Audio Precision APx516B Review

[johny_2000]

Also I'm really interested if the AP software would work well with this kind of setup.

This was my idea too and I am going to test the APx500 Flex software with Cosmos ADC/APU devices and also with RME ADI-2/4 Pro SE soon.
*I do not own the E1DA Cosmos DAC / #9039S and Scaler.*

Personally, I really like the freeware REW and Multitone software, which can do most of the "non-production" audio measurements you might need.
Just for fun, I'll compare the results with the AP Flex values.

 

[johny_2000]

Note, the RME interface I used is not on their list of calibrated interfaces, but it is fairly straight forward to calibrate on your own. AP has a very strong technical note on the process.

Could you share a link to this process / technical note?
Is this “TN139 QUALIFYING AN AUDIO INTERFACE FOR APX500 FLEX”?

 

[johny_2000]

This was my idea too and I am going to test the APx500 Flex software with Cosmos ADC/APU devices and also with RME ADI-2/4 Pro SE soon.
*I do not own the E1DA Cosmos DAC / #9039S and Scaler.*

Personally, I really like the freeware REW and Multitone software, which can do most of the "non-production" audio measurements you might need.
Just for fun, I'll compare the results with the AP Flex values.

Well, the APx500 Flex software has a huge drawback - it does not support different ASIO devices for I/O. By default, I can only select one device, which should be the output signal generator and the input ADC source. This is a huge limitation that can ruin the measurement results. For example, I can't use two different sample rates. And also use external AES-17 notch filters, which cannot be applied correctly to FFT measurements as a calibration file. I tried to get around these limitations with FlexASIO and ASIO4ALL, but the results were unsatisfactory due to unpredictable buffer delays and glitches in the waveforms. Sigh...

 

[Rja4000]

Well, the APx500 Flex software has a huge drawback - it does not support different ASIO devices for I/O. By default, I can only select one device, which should be the output signal generator and the input ADC source. This is a huge limitation that can ruin the measurement results. For example, I can't use two different sample rates. And also use external AES-17 notch filters, which cannot be applied correctly to FFT measurements as a calibration file. I tried to get around these limitations with FlexASIO and ASIO4ALL, but the results were unsatisfactory due to unpredictable buffer delays and glitches in the waveforms. Sigh...

Fully agree !

And there really is no reason for that.
They could allow different ASIO drivers for inputs and outputs and even different sample rates, and the software would instantly gain a lot more use.

The much cheaper Virtins MultiInstruments allows this, so why not AP ?

And ASIO4ALL is a nightmare to use, indeed.
And still doesn't solve the different sampling frequency issue.

Another point that would be highly beneficial: allow to pause and change scale between the Dynamic range AES 17 measurement.
As is, you're limited by the ADC dynamic range, which is most of the cases less than the DAC's.
What I have to do is use another software and 2 different input gains to measure dynamic range efficiently. Which should be possible with AP.

There are multiple other things I'd like to see improved (like using averages or longer acquisition for bench meters, or adding THD and SNR meters as well,...) , but those are the most penalizing.

 

[morillon]

between rew and multitones of pkane.....see the powerful virtins... there is something to do ;-)

 

[KSTR]

REW, when running on Windows, allows multiple instances and that's what I use all the time, and especially for differing sample rates for input and output.
Or alternatively, I use a second PC/laptop. This the only option when both devices would run the same ASIO driver (like RME)

But I fully agree, software should not restrict the possibilities of the OS / driver architecture.

 

[Rja4000]

This the only option when both devices would run the same ASIO driver (like RME)

UCX II is using a different driver (fireface) than ADI-2 or UFX III (madiface).

@MC_RME
is it (or would that be) possible to allow different sampling frequencies on different Madi devices, like ADI-2 Pro and UFX III ?

 

[MC_RME]

Nope. The ASIO architecture does not allow that within the same driver. And for different ASIO drivers the app/DAW typically does not allow that.

 

[KSTR]

And for different ASIO drivers the app/DAW typically does not allow that.

But that's an artificial limitation, which is the point here. They could have allowed it, and some software does, apparently.
The RME driver could do that as well if it were possible to launch several fully independent instances. Make the OS believe it is handling different drivers, basically.

 

[KSTR]

@Rja4000 , does APX 500 Flex allow multiple instances?

 

[Rja4000]

Nope. The ASIO architecture does not allow that within the same driver.

ok

And for different ASIO drivers the app/DAW typically does not allow that.

Virtins does.

 

[Rja4000]

@Rja4000 , does APX 500 Flex allow multiple instances?

I can check.
But even if it does, it will still have to work in sync to allow sweeps.

 

[johny_2000]

@Rja4000 , does APX 500 Flex allow multiple instances?

No, it doesn't.
I'm guessing they put all these limitations into the Flex software so they wouldn't ruin the market for their hardware analyzers.

At this time, I get the best measurement results with REW, and the second place is taken by Multitone Analyzer.

 

[Rja4000]

I get the best measurement results with REW, and the second place is taken by Multitone Analyzer.

What do you mean by "best" ?

 

[johny_2000]

What do you mean by "best" ?

I mean most of the features like different ASIO I/O/sampling rates, level calibration, notch filter calibration, as well as THD+N, SNR, A-weighting, AES-17, etc. Accuracy matches APx555 DUT measurements to fractions of a dB. And all for free!

 

[johny_2000]

I was able to run the APx500 Flex with two different ASIO devices for output and input. FlexASIO worked with this:

Overall (IMO) AP Flex doesn't offer anything better than REW and Multitone Analyzer for hobbyists.

AP Flex software does not allow use of a frequency response calibration file for an external AES17 Notch filter.
So, actual SINAD (no-wt) = 88.3 dB + 30 dB(Notch) = 118.3 dB. Meets DUT specifications.

 

[Rja4000]

AP Flex software does not allow use of a frequency response calibration file for an external AES17 Notch filter.

It does.
You should define the compensation as EQ.

 

[Rja4000]

I was able to run the APx500 Flex with two different ASIO devices for output and input. FlexASIO worked with this

Yes. FlexAsio or Asio4All.
I think Amir is using ASIO4ALL from time to time.

I don't like either.
The issue is that You can't set 2 different sampling frequencies, anyway.

 

[johny_2000]

It does.
You should define the compensation as EQ.

View attachment 389912

I'll try tomorrow. Thank you!

 

[johny_2000]

You should define the compensation as EQ.

It works! I made a Notch frequency response table and created an EQ file. I should note that AP uses an inverted data format compared to REW and Multitone.