Yes, you can use Alt-P/letter to use the Page menu and Alt-C/letter for the command menu, although I noticed after the last post that I forgot to add an accelerator for the Settings page (oops). That’s fixed whenever I update.
Thank you.
Mark
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I was wonder if could be run on Linux with Wine ? I tried to install it with your link without any luck .
Hey there, awesome software. Been using since early versions.
It seems i cannot find if measuring the Phono preamplifiers (RIAA) is possible with it. Is it just for Line level signal?
Thanks!
Hi @aleks, there’s no reason you can’t measure a phono signal but it doesn’t have RIAA compensation curves built in for comparison. Otherwise it’s totally happy. You can use a microphone compensation curve when doing the Frequency Response test but I don’t have an RIAA one.
@thumb - I have no idea, sorry. The application uses C# and WPF and a couple of libraries and relies on .NET version 9. The last time I looked at Wine it couldn’t do WPF but that was many years ago.
Mark
Latest version 1.2.01 update→ this will probably be my last holiday update unless I find a nasty bug which is entirely possible.
The biggest change is default to the Menus (not Tabs) option. I strongly recommend folks delete their default configuration to let QA40xPlot populate the latest defaults. Note there is now a new “Save Configuration as Default” command (see menu) so you can trivially save defaults.
To make this more palatable, @TimoJ , I’ve added Quick Page buttons that are much smaller than the old Tabs but just as useful imho. You can hide them if you always just use the menus.
I’ve also completely changed the THD vs Frequency page. Picture is below. The biggest change is that it supports sweeping with multiple generator voltage levels. The GUI will migrate to the THD vs Amplitude test soon where you will be able to sweep on Frequency.
Please note that the new noise floor first-calculation in THD vs Frequency is much slower than it used to be as I found that in many cases the very first noise floor would be wrong due to circuit settling - which takes at least 3.5 seconds in my tests. I’ve decided to be very conservative for now since waiting a few seconds is better than bad numbers.
Happy Holidays!
Mark
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@MarkZ hanks for the prompt reply. Would it be possible to load/import the RIAA compensation file from the default QA software? I work a lot with phono preamps, would be awesome to have a possibility to jump between both standard and RIAA compensation. It would make your software perfect.
Thank you for the fantastic work on this!
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@MarkZ in the QA40xPlot.application file it state a “QA40xPlot.exe” file ! But I do not find it anywhere, is that the end “complied” target file ? Hmm I guess I have to test it on windows machine.
@thumb : The current executable program lives here The Github.io Repository before it’s downloaded by the .application installer if you’re looking for a file set. You would get the same set by installing the program on a Windows PC.
If you dive then into the QAPlot application files folders you’ll find all the executables and such.
Mark
Hmm funny how Windows hide programs in install, anyway I tried your link and Wine complain about some DLL missing wine:
”Call from 00006FFFFF3BD887 to unimplemented function icu.dll.uloc_canonicalize, aborting”
So that a no go for now
The original QA40 app works on Linux, and it would be fantastic if your app could work to. I am all Linux shop so…
Hi @aleks I think this is a working compensation file but I don’t have a preamp to test with. You should be able to check response with a flat input to phono and see a flat response with this compensation - I think.
@thumb I’m sorry but from a quick read Linux Wine only supports .NET core 3.1 and I’m using .NET Framework 9.0. As you can imagine that’s not a trivial port and not something I have the bandwidth to deal with at this time.
Mark
Re: the compensation file. You may not know this… the Frequency Response test supports a microphone compensation file. The file name is specified in Settings and then there’s a checkbox in the FR test to enable the compensation. If it all works - you should be able to send a very low-voltage chirp to the phono preamp and the response will then look flat in the test when compensated.
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Is it possible to measure phase? i.e. left vs. right channel phase differerence 20Hz-20kHz.
REW can do it, but it would be nice to use QA40xPlot for it.
The Gain measurement in the Response tab does a full Bode (gain and phase) plot. The right channel provides the reference signal for the phase math.
Mark
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I have disabled mini-plots, but they still always appear when I start Gain measurement. Why?
Another weird thing, not sure if this is a hardware “feature”. I’m using unbalanced wiring and the negative inputs are shorted. But if I instead short the positive input and feed R signal to the negative input, instead of constant 180 phase difference I get this. (but it works fine if I use negative output to feed R positive input)
Hi @TimoJ
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The mini-plots button is a bit squirrely. It’s intended to let you turn on the miniplot when the plot is finished and the miniplots are auto-hidden. And even that it pretty much fails it. I’ll spend some short quality time on it and make it do what everyone thinks it should (hide the miniplots) since once the plot is finished you don’t really want to see the latest miniplot ever.
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The phase plot I’m not that concerned about. 180 and -180 are really the same phase (π) so if it’s 179.999999 it will plot positive and if it’s 180.000001 it will plot negative. If I plotted phase as 0…360 instead of -180…180 it would seem to be a horizontal line.
Mark
By the way, if you’re measuring gain at 20-20K I’d consider the Chirp option since it’s much faster and you’ll get way better frequency resolution and the accuracy is good (Chirp is always worse than a discrete sweep but in this case it’s not much worse). Chirp is mediocre for Crosstalk testing because signal levels are so low but it’s good for the other tests as long as you realize it’s a bit rough at the extreme high and low frequencies.
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Is it possible to lock phase range when doing gain measurements? It always seems to revert to ±360.
Also, is it possible to measure/compare channel delays? I have used scope tab with chirp tone for it and then compared burst starts between the two channels. But something more exact, build-in way would be nice to have.
At the moment there’s no way to measure the time delay differences. I print them to the console in debug mode before using the minimum delay for the stereo inputs but they aren’t surfaced anywhere and for most measurements they include phase difference. Let me see if there’s a low-impact way to maybe add that to the scope test.
I’d probably use square wave or impulse instead of chirp for doing it accurately. I think chirp is least likely to get an accurate delay value since it starts up very slowly.
As for phase in the frequency response tab, I’ve just procrastinated at adding a phase Axis setting on the right side because no one has asked. Sigh, that’s no longer true. I’ve been adding ‘fun’ stuff during the holidays so I’ll tack that on.
Mark
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Square wave is constant signal? How do I see where it “begins”? For example for 3ms delay difference.
But with chirp this was easy to see, since it pauses between chirps. I could measure delay with about 0.2ms accuracy.
Nice extra scope feature would be to add some sort of cursor function allowing to measure time between two peaks etc.
Also: there are “click to pin the current graph range” icons, but they don’t seem to change color when I click them. Are they functional? If they are, could you add some of indication/color change to them?
You are looking for inter channel phase differences, right? A ‘scope is best for that anyway. If you have a phase/delay error that changes vs frequency (like an early CD player with a time multiplexed single D/A) you can either use a sweep, spot and use either twin traces or for a pretty display with easy calculations- XY. Cursors and math (on a DSO) will give you a continuous real time result.
I just released 1.2.2 my ‘holiday’ release. After plenty of family it was time for fun projects so I did things to help with RIAA (my niece owns a record store) for phono preamp testing along with some things requested by folks or that I’ve been wanting. In order:
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Support for RIAA preemphasis on chirp signals so you can test phono preamps (@aleks) . RIAA preemphasis is also supported by both chirp and standard sweep in the Response & Gain tests. The chirp/sine maximum amplitude will be approximately the specified voltage. Note that swept frequency (x/octave) is more absolute accurate than chirp with RIAA testing.
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Addition of the Attenuator gui (auto/manual) to all of the previously-auto-only tests. Particularly with RIAA the auto attenuator may struggle, but it’s also nice to have constant noise floor for the swept voltage tests. Set the Attenuator to Autorange to match 1.2.1 and earlier operation.
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Support for using a WAV file with the generators. Just select Wave File in the combo and you’ll get a selector for the file name. The file is resampled to your FFT sample rate and then truncated or padded to fit the fft size. This is great for checking time delay since it isn’t a repeating waveform.
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The oscilloscope test Data Summary now contains a readout for the time delay between left and right channels assuming they carry the same signal.
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Addition of Phase Axis control for Gain and Impedance tests. (@TimoJ )
Mark
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