Review and Measurements of Topping DX3Pro DAC and Headphone Amp

[kukocz]

No one. Minimum voltage is 12v, maximum voltage is 25v.

I'm wondering why then they used 15V power supply instead of 12V which is more common on the market and easier to find replacement? What is the safe input voltage margin for tps54331 to have safe step-down to 10V?

Edit: I found it. It's Vin>=Vout+2V

 

[JohnBooty]

I realize this is extremely trivial compared to the reported reliability issues!

But I was pleased to find that the DX3 uses the same chassis as Topping's PA3 amp. This makes for a really nice little desktop combo stack. Purely in terms of aesthetics, I think this is tough to beat.

Even the volume knobs line up perfectly. Although, if you're really OCD, you might be bothered by the differently-sized Topping logos in the upper left.

Back to matters of actual importance...

The DX3 has been rock solid for me so far. I'm using the optical input exclusively, not USB. Subjectively it sounds great to me.

So far my only complaint is that I wish the line-level outputs muted themselves automatically when headphones are connected. The auto power-off feature is perhaps a little aggressive but hasn't been an issue, since it's also very quick to auto-power back on. Oh, and the remote didn't come with a battery.

All in all this is a combination I think I'll enjoy for quite a while. The PA3 puts out ~50 clean watts into 8ohms which IMHO is plenty of horsepower for the vast majority of residential situations so this isn't necessarily limited to desktop duty.

 

[yue]

Yes, I specifically use the one that came with this second unit.

I would try shooting some static electricity on it.

 

[artburda]

No one. Minimum voltage is 12v, maximum voltage is 25v.

Thanks. Good to know.

 

[bleachershane]

Are you sure that 25V is safe maximum? This means I could use also laptop power supply giving 19.5V 4A or so?

I really would not go anywhere near the 25v end of the scale just because the capacitors are rated at that, you should always avoid running any components at the top end of their capabilities. I'm assuming no one here has tried a supply over 15V, but if anyone wants to be a guinea pig then they can do so with their own units!

There have been a few users here have seemingly used 12V supplies with no issues, but this obviously deviates from what Topping originally supplied.

 

[MattG]

I'm wondering why then they used 15V power supply instead of 12V which is more common on the market and easier to find replacement? What is the safe input voltage margin for tps54331 to have safe step-down to 10V?

Edit: I found it. It's Vin>=Vout+2V

Based on what you found, it looks like 12V is the minimum voltage supply to have everything work as expected.

My guess as to why they went with 15V adapter: it's probably not regulated, meaning its actual output voltage likely fluctuates with mains voltage. (I used to think all SMPS were implicitly regulated, but that's not the case.) So again with speculation: if indeed 12V is truly the minimum needed for reliable DX3Pro operation, then you should be able to quite safely use a regulated 12V PSU.

 

[gypsygib]

My guess as to why they went with 15V adapter: it's probably not regulated, meaning its actual output voltage likely fluctuates with mains voltage. (I used to think all SMPS were implicitly regulated, but that's not the case.) So again with speculation: if indeed 12V is truly the minimum needed for reliable DX3Pro operation, then you should be able to quite safely use a regulated 12V PSU.

How to you measure whether the output voltage is fluctuating? I measured the PS that came with mine and it was 15.1 every time. Forgive the noob question, but would that voltage output change when plugged into the device?

 

[amirm]

Forgive the noob question, but would that voltage output change when plugged into the device?

Yes. Measure of merit for power supply regulation is how well it holds the voltage versus amount of current drawn from it.

 

[gypsygib]

Yes. Measure of merit for power supply regulation is how well it holds the voltage versus amount of current drawn from it.

Would that mean it's better theoretically to have a lower voltage power supply that reliable outputs, say 12V -14V, instead of a constant 15V for the longevity of the device? I ask because I just bought a meanwell 15V 1.66A powersupply after hearing stories on here of bad ones potentially causing issues. I could still return it and get a lower voltage one.

 

[amirm]

Would that mean it's better theoretically to have a lower voltage power supply that reliable outputs, say 12V -14V, instead of a constant 15V for the longevity of the device? I ask because I just bought a meanwell 15V 1.66A powersupply after hearing stories on here of bad ones potentially causing issues. I could still return it and get a lower voltage one.

I would use the same voltage as the one that came with it. In this case, 15 volt.

 

[MattG]

How to you measure whether the output voltage is fluctuating? I measured the PS that came with mine and it was 15.1 every time. Forgive the noob question, but would that voltage output change when plugged into the device?

What Amir said is right: unregulated power supplies will have voltage fluctuations with load (i.e. current draw).

But, your mains voltage (i.e. your home's AC outlet) can also fluctuate. I'm not sure about unregulated switch-mode supplies, but at least for traditional transformer + rectifier, AC to DC supplies, the output voltage is proportional to the input voltage (i.e. mains voltage), and that can and does go up and down quite a bit. I have an uninterruptable power supply (UPS) which allows me to query the mains voltage it's seeing. I log this. Over the last year, my mains voltage has swung between 105V and 130V, which is about 20% variance.

If you assume my mains power fluctuation is typical (20%), then a simple transformer+rectifier power supply targeting 15V would actually give 12v to 18v in practice. The gap is actually bigger, once you factor in Amir's comment, that the voltage is likely to drop even further under load.

Would that mean it's better theoretically to have a lower voltage power supply that reliable outputs, say 12V -14V, instead of a constant 15V for the longevity of the device? I ask because I just bought a meanwell 15V 1.66A powersupply after hearing stories on here of bad ones potentially causing issues. I could still return it and get a lower voltage one.

I would say yes to this if indeed my speculation is correct, that powering the DX3 Pro with 12V is sufficient. But, as that's speculation, without getting confirmation from Topping directly, best is to use 15V to be on the safe side. (Having said that, again, if my guess is correct, a 12v supply will generate less heat within the DX3 Pro compared to a 15v supply. And lower heat generally means greater longevity. However, Amir showed in his thermal analysis that even at 15v supply, all the components are well within their safe temperature range. So while theoretical longevity could be increased, in practical terms, I highly doubt it matters.)

 

[pejakovic1]

Very strange.
I was sure the problem was with these cheap power supplies. I immediately threw out the standard power supply and used quality ones.
The DX3 never shut down.

Nope my still shut down on meanwell.

 

[yue]

Nope my still shut down on meanwell.

did you contact topping? they are collecting faulty units.

 

[pejakovic1]

Would that mean it's better theoretically to have a lower voltage power supply that reliable outputs, say 12V -14V, instead of a constant 15V for the longevity of the device? I ask because I just bought a meanwell 15V 1.66A powersupply after hearing stories on here of bad ones potentially causing issues. I could still return it and get a lower voltage one.

My unit shut down 2 times with the same meanwell power supply you bought, and one or two times on stock PS. First time it was during a game. Secone time was when i restarted the pc and the shutdown was expected because the device is on auto standby mode and i havent touched the pc since restart, so no buffer was opened and it shutdown because it detected no music.

 

[pejakovic1]

did you contact topping? they are collecting faulty units.

The fact is replicating it is hard, my device shutdown 3-4 times in total in 3 months.

 

[bellyofthebizd]

Nope my still shut down on meanwell.

Maybe something else pluged into your setup is causing this. I would say get a power cord and plug it to different electric socket. With mine setup there are so many devices pluged to one so it is causing problems. Ive got one power off when ive started a game and graphic card turn on its fan so yeah... Pc might be the noisy one

 

[Klenfo]

Maybe something else pluged into your setup is causing this. I would say get a power cord and plug it to different electric socket. With mine setup there are so many devices pluged to one so it is causing problems. Ive got one power off when ive started a game and graphic card turn on its fan so yeah... Pc might be the noisy one

Many users have already written about self shutdown. It happened to me a few times too. But this did not happen in the last month of use. Obviously this is a problem in the device, and not in the power supply or wires, power cord or electric sockets, since so many people write about the same thing.

 

[gypsygib]

My unit shut down 2 times with the same meanwell power supply you bought, and one or two times on stock PS. First time it was during a game. Secone time was when i restarted the pc and the shutdown was expected because the device is on auto standby mode and i havent touched the pc since restart, so no buffer was opened and it shutdown because it detected no music.

Mine has never shut down unexpectedly (fingers crossed it never does) or had any other issues. I used the stock PS until yesterday when my Meanwell SGA25U15-P1J arrived. It's more of an abundance of caution than any issue really. Someone posted earlier that his shutdown and wouldn't turn on until he switched the PS, but by then the damage was already done so it would turn on but the unit was broken.

I just I wanted to eliminate any chance of the stock PS degrading or breaking something. Really though, my stock PS was probably perfectly fine. If 3%-7% of consumer electronics fail in the first year, there should be a good 25 or so people having issues if my minimum sales guess are anywhere near accurate.

But again, knock on wood! I like this thing a lot, would hate to have issues. Going on close to 4 weeks with no issues. It shuts down only when my PC goes to sleep and starts up immediately upon wake. Most seemed to have issues in the first month, with one person having theirs break after around 7 weeks. I find comfort in the fact that probability is heavily on my side.

 

[MusicNBeer]

Two weeks in my DX3 is rock solid. I leave it on most of the time as a standalone dac feeding my Benchmark DAC1 HDR analog in. Sounds great, better than DAC1, sighted yes, blind, who knows. Regardless, my 19xx unit has no functional problems.

 

[haroharo]

I still got my unit and have experienced the random shutdown for the third time. First time day 17, second time day 31, third time day 51. I turn it back on right away and it seems fine. Using stock power supply.