Audio Precision APx516B Review

[kelesh]

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.

If there is a market for it, maybe the usual Chinese suspects will reverse engineer units like this and put out a few $250 comparable devices.

 

[restorer-john]

I have not kept up with QA lately but the version I tested a while back had a SINAD of 99 dB (test conditions may not be identical)

The current model QA403 is quite amazing. (4V in 4V out)

You can hit -120dB (0.0001%) THD as is, loopback using its own DAC and ADC and get better again if you wanted to feed it with an even better gen.

 

[peniku8]

I wonder if they downgraded the performance deliberately to not cannibalize their flagship or if the pricing constraints just did not allow even better performance.

Of course they did. You can get a 120dB SINAD DAC-ADC loopback for 300USD in terms of hardware. The technical performance of this device is nothing short of a slap in the face of every AP customer. Sure I understand that the software (mostly the automation side of it) is great and that you can kit out the analyzers to your liking which is also really cool, but placing a DAC and ADC with this kind of performance into a modern audio analyzer at any price really is a really poor showing.
If Ivan finished the Cosmos DAC and then were to put the DAC, APU, Scaler and ADC into a software controlled master unit, you'd have hardware that is more capable than even the APx555 for like 2% of the cost. But their monopoly won't go away because software development is expensive, which means the E1DA analyzer will never exist. I really liked @mcdn 's idea of opening up the REW api for scripted automation. It would make the E1DA+REW combo more viable for professionals.
Also I'm really interested if the AP software would work well with this kind of setup. The first big issue I see is not having software-controlled auto gain features.

 

[amirm]

Thanks for the review @amirm, did you mean to say APx555?

Yes, thanks. Fixed.

 

[amirm]

Of course they did. You can get a 120dB SINAD DAC-ADC loopback for 300USD in terms of hardware. The technical performance of this device is nothing short of a slap in the face of every AP customer.

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.

 

[amirm]

I wonder if they downgraded the performance deliberately to not cannibalize their flagship or if the pricing constraints just did not allow even better performance.

Well, they have left complete blocks behind such as analog signal generator with it is much lower harmonic distortion. And dual ADC architecture. These represent cost savings and not just dumbing the thing down.

 

[DamianW]

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.

The QA403 has scaling built in and can handle input voltages of 112V peak to peak or +-56V. This allows for testing of amplifiers upto 400W with a 4 ohm load.

 

[Blumlein 88]

Did the QA403 fix the noise floor modulation issues the previous version had? If so I'd think it would be a good bang for buck for most companies and certainly good enough for production testing.

Glad to see this test of the lower model AP unit.

 

[sam_adams]

I really liked @mcdn 's idea of opening up the REW api for scripted automation.

See links here.

 

[Grooved]

For 1kHz loopback I get 113dB with a Topping D90 balanced direct to a Cosmos ADC, vs the 106dB of the APx516 and 122dB of the APx555. Using an SMSL D6S, Cosmos APU, Cosmos Scaler, and Cosmos ADC @sarieri got 125.5dB (https://audiosciencereview.com/foru...-testing-with-aes17-filter.46684/post-1885195)
View attachment 350652

I really really hope we can persuade @JohnPM to add an API to REW so it can be scripted for automated test procedure execution though, that would really push AP!

Hi, I'm a bit surprised that you can't get more than 113dB with a D90. Amir measured it at 120 (not 122), and you should be around that too.
The last device I measured was at 118 on ASR, and that's what I got with the Cosmos ADC alone (without using the APU and Scaler)

And regarding the automated feature, it would indeed be great if REW had it, but it's at least possible with Multitone Analyzer already

 

[amirm]

The QA403 has scaling built in and can handle input voltages of 112V peak to peak or +-56V. This allows for testing of amplifiers upto 400W with a 4 ohm load.

That is not what I was responding to.

 

[raif71]

Does the analyzer have the voltage switch of 120/240 V ?

 

[mcdn]

REW API beta releases and discussion.

REW API help.

Oh cool! Will look into it and see if I can help. This stuff is my day job

 

[sam_adams]

And regarding the automated feature, it would indeed be great if REW

See here.

 

[mcdn]

Hi, I'm a bit surprised that you can't get more than 113dB with a D90. Amir measured it at 120 (not 122), and you should be around that too.
The last device I measured was at 118 on ASR, and that's what I got with the Cosmos ADC alone (without using the APU and Scaler)

And regarding the automated feature, it would indeed be great if REW had it, but it's at least possible with Multitone Analyzer already

I’m sure I can do better, that was with the higher input impedance 43Vrms setting of the Cosmos ADC. I’m more into amps and speakers so haven’t bothered to optimise my measurements for DAC levels of distortion.

 

[Grooved]

I’m sure I can do better, that was with the higher input impedance 43Vrms setting of the Cosmos ADC. I’m more into amps and speakers so haven’t bothered to optimise my measurements for DAC levels of distortion.

If you used the 43Vrms, I understand now.
And yes, one XLR Y-cable to use the mono mode of the Cosmos ADC should allow you to get far better results for things like DACs

 

[xema]

could you test dscope m1 by any chance?

 

[restorer-john]

The (lack of) fan noise is a big plus.

Power consumption must be way down on the APX555 if they can get away with one fan, and that one is a thermo unit mostly off, or running slow. I wonder if AP could/would make a 'silent' fan kit add-on for the 555, with a few temp sensors, silent fluid bearing fans etc.

Fan noise on test gear is something I hate, and yes, I know they need to have the internals thermally stable, but some gear (DSOs) have such noisy fans, I end up only turning them on if I really need the digital storage aspect- I can leave analogue scopes on all day and they are silent, as are several other pieces of test gear.

 

[RKV1]

This is like the reincarnation of the AP One.

I see this being something repair shops would buy, definitely not for R&D.

Still too expensive for most repair shops. A QA403 would be a better fit.

 

[KEFCarver]

The current model QA403 is quite amazing. (4V in 4V out)

View attachment 350662

You can hit -120dB (0.0001%) THD as is, loopback using its own DAC and ADC and get better again if you wanted to feed it with an even better gen.

I was thinking the same thing when I saw the thd/snr plots for the apx516b and remembered seeing your plot earlier on the QA forum