Review and Measurements of Topping DX3Pro DAC and Headphone Amp

[yue]

Thanks for letting me know. If this is really the case I will cancel return.

@amirm I will send you PM.

David

can you shot a video on how it fails? just curious.

@amirm is collecting dead units for investigation. See here and here and here.

 

[yue]

The apparent failure rate of this product is alarming.

However, these failures seem display the same symptoms, namely the standby/sleep issue. Perhaps this points to a single point of failure.

If this is the case, then a redesign would probably fix the issue.

Let's hope Amir can get a few "dead" DX3 units and figure out what fails.

I don't know for sure but I would say it's probably a power design issue, and even if @amirm get a broken device it may work fine for him. Two years ago I designed some DIY arduino "Smart Home" circuits in my office and it works great. But when I got home it always have some reliability issue (frequent shutdown, or display with random characters). A year ago I moved to a new place and the issue never occurs again. I believe my office or my current house has better electricity supply, and the previous one doesn't as there're hundreds of families reside in the same community. So where do you live may have impact on electronic device's reliability.

DX3 probably has some design issues with the power circuit. They also don't provide decent power switcher, which lead to some devices having issue while others run like a clockwork. I would suggest people having issues report to Topping directly, and ask them to improve their power circuit design.

 

[david99]

can you shot a video on how it fails? just curious.

@amirm is collecting dead units for investigation. See here and here and here.

Here is video

I just realized that amirm is interested only in units from US, I'm not US based.

 

[zephyros]

This may sounds weird, but if the PS is the problem maybe one can try another socket around the house or another place to see if it turns on?

 

[david99]

This may sounds weird, but if the PS is the problem maybe one can try another socket around the house or another place to see if it turns on?

Just tried that it is the same everywhere. I do not have another 15V PSU to test but I really do not believe it is power brick problem.

 

[bboris77]

All these reports of various problems made me cancel my order for this unit...I ordered the D50/Atom combo instead. It's a shame that we still have to play a lottery with all these manufacturers, regardless where the units are made. It seems that the pattern is that the Topping engineers their products better but suffers from poor QC especially for their low-end units and companies like Schiit have good QC and support but their engineering takes a very creative approach to certain elementary things like grounding. Rant mode off.

 

[noel_fs]

Just tried that it is the same everywhere. I do not have another 15V PSU to test but I really do not believe it is power brick problem.

Its not the psu, anyone you sure have a 12v psu, try that one. I used it by mistake for a few hours, nothing bad happened and it worked well.

 

[Yuno]

and companies like Schiit have good QC and support but their engineering takes a very creative approach to certain elementary things like grounding

Schiit is not exactly famous for their QC either. If there is any company that seems to be good in both QC and engineering department, it's JDS Labs, but anyways it's not like they make anything that can quite replace dx3 pro. The element with with ol switcher somewhat could, except then you are looking at $400 instead of $160.

 

[Veri]

Schiit is not exactly famous for their QC either. If there is any company that seems to be good in both QC and engineering department, it's JDS Labs, but anyways it's not like they make anything that can quite replace dx3 pro. The element with with ol switcher somewhat could, except then you are looking at $400 instead of $160.

They are working on new dac, and a dac/amp with Atom amp embedded will surely be competitive. Probably pricier though (current-gen element is what, $350? is indeed a lot more money than the DX3).

 

[noel_fs]

They just have to take khadas and make a case for it, not very difficult for them i guess xd.

Also ship it to europe without charging fucking 40$ for shipping cost. It would be sweet if they could declare it under 30$ like china does.

 

[nero626]

My unit has been pretty problem free until lately where sometimes when I start my computer up, it turns on automatically and shows it's connected but there's no sound via line out or 3.5mm? youtube videos also wouldn't play until I unplug the USB (guess it not actually receiving the audio packets or something), and the unit goes back to normal after a full power cycle, has anyone experienced this? I tried searching in this thread but couldn't find a similar issue

 

[yue]

My unit has been pretty problem free until lately where sometimes when I start my computer up, it turns on automatically and shows it's connected but there's no sound via line out or 3.5mm? youtube videos also wouldn't play until I unplug the USB (guess it not actually receiving the audio packets or something), and the unit goes back to normal after a full power cycle, has anyone experienced this? I tried searching in this thread but couldn't find a similar issue

I experienced it dozens of times.

 

[nero626]

I experienced it dozens of times.

any idea what causes it? weird thing is it doesn't happen all the time, and soft power cycling (via remote or button) doesn't fix it, nor does replugging the usb. not as bad as the other issues here but shouldn't have to reach to the back to reset it all the time

 

[yue]

any idea what causes it? weird thing is it doesn't happen all the time, and soft power cycling (via remote or button) doesn't fix it, nor does replugging the usb. not as bad as the other issues here but shouldn't have to reach to the back to reset it all the time

It appears randomly. See my earlier post
https://www.audiosciencereview.com/forum/index.php?threads/dx3-pro-issues.6449/

Topping themselves experienced this issue during early prototype stage and they thought probably a weak usb connection or static electricity might be the cause. They don’t have the issue in later prototypes so they ignores the problem.

Please contact them directly and let them know.

 

[yue]

Its not the psu, anyone you sure have a 12v psu, try that one. I used it by mistake for a few hours, nothing bad happened and it worked well.

Good psu supplies power with less fluctuations. Your 12v power supply works doesn’t mean topping's 15v work the same.

 

[noel_fs]

Good psu supplies power with less fluctuations. Your 12v power supply works doesn’t mean toppings 15v work the same.

hey, i just said it worked, for testing purposes it should be fine. i dont mean that we should use the 12v

 

[amirm]

I experienced it dozens of times.

So how about organizing to get your unit to me? I prefer to get one from US but a situation like yours where the problem comes and goes is ideal to try to a) replicate and b) see if variations of power/temp will make it worse or better. Happy to pay you for the price of the unit.

 

[yue]

So how about organizing to get your unit to me? I prefer to get one from US but a situation like yours where the problem comes and goes is ideal to try to a) replicate and b) see if variations of power/temp will make it worse or better. Happy to pay you for the price of the unit.

If you want to get my unit just PM me and lemme know your address. Please be aware that mine does not die --- I believe it's a different symptom as theirs where the units fully die ([1] [2] [3] videos of different devices showing the same dying behavior). While @Toku 's, @nero626 's and mine just stop (video) producing sound in the middle of a track, and requires unplugging/replugging the power chord to make it work again. All other behaviors look normal --- computer recognizes it as a USB DAC, the audio players (be it foobar2000 or mpd) play music happily, all DX3 UIs (volume adjustment and input/output selection) still work. it's just no sound being produced in either RCA or HP out.


I once ran it continuously in my office whole night and next morning it was still working properly. @Toku also ran it for a few days under different modes and the problem did not occur. Continuous test is not able to reproduce it, which makes it even harder to troubleshoot. I contacted Topping and they replied two days ago that it's a known issue when they were working on the prototype but didn't see it in the final product. They blamed lost USB connection (but the usb icon on the display doesn't blink, and my computer log message further falsify the usb disconnection hypothesis) or static electricity.

 

[amirm]

I once ran it continuously in my office whole night and next morning it was still working properly. @Toku also ran it for a few days under different modes and the problem did not occur.

Understood. I will swap it out for my normal one and see what happens there. I shut my machine down between uses so it will be intermittent use just the same.

 

[yue]

As expected, the digital volume control produces perfect response with essentially zero imbalance until you get to max volume attenuation of 99 db. No headphone amplifier using analog volume control comes remotely close to this kind of performance.

Just want to share an interesting implementation detail and correct you that DX3's volume control, albeit digital, is just software mixing. It's not doing volume control in the analog stage.
There're almost no difference between controlling via operating system volume vs controlling via DX3's hardware volume knob.
Unlike some products I have (such as Loxjie D20) which use dedicated volume control chip (e.g., NJW1194) or digital potentiometers (see JDS's C5 amp implementation), DX3's volume value is set in AK4497 chip.
This was confirmed by my discussion with Topping engineers two days ago.

The reason they need to use relays to hide the noise produced by AK4497 is exactly that. If there's a dedicated volume control chip, they could use that instead and avoid "clicking" noise entirely. But there isn't such chip in DX3 Pro. And unfortunately they also chose mechanical relays, which produce noise. I recommended them to change that to silent solid state relays in future batches of production. However they are celebrating Chinese New Year now so there's no future change plan yet.

IMHO this implementation is unconventional, as usually we expect DAC to output full 2Vrms signal, and use a dedicated amp for volume control, in order to minimize the noise floor of the DAC. You can achieve the same superb channel balance using a dac with software volume control (most Dacs have that. if not, Operating systems have software mixer volume control) + an amp running at maximum volume. Although I understand at this low price manufacturers have to cleverly balance the cost and may need to do some performance tradeoffs.