Review and Measurements of the HDPlex 200W Supply

[tpaxadpom]

In all fairness Amir you should have measured DC output from various power supplies using AP balanced input with the wide sweep. Do this with load present and unloaded and specify conditions for each.
Though my personal experience measuring audio gear with various power supplies (12V, 5V... as well as usb filters) using AP mirrors yours. Very faint difference if any. Though I suspect there maybe some gear that is sensitive. What people hear is completely irrelevant though. If they hear that difference you cannot take it away...

 

[jaynyc]

@amirm can you please help clarify something... in the Aug 2018 review of the Arcam rHead, just below the dashboard, it reads "As noted on the graph though there is mains leakage which is typical of devices fed by switching supplies.”

Does the switching supply from August 2018 generate different measurements than the switching supply in June 2019?
In other words, the Aug 2018 review features "Mains Hum" with the default 12V switching supply but the June 2019 does not?

 

[pwjazz]

it takes a lot for these to matter beyond showing up in measurements

That's the crux though, isn't it? The SINAD score isn't perceptually weighted, so a device with good distortion characteristics but a lot of mains leakage could have a poor SINAD score, which with linear PSU might improve significantly, yes?

 

[amirm]

@amirm can you please help clarify something... in the Aug 2018 review of the Arcam rHead, just below the dashboard, it reads "As noted on the graph though there is mains leakage which is typical of devices fed by switching supplies.”

Does the switching supply from August 2018 generate different measurements than the switching supply in June 2019?

My note for rHead in that review was a guess. A number of things can cause such mains leakage.

In general, for the reasons of emissions certification, there is usually a capacitor which connects the input to output and that cap will bleed mains to the output of the power supply.

 

[amirm]

That's the crux though, isn't it? The SINAD score isn't perceptually weighted, so a device with good distortion characteristics but a lot of mains leakage could have a poor SINAD score, which with linear PSU might improve significantly, yes?

The linear power supply has its own source of ground differential with respect to the rest of your gear. Indeed if a device is USB powered, it is usually in a better position in that regard than adding another power supply with its own source of mains differential/leakage.

Regardless, if you have an audible problem here, you will hear it in the form of hum. If such a noise is not there, then it matters not what the power supply does in that regard.

 

[HuskerDu]

The linear power supply has its own source of ground differential with respect to the rest of your gear. Indeed if a device is USB powered, it is usually in a better position in that regard than adding another power supply with its own source of mains differential/leakage.

Regardless, if you have an audible problem here, you will hear it in the form of hum. If such a noise is not there, then it matters not what the power supply does in that regard.

This feels like house wiring 101, except that I've missed the first month of material...

I read a power supply "cleaner" notion like this in the context of Chromecast Audio. I could not find a straight answer (before I found ASR) to my simple question of how the (5volt) power could affect a translation of ones and zeros. I bought the recommended wall wart and could not hear a difference. However, the other day I plugged the CCA into an Anker wall wart (it has two USB power jacks) and I COULD hear that thing hum. So I grabbed a different wall wart and the hum disappeared. Obviously I have no idea what was making the hum. I assume that the CCA will only take as much current as it needs from any standard-looking USB plug, but I'm no longer sure about that either...

I'd be grateful for a few solid recommendations for things I should read to help my understanding...?

 

[amirm]

I'd be grateful for a few solid recommendations for things I should read to help my understanding...?

If you can get through this presentation from start to end, you will know everything you ever needed to know about this topic! https://www.audiosciencereview.com/...d-presentation-on-grounding.7724/#post-182463

 

[Old Listener]

If you want to test the supply, test its consumption, test its regulation, test its voltage accuracy and its performance with all outputs loaded. In other words, test the device itself, not a DAC you strap on the end. Otherwise this review is just a hatchet-job IMO.

Did amir call your baby ugly?

 

[sbo6]

These products are not being sold on basis of functionality. Nor are they bought for that reason. They are purchased because people think it improves their sound, including when they replace the power supply on their routers, etc. Here is an example: https://hifi-opinions.com/en/review-hdplex-200w-linear-power-supply-lpsu/

View attachment 27154

I belivev they are purchased either and sometimes both reasons. You responses, unfortunately and as always back your subjective assertion. Providing one link doesn't justify your assertion.

 

[bequietjk]

Just a suggestion, but...

Being a measurement based forum, covering a vast spectrum of devices, mainly DACS and amps, would it be fair to say that an equal amount (more or less) of time should be spent using different power supplies with all this equipment?

@amirm For example, take the THX 789. You wish to perform the test on it but the HDPLEX was not capable of outputting that amount of voltage. Would it not be beneficial to the THX 789 Review thread and have yet another reference for a quality audio grade power supply if you had multiple PSUs? I may also be missing a component of your testing in that maybe you already have an effective range of power supplies, maybe adjustable that you already use.

In the past youve used additional power supplies in your testing of dacs/amps IF you had the PSUs on hand or what you have is capable of delivering that power, AC or DC. Is there any chance in the future you could do your tests with at least one or two other compatible PSUs, and note it in your post?

Sorry for the long post. Sitting in mt car right now drinking coffee and im very curious about this, because I too would like to see what a well renowned LPS/PSU could do for my THX 789.

 

[amirm]

@amirm For example, take the THX 789. You wish to perform the test on it but the HDPLEX was not capable of outputting that amount of voltage. Would it not be beneficial to the THX 789 Review thread and have yet another reference for a quality audio grade power supply if you had multiple PSUs? I may also be missing a component of your testing in that maybe you already have an effective range of power supplies, maybe adjustable that you already use.

There are internal regulators in just about every audio device that limits how much power it can deliver to the rest of the circuit. What is outside of the device cannot impact that limitation further downstream.

And since the 789 produces state-of-the-art distortion and noise ratings, there is nothing to improve with an external power supply on those fronts either.

 

[amirm]

Being a measurement based forum, covering a vast spectrum of devices, mainly DACS and amps, would it be fair to say that an equal amount (more or less) of time should be spent using different power supplies with all this equipment?

No. I have shown enough tests that you can safely assume external power supplies make no difference to performance of these devices. We already know that based on engineering of the devices. The tests simply confirmed what we already know.

 

[Veri]

Sorry for the long post. Sitting in mt car right now drinking coffee and im very curious about this, because I too would like to see what a well renowned LPS/PSU could do for my THX 789.

Don't buy into PSU nervosa. Just take a calm look at the THX dashboard measurement plot, there isn't a hint of mains noise in the analog output.
What, exactly, are you trying to improve?

Furthermore both the massdrop and monoprice THX AAA units use a regulated power supply on which the design is build around. It is simply unwise to plug in another power source without seriously knowing what you're doing. @AndrewMason from THX even strictly advised against it on the massdrop forum.

 

[AudioArchitech]

So your advice is to spend more money on a DAC vs a better power supply. But don't most of the higher end DACs come with better power supplies (with IEC Power sockets) in them, presumably they did this to improve the performance. SMSL SU-9 "The power source is implemented with shielded low noise conditioner. This improves both sound quality and power efficiency." More examples: Topping D70, D90, Denafrips Ares II, and up into the really expensive DACs.

 

[Bob from Florida]

I have an example where replacing a switcher power supply made a difference in the audio system. A number of years ago I purchased an Auraliti Linux based mpd music server along with my first ever DAC - Schiit Bifrost. The Auraliti was based on an Intel Atom motherboard inside a nice fan-less case. It was powered by a grounded 12 volt laptop switching power supply. My system was based on all tube separate electronics back then. The moment I powered the server up my sound system had a variable frequency swishing sound that coincided with the Auraliti "doing" stuff. Putting a cheater plug on the Auraliti power supply eliminated the noise so I knew it was switcher noise injected into the ground wire. I then ordered a fan-less Pyramid 6 amp linear power supply similar to the below for around $37 back then. Typical of these supplies - it actually is set for 13.8 volts. According to the Intel Atom motherboard specs this was out of tolerance. These Pyramid supplies come with schematics showing an adjustment potentiometer for fine tuning the output voltage. Since the adjustment range was not quite enough to get to 12 volts I had to change a reference Zener diode to allow exactly 12 volts output. Total cost - including Zener - under $40. This solved the noise problem and had long term reliability. To be fair a switcher power supply without a 3 wired ground power cord probably would have worked fine. If I recall I had a hard time finding one in the proper output current back then. The Pyramid solution was easier at the time.

 

[muzik-rain]

No. I have shown enough tests that you can safely assume external power supplies make no difference to performance of these devices. We already know that based on engineering of the devices. The tests simply confirmed what we already know.

So your mind was already made up... Why even measure it then, let alone at the device being powered instead of the actual unit under review.

Also, since this is purportedly a science - based forum, why is there no ABX testing being employed? How is it valid to show objective measured results and then provide subjective, "I hear no difference" results?

 

[trl]

@muzik-rain, the graphs Amir was showing in his review are pretty much identical, proving that there is no THD+N difference between the sound from the DAC source powered via USB vs. powered via 5V fed by the external PSU. You can also do the same by recording the audio signal from 1st test (powered fed by the USB port), then from the 2nd test (external PSU) and match the two sinewaves in Audacity or simply perform an ABX test by yourself with the recorded sounds; this way you will not be needing two identical DAC sources to perform such test.

However, there are DAC sources where clean power helps, but this is due to a rather average internal power regulation or by the ground loops, see https://www.audiosciencereview.com/...ynapse-neutron-v1-usb-isolators-review.59111/ where an USB isolator helps. I also had in the past a couple of DACs where feding them from external PSUs where lowering the noisefloor and/or eliminating the mains hum, but on the most of today's DACs this is not a thing anymore, because their internal power regulators are top notch and, on top of that, the audio opamps inside are of a newer genertion and they're providing a very good mains / noise rejection (>60dB).

So, feel free to take Amir's tests with a grain of salt if you want, but like I said: you can to simple tests at your home by yourself by recording with a decent ADC the audio signals coming from your DAC source with vs/ without an external PSU, then comparing the sinewave files in Audacity or in an ABX tests.