• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Review and Measurements of Topping DX3Pro DAC and Headphone Amp

pejakovic1

Member
Joined
Dec 4, 2018
Messages
52
Likes
28
I think it's time we admit to ourselves that the problem with random shutdown units might be either firmware or hardware related and not PS related. This is not taking into account the completely dead units, those may have different problems.
 

noel_fs

Active Member
Joined
Dec 12, 2018
Messages
270
Likes
181
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.
i would say its software related, either firmware or drivers. Are you using their drivers?
 

haroharo

Member
Joined
Jan 11, 2019
Messages
5
Likes
2
i would say its software related, either firmware or drivers. Are you using their drivers?
First time I got random shutdown I was not using driver but had latest firmware. Other 2 times it happened I was using driver and latest firmware.
 

noel_fs

Active Member
Joined
Dec 12, 2018
Messages
270
Likes
181
First time I got random shutdown I was not using driver but had latest firmware. Other 2 times it happened I was using driver and latest firmware.
well then we can say its not driver related. you could try reapplying the firmware, just to do a checklist..

all of the times was playing music? using same player?
 

haroharo

Member
Joined
Jan 11, 2019
Messages
5
Likes
2
well then we can say its not driver related. you could try reapplying the firmware, just to do a checklist..

all of the times was playing music? using same player?
I guess it doesn't hurt to reapply firmware.
1st time - Youtube
2nd time - Foobar+Gaming
3rd time - Twitch+Gaming
 
Last edited:

HammerSandwich

Major Contributor
Forum Donor
Joined
Nov 22, 2018
Messages
1,137
Likes
1,497
I've not bought this unit yet, but the intermittent power-off problem seems hard to duplicate. The DX3Pro supports remote. Are you guys sure it's not this problem?
 

Vexed hex

Member
Joined
Jan 25, 2019
Messages
20
Likes
17
I had a set of Kanto Yumi speakers that did the same thing people are reporting about the dx3 powering off while in use. In my opinion the problem is with the auto shutdown feature when music is not detected. Either the signal is not strong enough for this feature to detect the music playing or it has gotten degraded or become damaged maybe from too strong of a signal.

Either way in my opinion this issue is the auto shutdown feature not functioning correctly.
 

Wolven

Active Member
Joined
Nov 10, 2018
Messages
226
Likes
113
First time I got random shutdown I was not using driver but had latest firmware. Other 2 times it happened I was using driver and latest firmware.

I had the unit turn off twice since late November, with new firmware. Both times in DAC mode. Last time while playing in Foobar, previous time cannot remember.
 

John Hammond

New Member
Joined
Feb 14, 2019
Messages
4
Likes
29
Hey everyone. I wanted to share my findings in performing failure analysis on my failed DX3pro in the hope that others may find this information useful.

I purchased a DX3pro (SN 1812594045) from an eBay seller and have been using it primarily with Shure SRH1540 headphones (46 ohm) for the past month at work with the stock wall-wart PSU. I never unplugged the unit during this time, but let it automatically transition to and from standby based on whether or not an audio stream was being sent from my computer. Last week, I returned to my desk from a meeting to discover that it had suffered a failure similar to those others have been describing: the right channel of my headphones was producing only a hissing noise, and upon removing the headphone plug from the DX3pro's jack, there was a loud 'pop' and the DX3pro went into standby mode.

In the case of my particular unit, it appears the right channel of the headphone amplifier has failed and is outputting approximately -9.5V DC on the right channel of the headphone jack. The left channel appears to be operating normally. I traced the headphone amplifier circuit and it is a fairly straightforward op-amp based design with its output boosted by a single complementary BJT stage (2SB649/2SD669). Heres's an example of an extremely similar circuit: http://sound.whsites.net/project113.htm

On my unit, it appears the PNP transistor to the -10V rail on the right channel has failed with a short from collector to emitter, resulting in the DC level present at the headphone output. I don't have good root-cause on why this transistor failed, but I suspect either a design issue (such as excessive bias current resulting in excessive heat and consequent damage) or a part quality issue. I'll keep working on this tomorrow to see if I can identify any issues.

Also FWIW all other functions of my unit still appear to be working normally (user interface, entering/exiting standby, etc.).
 

Attachments

  • dx3pro_failed_pnp_02132019.jpg
    dx3pro_failed_pnp_02132019.jpg
    769.8 KB · Views: 547

yue

Active Member
Joined
Jul 21, 2018
Messages
275
Likes
294
Hey everyone. I wanted to share my findings in performing failure analysis on my failed DX3pro in the hope that others may find this information useful.

I purchased a DX3pro (SN 1812594045) from an eBay seller and have been using it primarily with Shure SRH1540 headphones (46 ohm) for the past month at work with the stock wall-wart PSU. I never unplugged the unit during this time, but let it automatically transition to and from standby based on whether or not an audio stream was being sent from my computer. Last week, I returned to my desk from a meeting to discover that it had suffered a failure similar to those others have been describing: the right channel of my headphones was producing only a hissing noise, and upon removing the headphone plug from the DX3pro's jack, there was a loud 'pop' and the DX3pro went into standby mode.

In the case of my particular unit, it appears the right channel of the headphone amplifier has failed and is outputting approximately -9.5V DC on the right channel of the headphone jack. The left channel appears to be operating normally. I traced the headphone amplifier circuit and it is a fairly straightforward op-amp based design with its output boosted by a single complementary BJT stage (2SB649/2SD669). Heres's an example of an extremely similar circuit: http://sound.whsites.net/project113.htm

On my unit, it appears the PNP transistor to the -10V rail on the right channel has failed with a short from collector to emitter, resulting in the DC level present at the headphone output. I don't have good root-cause on why this transistor failed, but I suspect either a design issue (such as excessive bias current resulting in excessive heat and consequent damage) or a part quality issue. I'll keep working on this tomorrow to see if I can identify any issues.

Also FWIW all other functions of my unit still appear to be working normally (user interface, entering/exiting standby, etc.).

That's very interesting finding! Actually I found different units have different behaviors when failing:

- some units failed on the left channel rather than the right one you are experiencing. See https://www.audiosciencereview.com/...ac-and-headphone-amp.4967/page-73#post-132473

- some units automatically shut off without producing the hissing noise that you experienced, see https://www.audiosciencereview.com/...c-and-headphone-amp.4967/page-138#post-150264

- some units are not able to turn back on again, while you can still turn it back on. see https://www.audiosciencereview.com/...ac-and-headphone-amp.4967/page-67#post-128948

- some units such as @Toku's and mine, don't enter standby mode, they just stopped producing noise in the middle of a track. see https://www.audiosciencereview.com/forum/index.php?threads/dx3-pro-issues.6449/#post-143382

This is so mysterious!

For the first time we are able to get a fully dead unit not returned to the seller. You can contact @TP-Wong or <[email protected]> and he would be happy to investigate!


the right channel of my headphones was producing only a hissing noise, and upon removing the headphone plug from the DX3pro's jack, there was a loud 'pop' and the DX3pro went into standby mode.


did the pop come from the relay?

My assumption is that while you are unplugging the headphone, it creates a huge amount of current (because it's 10v dc, and there's short period of time that the headphone jack will create a short circuit when plugging/unplugging. and to make it worse, the output impedance of the device is super low.) That current essentially put the chip (very likely STM8 chip. xu208 is also possible) into shutoff mode.

Very likely the transistor was already broken by overcurrent when you heard the hiss noise. Topping intentionally use low output impedance design. I guess the elimination of the protection transistor makes it too easy to fail when using low impedance headphones.

@parkerlewis @haroharo @Stein @exaudio @david99 @Wolven quick question --- when your DX3 died, what headphone were you using? Are they low impedance headphones?
 
Last edited:

yue

Active Member
Joined
Jul 21, 2018
Messages
275
Likes
294
In my opinion the problem is with the auto shutdown feature when music is not detected.
This is clearly not the case. Mine stop producing sound in the middle of a finale coda, which by no means it cannot detect the music.
Other people experienced the shutdown and are not able to turn it back on.
 

david99

Member
Joined
Feb 3, 2019
Messages
50
Likes
37
That's very interesting finding! Actually I found different units have different behaviors when failing:

- some units failed on the left channel rather than the right one you are experiencing. See https://www.audiosciencereview.com/...ac-and-headphone-amp.4967/page-73#post-132473

- some units automatically shut off without producing the hissing noise that you experienced, see https://www.audiosciencereview.com/...c-and-headphone-amp.4967/page-138#post-150264

- some units are not able to turn back on again, while you can still turn it back on. see https://www.audiosciencereview.com/...ac-and-headphone-amp.4967/page-67#post-128948

- some units such as @Toku's and mine, don't enter standby mode, they just stopped producing noise in the middle of a track. see https://www.audiosciencereview.com/forum/index.php?threads/dx3-pro-issues.6449/#post-143382

This is so mysterious!

For the first time we are able to get a fully dead unit not returned to the seller. You can contact @TP-Wong or <[email protected]> and he would be happy to investigate!





did the pop come from the relay?

My assumption is that while you are unplugging the headphone, it creates a huge amount of current (because it's 10v dc, and there's short period of time that the headphone jack will create a short circuit when plugging/unplugging. and to make it worse, the output impedance of the device is super low.) That current essentially put the chip (very likely STM8 chip. xu208 is also possible) into shutoff mode.

Very likely the transistor was already broken by overcurrent when you heard the hiss noise. Topping intentionally use low output impedance design. I guess the elimination of the protection transistor makes it too easy to fail when using low impedance headphones.

@parkerlewis @haroharo @Stein @exaudio @david99 quick question --- when your DX3 died, what headphone were you using? Are they low impedance headphones?

Hi Yue,

I was using Bower Wilkins P5 S2 - 22 ohm adn planning using Bower Wilkins P9 also 22 ohm when I will buy new one. My question is. Is this DX3 PRO like dangerous for low impedance HP?

Thanks.
 

yue

Active Member
Joined
Jul 21, 2018
Messages
275
Likes
294
Is this DX3 PRO like dangerous for low impedance HP?
My suspicion is broken unit / random shutoff unit are caused by over current --- probably the circuit is not good enough to handle low impedance headphone + a zero output impedance. Seems most of you guys who have a dead unit use low impedance headphone, this further makes my assumption more likely to be true.
 

david99

Member
Joined
Feb 3, 2019
Messages
50
Likes
37
My suspicion is broken unit / random shutoff unit are caused by over current --- probably the circuit is not good enough to handle low impedance headphone + a zero output impedance. Seems most of you guys who have a dead unit use low impedance headphone, this further makes my assumption more likely to be true.

Makes sense for me. So if it is true this means that for this to be fully remediated we need to wait for topping to come with redesign of DX3 PRO
 
Last edited:

kagwind

Member
Joined
Feb 2, 2019
Messages
8
Likes
3
My assumption is that while you are unplugging the headphone, it creates a huge amount of current (because it's 10v dc, and there's short period of time that the headphone jack will create a short circuit when plugging/unplugging. and to make it worse, the output impedance of the device is super low.) That current essentially put the chip (very likely STM8 chip. xu208 is also possible) into shutoff mode.
Based on your assumption, I think it is at least good practice, although not a complete avoidance of issues, to power off the unit before plugging/unplugging the headphone.
 

Yuno

Active Member
Joined
Oct 26, 2018
Messages
215
Likes
266
Incidentally my unit just shut off for the 4th time now. Frequency about once per 3 weeks. So now I can fully agree that we can cross PSU from our list, as I was using Meanwell GS25A15-P1J (15V, 1.66A) since the beginning of this month. Also no other remotes in sight.
I guess one possibility is remote is faulty and sends signal to power off on it's own, but I would really doubt it. I'm connecting dx3 pro to APC ups, maybe that is a factor too, but frankly if anything this should be a positive since it regulates power somewhat (it's standard offline back-ups).
 

777

Senior Member
Joined
Jan 1, 2019
Messages
486
Likes
359
Hey everyone. I wanted to share my findings in performing failure analysis on my failed DX3pro in the hope that others may find this information useful.

I don't have good root-cause on why this transistor failed, but I suspect either a design issue (such as excessive bias current resulting in excessive heat and consequent damage) or a part quality issue. I'll keep working on this tomorrow to see if I can identify any issues.

Also FWIW all other functions of my unit still appear to be working normally (user interface, entering/exiting standby, etc.).

In my Dx3Pro the bias current it is 0.0075V/4.7ohm=1.6mA on each channel, left and right.
 

kotgnk

Member
Joined
Jan 26, 2019
Messages
5
Likes
0
I have the same failed. Spike or tension in the right earpiece. Left is working fine. Headphones 32 ohm.
 
Top Bottom