Review and Measurements of Topping DX3Pro DAC and Headphone Amp

[Pavel]

I have suspicions....
The problem is possible in not the OPA2140 itself, but in the technological process. Topping uses refractory solder. When assembling PCB at the factory, they were forced to raise the temperature above 275C. Apparently for such harsh conditions, the OPA2140 turned out to be a weak link. Very similar to the overheating of the chip when soldering. It may still live for a while, but then it will die.

 

[agjell]

I have suspicions....
The problem is possible in not the OPA2140 itself, but in the technological process. Topping uses refractory solder. When assembling PCB at the factory, they were forced to raise the temperature above 275C. Apparently for such harsh conditions, the OPA2140 turned out to be a weak link. Very similar to the overheating of the chip when soldering. It may still live for a while, but then it will die.

Isn't that what @amirm stated in an earlier post?

Based on what I understand, it is the soldering of the parts that resulted in this failing. So the fix is more care in manufacturing and not a design issue.

 

[Smatas]

Replaced OPA2140 with OPA1612. OPA1612 was preserved with me when I installed MUSES02. Subjectively, the sound became better and is already similar with my external A-class headphone amplifier.

I don't want to risk to blow one more tweeter, would like to get safe and stable dac. If I replace opa2140 with opa1612, will it work? Or should I change something else too?
Will the headphone amp work after this mod?

 

[vincent_emerald]

I don't want to risk to blow one more tweeter, would like to get safe and stable dac. If I replace opa2140 with opa1612, will it work? Or should I change something else too?
Will the headphone amp work after this mod?

I Suggest raising a complaint with Topping. Their bad manufacturing process has led to your equipment failure. This has to be compensated by them due to their bad manufacturing process, provided, its proved this lead to the failure

 

[Pavel]

While there was no official statement from Topping about the causes of the problem, we cannot assume 100% that the DX3 after the mod has become safe.
P.S. Here is another interesting find about OPA2140 - http://e2e.ti.com/support/amplifiers/f/14/p/539552/1966671#

 

[david99]

While there was no official statement from Topping about the causes of the problem, we cannot assume 100% that the DX3 after the mod has become safe.
P.S. Here is another interesting find about OPA2140 - http://e2e.ti.com/support/amplifiers/f/14/p/539552/1966671#

That is really suspicious. Do you know from where to get 100% genuine OPA2140?

 

[maxxevv]

That is really suspicious. Do you know from where to get 100% genuine OPA2140?

If you're based in the USA, mouser.com:

https://www.mouser.sg/Search/Refine?Keyword=opa2140

If in Europe, maybe RS-Components.

 

[Pavel]

I do not understand the choice of Topping in favor of the OPA2140 for the amplifier.
I believe that the banal NE5532 in the headphone amplifier circuit is more logical and absolutely reliable to use.

 

[david99]

I do not understand the choice of Topping in favor of the OPA2140 for the amplifier.
I believe that the banal NE5532 in the headphone amplifier circuit is more logical and absolutely reliable to use.

What are the cons of using OPA1612 instead OPA2140?

 

[Pavel]

No cons

 

[david99]

No cons

So only advantages?

 

[Pavel]

Replaced, worked well and the sound seemed to be better.
But these are subjective impressions. In this forum, such an opinion without measurements is not welcome.
I went further. Increased the quiescent current of the transistors to 60mA. This mod turned out to be a very significant change in the sound quality of the built-in headphone amplifier. The disadvantage of this mode is in the high heating of the transistors. Their replacement with the TO-126 case is required.

 

[david99]

Replaced, worked well and the sound seemed to be better.
But these are subjective impressions. In this forum, such an opinion without measurements is not welcome.
I went further. Increased the quiescent current of the transistors to 60mA. This mod turned out to be a very significant change in the sound quality of the built-in headphone amplifier. The disadvantage of this mode is in the high heating of the transistors. Their replacement with the TO-126 case is required.

What means very significant change in sound quality? And how did you modified current of the transistors?

 

[Pavel]

What means very significant change in sound quality?

Improved bass. He became more and he became resilient. The overall quality is nearing my external headphone amplifier.

And how did you modified current of the transistors?

Increased bias current. And removed the "non-musical" aluminum capacitors.
But the thermal stability of this scheme is not great. Probably should be replaced by another 4.7Ohm 15-22Ohm.



Added to output 10 Ohm to increase the stability of the amplifier.
I disagree with @amirm that the output impedance of the headphone amplifier should be as low as possible.

 

[MetalheadRich]

I have suspicions....
The problem is possible in not the OPA2140 itself, but in the technological process. Topping uses refractory solder. When assembling PCB at the factory, they were forced to raise the temperature above 275C. Apparently for such harsh conditions, the OPA2140 turned out to be a weak link. Very similar to the overheating of the chip when soldering. It may still live for a while, but then it will die.

What is the reason for doing that? Almost no semiconductor devices are specified for a peak temp of above 260.

 

[Pavel]

What is the reason for doing that? Almost no semiconductor devices are specified for a peak temp of above 260.

This is my guess. Of course I do not know the brand of solder. When I removed factory parts from a pcb DX3, I needed to raise the temperature to 270. Therefore, I concluded that Topping used refractory solder.

 

[bleachershane]

This is my guess. Of course I do not know the brand of solder. When I removed factory parts from a pcb DX3, I needed to raise the temperature to 270. Therefore, I concluded that Topping used refractory solder.

Googling the term 'refractory soldering' comes up with nothing for me, what is refractory soldering, it is not a term I've ever heard?

 

[eziitis]

technically "refractory" means "heat resistant" anyway, I would rather think that it could be also a "non-premium" batch of OPA2140 ...

 

[bleachershane]

technically "refractory" means "heat resistant" anyway, I would rather think that it could be also a "non-premium" batch of OPA2140 ...

My thoughts would be a bad or fake batch of OPA2140.
Tempted to attempt a change to some SOIC LM4562 opamps I've had around for a few years. DIP LM4562s were always my go to opamp over the last ten years or so, never soldered in SOIC though.

 

[eziitis]

SOIC should not be a problem perhaps it could be done more elegantly, but my approach is as follows:
A. Desoldering.
1. Put some flux on pins.
2. Heat all 4 one side pins with T12-K tip (or any other appropriate). Temperature controlled soldering station is a must.
3. With forceps catch the package and very slightly elevate heated side to detach the pins. Opposite pins will bent a little.
4. Heat opposite pins and remove the package.
5. Wick excess of the solder from pads.
B. Soldering.
1. Carefully adjust the package on the pads and fasten it touching 1/5 pin with soldering tip.
2. Take a second look is it OK.
3. Properly solder pins 1-8.

It might be even easier with hot air reworking gun, but I do not like to use it in crowded areas