Review and Measurements of Topping DX3Pro DAC and Headphone Amp

[TiborG]

Thanks for sharing the experiences. It is good to know that AptX-HD works well. I do not have bluetooth 5.0 device at the moment. Will have to try it someday!

Interesting that people are still listening to This Mortal Coil! Blood is very good for listening test.

Unfortunately, I do not have the AptX-HD cable, just the Apt-X TRN V10 cable with MMCX connectors and I'm testing FiiO FH5 or FiiO F9. Also good results. So Vikefon is just a source of stream to the DX3 and from it to HP or the amplifier. The only one !! AptX-HD cable I found on Amazon for 149 Eur Westone. And Sony LDHC

 

[finneybear]

Just got this update from seller
"We just got the good news. Topping has solved this problem. It is expected to start producing new products next month, so please don't worry, I hope I can help you, thank you."

If they just increase the cap value for the digital 3.3V supply to delay the wake up time of the MCU, I will not consider it as a real fix. Hopefully they have done something more comprehensive.

 

[finneybear]

I rolled Muses02 in it. It's a bit less clinical sounding than opa1612.

I also tried 1642 which wasn't a success.

I did replace all the TL072Cs in my active speakers with opa1642 where they perform superb. It's a good opamp. But maybe not for the lpf of this dac

What did you hear from 1642? 1642 needs very clean signal path otherwise the mid will sound rough. What have you done with the 4493 coupling caps?

Did you hear any improvement on bottom with MUSES02? MUSES02 is very similar to 8820.

 

[finneybear]

Initially you wanted to install these capacitors https://www.arrow.com/en/products/t520a107m006ate045/kemet-corporation
Why did you change the decision?

Generally I would avoid using polymer caps for signal coupling due to the large leakage current.
The cap output includes both audio signal and leakage current. If the leakage current is large, you will get this extra signal for next stage.

If the space is limited, Niobium Oxide cap by AVX will be a better choice. It's even a bit better than regular EL caps actually.

 

[finneybear]

Unfortunately, I do not have the AptX-HD cable, just the Apt-X TRN V10 cable with MMCX connectors and I'm testing FiiO FH5 or FiiO F9. Also good results. So Vikefon is just a source of stream to the DX3 and from it to HP or the amplifier. The only one !! AptX-HD cable I found on Amazon for 149 Eur Westone. And Sony LDHC

Thanks again. I thought people would only use AptX-HD over bluetooth? Not aware there are AptX cables exist?

 

[TiborG]

Thanks again. I thought people would only use AptX-HD over bluetooth? Not aware there are AptX cables exist?

I do not know whether I understand the question properly. I use AptX + MMCX IEM cables, not AptX-HD, I have not found the price yet. And the DX3 is just a receiver, so something like Vikefon is essential. I take BT headphones as waste, it does not make sense to experiment

 

[tired_guru]

Just got this update from seller
"We just got the good news. Topping has solved this problem. It is expected to start producing new products next month, so please don't worry, I hope I can help you, thank you."

The question is how can we be sure if this is the final version ? By checking serial numbers or some extra notes on the device ?

 

[splkn]

For the four analog power caps for 4493, I am thinking of having a 220uf low ESR cap paralleled with a 100uf solid polymer. Low ESR cap takes care of the low frequencies. Solid polymer will remove HF noises. The space is good enough to put through hole parts there.

I cant see the simple output sum-up of 4493 will do much good in DX3. For true mono-mono mode with XLR outputs, it will give you extra 2 or 3db improvement yet this is not the case with DX3.

So I plan just to use one set of outputs for each 4493. This way I can remove the coupling caps. For the second set of outputs, now I can have enough space to use Silmic or Muse caps for coupling. This way, I can add the second set of outputs back as an option.

And what if we install another operational amplifier? And summarize the signals after the op amp? To get rid of feed-through capacitors.О

 

[Pavel]

So I plan just to use one set of outputs for each 4493. This way I can remove the coupling caps.

Differential DC was present at the outputs of the AK4493. I tried to use only one channel without coupling caps. But it was a bad idea. After the power amplifier on DC speakers it was already 1.5V in one and 0.6V in the other channel. The solution could be OPA1632 with offset compensation. But this greatly complicates the design.

 

[finneybear]

And what if we install another operational amplifier? And summarize the signals after the op amp? To get rid of feed-through capacitors.О

Yes, there are several ways of doing this. The easiest one is one dual OP per channel - one set of outputs for the positive side of XLR, and one set for the negative side. For RCA, you will only use one set.

 

[finneybear]

Differential DC was present at the outputs of the AK4493. I tried to use only one channel without coupling caps. But it was a bad idea. After the power amplifier on DC speakers it was already 1.5V in one and 0.6V in the other channel. The solution could be OPA1632 with offset compensation. But this greatly complicates the design.

Yes, same as 4497, you need to keep the 1:3 ratio between P and N outputs. This is easy with DX3 for its simple LPF design. One side will have value 3X of the other side. Do make sure both have the same FC frequency.

 

[david99]

The question is how can we be sure if this is the final version ? By checking serial numbers or some extra notes on the device ?

So far there is complete silence from Topping side so very hard to say what is going to change and how to find out if you will really get new revision.

 

[simonchretien]

First of all we dont even know if this fix thing is true or just bullshit from a seller.
I guess if it was theyd just give us some info.

 

[david99]

First of all we dont even know if this fix thing is true or just bullshit from a seller.
I guess if it was theyd just give us some info.

My personal guess is also that there is no official resolution yet. Or maybe the resolution is design change and they just don't wanna to share it because a lot of owners will start asking for replacement?

 

[kotgnk]

There is information from the Topping service that mass breakdowns are not a constructive defect. Allegedly, this is a defect of individual copies.

Hello

Thank you for your mail. We're happy to assist.

According to the info we got now, we don't think this is a common problem. So I don't think you will receive another defective product.

Since the seller already send out a new product, I recommend you to wait for it and keep using it. You can keep contact with the seller to know where your package is.

Even if you met the worst situation, I think we are able to give you a satisfied solution. Relax, everything is fine.


Best Regards!
----------------------------------
TOPPING service

 

[david99]

There is information from the Topping service that mass breakdowns are not a constructive defect. Allegedly, this is a defect of individual copies.

Hello

Thank you for your mail. We're happy to assist.

According to the info we got now, we don't think this is a common problem. So I don't think you will receive another defective product.

Since the seller already send out a new product, I recommend you to wait for it and keep using it. You can keep contact with the seller to know where your package is.

Even if you met the worst situation, I think we are able to give you a satisfied solution. Relax, everything is fine.


Best Regards!
----------------------------------
TOPPING service

But this still doesn't say what has topping find out, if already has. I will wait for official statement from topping I think that users and potential customers will deserve it.

 

[amirm]

But this still doesn't say what has topping find out, if already has. I will wait for official statement from topping I think that users and potential customers will deserve it.

I think they got their noses bashed in the last time they told member Yue what they were working on. So I suspect they may not as forthcoming as a result.

 

[amirm]

FYI I received the broken unit that won't come out of standby. There is a soft control from the microprocessor that turns on the power supply to the analog output. In the broken unit, the microprocessor does not assert this so the unit remains powered off (enable pin low on the switching supply). I replaced the front panel with a good one but it made no difference so the control signal to the processor seems fine.

 

[kotgnk]

FYI I received the broken unit that won't come out of standby. There is a soft control from the microprocessor that turns on the power supply to the analog output. In the broken unit, the microprocessor does not assert this so the unit remains powered off (enable pin low on the switching supply). I replaced the front panel with a good one but it made no difference so the control signal to the processor seems fine.

I had the same thing. After several plugging of the power adapter and resetting it to the factory settings, the processor started working normally. But after that, it turned out that the right headphone output channel is not working well. There was a strong hiss in the right earpiece. When the +9 db mode was turned on, a constant voltage was generally output to the right earpiece. Left earphone and line-out worked fine.

 

[gypsygib]

I had the same thing. After several plugging of the power adapter and resetting it to the factory settings, the processor started working normally. But after that, it turned out that the right headphone output channel is not working well. There was a strong hiss in the right earpiece. When the +9 db mode was turned on, a constant voltage was generally output to the right earpiece. Left earphone and line-out worked fine.

Mine has an intermittent noise in the right earpiece as well on high gain only. Seems to go away if I unplug the RCAs. I discovered today that I can have the RCA cables not plugged into anything but the DX3 (just hanging loose from the back not connected to any speakers, ect.) and I'll get the same intermittent noise on high gain.