DrCWO]

Jump where? At the chart?
Just change the vertigal units to dBFS.

Yes at the chart.
I changed to dBFS and see the 1kHz at 9,4dB. If I decrease the input to -9,5dB it goes to 0dB

So far so good.

But how to set the voltage for dBFS? I saw the litte box below the vertical units setting but whatever I enter here the 1kHz peak stays at 9.4dB in the display.


EDIT:

As you can see the bar during measurement is green (below 0dBFS) but it shows 9.39dBFS

EDIT2:
This really drives me crazy. If I select dBr and measure with -10dB I see this

But in the chart the 1kHz Peak will be shifted up to 0dB at the end of the measurement even if the scale of the chart says it is in dBr

Isn't there a switch to prevent this scaling up to 0dB et the end of the measurement?

 

[Sokel]

Yes at the chart.
I changed to dBFS and see the 1kHz at 9,4dB. If I decrease the input to -9,5dB it goes to 0dB

So far so good.

But how to set the voltage for dBFS? I saw the litte box below the vertical units setting but whatever I enter here the 1kHz peak stays at 9.4dB in the display.


EDIT:

As you can see the bar during measurement is green (below 0dBFS) but it shows 9.39dBFS
View attachment 459413

First you measure the output with a DMM, then you take a measurement and then you enter the value at the little box (use the dots, it'll open a new window) .
Check in case you're using a cal file.

 

[DrCWO]

First you measure the output with a DMM, then you take a measurement and then you enter the value at the little box.
Check in case you're using a cal file.

No cal file used and no change whatever I enter in the box.

In my understanding the maximum level dbFS can have is 0dBFS as the ADC can't output more. The green bar during measurement shows the scale so if it gets red I have reached the 0dbFS. I wonder how the displayed 9.4 dbFS should be achieved. In my eyes this is an error in the application.

Maybe @pkane can tell us more about that...

 

[Sokel]

No cal file used and no change whatever I enter in the box.

In my understanding the maximum level dbFS can have is 0dBFS as the ADC can't output more. The green bar during measurement shows the scale so if it gets red I have reached the 0dbFS. I wonder how the displayed 9.4 dbFS should be achieved. In my eyes this is an error in the application.

Maybe @pkane can tell us more about that...

It's probably ADI's input sensitivity as it's adjustable.
Check this out too.