Output from QA401 Left and Right independently

To make the quickest testing of our device, I want to connect different things to the left and right I/O of my QA401. The input is easily accommodated by specifying to measure left or right channel within the Tractor test. However, I do not see how within Tractor (or within the QAAnalyzer for that matter) to only output on left or right outputs.

Hi @RickGeek, as you point out, you should have the option to pick measure left channel or measure right channel in just about every test. And if you check the left channel but not the right channel, then the right channel output should be muted. If it’s not muting the unused channel, then it’s a bug we’ll fix right away. The reason for this is to allow you to test really high power amps independently so that you can measure the power consumed on each channel if needed.

One thing this doesn’t do yet (but will come) is correctly set the display on the QA401. The measurement is correct, but on a test where only the left channel is being measured, then just the left channel button should be automatically pressed on the QA401 before the test. And if you have left + right both specified, then you should have the view of both too when the test runs. That will come. The workaround is to just leave Left + Right display buttons pressed all the time during automated testing and then that way you can see both traces captured in the log.

In the Analyzer app, you can mute one of the channels in the Signal Generator Settings box. Just specify which to mute.


You’ll see an indicator show up on the main screen to remind you that either the left or right is muted. Again, this can help a lot when testing a high power amp.

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Hi Matt - thanks for the quick reply. What I am seeing in Tractor is that it doesn’t matter if I select “Measure Left Channel” or “Measure Right Channel” only, the signal still goes out both outputs.

Really this would work best if in Tractor you could select which output to send out and which input to measure.

Regarding the Signal Generator Settings screen, I’m not seeing where to get that screen. I’m Using QAAnalyzer 1.907 on Windows.

Hi @RickGeek, this should be fixed in a release coming in the next 24 hours. Thanks for reporting. There are also a few more changes in that release too, but they shouldn’t impact your current path. It will post on github hopefully later today, but if not, then early tomorrow. I’ll try to remember to drop a note here when it does.

Thanks again for reporting.

Wow - you guys are amazing - thanks

Hi @RickGeek, this posted last night. You’ll need to update the QAAnalyzer and Tractor apps. Unfortunately, these cannot be signed until the end of May as DigiCert is migrating certificates and thus they cannot be installed on the new build machine until the migration is done.

But you should see in all plug-ins that if a measurement for a given channel is un-ticked, then that channel will be muted during the test AND its output won’t be display. So, if you specify a left channel measurement, the display will only show left channel.

Let me know if you see anything strange. The same change was made to all tests, but it was a pretty straightforward cut and paste change and it was only tested on two. More testing will come in the coming weeks.

Hi Matt - that is working just as I need it - thanks! You guys are incredible with the support. Really got me out of a jam on my deadline.

Again, I’d suggest for a future revision that you be able to specify inputs and outputs to use independently. I’ve used that kind of setup with APs in the past, sometimes you need to send out Left and then do two different measurements on Left and Right. You could imagine that on an AB box for instance. Or even more so on measuring mixer input channels where you want to look at the pan controls, so you first send from left, adjust pan to a few points and then send from right and do the same.

Hi @RickGeek, got it and noted.