Audio Precision APx516B Review

[mcdn]

Nope. Cosmos works with both fixed input gain and high input impedance. The Scaler fix a bit of that, but it will never be as precise as an AP as it is. Not to mention, the limitation at 43Vrms to measure amplifiers (and most importantly, the gap between 10Vrms and 43Vrms, so you're working less precisely in this wide gap).

The APx555 for sure. This model? Not so much. A good DAC directly into a Cosmos ADC has enough headroom already to beat the APx516 on test here at at typical voltages. Add a Cosmos Scaler for low DUT output voltage measurements and you get close to or beyond the APx555.

One thing the DIY chain does fall short on is high voltage output for low gain power amp testing, but again the Cosmos scaler goes up to 20Vrms balanced out, and isn’t needed on the measurement side for power amps, so can be repurposed.

 

[xema]

I used the original dscope years ago. It too has excellent software but performance was not in the same league as AP.

m1 is a new design, not a ds3 variation

dScope M1 audio analyzer - Spectral Measurement

Use the new dScope M1 audio analyzer to make and automate all your analog and digital audio measurements like distortion, noise and frequency response.

www.spectralmeasurement.com

 

[restorer-john]

Now people are talking about it, I'd love to see QA403 measurements as well. It costs $600 - might as well get the QA403 instead of yet another DAC or an amp I don't need.

Here:

https://cdn.shopify.com/s/files/1/1631/5609/files/QA403_Product_Sheet_REVH_February_2022.pdf?v=1645842772

 

[SSS]

Link to Technical Information and specifications:

https://www.ap.com/download/apx516-b-series-installation-instructions-and-specifications/?wpdmdl=15165

Read the specs of the device which seems to be made in professional quality and guaranteed specs for each instrument. Had you the chance to find out what ADC and DAC chips were used ?
To me it looks like that probably selected standard chips like in audio gear were used.

 

[amirm]

If you are using unbal (SE) "+" inputs, does the unit automatically short/relay the "-" input on the XLR and 4mm or do you check a box on the AP software?

Single ended is completely independent of balanced. The old AP hardware had software controlled relay. The new generation APx does not. So I use a jumper cable to from the adjacent ground terminal.

 

[amirm]

Read the specs of the device which seems to be made in professional quality and guaranteed specs for each instrument. Had you the chance to find out what ADC and DAC chips were used ?
To me it looks like that probably selected standard chips like in audio gear were used.

Not that I have searched for it but have never seen it specified which ICs they use.

 

[amirm]

m1 is a new design, not a ds3 variation

dScope M1 audio analyzer - Spectral Measurement

Use the new dScope M1 audio analyzer to make and automate all your analog and digital audio measurements like distortion, noise and frequency response.

www.spectralmeasurement.com

Ah, didn't know they had updated it. For a while I thought they had given up on this market.

Just looked and their "THD" spec seems to be -108 dB for stock version and -110 for the upgraded one. Assuming they really mean THD+N, those are slightly better than what I measured here.

I might ask them for an eval unit to compare. Their software while different than AP, is also quite functional and much better than other solutions I have seen.

 

[Billy Budapest]

And what can you measure with this kind of performance? DACs from 20 years ago? What's the purpose of this product?

More like DACs from 5 years ago. But yes, useful for measuring amps, etc.

 

[IamJF]

Finally a silent tester! How an audio test company can make such loud equipment ...

So let's do a little contribution - here are my measurements of APx515. They look different as I don't have the used Bench Mode in my little model.

So it's a little less noise as the APx516 but about the same distortion.
I use it most for microphone and speaker measurements, it has more than enough performance for that! For electronics development of state of the art gear ... you need a state of the art analyser. And state of the art doesn't need to be super expensive when we have a look at the ranking lists.

There is one area which is a little underrepresented in the measurements here - noise! For ME noise is more important as if SINAD is 110 or 120dB - cause you always hear noise when it's present and it masks fine details - but you can't hear 100dB SINAD. Also A weighted noise is industry standard and makes sense beside of delivering better looking values ;-)
So here the loopback noise levels - unweighted, A weighted. And referenced to 4Vrms:

There would be one more interesting test - useing the hp generator of the 555 and feed into the 516. Just the spectrum and first page. I asume that some of the THD we see is in the digital audio generation, so it also shows when useing an DAC?

 

[peniku8]

It is not so simple. APx516 has auto-scalar which can handle up to 120 volt peak to peak. You have no scalar in your solution let alone one that can handle such high voltages which is necessary to measure high power amplifiers. Much of AP's claim to fame has been its front-end that handles such situations. You can't ignore that.

My point is not really about the implementation and software and what not, because we know that is great. The issue in my opinion is the fact that for no real added cost in parts (in relation to the current total cost of the device), this analyzer could've been performing a lot better, but AP made the performance worse on purpose as to not obsolete the much more expensive models.

Nonetheless, on points you address, the Cosmos Scaler I mentioned has an auto gain function and it's a device that costs less than 150$. Having a large voltage range is a matter of padding the incoming signal down more with resistors. The Scaler can apply a maximum of 26dB gain and take 10Vrms unbalanced. If you add a switchable 12dB pad in front of the Scaler, then you can measure amplifiers at the same 120Vp-p while also being able to measure high performance DACs. Additionally, the APU has a notch and low noise preamp which make it possible to evaluate devices that outperform even that setup, so you've got all bases covered. The hardware is not magic, but like I said, the main thing AP got going for them is the software integration.
And on the note of 120Vp-p, that is 42Vrms or 220W into 8 Ohms. So the amp manufacturer has to be solely manufacturing amps that output less than that, or they won't be able to assess the performance of the higher powered devices. But AP probably got you covered with a 2000$ upgrade module for measuring Vp-p of 1000V so they can cover the largest currently available amps too.

See links here.

REW API beta releases and discussion.

REW API help.

That's exciting news, I totally missed that! Thank you so much for linking that, I'll definitely delve into this soon. Automating my measurements would make this entire process so much more comfortable. I keep forgetting stuff every time I test a device

 

[peniku8]

The APx555 for sure. This model? Not so much. A good DAC directly into a Cosmos ADC has enough headroom already to beat the APx516 on test here at at typical voltages. Add a Cosmos Scaler for low DUT output voltage measurements and you get close to or beyond the APx555.

One thing the DIY chain does fall short on is high voltage output for low gain power amp testing, but again the Cosmos scaler goes up to 20Vrms balanced out, and isn’t needed on the measurement side for power amps, so can be repurposed.

The Cosmos ADC has a high level input which goes up to 43Vrms, which is pretty much the same level this new AP analyzer supports (120Vp-p is about 42Vrms). If the amp has really low gain, you could theoretically place the Scaler between your DAC and the amp and feed the amp a 10Vrms input signal. Technically you can achieve almost anything you like with a combination of these neat little devices.

 

[FrantzM]

It's oddly amusing when considering the cost of test equipment necessary to assess the ultimate performance of inexpensive devices.

OTOH some would balk at seeing+$20,000 equipment being measured with a $10K device..

Peace.

 

[DonR]

It's oddly amusing when considering the cost of test equipment necessary to assess the ultimate performance of inexpensive devices.

Happens all the time in engineering. The cost of equipment to characterize a diode worth a tenth of a penny is many, many orders of magnitude greater.

 

[Grooved]

More like DACs from 5 years ago. But yes, useful for measuring amps, etc.

Indeed, but just to create a "proof" that it's perfect for that, it would be great if @amirm can measure an amp that he already measured with the APx555, and see if the result is exactly the same with this APx516b and with the APx555.
Obviously, it has to be an amp in the 80 to 105dB SINAD range, not one of the top SINAD that this APx516b can't measured correctly for sure

 

[mk1classic]

Slight offtopic... The way the x555 measures in loopback, means it should be one of the best DACs in the market.
How well does it playing music? It must be the reference for all high SINAD DAC manufactures!
AP should start manufacturing DACs only...

 

[pma]

Topping DX5 + E1DA Cosmos ADC. THD = -128dB, THD+N = -118dB.

 

[AdamG]

Hi Amir,

Outstanding review and this new model means that Manufacturer's and Reviewers can get into the Measurement game for a much smaller chunk of their ass than before. I hope this leads to more measurement data being published.

Just FYI Boss. You dropped this Review on Sunday afternoon. Clearly indicating that you still do not know the difference between a Work Week and a Weekend.
You sir are a machine. I am considering starting a new Labor Union for Content Moderation. So far I have one member.

 

[al2002]

I haven’t read the whole thread, so not sure if this is been mentioned before, but the AP 516 appears to be not much better than the Quantasylum 403 which is significantly cheaper.

 

[morillon]

it is that thanks to the crossing with the 555, it would be interesting to see who does what with 516 ,with sweeps, what concerns the generator and what comes from the adc
;-)

 

[Roland301]

How would a E1DA Cosmos ADC plus scaler with the Topping DX70 fare if you always had AP’s software?

APx500 Flex Audio Analyzer

www.ap.com

While there is certainly value in being able to present data in the same format as AP software, I think REW provides a lot of the main functionality for free, with more flexible DUT audio I/O (no need for universal ASIO), and a simpler layout. Much more accessible for hobbyists.

You will also end up paying considerably more than $3300 for AP Flex once you add on some of the options you need. For example, Bench Mode (the "dashboard view" most often seen at the top of these reviews) is not included with the base package, and neither are stepped level sweeps or IMD measurements.

I personally prefer the REW software layout for doing multiple comparative measurements; each sweep generates its own complete set of plots, and flipping between them is clear and simple. Also MUCH easier to import past measurements and overlay in REW, which in AP I think you have to do plot by plot; you can't just import a project file over top of an existing one.

The main advantage of the AP software is its automation capabilities, i.e. being able to set up a sequence of tests and have them run automatically. There is also a Python programming interface that enables scripting more complex types of measurements than the software itself allows, such as a 3D distortion over level/freq plot.