Topping DX3 Pro+ Review (DAC & Headphone Amp)

[Toku]

if you choose method 2) it's extremely safe and there will be no disadvantage. it's called "impedance balanced" and many professional audio equipments are wired this way. it has all the nice properties balanced output has, such as common mode noise rejection, ground loop elimination, etc.
See the table in http://www.paformusic.org.uk/gl_b.htm#Balanced

The maximum output is 2V instead of 4V. if you don't listen at that high volume a lower voltage is even better.
This means even DX5 has 6 db higher dynamic range, because 4V is 6db hotter than 2V, DX3Pro+ has the same low absolute noise level as DX5.

The RCA to XLR connector is easy to do: connect RCA+ to XLR Pin 2, RCA ground to XLR Pin 1, and a 20Ohm resistor between XLR pin 1 and 3. Then you're all set.
The method works because the 20Ohm resistor is exactly what DX3 Pro+ has in its final output circuit.

Here's the wiring from google image search:
View attachment 195336

(please replace the 100 Ohm to 20Ohm)


See it in action:

View attachment 195337


If you want to apply this solution to another unbalanced product, you have to change the resistor value.
In some rare cases, you need to get the DAC output circuit and copy more passive components to Pin3 as well.
Fortunately for DX3Pro+ only a 20Ohm resistor is needed.


Conclusion: If you don't need full 4V output, just stay with your DX3 Pro+. It's trivial to make it balanced.
Don't purchase DX5 for its balanced output.

The connection method you have proposed does not form a balanced connection. This method is a connection method when you want to have the effect of canceling the inductive noise of a balanced connection when an unbalanced signal is connected to the input in a balanced manner. The audio signal is just an unbalanced connection. The resistance of 100Ω varies depending on the connected device. It is impossible to call this a balanced connection.

 

[audiofun]

The connection method you have proposed does not form a balanced connection. This method is a connection method when you want to have the effect of canceling the inductive noise of a balanced connection when an unbalanced signal is connected to the input in a balanced manner. The audio signal is just an unbalanced connection. The resistance of 100Ω varies depending on the connected device. It is impossible to call this a balanced connection.

I am astonished to see this comment coming from an experienced engineer.

Please read more literatures and learn what "balanced connection" really means. The above link I posted is a good start. The term "balanced" has nothing to do with sending inverted signal in the cold line, which really helps nothing other than having a higher output voltage.

The "balanced connection" actually refers to having same output impedance in hot and cold line. See wikipedia: "In telecommunications and professional audio, a balanced line or balanced signal pair is a circuit consisting of two conductors of the same type, each of which have equal impedances along their lengths and equal impedances to ground and to other circuits."

Short answer: sending negative polarity signal, which is your wrong definition of "balanced", only has one benefit: higher output voltage. But that benefit can be easily achieved by adjusting the output op amp gain resistor in an unbalanced situation. Having same output impedance already suffice the definition of "Balanced Signal". The above wiring can give you all benefits balanced signal offers, including ground loop and inference noise elimination.

 

[dsnyder0cnn]

My current desktop system includes the DX3 Pro+, and I'm quite pleased with it; however, I do have a E50 + L50 + PA5 stack arriving soon. I think the new stack will be a nice upgrade, adding the option of driving passive speakers.

Most outlets still sell an E50 + L50 combo for a little over $500, including a pair of short TRS cables. If you have the space on your desk, I think this two-box stack represents a true upgrade over the DX3 Pro+ for not much more than the new DX5. Besides infinitesimally better SINAD, the big selling points for the DX5 are the internal power supply and new cosmetics.

I applaud Topping for continuing to innovate, but, I'm a little disappointed in the DX5's design. I think it could have won me over if Topping had included a pair of analog inputs. Looks like there would have been space if they had stuck with TRS instead of flipping back to XLR. I'm sure plenty of folks will love it, but I'm happy with the DX3 Pro+, and I'll have a blast with the stack (ordered mine in red)!

 

[ragecandy]

So in the end does this play well with the edition xs? they’re 18 ohms I think, wanna replace my liquid spark stack with this just cause I love the look of the dx3 and it’s on sale rn lol

 

[aromig]

So in the end does this play well with the edition xs? they’re 18 ohms I think, wanna replace my liquid spark stack with this just cause I love the look of the dx3 and it’s on sale rn lol

Well, based on 18Ω with a sensitivity of 92dB/1mW, the Edition XS would need 1.07 volts RMS to hit a 110dB sound pressure level. Looking at Amir's graph, the DX3 Pro+ can hit over 2Vrms at 16Ω, which means it would push the XS well past safe listening levels. Whether that is sufficient for your needs is up to you.

 

[Kachda]

For those who ordered this from Apos, roughly how long did it take to arrive? I ordered this on 5th March, and I see in the tracking that it was just handed over to the airline yesterday!

Finally received it today. 22 days from ordering to receiving for those who want to know.

 

[FlexYoFace]

I got mine today from China, took almost 4 weeks. My remote takes AAA batteries.

 

[Tks]

I am astonished to see this comment coming from an experienced engineer.

Please read more literatures and learn what "balanced connection" really means. The above link I posted is a good start. The term "balanced" has nothing to do with sending inverted signal in the cold line, which really helps nothing other than having a higher output voltage.

The "balanced connection" actually refers to having same output impedance in hot and cold line. See wikipedia: "In telecommunications and professional audio, a balanced line or balanced signal pair is a circuit consisting of two conductors of the same type, each of which have equal impedances along their lengths and equal impedances to ground and to other circuits."

Short answer: sending negative polarity signal, which is your wrong definition of "balanced", only has one benefit: higher output voltage. But that benefit can be easily achieved by adjusting the output op amp gain resistor in an unbalanced situation. Having same output impedance already suffice the definition of "Balanced Signal". The above wiring can give you all benefits balanced signal offers, including ground loop and inference noise elimination.

Every few months I have someone explain what balanced actually means. Maybe I just need to keep notes and invoke all those definitions simultaneously whenever the discussion starts so I can go down the list and prompting the other person to tell me which one they're talking about :-]

 

[dreamscene]

For $200 All In One unit for headphones, DX3Pro+ still reigns supreme.

 

[TNT]

A regime that send both a positive and a negative version of the signal is called differential. If both legs has the same impedance seen from the sender, it is a balanced. A differential and balanced connection is nice. When a differential interface is balanced, it will offer higher suppression of common phase disturbances as the disturbances will be more equal reaching the summation point than if the impedance would differ between the + and - lines. This is also why one should keep differential lines tight together to preserve disturbance equality in the lines.

A ground is most often involved making a differential system a 3 wire connection. Most common connector is XLR but also RTS is seen.

Why amir repetitively claims that a balanced (maybe he means differential?) connection interface breaks ground loops sounds a bit strange... It will if it is trafo coupled and floating but most you see in the cheaper devices are not - these do not offer ground isolation, only cable/line interference suppression, thanks to the differential summing.

//

 

[audiofun]

A regime that send both a positive and a negative version of the signal is called differential. If both legs has the same impedance seen from the sender, it is a balanced. A differential and balanced connection is nice. When a differential interface is balanced, it will offer higher suppression of common phase disturbances as the disturbances will be more equal reaching the summation point than if the impedance would differ between the + and - lines. This is also why one should keep differential lines tight together to preserve disturbance equality in the lines.

That's true.

However, Topping's (and most other manufacturers') balanced DAC products' cold signal are not inverted from the hot signal.
The hot and cold are directly got from the DAC chip, without any summing and inversion, to save cost.
They are differential, but positive voltage does not equal to negative voltage's absolute value.
That's why people can't just use D10Balanced DAC's hot and ground wire as unbalanced, which will result to having lots of noise and significant DC offset.
In this configuration, differential offers no good value other than having higher voltage (4V vs 2V).
It's balance configuration (equal impedance) that offers the nice properties (ground loop elimination, noise reduction).

Why amir repetitively claims that a balanced (maybe he means differential?) connection interface breaks ground loops sounds a bit strange... It will if it is trafo coupled and floating but most you see in the cheaper devices are not - these do not offer ground isolation, only cable/line interference suppression, thanks to the differential summing.

Balanced signal does mitigate the ground loop to great extent. With additional ground wire, the ground current can transfer through the ground wire, and both hot/cold wires have same ground noise voltage (because they have same impedance, so V=I*R is the same) values relative to the ground wire, so the difference will be canceled out. No need to use a transformer to physically isolate. You can actually try and see if that's the case. I did --- I intentionally introduced a ground loop via unbalanced connection in my experiment; then I wired my DX3Pro+ to balanced and it did completely remove the noise.

 

[TNT]

OK!

"my experiment; then I wired my DX3Pro+ to balanced and it did completely remove the noise."

Can you describe this a bit more - cant envision the setup.

//

 

[audiofun]

OK!

"my experiment; then I wired my DX3Pro+ to balanced and it did completely remove the noise."

Can you describe this a bit more - cant envision the setup.

//

It's simple. Just connect computer-> DX3Pro+ unbalanced out -> ADC balanced in with ground = cold (cosmos adc, for instance) -> same computer. You'll likely to have a ground loop. Mine has and the noise floor rises by 20db.

To eliminate the ground loop there're a few ways:

1. computer with battery power ->DX3Pro+ unbalanced out -> ADC balanced in with ground = cold -> different computer with battery power.
2. SPDIF fiber ->DX3Pro+ unbalanced out -> ADC balanced in with ground = cold -> computer. [DX3 Pro+ not connected to computer]
3. computer ->DX3Pro+ with the above 20Ohms impedance balanced mod -> ADC balanced in -> same computer.

1 and 2 basically breaks the loop. 3. use balanced to cancel the loop. I can see in all three cases the 20db noise floor rise is gone. They have almost identical THD+N result.

 

[TNT]

Cool!

I read your post like "I rewired my pro+ to balanced" - but you connected it to a balanced input.

//

 

[audiofun]

Cool!

I read your post like "I rewired my pro+ to balanced" - but you connected it to a balanced input.

//

That's correct. Balanced output is trivial --- one just need to make sure the hot/cold wires have the same impedance.
One can convert any cheap single ended output DAC to balanced this way and save tones of money.
The part that does the actual work is the balanced input.
It's the differential op amp from the balanced input device (be it ADC, amp, or active monitor) that does noise cancellation, ground loop elimination, etc. In most cases you can't easily mod a singled ended input device to balanced.

 

[Smitty2k1]

That's correct. Balanced output is trivial --- one just need to make sure the hot/cold wires have the same impedance.
One can convert any cheap single ended output DAC to balanced this way and save tones of money.
The part that does the actual work is the balanced input.
It's the differential op amp from the balanced input device (be it ADC, amp, or active monitor) that does noise cancellation, ground loop elimination, etc. In most cases you can't easily mod a singled ended input device to balanced.

If I end up getting a pair of powered speakers like have been suggested to me in my "$500 desktop audio setup" thread and have noise I'll definitely be coming back here to make some cables! I just bought a new soldering station and am going out of my way to find projects. DX3 Pro+ already on the way.

That said I've also got a pair of Elac DBR62 and a "pre BMR Philharmonic" mini monitor "Alexis Sound Rebecca" coming this weekend so may end up with one pair for the main listening area and one pair for the desktop and skip the active speakers altogether.

 

[selthier]

hello, i have some question with anyone who also plug in this with speaker

so does the auto off will active even when you are doing something in pc but dont listen some music ?

and how bout the heat compare to L30?

thx b4

 

[dsnyder0cnn]

hello, i have some question with anyone who also plug in this with speaker

so does the auto off will active even when you are doing something in pc but dont listen some music ?

and how bout the heat compare to L30?

thx b4

This is how I use it with my desktop setup…RCA's out to a pair of iLoud Micro Monitors. I've not noticed it switching off on its own, but perhaps I don't have auto-off enabled. Mine is always cool to the touch, no matter what I'm doing. The DX3 Pro+ uses a very different power supply than the L30/L50.

 

[g3force7]

Hey guys. Can I pair this with my Moondrop Aria, CoolerMaster MH-751 and ATH-M40x without any issue?

 

[dsnyder0cnn]

Hey guys. Can I pair this with my Moondrop Aria, CoolerMaster MH-751 and ATH-M40x without any issue?

Probably not all at the same time, but yes.