Beta Test: Multitone Loopback Analyzer software

[pkane]

Just noticed that through my post here:

Actif analog crossovers

Seems to me there are lots of benefits to using actif analog crossovers over DSP crossovers, if you are using a Dac to convert to analog then using a dsp, are you not converting back to digital? Can't be good. If you are using an actif analog crossover you don't need a 8 chanel Dac. Also with a...

www.audiosciencereview.com

Why SNR is so different in this version between MTA and REW,they used to be very near.

(hope it's not me messing stuff as usual)

Can you please check this REW setting in your set up and make sure it's unchecked?

When checked, this makes the peak of a full-scale sine wave +3dBFS, and results in a higher SNR result in REW. Multitone always treats 0dBFS as the peak of a full scale sine wave, and not as RMS level.

 

[Sokel]

Looks the same:

but check the rest of them while we are here,it's maybe something else.

Edit:I also unchecked the soundcard error thing,nothing changed.

 

[n3mmr]

You need to run a measurement that detects signal level, measure that signal with a voltmeter, and then enter the value into the window that pops up to specify how the measured value in dB maps to Volts.

View attachment 346035

OK, got it.
The wording was marginally unclear , I thought it talked about measuring the true voltage to use for calibrating.....
Sorry.

 

[Sokel]

I also did it with 96Khz so to be the same,no change though:

 

[pkane]

Looks the same:

View attachment 346175

but check the rest of them while we are here,it's maybe something else.

Edit:I also unchecked the soundcard error thing,nothing changed.

Strange that nothing's changed. It should change the SNR computation due to the different treatment of 0dBFS in REW. Can you please run a measurement in Multitone that shows this difference and export it from history and share the file? I'd like to try to reproduce it. With that REW option turned off, my measurements with MTA match REW to within 0.1-0.2dB for SNR.

 

[Sokel]

I took care so the level is very near to the REW's peak value.

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[n3mmr]

This might be inappropriate for this thread, BUT are there DACs/ADCs/AudioIFs where in- and output voltage levels can be programmatically controlled, rather than by a manual and uncalibrated control knobs??
And, could Multitone use such controls???

( You can probably tell that I am not very well versed in the market state of audio interfaces. )

I am aware of the QA403, but that is a rather special POHW, with an FPGA doing much of the calculations.

 

[pkane]

As suspected, v1.1.4 preview was using N+D for SNR computation instead of N. That's fixed in v1.1.5 (@Sokel - thank you for reporting, and please check):

https://app.box.com/s/ue7ll9xmvwogst817x2l1xg09opvgy47

 

[Sokel]

As suspected, v1.1.4 preview was using N+D for SNR computation instead of N. That's fixed in v1.1.5 (@Sokel - thank you for reporting, and please check):

https://app.box.com/s/ue7ll9xmvwogst817x2l1xg09opvgy47

Yep.
Only 0.1db difference now.

Thank you!

 

[Guy.Cohen]

Hello Paul,

I hope you are doing well, just a strange question. In the front page of the MTA website, the first picture is
a multitone (64) test.

It is a real DAC that has such a nice performance? I wonder which one as it is really a good shot.

I hope you are working (also) on the new version of MTA, now I am using an official V1.1.3 that works great.

Best,
Guy

 

[Guy.Cohen]

Un official....

 

[pkane]

Hello Paul,

I hope you are doing well, just a strange question. In the front page of the MTA website, the first picture is
a multitone (64) test.

It is a real DAC that has such a nice performance? I wonder which one as it is really a good shot.

I hope you are working (also) on the new version of MTA, now I am using an official V1.1.3 that works great.

Best,
Guy

That is a difficult question! It was years ago, and probably a few hundred devices measured since

There's is a new preview version 1.1.5 available that will likely become the next official version in the next few days, if no more issues are discovered. If you have the auto-update option turned on in settings, you'll see MTA prompt to update to the new version when it's published.

 

[Guy.Cohen]

Thanks. Looking forward to the latest version, thanks for the beta.
I hope it is still more aggressive (or less, depends on point of view) AES weighting for my stupid SMSL DO300EX with it's relative wide skirt.

I am wondering about the possible device that has such a marvelous Multitone 64 as it has almost free 150db down to 5hz, no distortion, no 1/f. I was thinking about digital loopback but this is not good enough for pure digital .
So good DAC, I want to have one for myself !

 

[pkane]

I hope it is still more aggressive (or less, depends on point of view) AES weighting for my stupid SMSL DO300EX with it's relative wide skirt.

It's more aggressive than previous versions, but not as aggressive as 1.0.3 I posted earlier. If you need to take care of a very wide skirt, you'll need to turn on the AES-17 notch filter.

 

[Guy.Cohen]

Yes, of course, and you are not responsible for the skirt.
After all if one gets 126db THD+N as the DO300EX, then skirt has much more impact.
I tried to figure out the source of that skirt with the kind help of diyaudio member bohrok2016.
Eventually, we could not completely understand the source (some chips are sanded off). What we understood is that the DAC is generating it's MCLK internally, by PLL and it depends on the input source, USB, optic, coax, I2S.
It is not clear that crystals replacement will do anything (used only under USB) as for all inputs, same performance, even I2S.

 

[pkane]

Yes, of course, and you are not responsible for the skirt.
After all if one gets 126db THD+N as the DO300EX, then skirt has much more impact.
I tried to figure out the source of that skirt with the kind help of diyaudio member bohrok2016.
Eventually, we could not completely understand the source (some chips are sanded off). What we understood is that the DAC is generating it's MCLK internally, by PLL and it depends on the input source, USB, optic, coax, I2S.
It is not clear that crystals replacement will do anything (used only under USB) as for all inputs, same performance, even I2S.

Does anything change if you use optical input? Different PLL settings? Different sampling rates (48k vs 44.1k)?

 

[Guy.Cohen]

I checked coax, I2S, USB, the same.
I will check optical but I am sure it will be the same. They did a job

 

[pkane]

I checked coax, I2S, USB, the same.
I will check optical but I am sure it will be the same. They did a job

Check 44.1k vs 48k rates. These may be implemented using the same oscillator, and clock scaling may be done poorly.

 

[Guy.Cohen]

I will recheck but I think I have already checked.
There are two crystals (45..., 49...)
used only for USB input. Others inputs seems to take something from a 27M crystals and PLL.
The I2S is also reclocked
Martti thinks it might be a 4 bit counter that divide MCLK by 4 to AK4191 (11M or 12M) that might be too slow for the purpose.

I will recheck 44/48 even with optical input.

 

[Grooved]

I am wondering about the possible device that has such a marvelous Multitone 64 as it has almost free 150db down to 5hz, no distortion, no 1/f.

I was thinking about digital loopback but this is not good enough for pure digital .

Indeed, it looks great, but don't forget that it was done on MTA 1.0.6, one the first versions, and the results have been adjusted since.
I have a DAC+ADC combo that was almost at -124 TD+N in a old version of MTA and it's only -118 now (but this -118 looks more accurate compared to what Amir measured)

And I'm not sure if it was not digital, because if you look at the other measurements bellow, all the noise is very low. Which is strange is that on the graph, I get the same with a digital loopback, but the results is not so great compared to what I get:
60Hz+7kHz : -127.3dB @-2dB while I get -141.5dB

And another strange thing, never saw a such thin line at 60Hz with an FFT of 64k, I need to use at least 512k to get that kind of line