Review and Measurements of Topping DX3Pro DAC and Headphone Amp

[Veri]

I was saying you need an isolator which can do at least USB 2.0 *high speed*. USB 2.0 *full speed* one is useless. 99% of USB isolators on the market can only do USB 2.0 *full speed* which is 12Mbps. They are all based on the ADI ADUM USB isolation chips. USB 2.0 high speed is 480Mbps and no isolation chip can support that yet.

Hey I owe you an apology. Makes sense now thx

 

[KT88]

Did anyone else run into a problem with the unit just failing to power up/respond?
I've had mine for a few weeks now, with 1.04 fw version, and working nicely.
A few minutes ago it just went dark. No response, only a single dot on the display. Trying to turn it on it won't respond, this dot goes off and then on again. Hard reset seems to respond (all display lights up for a sec), but then goes back to not responding. Its still visible from the PC as an audio device, but nothing else.

edit:
found this one:
https://www.reddit.com/r/headphones/comments/aabewq seems to be the exact issue I'm having. Will contact the seller on AliExpress in the hopes I can send it back for refund/replacement.

 

[Toku]

Did anyone else run into a problem with the unit just failing to power up/respond?
I've had mine for a few weeks now, with 1.04 fw version, and working nicely.
A few minutes ago it just went dark. No response, only a single dot on the display. Trying to turn it on it won't respond, this dot goes off and then on again. Hard reset seems to respond (all display lights up for a sec), but then goes back to not responding. Its still visible from the PC as an audio device, but nothing else.

edit:
found this one:
https://www.reddit.com/r/headphones/comments/aabewq seems to be the exact issue I'm having. Will contact the seller on AliExpress in the hopes I can send it back for refund/replacement.

This is my experience. Please refer to something.

I use two DX3 Pros, but both experienced the same symptoms.
At that time, noise comes out from the speaker, click noise comes out when you up/down the volume.
At that time, I did a factory reset many times, but the symptoms did not improve.

The best way is to unplug the AC adapter from the outlet, leave it for over 1 hour, completely discharge the main body and reset.
Then, plug the AC adapter into the outlet again and turn on the power.
If it does not resurrect, I will repeat it again.

I initially thought that the DX3 Pro main body was completely broken, but it was restored by these operations.

I am experiencing similar symptoms with DX7s.

 

[kprog]

Hello, someone tested DX3 with DT990Pro 250 ohm?
I would like to know if it has power to spare for them.
It seems a fair bit no? or am I wrong?
Someone who has tried it can inform me. If you need to put the volume to the maximum to get a good performance, (or it is impossible to climb to the maximum because it has power to spare, which would be ideal)

 

[splkn]

Ok, so if you want to remove the cap, the easiest solution is to remove the four caps and only connect one set of outputs.

I offer another option. Disable capacitors only on one set of outputs. Leaving connected all sets of outputs.

 

[777]

I offer another option. Disable capacitors only on one set of outputs. Leaving connected all sets of outputs.

Very interesting...

 

[KT88]

This is my experience. Please refer to something.

I use two DX3 Pros, but both experienced the same symptoms.
At that time, noise comes out from the speaker, click noise comes out when you up/down the volume.
At that time, I did a factory reset many times, but the symptoms did not improve.

The best way is to unplug the AC adapter from the outlet, leave it for over 1 hour, completely discharge the main body and reset.
Then, plug the AC adapter into the outlet again and turn on the power.
If it does not resurrect, I will repeat it again.

I initially thought that the DX3 Pro main body was completely broken, but it was restored by these operations.

I am experiencing similar symptoms with DX7s.

Thanks. Have tried that a couple of time, didn't seem to come back to life. Will give it another go with hope of better results.

 

[Sangram]

A good LPF is more important than the loss of 3db. As I have said, the DC is very low. Some AKM reference circuits also remove the coupling caps.

I'm not sure what you mean.

The DC at the DAC output is exactly half the supply voltage. That is how it works. The input voltage for analog stage is 3.3V, so you will have exactly 1.65V at the output pin. No transformer for audio coupling is designed to handle that level of DC voltage. The only way to null the DC is to use both outputs in diff mode (which is why the ref designs use no caps), use a series cap (if using just one end of the DAC output), or hook up the transformer to the opamp output (which again makes no sense).

 

[SiW]

Hello, someone tested DX3 with DT990Pro 250 ohm?
I would like to know if it has power to spare for them.
It seems a fair bit no? or am I wrong?
Someone who has tried it can inform me. If you need to put the volume to the maximum to get a good performance, (or it is impossible to climb to the maximum because it has power to spare, which would be ideal)

Works fine - I’m using it in low gain and around -10 level.

 

[splkn]

Very interesting...

For example, remove capacitors from pins 25 and 36.

 

[kprog]

Works fine - I’m using it in low gain and around -10 level.

okay. Thank you.
Do you think that in high gain you could have the maximum performance of the dt990?
what would happen if you put high profit and give volume to the maximum?

 

[SiW]

okay. Thank you.
Do you think that in high gain you could have the maximum performance of the dt990?
what would happen if you put high profit and give volume to the maximum?

Don’t know - it’s plenty loud enough but retains its performance for me

 

[Cidious]

I ran 600ohm Tesla (Beyerdynamic clones) drivers on it without any issue. And my Mad Dogs (which need a ton of power) work fine too without lacking in volume or bass. I think your DT990 250 Ohm will be a piece of cake.

 

[MetalheadRich]

Hello, someone tested DX3 with DT990Pro 250 ohm?
I would like to know if it has power to spare for them.
It seems a fair bit no? or am I wrong?
Someone who has tried it can inform me. If you need to put the volume to the maximum to get a good performance, (or it is impossible to climb to the maximum because it has power to spare, which would be ideal)

it drives my 300 ohm HD600s with ease on low gain setting. i've never bothered with the high gain setting.

 

[777]

I'm not sure what you mean.

The DC at the DAC output is exactly half the supply voltage. That is how it works. The input voltage for analog stage is 3.3V, so you will have exactly 1.65V at the output pin. No transformer for audio coupling is designed to handle that level of DC voltage. The only way to null the DC is to use both outputs in diff mode (which is why the ref designs use no caps), use a series cap (if using just one end of the DAC output), or hook up the transformer to the opamp output (which again makes no sense).

No, the output voltage is between 150mV-250mV DC

 

[splkn]

No, the output voltage is between 150mV-250mV DC

Did you measure it at the exit from the topping? Or in front of capacitors?

 

[MacDac]

CMOS junction can withstand up to 100 celsius. Sustained 80 celsius is also OK. It will be very hard to reach a temp that high in DX3.

Just gave a cap mod list to Cidious. Will see whether there's any improvement after the cap swap.

It wasn't that hard for my (no-name, Chinese) DAC to reach 98 C on hot days, so...
Btw, max operational temperature for AK4493 is 85 C. It probably won't burn at this level, but may fail to operate properly, I assume.

 

[finneybear]

Hey I owe you an apology. Makes sense now thx

No biggie, really. You are more than welcome to bring out a different opinion. Sometimes I type so fast I would make so many errors along the way. Not even mention when I read a message, I may miss the point here and there.

 

[finneybear]

I'm not sure what you mean.

The DC at the DAC output is exactly half the supply voltage. That is how it works. The input voltage for analog stage is 3.3V, so you will have exactly 1.65V at the output pin. No transformer for audio coupling is designed to handle that level of DC voltage. The only way to null the DC is to use both outputs in diff mode (which is why the ref designs use no caps), use a series cap (if using just one end of the DAC output), or hook up the transformer to the opamp output (which again makes no sense).

Sorry that I confuse you a bit. I was talking about very little DC current. The current is really not a big deal to the beefy transformer.
As for DC voltage, remember tube amp has long been using output transformers? That is mighty DC voltage.

 

[finneybear]

Did you measure it at the exit from the topping? Or in front of capacitors?

I think he measured the output when 4493 is idle. The output is shutdown when there's no data input.