Review and Measurements of the HDPlex 200W Supply

[amirm]

There was a time when my brain was abducted in Computer Audiophile and I 'thought' (sorry for the exageration) that an external LPS for the DAC+a reclocker was the ticket for the audiophile grail. Happily, I didn't expend a cent.

It is such an accepted practice. I get a ton of private messages asking if they should buy linear power supply for some DAC. They have done a disservice to the community there. The people dispensing advice have no objective data or engineering knowledge to know better. Yet they preach this myth.

 

[pwjazz]

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.

Hah sorry, that's what I get for skimming! Yes, I was thinking of headphone amplifiers such as the Garage 1217 Ember, which is purported to perform better with a linear PSU.

 

[Newk Yuler]

It is such an accepted practice. I get a ton of private messages asking if they should buy linear power supply for some DAC. They have done a disservice to the community there. The people dispensing advice have no objective data or engineering knowledge to know better. Yet they preach this myth.

Would not some older and/or less well designed DACs possibly benefit from a cleaner PSU if they were not designed to better filter or reject noise from a noisy PSU? Assuming the less well designed DACs exist because decent common sense dictates a likelihood. Saying perhaps their DAC sections are well enough designed and the power section not? Why is it okay to make a blanket assumption about DACs and whether all can't possibly benefit from a cleaner external PSU? Unless there is measured proof that all DACs, every DAC individually measured, can't possibly benefit from cleaner PSUs?

Eh. I came here from the adjacent audio cable thread and I'm still wearing my imaginary waders. Linear PSUs and audio cables at ASR. Prime fodder for the purists. Observers need to armor-up like participating in a paint ball firefight.

 

[dinglehoser]

One thing that does make a measurable difference, however minute, is a PWM light dimmer pretty much anywhere in the vicinity (particularly on the same circuit). My phono preamp setup (admittedly kludgy) has a noise floor of -90dB, according to the extremely accurate (*cough*) spectrum analyzer on my RME ADI-2 DAC. The moment I turn on any light on a dimmed circuit, the noise floor increases to -78-86dB, depending on the amount of dimming involved. (Note: all connections in the phono preamp setup are unbalanced. Would be interesting to repeat this with a balanced setup.)

I wonder ... would a linear power supply fundamentally be better about filtering *input* switching noise dumped straight into the mains, relative to a switching power supply?

 

[amirm]

Would not some older and/or less well designed DACs possibly benefit from a cleaner PSU if they were not designed to better filter or reject noise from a noisy PSU?

Maybe. The issue there is that you wouldn't want to spend so much money on a power supply and instead, go and buy a better DAC. Further, from past tests, the artifacts of these DACs take over any improvements that the power supply may bring. I can try to test it though...

 

[amirm]

Saying perhaps their DAC sections are well enough designed and the power section not? Why is it okay to make a blanket assumption about DACs and whether all can't possibly benefit from a cleaner external PSU?

It comes from testing this theory so many times. I have done a lot of testing with my lab supply, audiophile linear supplies, etc. There has never been any kind of real difference at all. Even cheap DACs have filtering and in many cases, switching power supplies. But again, I will try to see if I can get more data points.

 

[g29]

It comes from testing this theory so many times. I have done a lot of testing with my lab supply, audiophile linear supplies, etc. There has never been any kind of real difference at all. Even cheap DACs have filtering and in many cases, switching power supplies. But again, I will try to see if I can get more data points.

If memory serves, you measured at least 1 USB device that could benefit from a better power supply.

 

[amirm]

Here is a round of tests using the Arcam rHead Headphone amplifier. Its stock switching power supply is 12 volt so I used the fixed 12 volt out of HDPlex 200W for testing.

First, the dashboard with unity gain with its own power supply:

And now with HDPlex 200W:

There is absolutely no difference.

Let's measure signal to noise ratio at 50 millivolts:

Again identical so no improvement in noise floor, black backgrounds, etc.

Finally 1 kHz FFT with wide bandwidth:

There is a tiny differential above 50 kHz but totally inconsequential.

 

[restorer-john]

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.

I think the big picture is being missed here.

It's a 200W supply, capable of running several devices at once on different voltages and serving as a single, high quality supply for all of them. Fixed 12V and 19V too.

Fewer cheap-ass wall warts clogging up the power boards, and from my perspective, considerably less radiated noise and definitely better reliability. Consider the majority of 'engineers' that designed the gear, had nothing to do with the sourcing of the cheapest SMPS external DC supply money could buy to go in the retail box and hopefully fail just out of warranty.

It can also be used to power SFF or compact streamer/HTPC PCs with the key voltages needed from a PSU. And with no fan noise.

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

Testing it with a few D/A converters and then proclaiming it's a 'waste of money and electricity' is ill-considered. Consider how often I (and probably you too) have had to replace failed small wall-wart SMPS supplies running small NASs, modems, routers, laptops, HTPCs etc and you might think otherwise.

Do I want one? No. But I can see it is valid, useful, and appears to be a well made product.

 

[BillG]

Consider how often I (and probably you too) have had to replace failed small wall-wart SMPS supplies running small NASs, modems, routers, laptops, HTPCs etc and you might think otherwise.

In my 3+ decades now of dealing with computing technology, I've not once had to replace a small, external SMPS. Am I lucky? No, I deal with this stuff professionally and my usage of them would be higher than normal...

 

[amirm]

Testing it with a few D/A converters and then proclaiming it's a 'waste of money and electricity' is ill-considered. Consider how often I (and probably you too) have had to replace failed small wall-wart SMPS supplies running small NASs, modems, routers, laptops, HTPCs etc and you might think otherwise.

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/

 

[amirm]

In my 3+ decades now of dealing with computing technology, I've not once had to replace a small, external SMPS. Am I lucky? No, I deal with this stuff professionally and my usage of them that would be higher than normal...

I too use countless ones. The only failure I have had has been a POE Injector. I have also had a couple of PC power supplies die but the notion of using linear power supply for them is insane. Way too much of power loss.

 

[Bones]

It seems that in the review of the SOTM 200 you tested the unit with multiple power supplies and found a reduction in mains noise with the Vinni Rossi power supply. Would this unit have value in such a scenario?

 

[restorer-john]

These products are not being sold on basis of functionality. Nor are they bought for that reason.

That's simply not true.

Go read the manufacturer's website, instead of quoting "hifi-opinions.com". It is all about functionality. It is all about specs and they even provide full schematics. It's a well designed product and they make no wild sonic claims I can see.

https://www.hdplex.com/hdplex-fanless-200w-linear-power-supply-for-pc-audio-and-ce-device.html

"19V/12V/Adjustable Rail Independent Output
True Separate Rail Design. No shared Ground. Guarantee No Cross RFI/EMI Interference. This is a must for multi-rail Linear PSU. All output can work at the same time with no loss of performance and no cross-talk with each other. "

The fact that some audiophiles who want a quality fan-less linear supply and have discovered these things is not surprising. That they attribute massive improvements when using them shouldn't be surprising either.

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.

 

[garbulky]

In my 3+ decades now of dealing with computing technology, I've not once had to replace a small, external SMPS. Am I lucky? No, I deal with this stuff professionally and my usage of them that would be higher than normal...

I've had several SMPS fail on me - mostly the internal PS in a computer. The stock PS almost always tends to fail. But I've also had several brand name units fail. My best experience has been with Corsair so far. I've also had several external smps fail - usually the laptop power adapters. On rarer ocassion I will also have the USB powered hub SMPS fail as well as well as one SMPS for an external headphone amplifier used for PC use. I have had surprising reliability with switchers used for routers and the such and I am impressed because they are left on permanently.

 

[pwjazz]

Here is a round of tests using the Arcam rHead Headphone amplifier. Its stock switching power supply is 12 volt so I used the fixed 12 volt out of HDPlex 200W for testing.

First, the dashboard with unity gain with its own power supply:
View attachment 27150

And now with HDPlex 200W:

View attachment 27151

There is absolutely no difference.

Let's measure signal to noise ratio at 50 millivolts:
View attachment 27152

Again identical so no improvement in noise floor, black backgrounds, etc.

Finally 1 kHz FFT with wide bandwidth:
View attachment 27153

There is a tiny differential above 50 kHz but totally inconsequential.

Not surprising as the stock measurements are already quite clean. Every now and then you review something that has a ton of noise around 50hz, but maybe that's mostly devices with an internal power supply?

 

[amirm]

That's simply not true.

Go read the manufacturer's website, instead of quoting "hifi-opinions.com".

John, I know this company. And I know countless subjectivists who buy their products. As to their website, here it is the extract from the product page for 200W:

Pretty clear who they are targeting with the product.

Here is a 20 page thread on CA about its audio uses: https://audiophilestyle.com/forums/topic/46748-new-hdplex-200w-lps/

There are threads on just about every audiophile forum about it.

Yes, the company also makes PC power supplies and such so they do get use outside of audio. But their linear products are sought after for audio tweaks.

 

[amirm]

Not surprising as the stock measurements are already quite clean. Every now and then you review something that has a ton of noise around 50hz, but maybe that's mostly devices with an internal power supply?

There are vagaries in audio products with respect to mains leakage especially with single-ended/RCA interconnects. Changing the power supply can change this behavior due to level of leakage being different. Our threshold of hearing in mains frequencies is very high so it takes a lot for these to matter beyond showing up in measurements.

 

[amirm]

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.

No one sticks a headphone or speaker to the end of a DC cable for a power supply. So what that connection looks like is not material. The only thing that matters with these devices is whether the analog waveform coming out of our devices are improved or not. If not, then it makes no difference whatsoever what these devices do.

Manufacturers love for us to focus on precisely what you say. This is why they show improvements in the output of their products, not the output of the audio products we care about. Use that to prebias the listener and they readily imagine the sound is improved and a sale is made.

So no, I am not going to cater to that. If we had found a difference we cared about, sure, I would the analyze the source. I have a B&K electronic load and could easily test it that way. But not until there is a reason to chase that rabbit.

 

[Dongulus]

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.

Some lamps are designed to adjust their brightness by gating the AC supply in order to modulate the amount of time the lamp is on in a cycle. Looks like this https://dxarts.washington.edu/sites/dxarts/files/3f9a9.jpg . Sudden load variations can cause nasty effects in a home power distribution network which potentially will impact other devices.