Review and Measurements of Topping DX3Pro DAC and Headphone Amp

[Heals0911]

Just out of curiosity, does anyone else have a DX3 Pro serial number starting with 1808?

 

[Toku]

Just out of curiosity, does anyone else have a DX3 Pro serial number starting with 1808?

The S/N of the two DX3 Pros I'm using is 1808xxxxxx.

 

[kukocz]

Just out of curiosity, does anyone else have a DX3 Pro serial number starting with 1808?

Mine is 1808 too

 

[Heals0911]

Mine is 1808 too

I was seeing a lot of S/N# 1812 being posted, just wanted to check. I have had no issues with my unit for anyone keeping track. Thanks for the replies @kukocz and @Toku

 

[bleachershane]

I was seeing a lot of S/N# 1812 being posted, just wanted to check. I have had no issues with my unit for anyone keeping track. Thanks for the replies @kukocz and @Toku

1812 here, still working, only used for say three hours a week at the moment.

 

[Wolven]

My 1808 turned itself once, other than that is working. In constant operation since around November 25, mostly pure DAC, run headphones for couple days.

 

[kukocz]

I was seeing a lot of S/N# 1812 being posted, just wanted to check. I have had no issues with my unit for anyone keeping track. Thanks for the replies @kukocz and @Toku

I've been using mine for over 2 months now with no issues.

 

[Jestercow]

has anyone had theirs shut down while operating as DAC only?

 

[Yuno]

has anyone had theirs shut down while operating as DAC only?

Yep, I did, but in dac volume controlled mode. Also it was basically idle too, so I don't think overheat, overload or anything of that kind could be a reason.
1808 for the record.

 

[Woody Stool]

Has anyone had any communication with Topping regarding some of these failures and whether they see a common problem and will correct it in their next manufacturing run? I bought one from Massdrop and really really liked it - and then it quit, and back it went. I'd really like to buy another one if they have found a root cause and corrected it.

 

[simonchretien]

Has anyone had any communication with Topping regarding some of these failures and whether they see a common problem and will correct it in their next manufacturing run? I bought one from Massdrop and really really liked it - and then it quit, and back it went. I'd really like to buy another one if they have found a root cause and corrected it.

Yeah check back, when I wrote them they said they dont have problemtic units and have no idea.

 

[amirm]

So I finally got a long enough allen wrench to open the unit. As promised, here is the thermal analysis.

This is the main PCB:

I connected the unit to a 33 ohm dummy load and let it drive it at nearly max volume, outputting 5 volts RMS. Here is the thermal image:

The two red squares in the middle right are the AKM DAC chips. As you see from the red color, they are barely warmer than room temp.

The hottest spots are in white. There is a vertical array on the bottom right which are the output transistors for the headphone stage. The only other hot spot is in top left which is the XMOS USB controller.

I zoomed in on the XMOS:

As you see, it is just 33 degrees C.

The design from thermal point of view is excellent with nothing remotely being stressed. I get worried when temps approach 60 degrees C.

Just to be darn sure, I will cook the board with a blower next and report back on that.

For now, I also inspected the soldering. The headphone connector is soldered well as are the other through-hole components. The general soldering is not first class with some parts crooked, and a bit of solder splatter here and there. I would give it a B or B+. Nothing jumps out as reliability issue although mine is an early unit and may have been assembled differently than the units you all have.

 

[amirm]

OK, I cooked it and cooked it good:

EDIT: this is after a hairdryer on hot setting raised the temps to see if anything fails:

As you see temps are now nearly 70 degrees C. The unit operated perfectly and continues to do so as I type this.

We really need some broken units to make progress here.

If you have a broken DX3 Pro and live in US, please contact me and I will purchase it from you.

 

[finneybear]

Yeah check back, when I wrote them they said they dont have problemtic units and have no idea.

Still have not got my long hex key to pull up the main board yet. From the 1/5 of mainboard I can, those E-caps are a big concern to me. They are cheap, non brandname parts. I am wondering whether those e-caps have very inconsistent quality hence some may have a value much lower than what supposed to be. If you ran into bad caps at a few critical spots then your luck would run out.

Just a guess. When I remove those caps, will do a measurement on them.

 

[finneybear]

OK, I cooked it and cooked it good:



As you see temps are now nearly 70 degrees C. The unit operated perfectly and continues to do so as I type this.

We really need some broken units to make progress here.

If you have a broken DX3 Pro and live in US, please contact me and I will purchase it from you.

Did you run it in the enclosure then put out the board quickly for the measurement?

 

[mikehoopes]

1808, ~2 hrs/day, 60% headphone. No issues so far.

Did you run it in the enclosure then put out the board quickly for the measurement?

I've done a lot of temp tests over the years. We used K-type thermocouples affixed with cyanocrylate, and ran them into the enclosure, sometimes with small holes drilled to prevent damage to the thermocouple wires.

An open-air thermal imaging test is a valid relative measure. People have been talking about the idea of heat sinks on the DAC chips, without knowing how much heat they are dissipating. I think this clearly shows where the heat is. 21C is still a relatively low ambient temp (close to what we would attempt to regulate in a environmental chamber for non-accelerated tests). Go ahead and add 20C to the whole thing (above what Amir added in the second test), and you're still within the DAC manufacturer's specified limits (AK4493 operational temp -40C to 85C).

I'm not a big fan of the elevated temps near the electrolytic caps, but they appear to be at a sane temp, themselves. The aluminum enclosure itself is going to be a half-decent radiator, and the black version marginally better. I think that planar guys living in the tropics are the only ones that are going to achieve these elevated temps in practice.

 

[yue]

I believe most, if not all, people who experienced a dead unit here is able to turn it back on a few hours later. So it would be hard to send a fully dead one to @amirm for inspection. If it is totally broken such issue would be much easier to be fixed.

 

[finneybear]

I believe most, if not all, people who experienced a dead unit here is able to turn it back on a few hours later. So it would be hard to send a fully dead one to @amirm for inspection. If it is totally broken such issue would be much easier to be fixed.

My speculation now is those no brand e-caps ripple current drops fast along the rise of temperature. When temp drops, those caps work fine again. Then it will also depend on where those bad caps are. Amir's thermal shot shows caps are relatively cool though.

Anyway, wait until I get a chance to measure those caps.

 

[amirm]

Did you run it in the enclosure then put out the board quickly for the measurement?

No the board is sitting open as the picture shows. It runs so cool that it doesn't matter if it is inside the box or not. And at any rate, I cooked it good in the open and it did not even blink. I am listening to it right now...

 

[amirm]

I believe most, if not all, people who experienced a dead unit here is able to turn it back on a few hours later. So it would be hard to send a fully dead one to @amirm for inspection. If it is totally broken such issue would be much easier to be fixed.

I will take one with those symptoms too but yes, a completely broken one may be better.