• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Review and Measurements of Topping DX3Pro DAC and Headphone Amp

Joined
Jan 14, 2019
Messages
10
Likes
2
Hmm, I was pretty happy with this device until just now. When connecting digital coax, device is starting to make quite loud buzzing on the line out, which is connected to the active monitors. Interesting, no buzzing at all from the headphones out with the same connection. My primary intention is/was to use device as the source for active monitors.

All devices are on the same extension cord/phase, tried to disconnect all other sources... nothing helped. It's enough to touch with shield of the coax to make buzzing, which leads me to some grounding problem. Now I'm going to buy optical cable. That should fix the problem but there is only one optical input...

What's causing the problem? Any solution?
 
Joined
Nov 19, 2018
Messages
10
Likes
5
Hmm, I was pretty happy with this device until just now. When connecting digital coax, device is starting to make quite loud buzzing on the line out, which is connected to the active monitors. Interesting, no buzzing at all from the headphones out with the same connection. My primary intention is/was to use device as the source for active monitors.

All devices are on the same extension cord/phase, tried to disconnect all other sources... nothing helped. It's enough to touch with shield of the coax to make buzzing, which leads me to some grounding problem. Now I'm going to buy optical cable. That should fix the problem but there is only one optical input...

What's causing the problem? Any solution?
An optical cable will definitely solve it but not really find the root cause. The culprit could be coming from other equipment on the line. Maybe an AMP? You can also try on of these, I have the USB purifier and it really does eliminate all audible noise.

https://ifi-audio.com/products/dc-ipurifier2/
 
Joined
Jan 14, 2019
Messages
10
Likes
2
Just bought an optical cable and as expected, no electrical connection - no buzzing.

Does anyone have full schematic of the DX3Pro? I would like to see why headphones out is not affected. Maybe line out can be modified in similar way.
 
Joined
Jan 29, 2019
Messages
18
Likes
7
Hmm, I was pretty happy with this device until just now. When connecting digital coax, device is starting to make quite loud buzzing on the line out, which is connected to the active monitors. Interesting, no buzzing at all from the headphones out with the same connection. My primary intention is/was to use device as the source for active monitors.

All devices are on the same extension cord/phase, tried to disconnect all other sources... nothing helped. It's enough to touch with shield of the coax to make buzzing, which leads me to some grounding problem. Now I'm going to buy optical cable. That should fix the problem but there is only one optical input...

What's causing the problem? Any solution?
Probably a ground loop. There is only a 75ohm resistor and cap at input to ak4418. Use a digital transformer Murata DA101C at the spdif input if you have a ground loop problem.
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
22,741
Likes
35,682
Location
Seattle Area
Does anyone have full schematic of the DX3Pro? I would like to see why headphones out is not affected.
The headphone out is "floating" since there is no connection to mains in your headphones. The buzzing is due to ground currents floating to the powered monitors.
 
Joined
Jan 14, 2019
Messages
10
Likes
2
Thx you guys for answers. I knew that is ground loop problem and that I need some kind of galvanic separation to prevent stray currents.

@ChuckT Just reading datasheet of Murata DA101C. Funny, everything is there except freq or bitrate range. Only found 100kHz-3MHz. Does it support all bitrates supported by DX3Pro?
 
Joined
Jan 29, 2019
Messages
18
Likes
7
Thx you guys for answers. I knew that is ground loop problem and that I need some kind of galvanic separation to prevent stray currents.

@ChuckT Just reading datasheet of Murata DA101C. Funny, everything is there except freq or bitrate range. Only found 100kHz-3MHz. Does it support all bitrates supported by DX3Pro?
It should support at least 192k, which is the max for the spdif input anyways.
 
Joined
Jan 14, 2019
Messages
10
Likes
2
Do you have schematic how to connect DA101C? I'm just searching and found suggestion to put resistor on both side to keep impedance to 75 ohms. Does it require any power supplied? As the transformer, should be passive element.

I also found that: "the Murata DA101C, has a measured frequency span (-3 dB down) from 2.2 kHz to about 100 MHz, in an 50 Ohm environment" and in this pdf: "The transformer used in the professional interface should be capable of operation from 3.6 to 24.6 MHz, which is the audio data rate of 28 kHz to 192 kHz after biphase-mark encoding."
 
Joined
Jan 15, 2019
Messages
42
Likes
11
An optical cable will definitely solve it but not really find the root cause. The culprit could be coming from other equipment on the line. Maybe an AMP? You can also try on of these, I have the USB purifier and it really does eliminate all audible noise.

https://ifi-audio.com/products/dc-ipurifier2/
Two more such devices need to be installed inside for the analog line power circuit.)))
 
Last edited:
Joined
Mar 8, 2019
Messages
5
Likes
1
Joined
Dec 10, 2018
Messages
55
Likes
19
Location
Detroit, MI
I currently have the D3 for desktop use with my M50's. I'm thinking of getting this or the NX4, what do you guys think will sound better? I a, interested in possibly using the bass boost on the NX4 when listening to Electronic music.
For a neutral sounding "studio monitor" M50, I think you may want some warmer DAC. I heard M50, which is similar to my cd900st in sound signature. CD900st didn't pair well with my D3(hiss in highs more obvious and a little bit "dull and lifeless" in the lows "IMHO" in similar volume A-B testing by ear, which is not reliable). And you probably need that bass boost after all.

Well, if you are in U.S., just wait for D3 is available for Amazon prime again, then you could test both them out.
 
Last edited:
Joined
Feb 5, 2019
Messages
27
Likes
16
Location
Seattle
Well, I bought one on Amazon, and it worked out of the box. There was some weirdness with the power supply- it came with a European plug and a US adapter... SMH. I ordered a mean well 15vdc 1.2A wall wart. I've been listening to it for six hours now, going back and forth between this and my Schiit stack(USB Bifrost w/ original 4399 boards, Asgard 2) with my trusty Fidelio X2. I don't know if it's a house sound thing or what, but I like the Schiit stack better despite it not being quite as clear. If I had to put numbers on it, it's like the DX3 Pro has a 5% bump in clarity over my Schiit. The stack just has better authority in the bass region- a little more nuance with a little less effort, like it's not working as hard as the Topping. No argument that it's got some haze or grunge blanketing the sound, but what's there is more engaging.

I think my tastes run toward "flavored" instead of dead neutral. I love listening to midrange-forward, slightly rolled off highs, and big bass. That puts me squarely in hybrid tube amp range, or in this case, pure inefficient class A. I'm glad I have the Topping, and I'm still looking forward to the D70, but the DX3 Pro is going to get moved around a bit. It's too neutral for just enjoying the music in my reference setup.

I realize that at $219 (plus $20 for a shipped US wall wart), it wasn't designed to be "reference" quality, but it's very good for the price and offers a lot of utility. I'll be happy to use it with the xbox, and my computer, and my girlfriend's computer, and wherever else I plug it in. It just won't replace the Schiit stack as my primary headphone rig.
 
Joined
Dec 10, 2018
Messages
55
Likes
19
Location
Detroit, MI
Well, I bought one on Amazon, and it worked out of the box. There was some weirdness with the power supply- it came with a European plug and a US adapter... SMH. I ordered a mean well 15vdc 1.2A wall wart. I've been listening to it for six hours now, going back and forth between this and my Schiit stack(USB Bifrost w/ original 4399 boards, Asgard 2) with my trusty Fidelio X2. I don't know if it's a house sound thing or what, but I like the Schiit stack better despite it not being quite as clear. If I had to put numbers on it, it's like the DX3 Pro has a 5% bump in clarity over my Schiit. The stack just has better authority in the bass region- a little more nuance with a little less effort, like it's not working as hard as the Topping. No argument that it's got some haze or grunge blanketing the sound, but what's there is more engaging.

I think my tastes run toward "flavored" instead of dead neutral. I love listening to midrange-forward, slightly rolled off highs, and big bass. That puts me squarely in hybrid tube amp range, or in this case, pure inefficient class A. I'm glad I have the Topping, and I'm still looking forward to the D70, but the DX3 Pro is going to get moved around a bit. It's too neutral for just enjoying the music in my reference setup.

I realize that at $219 (plus $20 for a shipped US wall wart), it wasn't designed to be "reference" quality, but it's very good for the price and offers a lot of utility. I'll be happy to use it with the xbox, and my computer, and my girlfriend's computer, and wherever else I plug it in. It just won't replace the Schiit stack as my primary headphone rig.
Haha, same here, my D3 is moved to my friend's house now : ) One thing I liked is to use it while play FPS games, the sound is pale that consistent gun shots in the game will not bother me that much.
 
Joined
Jan 10, 2019
Messages
40
Likes
22
Well, I bought one on Amazon, and it worked out of the box. There was some weirdness with the power supply- it came with a European plug and a US adapter... SMH. I ordered a mean well 15vdc 1.2A wall wart. I've been listening to it for six hours now, going back and forth between this and my Schiit stack(USB Bifrost w/ original 4399 boards, Asgard 2) with my trusty Fidelio X2. I don't know if it's a house sound thing or what, but I like the Schiit stack better despite it not being quite as clear. If I had to put numbers on it, it's like the DX3 Pro has a 5% bump in clarity over my Schiit. The stack just has better authority in the bass region- a little more nuance with a little less effort, like it's not working as hard as the Topping. No argument that it's got some haze or grunge blanketing the sound, but what's there is more engaging.

I think my tastes run toward "flavored" instead of dead neutral. I love listening to midrange-forward, slightly rolled off highs, and big bass. That puts me squarely in hybrid tube amp range, or in this case, pure inefficient class A. I'm glad I have the Topping, and I'm still looking forward to the D70, but the DX3 Pro is going to get moved around a bit. It's too neutral for just enjoying the music in my reference setup.

I realize that at $219 (plus $20 for a shipped US wall wart), it wasn't designed to be "reference" quality, but it's very good for the price and offers a lot of utility. I'll be happy to use it with the xbox, and my computer, and my girlfriend's computer, and wherever else I plug it in. It just won't replace the Schiit stack as my primary headphone rig.
Well youre comparing a 200$ all in one, versus a 650$ stack. I sure hope there's something better with the stack hehe.
 

Stonetown

Member
Patreon Donor
Joined
Jan 21, 2019
Messages
46
Likes
49
The DX3Pro is making my vintage Denon POA-2400 sounding fantastic!

And by reducing the max volume with the attenuator potentiometers on the amplifier front, a speaker accident by pressing the DAC-button on the remote is avoided. Highly recommended to do this "hardware" volume limit. Also dynamic range from the DAC will be more optimum, compared by using the max gain in the power amp.
Cheers,
Per
IMG_4794.jpg
 
Last edited:

TiborG

Member
Patreon Donor
Joined
Feb 18, 2019
Messages
24
Likes
13
The DX3Pro is making my vintage Denon POA-2400 sounding fantastic!

And by reducing the max volume with the attenuator potentiometers on the amplifier front, a speaker accident by pressing the DAC-button on the remote is avoided. Highly recommended to do this "hardware" volume limit. Also dynamic range from the DAC will be more optimum, compared by using the max gain in the power amp.
Cheers,
Per
View attachment 23525
If I didn't start every playback at minimal volume, my respectable AVR Sony STR DB 830 QS he would always reward me with the replacement of glass and door panels. DX3 Pro Measures Power with DX4 DSD and Even After a Month I Can't Give a Winner's Wreath for Line Out Sound.
Of course, it is grilled on AVR just for taking pictures
03.jpg
 

Similar threads

Top Bottom