Audio Precision APx516B Review

[Roland68]

Yes that is a very good point. I've no idea exactly how many units they sell of each model but it's not that many. I had a quick look and they have a Revenue of
$22.7 Million which might sound like a lot but it's nothing compared to Apple and if their most popular model costs ~$50k that's just ~450 units per year across 9? models so maybe 50 units per year of each model. Not very many unit sales per model to share the development and all other costs across. Plus a share of that revenue will be software sales so maybe even much less than 50 of each model of physical units are sold.


How much value do you put on that level of support as well? As a business user I would put a high value on good support like that.

If you're a hi-fi manufacturer selling thousands or maybe millions of units each year $9k is a tiny amount to pay for the ability to test your designs properly. If you're so small you can't afford that, then Amir or others may be willing to help you with testing before you release a final product?

Anyway. I agree it's not fair to try and cost such a product based only on it's bill of materials.

You got to the heart of the problem perfectly. Most people don't realize that most products have a tight price calculation, often too tight. This is especially true for budget and entry-level products, whether it's small DACs or amplifiers, or the APx516B from this thread.

We are a small industrial company with our own production and I am happy when a manufacturer can offer support and service. We have a lot of special machines and devices in our production here, just like measuring equipment. When production stops, the hut burns.
What do people complain about most in the forum, especially when it comes to cheap devices? Service, support and lack of repair options and ability of the devices.
Audio Precision, RME, Lake People/Violectric and Thomann (dealers and manufacturers) show how it can work, but of course it also costs a lot of money.

When I consider that our oscilloscope with a high energy shunt cost 4x as much as the APx516B tested by @amirm ...
And that was already a heavily discounted special price. In comparison, this little Audio Precision is a real bargain.

 

[MC_RME]

As an APX555 owner I'm curious about the performance of the "B" version.

Amir, is your 555 a "B"version? What version of software are you running?

Being retired from the industry for the past few years, I'm seeing that equipment technical performance appears to be loosing relevence.

Not Amir, but - I have both. The 555 with Digital I/O Option equals the 555B, both in theoretical specs as well as in reality. Remaining difference is the CPU board which carries USB2 on the 555 and USB3 on the B (again no noticeable difference), and the included, now internal key box, which is an external part on the 555.

In other words: there is no need to update from 555 to 555B.

Oh wait, just remembered one little difference for AP nerds: the 555 usually does not have the hardware option EAG, which is standard on the B. This one allows to change the XLR output from differential (balanced) to single-ended (unbalanced. Pin 3 is no longer used and pin 2 gets double the voltage).

 

[HpW]

You got to the heart of the problem perfectly. Most people don't realize that most products have a tight price calculation, often too tight. This is especially true for budget and entry-level products, whether it's small DACs or amplifiers, or the APx516B from this thread.

We are a small industrial company with our own production and I am happy when a manufacturer can offer support and service. We have a lot of special machines and devices in our production here, just like measuring equipment. When production stops, the hut burns.
What do people complain about most in the forum, especially when it comes to cheap devices? Service, support and lack of repair options and ability of the devices.
Audio Precision, RME, Lake People/Violectric and Thomann (dealers and manufacturers) show how it can work, but of course it also costs a lot of money.

When I consider that our oscilloscope with a high energy shunt cost 4x as much as the APx516B tested by @amirm ...
And that was already a heavily discounted special price. In comparison, this little Audio Precision is a real bargain.

As long AP do not tell any specifications on the used Internal Timebase Reference and finally on master clock as ADC & DAC

 

[Roland68]

As long AP do not tell any specifications on the used Internal Timebase Reference and finally on master clock as ADC & DAC

It is always up to the manufacturer whether to disclose such information or not. You can simply ask AP about it, or look inside a device and publish it. Nobody will stop you, except perhaps the loss of warranty.
The APx516B is an audio analyzer sold with a specified generator output, including a frequency accuracy of 3 ppm (also applies to the optional digital modules). You can tell that the analyzer complies with the specifications by looking at the ISO 17025 calibration.
But what does this information give you? Does it change anything in the performance of the device or the results?
Of course, technology nerds are always interested in how something is solved and which solutions/parts are installed. But people or companies that use such a device are concerned with the results/quality of the measurement results, and not with how they are achieved.

Regardless of everything else, in the end it is up to you whether a device is worth the purchase price or not, or whether you lack functions or information and decide on a different product

 

[srkbear]

Link to Technical Information and specifications:

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

Having a bit of existential disorientation trying to figure out in my head how you managed to measure your measurer, but I’m sure it all makes sense somehow. Now that I’m privy to the price, there went the last lingering threat of me performing measurements myself. Thank goodness you’re here!

 

[weme]

I have received feedback on this review from students (first year electrical engineering students): 'They would have worked through the night to fully test the APx516B with the (calibrated?) APx555!

This is your forum, you determine the quantity and quality of your measurements. This review also shows us your progress in testing devices. Here is just one example of how you manage measurement errors:
...

Very well. Go and ask AP to see if they loan you both machines and then put said students to work. Don't come here complaining about my work after all the data that you just got without you or your students doing a thing.
...
but what was your excuse?

They are not my students.

You are forgetting a minority in your forum: People who can interpret measurements, people who want or need to measure audio equipment. Do you think your review is sufficient for these people?

Your measurements are basically very valuable and important: poorly constructed audio components are found. You have achieved acceptance through your SINAD table - the manufacturers have to react, and they do.

It's a pity that you didn't respond to my example (measuring the Output impedance):
Testing devices naturally requires comprehensive knowledge of how they work and their technical data. This information can be found in the operating instructions or in the technical data sheet. If the measured values deviate significantly, the manufacturer is usually contacted before publication in order to find the cause (error in the device, different measurement method, etc.) and to be able to react; measurement errors are corrected. This is how Test Laboratories work and how you could work too.

Although I don't use the SINAD tables, I have a few comments on them:

Some time ago, I converted the measured values of the first 10 top devices in the SINAD table and normalised them to 4,000 Vrms. The result: the ranking remained unchanged.

Your new table Top 20 DAC SINAD shows a ranking of the devices with a gradation of 0.1 dB at e.g. -123.3 dB.
The specification limits of the APx555 have long been exceeded:
ANALOG ANALYZER
Residual THD+N [2,3,4]
10 Hz to 20 kHz, 22 kHz BW
<= (–117 dB + 1.0 μV), V <= 9.3 Vrms;
<= –115 dB, V > 9.3 Vrms.
No relevant typically values
10 Hz to 20 kHz, 80 kHz BW
<= (–111 dB + 2.0 μV)
No typically values

[2,3,4]
NOTES to SPECIFICATIONS:
[2] System specification including contributions from both generator and analyzer.
[3] Generator load must be 600 balanced or 300 unbalanced.
[4] The "+" symbol in "THD+N" indicates rms summation of the two components. "THD" is the rms summation of H2 to H9. Specified residual THD+N and THD assumes the High Performance Sine Analyzer (HPSA) is ON.

Calibration of the APx555 does not appear to be necessary?
Have you carried out a measurement error calculation for this and can you show us the result?
Do these tested devices all have the same warm-up time and the same room temperature?

 

[amirm]

Calibration of the APx555 does not appear to be necessary?
Have you carried out a measurement error calculation for this and can you show us the result?
Do these tested devices all have the same warm-up time and the same room temperature?

Yes. I do that for every amplifier. For DACs, I occasionally do it if the manufacturer asks for it. Best case variation I have seen is about 1 to 1.5 dB. Most of the time it makes very little difference.

As to AP, as I have explained, company itself only recommends it for traceability, compliance with government standards and such. It is not needed nor recommended for testing audio gear as I do where the actual devices themselves lack the stability of AP.

 

[amirm]

It's a pity that you didn't respond to my example (measuring the Output impedance):

AP has no direct feature/mechanism for measuring impedance, input or output (I have complained to them). They have what I call at best a hack using NI libraries to generate such data. I don't like the presentation and the idea of installing half a gigabyte of software just for this. Where this matters, such as headphone amps, I have my own fixture and script to measure output impedance. Lately every such product has essentially zero output impedance so I don't run a distinct test. Where the impedance is higher than this, you can see it in the impedance power sweeps.

For compatibility with stereophile tests, I have added a 600 Ohm test for DACs which I have been reporting on. So the impact of low and high load impedances is characterized.

For input impedance, its only effect if it is low is to reduce the level equally across the full frequency response. I.e. it has no impact on audibility. So while everything "is nice to measure," per above I am not going to put resources into something that is not material.

 

[amirm]

Your new table Top 20 DAC SINAD shows a ranking of the devices with a gradation of 0.1 dB at e.g. -123.3 dB.
The specification limits of the APx555 have long been exceeded:

The impact of AP's own noise is constant across all devices I test. What this means is that the actual performance of the device is better, not that the comparison is wrong. There is just a derating factor.

That said, the top 20 graph is for fun and some silliness. I have said this a number of times. All of the devices in that ranking are superb and no reason to pick one against another based on that ranking alone.

 

[amirm]

You are forgetting a minority in your forum: People who can interpret measurements, people who want or need to measure audio equipment. Do you think your review is sufficient for these people?

I know how to read measurements as well and if someone had produced what I produce, I would kiss his feet. I have zero need and indeed distaste for graph after graph posted as to fill pages, drive advertising or look like you know what you are doing. People just turn off and don't read such dumps.

Remember, we are not trying to study a product. We are trying to see if it is a good purchase. For that, it all nets out to conclusion. That conclusion can easily be reached with the suite of tests I run. And even for learning about a product, there is plenty of information there to chew on.

At the limit though, it is precisely *against* my goals to satisfy people who want a product endlessly analyzed. I don't have the motivation, time or resources to do such analysis on new product reviews. If problems are found and specific reason and justification is given, I will run additional tests. But it is a complete non-goal for me to produce full QC/complete specs, etc. for products. You should ask manufacturers for this. Or go by other reviewers who enjoy and have the time for more detailed analysis.

My #1 challenge is getting ahead of constant reminders from members and manufactures on where their reviews are. The backlog is a killer and I can barely keep up my neck above water. As such, any requests for more tests comes at supremely high bar for justification. The effort, especially if requested after the fact, basically costs me and the forum another review.

You also don't see all that I do behind the scenes. I tested a speaker for hours and found an issue. Thought it was measurement related so repeated it all over again. Company then said I must have a bad sample and has sent me another one to test. So please don't tell me this or that student said I should stay up late night and do more. Much of my work is done at 2:00am already. I can't do more.

 

[JakeK]

I can't do more.

I really appreciate what you do. From my point of view I would still really value your work if you only published half the tests on each device as I still don't understand all of them. I rely on your interpretation of the notes, such as 16bits of distortion free range=good etc.. It's more important to me that you enjoy what you do and don't burn yourself out trying to please everyone. If you were to end up demotivated that would be a great loss to the world of hi-fi.

 

[weme]

I know how to read measurements as well and if someone had produced what I produce, I would kiss his feet. I have zero need and indeed distaste for graph after graph posted as to fill pages, drive advertising or look like you know what you are doing. People just turn off and don't read such dumps.

Remember, we are not trying to study a product. We are trying to see if it is a good purchase. For that, it all nets out to conclusion. That conclusion can easily be reached with the suite of tests I run. And even for learning about a product, there is plenty of information there to chew on.

At the limit though, it is precisely *against* my goals to satisfy people who want a product endlessly analyzed. I don't have the motivation, time or resources to do such analysis on new product reviews. If problems are found and specific reason and justification is given, I will run additional tests. But it is a complete non-goal for me to produce full QC/complete specs, etc. for products. You should ask manufacturers for this. Or go by other reviewers who enjoy and have the time for more detailed analysis.

My #1 challenge is getting ahead of constant reminders from members and manufactures on where their reviews are. The backlog is a killer and I can barely keep up my neck above water. As such, any requests for more tests comes at supremely high bar for justification. The effort, especially if requested after the fact, basically costs me and the forum another review.

You also don't see all that I do behind the scenes. I tested a speaker for hours and found an issue. Thought it was measurement related so repeated it all over again. Company then said I must have a bad sample and has sent me another one to test. So please don't tell me this or that student said I should stay up late night and do more. Much of my work is done at 2:00am already. I can't do more.

With my last comment, I am trying to provide more clarity:

As you saw, I agreed with that answer as well. I had no way of knowing that you would do everything yourself. I also have no way of knowing what the forum users read and understand.

Based on my knowledge and work, I have a good understanding of what you are doing here. That you absolutely need standardised, automatable processes: to ensure comparability, to avoid errors and to save time. Then there are the activities in the forum and, of course, outside the forum. Research work is therefore impossible - especially if there is no concept.

The following comments are just an example of my solutions to the processes I have criticised. It is only my opinion and, above all, not a text suggestion for a former top manager! With comparable answers from you, I would never have criticised you:

The output impedance was excellent at only 1.1 ohms (post to #1):
Correction: ... The output impedance should only be 35 mOhm, I can't measure values that low with the AP ... But don't worry ...

Audio Precision APx516B test report (post to #1):
... So, that's it. I don't have the time for further measurements. So please ask AP if you need more information.

So, stay healthy - we need you.

 

[Hemi-Demon]

I have received feedback on this review from students (first year electrical engineering students): 'They would have worked through the night to fully test the APx516B with the (calibrated?) APx555!

This is your forum, you determine the quantity and quality of your measurements. This review also shows us your progress in testing devices. Here is just one example of how you manage measurement errors:





If you are happy that many people today seem to buy Audio-components according to the "SINAD" table and no longer, for example, according to the output power "watts" as in the past, then that is fine with you. But, as you have already read here several times, there are people in this forum with very specialised knowledge: People who could help you take your measurements to a higher level and, above all, develop new, additional (!) measurement methods. Only then would a presentation at an AES (Audio Engineering Society) conference be logical and useful.

I would be very happy if I could read it one day:
... developed the new measurement methods with members of the ASR Forum ...

BTW:
Elsewhere here, you started a discussion about the planned measurement of MIC preamps. I have the feeling that you are (again) driven by the marketing aspect, i.e. that there will be an "EIN" table *) that is not based on the standard dBu but on dBV - simply because the dBV figures have higher values.
*)
Equivalent Input Noise table:
The input is shorted to 150 ohms, for example, to simulate the typical source resistance of a microphone. If a preamplifier does not add any noise, only the noise of the resistor (here 150 ohms) is measured:
150 ohms, 23 °C, 20 - 20,000 Hz results in -130.87 dBu or -133.09 dBV

Who are these magical students who are so willing to work through the night for free? What school do you teach at, and what is the name of the course or lab that you are leading ? Do you happen to have any published work that the ASR members can read through, critique and discuss as a comparative resource to all the reviews that Amir has completed?

I really tire of all the members that drop in with the singular SiNAD reference as if that's the only data point, and or analysis provided in each of these ASR reviews. Amir produces and entire suite of information, the tables are a summary, that's it.

Amir is one person for goodness sakes. Grab a device, post your own review and then let's all discus how you can improve on the methodology for all to learn from.

 

[Jimster480]

Who are these magical students who are so willing to work through the night for free? What school do you teach at, and what is the name of the course or lab that you are leading ? Do you happen to have any published work that the ASR members can read through, critique and discuss as a comparative resource to all the reviews that Amir has completed?

I really tire of all the members that drop in with the singular SiNAD reference as if that's the only data point, and or analysis provided in each of these ASR reviews. Amir produces and entire suite of information, the tables are a summary, that's it.

Amir is one person for goodness sakes. Grab a device, post your own review and then let's all discus how you can improve on the methodology for all to learn from.

I mean there are new tests that can be developed. However Amir is really backed up already with lots of hardware; so the chance he is going to spend time to develop new tests at this point in time probably isn't very high. I would personally like to see it; since so many devices have reached the tops of the current measurement charts. I would definitely like to throw a curve ball at these mfg's to further differentiate the devices being tested.

 

[babadono]

@amirm ,
Curious and this seems as good a place to ask as any, when you test Class D amps do you use a filter to remove the switching frequency? I'm sorry if you have already explained this somewhere and I am being redundant.

 

[staticV3]

@amirm ,
Curious and this seems as good a place to ask as any, when you test Class D amps do you use a filter to remove the switching frequency? I'm sorry if you have already explained this somewhere and I am being redundant.

Amir uses the AUX-0040 for testing Class D Amps, afaik.

 

[pac1085]

I'm thinking of buying one of these to replace my Levear VP-7725D audio analyzer. I mostly repair vintage 50's to 80's hifi gear as well as some more modern boutique gear (amps, preamps, FM tuners). The VP-7725D is great as a bench instrument but I want to create some semi-automated before/after reports. I whipped up some crude reports using GPIB/Python but the APx500 software suite looks so much better. I also figure I should get out of the VP-7725D while it still works.

I have some e-mails in with Audio Precision but there are two questions I have about the APx devices:
1. Is there any way to monitor the residual distortion waveform in software? I know these don't have analyzer monitor outputs like the older devices. I find this handy for adjusting bias, ac balance on older tube amps, FM discriminators, etc...
2. Are there filters in the software (such as a 200hz hpf/15khz lpf that I use for some FM receiver testing?). I see in older models they had hardware plugins you'd have to install in the unit, or external boxes all together.

 

[IamJF]

1. Yes, you need to use the headphone output of your computer. That's not as neat as with the old version but works well and stable. You can decide what to listen to and it helps a lot!
2. You can EQ outputs and filter + EQ inputs. At some measurements you can add filters for the measurement (e.g. noise. Put an A filter for the noise measurement but not to the input -> good for automations)

You could test the software with an audio interface in their stand alone version but when you add all the modules you need ... you are not too far from the complete price of the 516.

 

[pac1085]

1. Yes, you need to use the headphone output of your computer. That's not as neat as with the old version but works well and stable. You can decide what to listen to and it helps a lot!
2. You can EQ outputs and filter + EQ inputs. At some measurements you can add filters for the measurement (e.g. noise. Put an A filter for the noise measurement but not to the input -> good for automations)

You could test the software with an audio interface in their stand alone version but when you add all the modules you need ... you are not too far from the complete price of the 516.

Thanks for the info. I had a demo with their sales guy last night. You can view the distortion residual directly in the APX bench mode interface. The only downside was when working on 2ch systems, all of the traces are overlaid on the scope view. no way to offset them. so if you have 2 ch plus 2 residuals that's 4 traces piled on top of each other which isn't usable, so would have to disable the other channel and only view one at a time.

It looks like I should be able to do most of what I want, going to play around with the demo software some more over the next few weeks. The sequence mode seems to give me all of the things I was trying to script manually with my current hardware. The APX516b is 6k(no module) but I'd want flex pack 1 and 2 which are almost 3k a piece, so $12k.. I would plan on owning it 10 years...so if I went with the subscirption option instead of flex packs it would be about $15k... I made the mistake of asking about the APX525B, it's around 19k and doesn't need any of the option packs (maybe add on the AG52 upgraded generator)... plus has digital which I don't really need but not opposed to having, that's the way I'm leaning now, maybe once they release APX 9.x (so i get the free upgrade to 10.x)..