QA40x Release 1.181

Release 1.181 is up. See HERE

Release 1.181 (July 2023

  • Firmware release 58 (unchanged)
  • Mirroring can now be toggled using ‘m’ key
  • Chirp at 48K to 10 octaves, 96k to 11 octaves, etc. The chirp will now start two octaves lower than it previously did. In the prior release, for 48ksps, the chirp ended at 24k and began 8 octaves below that, which is 93.75 Hz. Now, the chirp begins 10 octaves below 24k, which is 23.43 Hz
  • RIAA high resolution user-masks added. Background HERE
  • Fixed bug in AmpCrosstalk automated test that was debuted in the last release.
  • Fixed bug where millihertz “mhz” was being incorrectly parsed in freq knob sensitivity for Gen1/Gen2
  • Add ability to specify default, wasapi shared and wasapi exclusive mode for mirroring in the Edit->Settings dialog (See PC Mirroring section)
  • Increased PC Mirroring Freq/Amp change pause delay from 2000 mS to 5000 mS
  • Better drawing of noise density values to improve readability when in rthz mode (accessed from dBV context menu)
  • Add NoisePlusDistortion measurement to REST interface
  • Add date/time stamp to main plot. This can be turned on/off in settings (default is off)
  • Add ability to restore state after automated test is run
  • Removed rounding in many Automated Test plugins that prevented you from using fractional step sizes
  • File->New Settings will not change display preference (eg light on dark or dark on light). Everything else will revert to defaults
  • Added DAC Linearity Automated Test. More (HERE)[DAC Linearity · QuantAsylum/QA40x Wiki · GitHub)
  • Added DAC Measurements with Notch Automated Test. More (HERE)[DAC Measurements With a Notch · QuantAsylum/QA40x Wiki · GitHub]
  • Added DAC Output Impedance Test. More (HERE)[DAC Output Impedance · QuantAsylum/QA40x Wiki · GitHub)
  • Fixed REST docs on MaskTest.
  • Added ability to revert to defaults in each Automated Test plugin (Menu at top of settings)
  • Fixed typo in -L command line response
  • Added ability to suppress logo on main screen and Graph screen

New UI for Mirror Audio Interface


New UI for Noise Density and Date Time

Note that scinot is replaced with friendlier notation. Note the date/time of acquisition is displayed in lower right portion of graph

Sample DAC Linearity Test Plot




Sample DAC Measurements with a Notch Plot


Sample DAC Output Impedance Plot


@matt great to see these new features. I tried the dac with notch using my cosmos apu. Its gain is 26db, but when I put that in the dialog it errors with passband gain must be <=18. Not sure what to do.

Also I can’t seem to do a notch characterization with amp/freq chirp.

Hi @Moto, OK, noted on 18 dBV limit. That will be bumped up to 30 dB for the next release (which should be out pretty quick as it has log interpolation on user filters along with THD-, THDN- and SNR- measurements relative to dBR, but it didn’t make the cut for tdoay).

I check the frequency response, and it seems to work sweeping the LOW-Q notch in a QA455.

Try this: Go balanced out of the QA403 into your notch with 26 dB of gain. Since you are going balanced, set the QA403 generator to -32 dBV. That means it will hit your notch at -26 (since it’s balanced), and then the notch will gain that up to 0 dBV in the passband. Then set your full scale input to 6 dBV and use a 64K FFT and see what you get.

Hi @Matt. I have downloaded and installed the new version 1.181. I find it very substantial and very interesting. I was wondering if it would be possible to extend the possibility of inserting the date and time, in addition to the main window, to all the various windows you get in the “Automatic Tests”. For me, it would be very useful to have this possibility as it would make it possible to avoid manually entering a chronological reference in the various graphs that are obtained. Thank you

Am I correct in presuming that with QA40x, x > 1? (meaning not QA400 or QA401)

Hi @BKDad, yes, correct. The QA401 software is called “QA Analyzer”

Hi @Moto, the 1.183 software is up and extends the notch gain parameter limits up to 30 dB. There are also some new measurements for those using a notch, and make it really fast and easy to get THD, THDN, SNR and Dynamic Range when using a notch. There’s a small tutorial at the link below.

Hi @Claudio The Date/Time settings for main display are also now respected for the Automated Test displays. Whenever a new trace is added programmatically to the graph, the date/time will update. Please check is works for you.


@matt I did that and get exactly the same graph as yours except my notch only goes to -30. Is there a way to generate that using pc mirror abd an external dac out of curiousity. The chirp didn’t seem to work properly with the topping e70.

I don’t understand your question. You wrote " Is there a way to generate that using pc mirror abd an external dac out of curiousity. "

What is ‘that’? Do you mean the graph that you already generated?

yes. instead of using the qa402 dac

here is the qa402 dac through the apu notch. am I correct leaving the 26db gain in the dbv panel? I guess not. I have to use 31.2db gain to get rms volts =1 on the display.
do the number look reasonable?

Here is just a 1khz view of the e70 using the same notch file I just created with the qa402 dac.
What gain do I use here?
Those harmonics are not real in the e70.

do the number look reasonable?

For the QA402, probably. The QA403 is quite a bit better. You have exported the notch it looks like. Can you try the measurement outlined at the link below? You have the output set to -0.3 dBV, which when balanced, would be 5.7 dBV. And then you’d have 26 dB of passband notch gain. So, you’d not use any user weighting, and enter your 0 dBr point at 31.7 dBV.

And then add a THD+N dBR

Here it is e70 , dbr set to 31.7. Still weird.

Here is my notch

Hi @Moto, the 31.7 isn’t a magic number for everything. it was for a specific config using the QA402 DAC at -0.3 dBV with your notch. If you are using the E70, then you 0 dBr reference point is different. It’s the max output of the E70 at 0 dBFS + the gain of your notch.

So, if your E70 at 0 dBFS generates 12 dBV, and you have 26 dB of notch gain, then your 0 dBr point is 26+12 = 38 dBV. But yours will be slightly different based on your E70. The link to the 1.183 release shows how to determine this precisely.

Also, you need to carefully set your input range correctly. So, if your (notchless) level would be 38 dBV, and your notch is giving 30 dB of suppression, then that says you’d need to be on the 12 dBV range (38 - 30 = 8 dBV).

Since you are dominated by harmonics, I’d suspect a Windows transcoding issue. Make sure your windows volume is at full, and then go into the Settings menu (see below) and try the different interfaces (Default, WASAPI Shared and WASAPI exclusive). I can’t tell you how much time I’ve wasted over the years tracking down issues related to Windows transcoding. And you could also drive the DAC from an ASIO generator to bypass the problem completely.


PS. I really think you’d want your notch depth to exceed the notch passband gain. Can you switch to 20 dB of gain instead of 26? That will take the 12 dBV signal and boost it to 32 dB, and then your notch will take that down to 2 dBV, and then you’d use the 6 dBV full scale input range. If you go this route, your dBr reference would be 32 dBV.

Let me know if it’s still not clear.

Here’s another measurement, using the Default Audio Interface:

Wasapi Shared:

And Wasapi Exclusive:

Note the height of the higher-order harmonics! that looks a lot like your plot.

PS. when your system is set up correctly, your peak should be at -30 dBr if your notch is delivering 30 dB of suppression.


  1. Measure DAC full scale output in dBV (see 1.183 link)
  2. Add to that your notch passband gain (20 or 26 dB in your case I think)
  3. You know your notch suppression is 30 dB.
  4. Set your dBR reference to what you measure in 1 + 20 or 26 dB
  5. Set your full scale input appropriately. If 1) is 12 dBV and you are using 20 dB of gain, that means the output would be at 32 dBV MINUS the notch suppression of 30 dB. That would give you a level of 2 dBV, so pick 6 dBV full scale input.
  6. Confirm the peak is at -30 dBR.

Yep. Sorry I had been thinking about 0dbfs on the e70 like 0 dbv.
So e70 output 4.2vrms=12.5dbv
Set the apu to 20db gain so 20+12.5=32.5
Set e70 to -.3db and substracted that from 32.5 giving 32.2 for dbr

As you had said earlier,

exclusive sucks which is what I had been using. Switched to shared and all good. I think.
Does this pic look right? Except SNR???
What is going on there?

I’m seeing the same thing on exclusive. It’s unusable on Win11. I wonder how many are buying a fancy new DAC and then using exclusive mode and getting $10 DAC performance…

That’s a bug in the SNR calc. This was tested with both left and right channels connected together, and a copy/paste bug was using right amplitude instead of left for the new SNR dBr calc. It will be fixed shortly.

Overall, very nice looking data thanks for sharing.

@matt the automated test on dac with notch sets full scale to 0 and does not ever switch higher so it errors out as dac output gets larger.

Hi @Matt. I tried version 1.183 using “AMP Frequency Response Chirp”. The date and time is displayed correctly!!! Thanks, that’s very useful for me.
PS I also find the possibility of logarithmic interpolation (LOGINTERP) very useful. This new function solves several problems for me that had arisen in the past. Thanks Matt

Hi! I received my 403 yesterday, installed 1.181 and am trying to get an overview. It seems that frequency sweeps run to the according Nyquist of the chosen sample rate but the display x-axis always ends at 20kHz. Is there a way to extend the x-axis over all the measured range?