Help GoldenSound / GoldenOne Get An Audio Precision Analyzer

[GoldenOne]

Thank you so much for the support Chris!

I think an APx555 would open the doors to so much interesting content. And I don't just mean "What THD+N spec does X product I'm reviewing have".
It would open the doors to all sorts of experimentation of everything from digital sources, power, cables, setups, software, everything.
Not just seeing 'which measures better', but actually, PROPERLY looking into how things might be DIFFERENT. Which is something that honestly seems to be completely missing from most other objective testing and reviews.

And of course anything that others might suggest or want answered. It would be an immensely valuable tool and so I'm eager to make it happen.

Thank you!

[GoldenOne]

28 minutes ago, SoundAndMotion said:

First off, I watched both MQA videos and want to commend you and say well done.

 

As for donating, I’m not so much cheap, as just very picky about where I spend money. But I’m very interested in your plans wrt the above quote. Please elaborate here or pm... I might like to $how my intere$t in a practical way...

 

Thank you very much!

Plans for content will evolve over time and be shaped by viewer feedback. But the use for the analyzer will be fairly extensive.

Firstly and perhaps most plainly, I'd like to use it to provide objective information with my reviews. This won't form the basis of any opinions and I will always measure a product AFTER subjective testing to avoid having it influence my thoughts. There are plenty of products I love that sound far from neutral and are not the epitome of measurement prowess..., and it'd be really interesting to explore more in-depth why they sound different. Why is it that the bifrost 2 sounds the way it does? It doesn't measure great but sounds so much fun.

But I'd also like to test things a bit more extensively than just "Here's THD+N goodbye".
Testing the jitter on different digital inputs, USB vs Coax vs AES etc. As many dacs have varying performance here. A recent example I tested being the schiit modius where the jitter on SPDIF/Coax/AES was poor regardless of the source device.

The analyzer could also be used to measure the jitter performance of DDCs directly as well, as the APx555 can completely demodulate the jitter from the signal itself and present it independently.

 

 

DDCs are a product area that I am particularly interested in, and there seem to be hardly any objective testing of.
Some examples of stuff I did on DDCs previously can be seen here:

Furthermore, products would be tested in 'normal' situations as well as test conditions. Different dacs might have poorer performance when connected directly to a PC vs a more ideal source for example. (As shown in the above video).

And even things such as cables. Previous testing I did showed that there was a repeatable, measurable difference between a generic 1m BNC cable and an Audioquest Carbon 1m BNC cable, even though the source device and DAC were unchanged.
I'd love to explore stuff like this further.

I think the idea would be to try to be as thorough as possible, testing stuff every which way, and seeing what changes performance.
And then looking at what the differences in measurements between products X and Y are and trying to get an implication of what measurements might be impacting the audible differences even though they are measuring to a degree that many would considder "transparent".

And of course, any theories or ideas that viewers might have. I thought actually it might be fun to do a video every month or so where I just quickfire test stuff from suggestions.
"Does dac X behave differently when upside down", "does the ifi ipurifier change anything on dac X", "how does a headphone impedance adapter for speaker amps change FR" etc.

So much interesting stuff that could be looked into. 

[GoldenOne]

18 minutes ago, SoundAndMotion said:

Thanks for the thorough and enthusiastic response. I think I’m in.... going to watch a couple more of your videos, figure out what Discord benefits are, and discuss with the Finance Minister (it’s my money, but she decides) before deciding what level.

 

Sorry for being a dick, but I have to ask: do you know how to use the AP?

Thank you very much!
Of course if I can answer any questions then do let me know.
In terms of videos with objective content, I'd recommend taking a peek at the DDC video, active vs passive preamps, and Bifrost 2 review.

As to the AP. I know how to use it yes, and also actually had a two hour call with a rep from audio precision walking through some of the more advanced features of the software.
I'd be lying if I said I knew EVERYTHING about it, but that's cause quite frankly the level of flexibility that device and software has is....beyond insane. Hence the nearly 800 page manual. I doubt there are many people who actually know how to use all of what the 555 offers.

But I do know how to use the AP software properly and how to correctly operate, prepare and discuss the measurements as well as identifying potential issues in tests and what may be causing them etc.

(Also have done plenty of measurements of stuff on the past though of course limited in performance by the hardware)

[GoldenOne]

2 minutes ago, fas42 said:

 

This is where the real movement in properly evaluating the behaviour of audio systems will come from - there is an audible change; therefore, there will be something to measure. The problem then becomes the determined blindness by many who do have access to the equipment, to not see anything meaningful in the measurements

Exactly! It's incredibly frustrating when a discussion can't be had because it goes something along these lines:

 

A: I think these two products sound different

B: impossible they both have 120dB sinad. 

A: I did an assisted double blind test and was able to correctly determine between them 

B: well the test must be wrong then. 

 

I just don't get it. Surely if there is a difference itd be in everyone's interest to explore what might be causing it? It seems that far too many people are determined not to find any reason that they could be different as you said. 

 

Personally I'd quite like to find out why these differences are present, and I'm sure others would too! 

[GoldenOne]

7 hours ago, PeterSt said:

 

 

Erm, you don't need that analyser to show differences. You need an other mindset than "but you won't be able to hear this" (under -120dB etc. etc. etc.).

 

Just saying : my mindset has been all right as long as I work on this stuff. I have that analyser as well; We create cables and DACs and what not, so I know what to expect. GoldenOne, by the time you need some pointers, just let me know. As long as you (or Chris) don't think I'm raining on your parade, it is fine.

 

I would have many first pointers, and I chose this one for today:

 

You won't get far without the experience of listening. Hence, you could see all kinds of spuria in contrary directions. It could take 10 years of reasoning out in writing to qualify them. For example, I wrote a few pages of essay on the subject of how the ultra lowest jitter clock (as in less than 1fs) sounded by far the worse (Mani may recall it). Later I proved with my own normal NOS1 ((rated at a theoretical 200fs) that tapping on the floor already implied jitter-changes (rated at a theoreticsl 200fs). I think I have screenshots of that. Again later I visited a university and observed a whatever it was low jitter requiring tiny device (I think it was telescope lense), assembled in a 5 meter wide and 7 meter high shock-absorber assembly, weighing a couple of tons. The jitter to achieve in there was higher than what I tried out with that ultra low jitter clock. ... I returned that clock.

 

So you see, like with the easy to understand turn table, DACs already can't be measured in a static environment. It requires music to play in order to catch the hammering of the sound waves via the floor and cabinet on to the oscillator(s). Measure without that and you'd having nothing of value. For Mani ... the NOS1 floating on water ... (many many pages of fun to begin with).

Leave out these more or less prerequisites and you'd measure the wrong thing.

 

Not-so-much-doable.

But from me too, the best of luck !

And most certainly ready to help, because the idea most certainly is fresh.

An analyzer isn't strictly necessary, but most certainly of immense help.
Though in this situation it's actually not entirely the hardware which would be the benefit. But the software. To be honest an ADI-2 Pro and 1khz notch gets you all the performance you could ever need for most 'standard' measurements.

But its the flexibility and configurability of the AP hardware/software package that makes them so immensely powerful and the reason why they're the industry standard even with many much much cheaper options available.

I appreciate the offer for help, I'm sure i'll be giving you a shout in future! Thank you!

[GoldenOne]

6 hours ago, Iving said:

Armed with your clear technical credentials, your reasonable and human approach, your exceptional ability to articulate a position - and now an APx555 possibly - well consider me a moral subscriber. All power to your Audio Precision Analyzer elbow!

Thank you very much! 
I really appreciate the support.

Though I would like to be clear that whilst I do like to think my communication skills are good, and I try my best to be reasonable and level-headed whenever I can, my technical credentials are only in the form of what is effectively hobbyist experience. 
I do not have a degree in EE and don't want to give anyone the false impression that I have that or something similar.

I've had my fair share of experience with related stuff, from building and racing electric cars to working for a company designing a smart-home lighting system, plus of course all of the audio stuff that I've done, but I want to be completely transparent that it is at the end of the day just experience and not professional qualifications.

Though I also don't think that professional qualifications are necessary for much of what I'm aiming to achieve. And I think that credentials top trumps is a bit of a problem in some other audio forums and not constructive in the slightest.
We should be encouraging EVERYONE who has an interest to try this sort of stuff.

[GoldenOne]

Just now, idiot_savant said:

@GoldenOne I applaud your efforts to provide objective measurements and try to provide more in-depth analysis. I would be happy to offer advice/insight, so I’ll start with this:

As unpopular as this may be, I’d really recommend looking to the efforts John Atkinson has provided over the years - he’s truly done exceptional work, trying to keep measurements consistent and I believe him to be a thoroughly decent man. 
 

your friendly neighbourhood idiot 

I couldn't agree more.
I disagree with John on MQA but the work he's done over the years is exceptional and he's provided immense insight both into the objective performance of various products as well as the reasoning for and explanations of his own and other testing methodology and the impacts of what is being shown.

His work is a hugely valuable resource.

[GoldenOne]

On 5/28/2021 at 7:17 AM, Confused said:

In terms of a large number of consistent measurements, it is also worth looking at the work of Paul Miller.  (Hifi News / AVTech Miller Audio Research)

 

Interestingly, he started out as a chemist. 

(and he worked out that MQA was not all it was claimed to be)

Yep paul miller certainly has some excellent stuff. Though I do wish the measurement suite was a little more thorough.

Which actually I suppose is a good question, what are some measurements that people wish were taken of more products?

[GoldenOne]

15 hours ago, idiot_savant said:

something to bear in mind is that there *may* be a bit of shenanigans going on for products dynamically optimising themselves for the AP test suite, feel free to ping me if you want a bit of devious thinking here

Oh I'm sure, in fact we've seen situations where this has occurred before like the SMSL M500  https://www.audio “science” review/forum/index.php?threads/strange-smsl-m500-high-3rd-harmonic.22710/

 

 

14 hours ago, idiot_savant said:

I’ve reread this, and sound like a right idiot…

 

I’m trying to applaud your efforts yet point out a bit of subtlety could be how you differentiate yourself from other measurement websites - it’s easy ( but not cheap! ) to just buy an AP and run the test suite…

 

your friendly neighbourhood idiot 

Not in the slightest! Don't worry I took it as constructive :)
I agree, pressing the "APx go brrr" button is pretty easy. But that's why I'm keen to get one, to do the 'other' stuff. To do additional tests and look deeper into things. And unlike 'certain other sites', not just to do everything solo. I'm fully planning to work with and get advice and input from knowledgeable and relevant people wherever possible because that's how stuff moves forward and it'll make for much better and more interesting content too.
 

 

11 hours ago, opus101 said:

have they increased that top limit on their newer models?

I believe the oscillator is still up to 200khz

[GoldenOne]

11 minutes ago, PeterSt said:

 

There has to be a typo somewhere. 🤪

DAC is 0.001hz to 80khz
sine oscillator is 5hz to 204khz

ADCs are 192khz bandwidth for the ultra-high performance stuff and then a little lower on the 1.2mhz bandwidth

So you can still test switching amps etc, but I don't think there's going to be a need to actually generate a signal at >200khz so it should be fine :P

[GoldenOne]

2 minutes ago, PeterSt said:

 

Of course it is fine. It is only that no oscillator of 200KHz or 192KHz etc. will be in there.

 

sine oscillator is 5hz to 204khz

 

Maybe they call it like that. But if so, that would be a (signal) generator. Thus something else again.

Oscillators in this realm will be in the xxMHz range.

 

And the LF oscillator in a synth should be able to go as low as 0.05Hz (preferably much lower). Haha.

 

The gist is clear: these (24 bit) machines still don't go beyond a useful range of 96KHz. Strange actually; Already 10 years or so back I asked "so what about DAC's being able to do 786KHz ? isn't it time that you dunk in an ADC doing that ?". ... The ADC's did not exist of course (not for 24 bits). This has changed now. ... I suppose AKM is not good enough for them ?

 

So Yes, I have been contemplating how my RME could be supplemental (I still did not unpack it).

To be specific I was referring to the analog sine generator. These are often referred to as oscillators such as here https://quantasylum.com/collections/frontpage/products/qa480 or general "Wien bridge oscillator" designs (though I don't know what specific design the one in the AP is.) 

I wasn't meaning crystal oscillators etc.

[GoldenOne]

2 minutes ago, The Computer Audiophile said:

Hi @GoldenOne Here's something I've been thinking about because the only way I know how to test it is kind of crazy. If there was a test to discover an issue like this, it would be really neat. Otherwise, only reviewers using equipment for periods of time like normal users, will discover this type of stuff. 

 

Issue: I had a component here that would stop playback and require a reboot when I flipped the switch for my bathroom fan. It turns out this only happened in the winter when the humidity in my house is really low. The component, I believe, built up static in a chip, that eventually caused the issue. I also believe there was an issue with pops and ticks at strange intervals when the air was extremely dry in my house. Like the static was being discharged only partially, rather than "fully" by the fan switch. 

 

Question: Can you think of a way to test for this?

That's an interesting one, and would definitely be a design fault.
I'd imagine it'd probably need some probing on the board itself rather than something that could be properly tested at the output, but the fact that it was so responsive to humidity is definitely odd.
Was this device grounded or floating?

To be honest I imagine there are some situations where buildup of charge or other similar things may impact a device. One that I've been curious about for a while is the schiit yggdrasil. That is notorious for having a DAYS Long "warmup" time. But It wouldn't really make sense for it to be a thermal issue. As that would sort itself out within a couple hours at most. It'd make more sense if it was some sort of buildup or stabilization of some other electrical property.

It'd certainly be interesting to look at. To create a proper test would probably need to know more about the specific component though.
The fact that it stopped playback when you turned on a mechanical component suggests that it could also be that it was extremely sensitive to DC on the mains. Fans, compressors, fridges etc are usually the main culprit for that. Any kind of reactive load.

[GoldenOne]

Just now, The Computer Audiophile said:

 

It took a little while to figure this one out, but I think the larger items of importance would be some way to test for things like this, even if not humidity related, there are likely many other ways products can exhibit strange behavior. 

I'm sure a device could be made in order to simulate mains DC offset and therefore test a devices resilience to it. Though would need to be careful as to the level of offset tested to avoid damaging something.

Normal ESD testing should be done by the manufacturer, and is part of the requirement to get the CE mark (though I'm sure many manufacturers put the CE mark on their products regardless of if they actually qualify for it or have had their product tested).
But that would only be protection from external ESD. 
As to buildup of static charge in the device itself or components in it, this would need to be done with a static meter https://fraser-antistatic.com/products/715-static-meter/
 

I think unfortunately even with the tools to do the above, it'd be tricky to get much insight as to how it affects the product and might just need to be something that feedback is given on through normal use. Because without having deeper knowledge of the design or working with the manufacturer it's not necessarily possible to know what acceptable or normal levels are and how abnormal levels might affect things.

Proper grounding should alleviate most issues though I'd expect
 

[GoldenOne]

So I'm going to have an APx555 here for a couple weeks (not mine, not keeping it, just here temporarily). This likely won't be long enough to do some of the more in-depth stuff but I'm going to measure anything I can get my hands on just cause why not, but also will probably do a brief video explaining a little about why the APx555 is different to just using a good ADC etc.

If anyone has anything specific that they think I should do whilst it's here lmk!

[GoldenOne]

Friend of mine sent a small present to keep the analyzer company. 

 

 

[GoldenOne]

16 minutes ago, Confused said:

I am a little surprised there was not more response to this one.  Anyway, reading through some recent threads here on AS gave me an idea of something that could be tested.

 

I believe you have an "NAA" type device?  (SOtM sMS-200?)  In other threads there has been debate about computer / PC "noise" that can find its way to the DAC, so how you play back a bit perfect file can influence the sound, depending on the configuration of the PC, software, noise etc. 

 

As a subset of such discussions, it has been suggested by some that "network attached end point" type devices should effectively be immune to whatever might be going on in the associated PC, as long as the said machine is delivering the bits, nothing else matters.  Others dispute this notion.

 

Which gives me an idea for a test.  You could measure the output of the NAA (or perhaps the output of a DAC connected to the NAA) using different PC's to feed the NAA, or maybe the same PC is different states, first just running simple playback software, then maybe have the computer mutli-task, running the playback software and at the same time with the PC running near to the processor limit running another task.  There are very many ways this could be done, but the key would be to have the feeding computer in definitively different states, or maybe use a simple LPS powered NUC versus a big noisy SMPS ridden high powered PC.

 

Just a thought, maybe it is a bad idea for some reason, maybe a more optimum test could be devised?

 

Might be interesting though?

I did actually touch on this briefly in my DDC video.

Using a network streamer can be a big benefit especially if you were previously using a beefy (and very electrically noisy) PC.
And dacs can and do indeed show different measurements in both things such as outright THD+N and Jitter when connected via a more ideal source such as a streamer vs a PC.
How much this change is will depend on the specific DAC, with some dacs showing very obvious changes, something like an apple dongle being a rather extreme example. And some dacs which have proper internal galvanic isolation like a Yggdrasil or May should have no change at all.

In terms of USB vs an I2S/AES/SPDIF streamer though, the latter will affect performance more due to the fact that the source device/streamer is the master clock, not the DAC itself.

[GoldenOne]

12 minutes ago, Confused said:

Yes, I enjoyed watching your DCC video, excellent stuff.  (Although I was left wondering how a Mutec MC3+USB might have faired, but you can't test everything I guess)

 

That said, what I am proposing is slightly different.  Not a PC direct versus NAA test or similar, but a fixed NAA / DAC system, with the only variable being the PC.  The question being, does the Ethernet / NAA route reduce susceptibility to noise from a big noisy PC, or does it eliminate it completely?  Maybe you have already established this?

Ethernet is by spec transformer coupled and so noise will not be an issue. (It would be a nightmare trying to overcome the levels of noise in something like a datacentre if it wasn't I imagine)

The only thing that would realistically ever change would be jitter, but due to how ethernet and TCP/UDP works this simply isn't an issue.
SPDIF/AES/I2S sources can and do make a difference, as do USB sources to a lesser degree (key component with USB is the USB implementation in your DAC), but with ethernet the simple answer is it just doesn't work that way and any audiophile Ethernet tweak I personally cannot see how it could ever make a difference.

I've tried a few different networking setups and was never able to hear an audible difference nor measure any change whatsoever.
 

I'd be more than happy to test as extensively as I could both subjectively and objectively if someone were to lend me an 'audiophile' switch/router. I'm always open minded, but at the moment there is no reason and no evidence that networking tweaks would make an improvement.

[GoldenOne]

2 minutes ago, firedog said:

I think JA's tests are great, and his comments/interpretations add a lot.  He is also willing to say sometimes that he doesn't understand the intersection of the subjective sound and the objective measurements.

 

The fact that Stereophile does a subjective review and then has JA test the unit is also a great setup. The reader often gets to see that the Stereophile reviewers have noticed something that then shows up in the measurements - or the opposite. That makes for a good read. 

Absolutely
Subjective impressions and objective performance are both important, and often they either don't align, or one provides insight to the other.

It's useful to do things in the way that stereophile is doing, providing subjective feedback and then independent objective testing.
I'll aim to do the same. I'll include objective tests in my reviews where I personally feel it is appropriate, but I'll always do the objective testing AFTER forming my subjective opinions to avoid having the measurements create a bias.

The full measurements will then be posted separately and without much in the way of opinion/comment. To allow the two approaches to stand on their own.

 

[GoldenOne]

I've been offered a loan which will cover much of the cost of the analyzer. So close now!
Selling anything I can that isn't tied down to try to cover the remaining amount.

But if anyone here is able to do so and has enjoyed the content I've made so far please do consider supporting even just for this month. Hoping to place the order in the next couple weeks!
 

[GoldenOne]

 

(Seriously, thank you so much to everyone who contributed to this! I'm really looking forward to making some good stuff with it.
Still need to work on getting a dummy load though)

[GoldenOne]

Audio precision is allowing me to keep this unit until mine is ready. I'll actually be going to visit Audio Precision in person to drop this unit off and pick mine up which should be fun.

Dummy Load arrived today, this is controllable from the APx software so I can incorporate it into fully automated test sequences, and not only does it do pure resistive loads, but also does proper reactive load testing too so this should allow for some very comprehensive testing.

There's been an interesting thread about resistive/test condition measurements vs reactive/real world stuff lately so hopefully this can help with some similar stuff: https://www.superbestaudiofriends.org/index.php?threads/oh-shit-sinad-can-suck-my-s.11175

Also I've put my ifi iGalvanic on the test bench, and an iUSB 3.0 (thank you ifi) to ensure that no DAC measurements are skewed by the source itself. It's actually been quite interesting just how some dacs perform differently with one USB source vs another

[GoldenOne]