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Review and Measurements of Topping DX3Pro DAC and Headphone Amp

777

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I tested the DX3 Pro broadband spectrum with its own power supply and that of the lab.

Own supply:

View attachment 20511

Lab supply:
View attachment 20512

There is almost no difference until 100 kHz. Even after that there is not much of substance. The noise spikes are internally generated or passed through from USB. Either way they are well above frequencies of interest.

There is much more noise with adapter, we saw on the oscilloscope but it is in higher band. That high frequency noise isn't random noise, it is in burst tones. That burst tones has 32khz frequency. So, if you can see Mhz, tens, hundreds of Mhz(harmonics of the noise) then you can see that burst tones too, from the lower frequency, at 32khz.

So, all depends of how big is the bandwidth of the FFT measurement.

Now become obvious, a linear external power supply and a better internal power supply decoupling, with proper capacitors and a proper grounding, will pushing Dx3Pro in highend class product at a small price.
 

yue

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There is much more noise with adapter, we saw on the oscilloscope but it is in higher band. That high frequency noise isn't random noise, it is in burst tones. That burst tones has 32khz frequency. So, if you can see Mhz, tens, hundreds of Mhz(harmonics of the noise) then you can see that burst tones too, from the lower frequency, at 32khz.

So, all depends of how big is the bandwidth of the FFT measurement.

Now become obvious, a linear external power supply and a better internal power supply decoupling, with proper capacitors and a proper grounding, will pushing Dx3Pro in highend class product at a small price.
You can document step by step what your changes are, and what the improvements are (in measurements), so people can follow. I can translate and send them to topping and see if they can incorporate those changes in future products.
 

yue

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There is much more noise with adapter, we saw on the oscilloscope but it is in higher band. That high frequency noise isn't random noise, it is in burst tones. That burst tones has 32khz frequency. So, if you can see Mhz, tens, hundreds of Mhz(harmonics of the noise) then you can see that burst tones too, from the lower frequency, at 32khz.
if you mean 32khz's harmonics in >1Mz field I would not worry about it at all.
Headphones can't output that high frequency. Even at 32khz, the sound produced by a headphone is super low. because the frequency response drops at high frequencies significantly. For instance for HD800S, at 25khz the response is already -30db below that at 1khz.

With 0.04vpp, the output for1khz tone for HD800s is around 65db. for 25khz it would below 35db. for anything 32khz multiples, I guess it would below 10db. the ultrasound is neither audible nor a potential health hazard. wikipedia says ultrasound higher than 120db may impair human hearing. 10db is very far away from that.
 
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kukocz

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Toslink is the best because there is no electric interference. Its result is similar to the el dac which uses ak4490 chip. The other two interfaces has usb/coax ground loop noise leak into the analog output.

I would like to see if topping could give a simple tutorial to fix the ground loop (similar to the smsl Su-208 mod)
Smsl Su-208 or Su-8? And what was the solution there?
 

kukocz

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sorry I mean su-8. there is a tutorial that teaches you modifying from version 1 to version 2.
Yup, now I'm know what you're talking about, I've seen this thread. Indeed, good improvement with relatively simple modification.
 

splkn

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if you mean 32khz's harmonics in >1Mz field I would not worry about it at all.
Headphones can't output that high frequency. Even at 32khz, the sound produced by a headphone is super low. because the frequency response drops at high frequencies significantly. For instance for HD800S, at 25khz the response is already -30db below that at 1khz.

With 0.04vpp, the output for1khz tone for HD800s is around 65db. for 25khz it would below 35db. for anything 32khz multiples, I guess it would below 10db. the ultrasound is neither audible nor a potential health hazard. wikipedia says ultrasound higher than 120db may impair human hearing. 10db is very far away from that.
All see that the headphones can not output this frequency. However, this frequency, in the process of sound, formation affects the sound in the range that we hear. This is especially important for the digital part.
 
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777

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And more than digital part. The analog parts are affected too by high frequency energy. It is not rare case when a radio station can hearing in the loudspeakers.
 

bleachershane

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I'm taking it to see if the buzz in speakers will be fixed, notice i said buzz, not hiss. So is 1.66A, 15V safe?
Reposting this from my earlier comment in this thread:

Voltage must match, current can match or be above the specifications of the original power supply, but should not be below.

The unit will draw the current it needs to use from the power supply, rather than the power supply 'pushing' that current into the unit.

Buying a power supply with a higher current rating simply means there's more current on tap, and the supply should run cooler if less current is drawn. Very often manufacturers of cheap electronics will supply units with power supplies running close to their maximum specifications to keep costs down, but current capability should always be over-specced to ensure longevity of the power supply.
 

zephyros

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Just got the DX3Pro. Works well as expected (though I admit not a fan of the click, but if it doesn't affect reliability then I suppose it's fine). The best thing is the digital amplifier. Having precise control of the volumes feel so much better than using analog pots since my headphone is very sensitive (Final Sonorous VI).
 
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amirm

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All see that the headphones can not output this frequency. However, this frequency, in the process of sound, formation affects the sound in the range that we hear.
But I have measured the part we hear and there is no impact. Just have someone do a blind test on you while switching power supplies and see if you can hear a difference if you don't believe me.
 

pejakovic1

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I don't think that can fix it. buzz/hiss are usually created by ground loops. It's very unlikely to be sourced from power noise (as usually switching power noise is usually either 60hz multiples or high frequency).
Makes total sense, except, every other dac/amp i tested with speakers works normally. Something is at fault with Topping and Adam T5V compatibility and i will find out what it is. Adams sound godlike on DX3 Pro. Its just that feint buzz that bothers me.

Btw i have hd660s, at first they sounded clean and dull, tho both dx3 and hd660s were new, now after burnin of both devices they sound perfect, like bass has become a bit strongers, upper midrange more separated and open, highs are better. Also gave a friend to test hd660s and he said at first they sounded like a 50 euro headphone and now he thinks the sound has changed too, to something of much higher value and quality. So it might have been the burn in of hd660s or dx3 pro, idk, would like to know.
 

zephyros

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So it might have been the burn in of hd660s or dx3 pro, idk, would like to know.
Pretty sure that's your brain doing the work. Measurements mostly shows burn-in should not be detectible in any way. It's shown that humans like sound that are familiar.
That, or maybe you just listen to it at different time. In the noisy city I mostly listen to music at night time since that's when my ears work the best since there's little background noises. Consistent noises (even something as trivial as AC running)) can mask your ears from lower level sound.
 
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pejakovic1

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Pretty sure that's your brain doing the work. Measurements mostly shows burn-in should not be detectible in any way. It's shown that humans like sound that are familiar.
That, or maybe you just listen to it at different time. In the noisy city I mostly listen to music at night time since that's when my ears work the best since there's little background noises. Consistent noises (even something as trivial as AC running)) can mask your ears from lower level sound.
For the feint buzz, maybe try taping the USB cables of Vcc pin or the ground pin and see if the problem persists? I tape the Vcc pin myself and it works fine, though taping the ground pin should be a test only to see if there's ground loop because while my personal test works fine, I have seen reports that it breaks some DAC.
Thats why i had my friend test it too without telling him anything changed. the burn in is real, at least the pads get adjusted to a persons head better.
 

kprog

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Hello, greetings to all!
Could you solve a doubt?
I have thought of buying something, this thinking of 2 options ..

1 monoprice liquid spark + topping D10
2 topping DX3 pro

I have some bayerdynamic DT950pro 250ohm

Which option would give me more power and more quality?
 

Veri

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Hello, greetings to all!
Could you solve a doubt?
I have thought of buying something, this thinking of 2 options ..

1 monoprice liquid spark + topping D10
2 topping DX3 pro

I have some bayerdynamic DT950pro 250ohm

Which option would give me more power and more quality?
Both would be fine, but if you care about elegance the DX3 being a single unit is very handy.
 
D

Deleted member 3566

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Is there any way to test between Bluetooth and USB-connection, and find the difference in sound quality? I use Spotify, which is 320kbps, and am wondering if I miss out on anything, when using BT, instead of cable. It's kind of cumbersome to have to connect a cable to my PC, and I would love to know if there was a way to find an answer to this question. It would certainly make my life easier. The question of latency is of some importance too, I guess.
 

MattG

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Actually, for units that suffer from random shutdowns or can't exit standby mode, this is what Topping suggests:View attachment 20519

I posted last week, doing this exact test:

Re: random power-offs (edit: actually not power-offs, but randomly goes into suspend/powersave/sleep mode)...

On Sunday, Jan 13, I found my 15v PSU. It's a MeanWell laptop-style brick (GS90A15-P1M) rated for 6 amps. Ludicrous overkill for the dx3pro, but it's what I have. At any rate, I swapped out the stock cheapie power supply for this one. We'll see if I have any more unexpected power-off events in the next month or so. I'm using this thread as my notes for when I did the PSU swap. :)

I came in to my office this morning with the unit in sleep mode: powered on, but only a single illuminated dot on the LCD display, and no sound. So it only made it about a week with the alternate power supply (Meanwell GS90A15-P1M).

So per Topping's email above, it appears to be a problem with the power circuit logic. Hopefully this is firmware fixable!

Edit: I sent Topping an email about this.
 
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pejakovic1

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I posted last week, doing this exact test:



I came in to my office this morning with the unit in sleep mode: powered on, but only a single illuminated dot on the LCD display, and no sound. So it only made it about a week with the alternate power supply (Meanwell GS90A15-P1M).

So per Topping's email above, it appears to be a problem with the power circuit logic. Hopefully this is firmware fixable!

Can you write them an email?
 
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