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Review and Measurements of the HDPlex 200W Supply

amirm

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#1
This is a review and detailed measurements of the HDPlex 200 watt linear, multi-voltage power supply. It is on kind loan from a member. The 200W costs US $485 from the company.

The enclosure is small but impressively hefty and quality feeling:

HDPlex 200 Watt Linear Power Supply Review.jpg

As you see, there are no controls or indicators in the front. The business end is the back:

HDPlex 200 Watt Linear Power Supply Back Panel Review.jpg


I was pleased to see so many concurrent outputs with two of them fixed and two programmable. For my testing, I only used the 5 volt output to power USB based DACs.

Use of an XLR connector is a bit unusual but is fine if one wires it up with heavier gauge wires. One adapter came with the unit that went from XLR female to 9 volt plug. That allowed me to test the unit with Topping D50. I also tested the 200W with Schiit Modi 3 DAC which requires a micro-USB cable. I managed to build an adapter to power that.

I wanted to test the 200W with my two best performing headphone amplifiers but could not. The JDS Labs Atom needs AC input and the voltage requirement for Massdrop THX AAA 789 was too high for the HDPlex 200W.

I see the list of regulatory certifications. Hopefully they are real and not just stamped on the unit.

The company provides pictures of the insides and it seems tidy and nice:





Measurements
As noted, I focused my testing on DACs that are USB powered. There always seems to be anxiety with regards to power coming out of a PC being "too dirty" to power a DAC. We have explained many times that the power is not used as is. Rather, the USB power is filtered and often converted to another voltage before use. But audiophiles persist and want to use linear power supplies anyway. So let's start with Topping D50, running a 1 kHz tone FFT spectrum to see if either distortion, spurious tones, or noise floor changes with different methods of powering the unit. I used a wide bandwidth way beyond our hearing range so there is no criticism of cleaner spectrum above hearing range. Here is the three-way comparison:

HDPlex 200 Watt Linear Power Supply Topping D50 DAC Audio Measurements.png


The baseline in orange is a little external USB charger adapter. Red uses the PC power supply and green is with HDPlex. If I were to squint, there seems to be a bit less random junk in there around 10 kHz compared to USB Power. But we are talking about levels well below -130 dB. With our best case hearing dynamic range being 116 dB or so, no way this is material.

Above is with USB audio input by the way. Schiit Modi 3 DAC powers itself from the USB data jack so I could not test it the same way. Instead, I used S/PDIF coax input when forced the DAC to power itself from the secondary USB jack. Here are the same three tests:

HDPlex 200 Watt Linear Power Supply Schiit Modi 3 DAC Audio Measurements.png


The USB adapter this time is a beefy 3 amp switching supply I use for testing streamers. The other two are USB power and HDPlex as before. This time I can't see any difference even if I squinted. Whatever is wrong here is the fault of the S/PDIF input on the Schiit Modi 3, not anything to do with how it is powered.

I want to make sure you all note that these are highly sensitive measurements. Through power of signal processing, we have a measurement noise floor of -150 dB. That is insanely low levels and hence the reason we can see tiny spikes deep inside the noise floor. Hearing some of these noise spikes would be akin to you hearing me flush the toilet at our house. :) It ain't going to happen!

Conclusions
The HDPlex 200W has a very quality feel to it with seemingly good choice of components. Price of nearly US $500 while somewhat high, is not really out of the range of what something like this could sell for. The issue is that such power supplies are a solution looking for a problem. Yes, our audio devices have incredibly high precision. Engineers know how to design power supplies for them that achieve that precision with no external help. The power is already cleaned internally because external power is assumed to not be so. No wonder then that adding a different power supply makes no difference.

So please put aside your intuition in judging such products. When even a $99 DAC shows no improvement with a power supply that costs $500, you should be on notice that there is no there there. If you spend thousands of dollars for your DAC and assumed its designer is even less competent, you really are leaving common sense at the door.

I read that people are hooking these up to their routers, computers, etc. Man, what a waste of money and electricity.

"Good news" is that nothing got worse by using HDPlex. So no harm is done.

Needless to say, I can't recommend this power supply as an audio tweak.

----------------------
Questions, comments, critique, etc. are welcome.

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Blumlein 88

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#2
You have a silent toilet no one can hear? Tell me more. ;)

We need Ray's shout-o-meter and a measurement of the decibel level during a flush to develop a hearable radius I'm afraid.
 
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Snafu

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#3
My experience with random usb wall charger/psu: it fed noise to mains even when it wasn't connected to D50. Then tube amps picked up that noise and it was audible from speakers (kind of like 50Hz hum). To measure that kind of problem you (i mean i) should measure output of pre- or poweramps because this "hum" doesn't go through DAC at all. Connecting or disconnecting DAC from psu didn't make any difference.

But with powerbank vs separate LPSU, no difference since they are both working well.

and separate LPSU looks cooler than wall PSU so i'm ok to pay 50€ for it :D
 
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#4
My experience with random usb wall charger/psu: it fed noise to mains even when it wasn't connected to D50. Then tube amps picked up that noise and it was audible from speakers (kind of like 50Hz hum). To measure that kind of problem you (i mean i) should measure output of pre- or poweramps because this "hum" doesn't go through DAC at all. Connecting or disconnecting DAC from psu didn't make any difference.

But with powerbank vs separate LPSU, no difference since they are both working well.

and separate LPSU looks cooler than wall PSU so i'm ok to pay 50€ for it :D

I'd like to see this - measure the noise on the mains instead of what comes out of the PSU. Im sure crappy and even good power supplys dump noise back into the mains and contaminate other appliances.

The worst offender I had, and got rid of it, was the the schiit eitr (with supplied psu). Everytime the fan was switched on or off or the fridge kicked on or even the AC, the eitr would completely mute for about quarter of a second. Are linear power supplies more susceptible to this surge switching from household appliances?
 

amirm

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#6
I'd like to see this - measure the noise on the mains instead of what comes out of the PSU. Im sure crappy and even good power supplys dump noise back into the mains and contaminate other appliances.
Other appliances need to not care about contaminated power. I am making all of these measurements with tons of switching power supplies running around including my computer, monitor and DAC and still manage to get exceptional measurements.

You can't live your life these days without numerous such switching power supplies in your home. What are you going to do, not charge your phone? Not watch TV? Not run your computer?
 

reza

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#7
Amir, had you been able to test this with the amplifiers, do you suspect there could have been any noteworthy difference? Or is it safe to assume that similar engineering decisions and designs already clean the power there too?
 

Snafu

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#8
^^
didn't you measure some tube amp that was affected by led lamp nearby ?
i guess it's similar "unpredictable distortion" that just should't be but whooop there it is (this and my problem were tube related obviously).
 

RayDunzl

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#9
I see the list of regulatory certifications. Hopefully they are real and not just stamped on the unit.
Which, if any, of those printed cost money to acquire?

Like UL - not free, and not there... Spent some time at UL in Raleigh with Shaker Table destructive testing for Nortel.
 

JulesOz

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#10
Very informative :)
Schiit themselves said it would be useless on the FAQ for Modi page.

"Well, I’m gonna get me a fancy-shmantzy linear power supply and plug it into the back your Modi 3, what do you think about that?
We think you’re a little strange, because the output of that fancy power supply is going into a switcher, anyway. But if it makes you happy, we’re not going to stop you. Nor will we try to sell you such a power supply."
 

Theo

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#11
Thank you Amir for bringing in these measurements which confirm that all audiophoolery around power supply, including cables of course, is BS.
On the question of power supplies, accent put on "s", does anyone knows if a power supply delivering 12V DC (or variable to have a choice) to a large number (>6...) of appliances such as DAC, Servers, Wifi... exists? Like what can be found at the back of the HDplex, but with more outlets. I have a jungle of cables and supplies plugged in multiple outlets and I would like to have one box for all.
 

trl

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#12
So, no AC ripple & noise from USB port, random PSU and HD Plex? :(
 

Tks

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#14
^^
didn't you measure some tube amp that was affected by led lamp nearby ?
i guess it's similar "unpredictable distortion" that just shouldn't be but whooop there it is (this and my problem were tube related obviously).
I had a problem with this ordeal concerning a lamp and a new monitor I bought a few months ago (Asus PG279Q). It was literally turning on and off at random times. Until the lamp was turned off, this would continue to happen. The only reason I happened to diagnose this issue was because I put the monitor on my second rig and noticed there were no problems (I thought I was unlucky and got a lemon).

Needless to say, even as a complete noob to electrical theory, I'm still perplexed at just what the hell that damn lamp was doing (it was a small flourescent lamp, around 6 inch mini tube inside that's not serviceable). So happy to have gotten rid of that nonsense, but regret not taking picutres of it and whatever ridiculous wall wart power supply it was connected with. Speaking of which, that damn power supply would be at the melting point after using the lamp for a few hours.
 
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#15
Im guessing Coax/opt over would likely give better results than this. Not that it would be very audible but at least you get measurable 1 or 2db SINAD improvements ?
 

pwjazz

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#16
Interesting, I've never considered a linear psu for DACs. I have wondered what they might do for amplifiers, especially tube and/or ones with high mains noise. Got any of those around to test @amirm ?
 

amirm

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#20
Interesting, I've never considered a linear psu for DACs. I have wondered what they might do for amplifiers, especially tube and/or ones with high mains noise. Got any of those around to test @amirm ?
You mean power amplifiers? If so, they usually have internal power supplies and this thing won't have enough power for them anyway. I noted that I failed to find a headphone amplifier to test. I will see if I can find something else.
 
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