As you said , there are a lot of nice SOUND CARD out there , and they woks pretty nice as SOUND CARD , almost !!!
well , measurement is a thing , a real thing , I have seen a bunch of graphs out there made by those cards , I even made some myself , then I decided to go the serious way 😀
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well , measurement is a thing , a real thing , I have seen a bunch of graphs out there made by those cards , I even made some myself , then I decided to go the serious way 😀
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Of course, he's completely trolling. I didn't remember why I put him on my ignore list, so I interacted to make a test, and now I remember 😀
He's just here to brag about his low quality gear, snark and annoy people.
If I needed a machine to measure distortion accurately, I'd get a RTX6001. The price is reasonable, it's less than 1 ETH. But in the first post, the OP says he wants something to test and debug a used amplifier, which means he needs a scope, even a cheap one, to know if the thing is oscillating or misbehaving in other ways that won't show up if the measurement bandwidth is too low, and at least a signal generator that will do sine/square. People who care about OP's question have answered.
He's just here to brag about his low quality gear, snark and annoy people.
If I needed a machine to measure distortion accurately, I'd get a RTX6001. The price is reasonable, it's less than 1 ETH. But in the first post, the OP says he wants something to test and debug a used amplifier, which means he needs a scope, even a cheap one, to know if the thing is oscillating or misbehaving in other ways that won't show up if the measurement bandwidth is too low, and at least a signal generator that will do sine/square. People who care about OP's question have answered.
Not at all , post 35 says :
" please share links with the best vfm oscilloscope/sound card/anything else in your opinion "
So I give him some useful infos and my opinion about sound card , that's it 😉
and peufeu will still think he knows it all , as usual 😀
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Can you back up this claim? Obviously this is your private opinion, nothing more. And pure BS in my opinion😛
Yes , it's my opinion to think that measurements ( this thread is all about that ) will be made by calibrated instruments thought and made for measurements
if you like to use other stuff for it , do it and have fun 😀
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if you like to use other stuff for it , do it and have fun 😀
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It depends on your requirements. The QA 402 is about one magnitude better in resolution than the average 24bit sound card. So the question is how many zeros of THD you want to resolve. Other measurements like frequency response, noise measurements, impedance and so on can be done with every off-the shelf 24bit soundcard. And yes, you can calibrate any soundcard using your standard analyzing software. So my personal opinion is: Nice you to have the QA 402, but with a restricted budget not really necessary for serious measurements.
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Everyone is choosing whatever he like as a tool for a job
my advice to Analyse_it , is to go for measurements device , as far as precision and reliability are his goal , and fact is that there are device , that are affordable and made for those kind of job , so why worry 😉
QA401 /402 , RTX 6001 , AP products are an option , and some other too , it's up to what you want / like / can
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my advice to Analyse_it , is to go for measurements device , as far as precision and reliability are his goal , and fact is that there are device , that are affordable and made for those kind of job , so why worry 😉
QA401 /402 , RTX 6001 , AP products are an option , and some other too , it's up to what you want / like / can
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Whether or not the QA 401 is affordable is a personal decision depending on your budget. Your decision is pro, my is contra - for obvious reasons. To get an idea of the limits with a standard sound card I refer to posting #38 of this thread.
The reason I strongly dislike QA is not budgetary, on the contrary it's awesome that a very low distortion device is available for this affordable price.
The reason is the designers needed many years to understand that a tool that can only be used with their own software is worthless compared to a tool that you can use with the actual software that will do the job you need it to do.
They seem to have got it, but only recently. I mean, they seem surprised that people would want to script a measurement device with python, matlab or labview.
Anyone who wants to script a measurement device is going to use python, matlab or labview. This is obvious, and I'm not buying any product from a company that does not understand the obvious, because who knows what else they got wrong. This is not open to any sort of discussion whatsoever.
Now, they're fixing it, which is good news. But the above link is from 2018 and three years later... while the API certainly goes in the right direction (it uses the correct protocol, it is multiplatform, it is not a stinky DLL), it is barely documented, and the available documentation does not cover the obvious, like how to stream a waveform to the device. And the ASIO driver is a somewhat unsupported project from another guy.
I certainly wish them success, but well, I'm not buying in the current state of things.
The reason is the designers needed many years to understand that a tool that can only be used with their own software is worthless compared to a tool that you can use with the actual software that will do the job you need it to do.
They seem to have got it, but only recently. I mean, they seem surprised that people would want to script a measurement device with python, matlab or labview.
Anyone who wants to script a measurement device is going to use python, matlab or labview. This is obvious, and I'm not buying any product from a company that does not understand the obvious, because who knows what else they got wrong. This is not open to any sort of discussion whatsoever.
Now, they're fixing it, which is good news. But the above link is from 2018 and three years later... while the API certainly goes in the right direction (it uses the correct protocol, it is multiplatform, it is not a stinky DLL), it is barely documented, and the available documentation does not cover the obvious, like how to stream a waveform to the device. And the ASIO driver is a somewhat unsupported project from another guy.
I certainly wish them success, but well, I'm not buying in the current state of things.
I have been using a QA401 with a variety of software via the asio interface and adding vb-cable to make a wdm hook to use older software. I see no real limos and the performance is excellent. Very close to an RTX. To get much better is a major task and major money.
Also all the software for the QA401 and 402 is open source. No one else is offering that.
QA chose a nonstandard audio format over usb for valid reasons. It's to make a more reliable link for measurements. The QA audio software has been improving steadily and is easy to use.
I have used the QA401 with Arta, REW, Virtins and even Praxis successfully. The QA 401 is not a limitation.
Also all the software for the QA401 and 402 is open source. No one else is offering that.
QA chose a nonstandard audio format over usb for valid reasons. It's to make a more reliable link for measurements. The QA audio software has been improving steadily and is easy to use.
I have used the QA401 with Arta, REW, Virtins and even Praxis successfully. The QA 401 is not a limitation.
I'd like something like the QA40x but with the latest ESS converters instead of TI. What IVX showed with his Cosmos ADC based on ES9822 looked very promising so far.
I considered buying a QA402 recently, but it said shipping on orders outside the US would be starting June without an exact date. However, I just checked their forum and apparently some units have been shipped to EU already.
I considered buying a QA402 recently, but it said shipping on orders outside the US would be starting June without an exact date. However, I just checked their forum and apparently some units have been shipped to EU already.
Audio test has some constraints that make test sequences a little more complex. Still there are scripting tools for QA401 as well as Virgins and even Praxis that make the process less complex.
I worked up some tools for traditional instruments using visual basic and it's a lot of work for what you get. The too from QA Tractor is more than adequate unless you are setting up an automated cell phone assembly line. In which case money or dev time is not the issue.
I worked up some tools for traditional instruments using visual basic and it's a lot of work for what you get. The too from QA Tractor is more than adequate unless you are setting up an automated cell phone assembly line. In which case money or dev time is not the issue.
I have QA401 and a Keysight EDUX1002G, and they are both good for audio test.
EDUX1002G offers extra WaveGen and thus bode-plotting cabability up to several mega Hz, fairly enough for audio testing and you can't find a scope with this function and sepc(50MHZ, 1GSa/s) at this price. With some hack, you can even upgrade the scope's bandwith to 70MHZ, 100MHz or more.
The scope provides more room for tolerance. With soundcard or USB scope, you usually have to be carefull with the input level, attenuation or so. And a scope like EDUX1002G generally tolerates higher input level, unless you're doing tube amp measuring, but in most cases you don't need to worry about that, the scope are designed to see all these signals without problems.
So I use 1002G for primary check, and QA401 for better resolution and more details like THD. But 1002G alone is good for most scenarios, you can get a good Bode diagram with one single scope, no other generator needed. If budget is an issue, maybe a MOTU M2/4 with ESS DAC is good for the detailed measurements.
Analogue Discovery 2 has 14bit resolution which is better than 8bit EDUX1002G and also cheaper, but I think Keysight's UI and user experience is more finely-tuned; it's intuitive to use FFT function than Siglent's, for example. I've tried AD2's software, Waveform, and I think it's a bit too simple and less intuitive UI IMO.
However, a USB scope with 14bit input/output is really worh considering; plus it has some more functions like LCR meter and impedance meter, that could be helpful for audio testing.
EDUX1002G offers extra WaveGen and thus bode-plotting cabability up to several mega Hz, fairly enough for audio testing and you can't find a scope with this function and sepc(50MHZ, 1GSa/s) at this price. With some hack, you can even upgrade the scope's bandwith to 70MHZ, 100MHz or more.
The scope provides more room for tolerance. With soundcard or USB scope, you usually have to be carefull with the input level, attenuation or so. And a scope like EDUX1002G generally tolerates higher input level, unless you're doing tube amp measuring, but in most cases you don't need to worry about that, the scope are designed to see all these signals without problems.
So I use 1002G for primary check, and QA401 for better resolution and more details like THD. But 1002G alone is good for most scenarios, you can get a good Bode diagram with one single scope, no other generator needed. If budget is an issue, maybe a MOTU M2/4 with ESS DAC is good for the detailed measurements.
Analogue Discovery 2 has 14bit resolution which is better than 8bit EDUX1002G and also cheaper, but I think Keysight's UI and user experience is more finely-tuned; it's intuitive to use FFT function than Siglent's, for example. I've tried AD2's software, Waveform, and I think it's a bit too simple and less intuitive UI IMO.
However, a USB scope with 14bit input/output is really worh considering; plus it has some more functions like LCR meter and impedance meter, that could be helpful for audio testing.
Bode plotting of amp response above 100kHz (to 1MHz) can also be done using a relatively cheap PicoScope like 2206B and the FRA4PicoScope app. That can be worthwhile for making it easier to assess stability margins in an amp (both low and high frequency margins). And of course the PicoScope includes the other typical functions of a modern digital scope.
