QA40x: PWR THD versus Frequency

21

Hi Matt,

Thanks for the reply !
In fact , I thought a bit about what could be “easely” done !

I wasn’t talking about modifying old stuff :wink:
However there is , I believe a wonderful “magic” trick that could be done : Your current software , which I can run on my old contraption (which is actually a quite old Mac Book pro twisted into a boot camp windows machine !)
Accepts csv files that it then displays ? Graphs in a very nice way No ?

If only it could read / convert the two or three file format that came out of my QA 400 , it would become more like a QA4000! :wink:

My grind is in particular with THD / FreQ csv files , eventually Amplitude vs Phase files, but as said I can get easy results from my DSO on that !
(Were they any other ? I think they are only three types of csv files no ?)

All that is needed is I believe some reformatting the csv ? before being fed to your current up to date software to display and make quick use of those old data formatted csv !?
It would rejuvenate completely what can currently be still done with a 400 :wink:

I imagine, maybe wrongly, that for the developer that wrote the current “graphing” routine could add a few line of code to detect and parse old formatted files and run some extra “fumbling” on the csv before feeding them to current graphing engine ?

Maybe I am just dreaming :slight_smile: ,However first step is obviously a comparaison of what was produced by QA400 and what is expected in the current CSV format ? to judge if and what can be “easily” or not be done :wink: A file description of both old and new format would help :slight_smile:

Thanks anyhow for the time you took to respond :slight_smile:

Didn’t realize time had flown so fast ! My tracking number via ups to France is in 2013 ! I don’t remember the price though. I was busy many years actually “building” the studio and only lately got back to maintaining and repairing / readying all for opening time…

Maybe I ought to invest in a new QA403, although technically the specs of the 400 are still enough to test consoles , preamps and RIAA stuff (vinyl lathe…) from the 70/80 ‘s !
With a notch I can probably even make measures on resistive voltage dividers Johnson noise :wink:

PS: I just pushes the envelope when it comes to “outdated” tech stuff which are still perfectly ok to use if only a bit twisted !
I find my Tek 2465b still way better , simpler and more serious test gear than my recent digital Rigol 924S scope, when in doubt I’ll look at the Tek to get a clear view !
Same for old analog audio gear !, I push to improove or rejuvenate / fix some old audio staples :wink:

Best Regards from le perche !

(if you ever visit chateaux de la Loire, we are driving distance, come by visit the studio and for a taste of food or wine or both !)

Eric @zenviewstudioslab

1 Like
22

I found another glitch with the PWR THD vs Freq routine. When I change the power level and re-run the routine, I get the error seen on the screen copy below. If you hit OK, the run is added to the graph and it looks fine, and you can continue running at another power level if you wanted, but will get the error as soon as you add it to the same graph again. I was going from 5w to 1w in this case:

1w error
1w error1205×885 72.6 KB

23

Hi @Var, I’m not able to repro. Can you please share your PwrTHDVersusFrequency Options settings?

Can you try this when time permits:

  1. File->New Settings
  2. right click on DBV and set in/out gains and load impedance
  3. Select PWR THD versus Frequency from automated test menu.
  4. In the menu of the options screen, select “DEFAULTS”
  5. Adjust Load Impedance as needed
  6. You’ll get a message stating the stop frequency has been adjusted
  7. Verify the gains are correct for 1W
  8. Let it plot
  9. Run again with 5W. Seems to work?

I see you have DBR tracking. I also tried with that enabled but it finished OK

image
image800×600 6.68 KB

24

@matt- I tried what you suggested and ended up with the same error again when adding the next plot to it. Looked a lot like your graph- cut it to 10khz. As long as I can add a plot to the graph that is what is important. If it helps I could make a video of the process from start to finish…

25

Hi. I confirm: the problem occurs to me as well when I click on “OK” in “Add to Exsting Graph”: an exception is thrown even though however the operation then succeeds. The strange thing is that the “exception” does not occur every time I try to add to an existing graph and also I have not yet been able to figure out what is the mechanism that triggers the “exception”. However, I reiterate that the graph overlay operation however is always performed correctly. All this as my small contribution

26

Thanks for the additional info @Claudio.

There is an existing bug where if an exception happens during an automated test, the app still thinks that graph window is a valid window. But that window doesn’t exist (phantom window). And so, when you you see the “add to existing graph” if the phantom window is selected, then another exception occurs.

I wonder if this is what you are seeing? Can you please confirm the window you are adding exists (based on the name of the window of the title)?

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Hi @matt. I have tried several times to verify what you are asking, but unfortunately in no attempt did the “exception” occur. As soon as it occurs, I will check the window name (based on the title) to see if it exists and report back