• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Audio Precision APx516B Review

Rate this audio analyzer:

  • 1. Poor (headless panther)

    Votes: 13 9.7%
  • 2. Not terrible (postman panther)

    Votes: 26 19.4%
  • 3. Fine (happy panther)

    Votes: 67 50.0%
  • 4. Great (golfing panther)

    Votes: 28 20.9%

  • Total voters
    134

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
44,860
Likes
243,571
Location
Seattle Area
This is a review and detailed measurements of the Audio Precision's APx516 audio analyzer. It is on loan from the company and costs from US $6,000. As tested, the cost is around $9,000.
Audio Precision APx516B Audio Analyzer Analog Balanced HDMI Review.jpg

The APx516B is featherweight compared to the much, much heavier APx555 analyzer I currently have. You can lift and carry it with one hand with no problem. Importantly, while it has a fan, it never came on during testing whereas my APx555 screams loudly requiring wearing a headphone to block it. A noisy analyzer could raise the noise floor of headphone measurements making the APx516 superior to my analyzer in that regard (I have mostly mitigated that however).

What one of the major reasons to get an Audio Precision analyzer is its software. It is easy to learn and given its closed loop nature, highly functional. The latter means the software can instruct the analyzer to do something, measure the results, and then continue with the next step. Such sweep measurements are critical and super useful. Other analyzers tend to run a test signal, capture the results and that is that. Note however that features are unbundled from the analyzer and may require additional licensing to use them.

Needless to say, the company was not about to obsolete its near US $30,000 APx555B series with this unit so performance is degraded. How much is the question. Let's find out.

Audio Precision APx516 Measurements
Let's start with a set of "loopback" measurements where the analyzer's analog signal generator feeds itself. Here, I simulated a balanced analog device with voltage set to 4 volts, measuring the combined performance of the signal generator and analyzer:
Audio Precision APx516B Audio Analyzer Analog Balanced Loopback.png

Distortion is comfortably low at around -119 dB. Noise however is high enough to sap fair bit of that performance bringing SINAD down to 106 dB. Here is my APx555 analyzer running the same test:

Audio Precision APx555 Audio Analyzer Analog Balanced Loopback.png

We see vanishingly low distortion courtesy of a dedicated analog generator instead of the DAC used in APx516. In addition, the APx555 uses a pair of ADCs to capture the signal independent of the noise and distortion resulting in much less distortion.

Performance however is voltage dependent so let's sweep that and see what is going on:
Audio Precision APx516B Audio Analyzer Analog Sweep Voltage Distortion Noise Balanced Loopback.png

We see that the gap is small during start of the sweep but once we get to around 0.22 volt, the APx516 auto-scales the input signal to better match its ADC dynamic range. This is much earlier than APx555 which runs "native" until 2 volts. Still, at lower measurement voltages, the gap is not that large.

Keep in mind that some other capabilities are limited such as what is noted: output voltage on APx516 is limited to around 14 volts. This limits testing of some ultra-low-gain amplifiers which may require as much as 20 volts to drive them to full power although this is rare.

We can bypass the analog generator effects by measuring a DAC, specifically the Topping D70s that I have on my desk. That way, only the analyzer performance is in play. Here is APx516:
Topping D70s APx516 Dashboard Measurement.png

Compare that to APx555:
Topping D70s APx555 Dashboard Measurement.png

The APx555 has much lower noise floor so visually the distortion spikes look taller but they are not. Not that it is material but the lower noise floor of APx555 reveals higher order distortions that are masked by the APx516.

Surprisingly, dynamic range measurements are the same between the two analyzers:
Topping D70s APx555 DNR APx516 Measurement.png


What this means is that for testing most of the recommended DACs, the APx516's own performance gets in the way. This much, I knew. What I wanted to find out was whether it could be good enough to measure amplifiers as their performance is not as good as DACs. So I powered up the Purifi reference amplifier and tested it with both analyzers:
Purifi Class D amplifier Measurement Audio Precision APx516B vs APx555B.png

As noted, up to about 18 watts (8 ohm load) performance is essentially the same. This means that we could compute the SINAD at 5 watts with either analyzer and arrive and close enough results. The rescaling of APx516 at 18 watts, sets it back a bit but that effect diminishes as the amplifier voltage increases, closing the gap between the two analyzers. Even at the limit, we are not talking about big difference.

Conclusions
The APx516 addresses two big shortcomings of the top of the line APx555 analyzer: cost and noise. It is also much more portable and having had to lug mine to events, can be an advantage if you are so situated. Naturally, you give up performance at the top end, limiting you to SINAD of about 105 dB or so. This is good enough to test many amplifiers especially since SINAD at 5 watts is close to my analyzer.

Yes, there are (much) cheaper analyzers out there. But you give up one major thing in the context of ASR: identical test parameters and graphing that I perform with APx555. This allows readers to much more easily comprehend the measurements.

If you are a manufacture and can't afford the APx555, and aim to have your product reviewed by me, I highly recommend getting the APx516. It will give you familiarity with my testing and very nice preview of what I may find.

Overall, I really like the APx516 with its light weight, much more reasonable price and good enough capabilities.

I am going to put the Audio Precision APx516B on my recommended list.
------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 
Last edited:
OP
amirm

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
44,860
Likes
243,571
Location
Seattle Area
Last edited by a moderator:

Matias

Master Contributor
Forum Donor
Joined
Jan 1, 2019
Messages
5,125
Likes
11,038
Location
São Paulo, Brazil
A shame no competitor can have the same performance and software automation for a fraction of the price. Some competition would be nice to have in this industry.
 

phoenixdogfan

Major Contributor
Forum Donor
Joined
Nov 6, 2018
Messages
3,367
Likes
5,339
Location
Nashville
Would be interesting to see how this APX 516b compares regarding features and specs against the E1DA Cosmos ADC which is $179 on Ali Express. The Cosmos obviously offers a much lower price of entry, and I have to wonder it's possible a unit like that has surpassed API's lower tier (older?) unit.

I know some members are using it along with the RME unit to do measurement sets, so it's fair to ask if a measuring unit with a 105db noise floor is a good buy at $9K. Guess the E1DA would not exactly replicate Amir's entire test set, but with a measured Sinad of 118db, it might be enough to accurately capture most of his tests for both DACS and amps.
 

Mikig

Senior Member
Joined
Jan 12, 2024
Messages
454
Likes
521
Location
Italia
This is a review and detailed measurements of the Audio Precision's APx516 audio analyzer. It is on loan from the company and costs from US $6,000. As tested, the cost is around $9,000.
View attachment 350626
The APx516B is featherweight compared to the much, much heavier APx555 analyzer I currently have. You can lift and carry it with one hand with no problem. Importantly, while it has a fan, it never came on during testing whereas my APx555 screams loudly requiring wearing a headphone to block it. A noisy analyzer could raise the noise floor of headphone measurements making the APx516 superior to my analyzer in that regard (I have mostly mitigated that however).

What one of the major reasons to get an Audio Precision analyzer is its software. It is easy to learn and given its closed loop nature, highly functional. The latter means the software can instruct the analyzer to do something, measure the results, and then continue with the next step. Such sweep measurements are critical and super useful. Other analyzers tend to run a test signal, capture the results and that is that. Note however that features are unbundled from the analyzer and may require additional licensing to use them.

Needless to say, the company was not about to obsolete its near US $30,000 APx555B series with this unit so performance is degraded. How much is the question. Let's find out.

Audio Precision APx516 Measurements
Let's start with a set of "loopback" measurements where the analyzer's analog signal generator feeds itself. Here, I simulated a balanced analog device with voltage set to 4 volts, measuring the combined performance of the signal generator and analyzer:
View attachment 350630
Distortion is comfortably low at around -119 dB. Noise however is high enough to sap fair bit of that performance bringing SINAD down to 106 dB. Here is my APx555 analyzer running the same test:

View attachment 350631
We see vanishingly low distortion courtesy of a dedicated analog generator instead of the DAC used in APx516. In addition, the APx516 uses a pair of ADCs to capture the signal independent of the noise and distortion resulting in much less distortion.

Performance however is voltage dependent so let's sweep that and see what is going on:
View attachment 350633
We see that the gap is small during start of the sweep but once we get to around 0.22 volt, the APx516 auto-scales the input signal to better match its ADC dynamic range. This is much earlier than APx555 which runs "native" until 2 volts. Still, at lower measurement voltages, the gap is not that large.

Keep in mind that some other capabilities are limited such as what is noted: output voltage on APx516 is limited to around 14 volts. This limits testing of some ultra-low-gain amplifiers which may require as much as 20 volts to drive them to full power although this is rare.

We can bypass the analog generator effects by measuring a DAC, specifically the Topping D70s that I have on my desk. That way, only the analyzer performance is in play. Here is APx516:
View attachment 350634
Compare that to APx555:
View attachment 350635
The APx555 has much lower noise floor so visually the distortion spikes look taller but they are not. Not that it is material but the lower noise floor of APx555 reveals higher order distortions that are masked by the APx516.

Surprisingly, dynamic range measurements are the same between the two analyzers:
View attachment 350636

What this means is that for testing most of the recommended DACs, the APx516's own performance gets in the way. This much, I knew. What I wanted to find out was whether it could be good enough to measure amplifiers as their performance is not as good as DACs. So I powered up the Purifi reference amplifier and tested it with both analyzers:
View attachment 350637
As noted, up to about 18 watts (8 ohm load) performance is essentially the same. This means that we could compute the SINAD at 5 watts with either analyzer and arrive and close enough results. The rescaling of APx516 at 18 watts, sets it back a bit but that effect diminishes as the amplifier voltage increases, closing the gap between the two analyzers. Even at the limit, we are not talking about big difference.

Conclusions
The APx516 addresses two big shortcomings of the top of the line APx555 analyzer: cost and noise. It is also much more portable and having had to lug mine to events, can be an advantage if you are so situated. Naturally, you give up performance at the top end, limiting you to SINAD of about 105 dB or so. This is good enough to test many amplifiers especially since SINAD at 5 watts is close to my analyzer.

Yes, there are (much) cheaper analyzers out there. But you give up one major thing in the context of ASR: identical test parameters and graphing that I perform with APx555. This allows readers to much more easily comprehend the measurements.

If you are a manufacture and can't afford the APx555, and aim to have your product reviewed by me, I highly recommend getting the APx516. It will give you familiarity with my testing and very nice preview of what I may find.

Overall, I really like the APx516 with its light weight, much more reasonable price and good enough capabilities.

I am going to put the Audio Precision APx516B on my recommended list.
------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Hi Amirm, interesting review, thanks.

I ask a perhaps trivial question: if I understand correctly, looking at the first two graphs, do some of the products you tested have the same degree of noise and distortion as that of the analyzer?

The analyzer would already be at "full scale" with some products, see Dac?
 

GXAlan

Major Contributor
Forum Donor
Joined
Jan 15, 2020
Messages
3,986
Likes
6,149

Sokel

Master Contributor
Joined
Sep 8, 2021
Messages
6,380
Likes
6,529
A general question so to understand what each one shows:

Why one reports 5Vrms in it's input and the other reports 8Vrms?
Is it a setting setting internal resistors?
 

RayDunzl

Grand Contributor
Central Scrutinizer
Joined
Mar 9, 2016
Messages
13,280
Likes
17,301
Location
Riverview FL

Jimster480

Major Contributor
Joined
Jan 26, 2018
Messages
2,923
Likes
2,082
Location
Tampa Bay
This is awesome, but as someone else mentioned... What about the AP500 key + the E1DA?
I'd really love to do some testing on products and search for the "golden sounds" that people always talk about.
 

peniku8

Senior Member
Forum Donor
Joined
Dec 9, 2020
Messages
382
Likes
770
And what can you measure with this kind of performance? DACs from 20 years ago? What's the purpose of this product?
 

GXAlan

Major Contributor
Forum Donor
Joined
Jan 15, 2020
Messages
3,986
Likes
6,149
And what can you measure with this kind of performance? DACs from 20 years ago? What's the purpose of this product?

It’s in the review — for assessing amplifiers.
 

Kervel

Active Member
Forum Donor
Joined
May 20, 2019
Messages
120
Likes
144
A question. In the dashboard figure, can't you just increase FFT length to reduce the measured noise floor, and then end up with a similar looking graph as the APx555?
 
Top Bottom