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Neutrik NA2M-D2B-Tx balancing transformer adapter review

Rate this adapter

  • Poor

    Votes: 15 22.7%
  • Not terrible

    Votes: 13 19.7%
  • Fine

    Votes: 32 48.5%
  • Excellent

    Votes: 6 9.1%

  • Total voters
    66
Source impedance is important, regarding distortion. Load impedance is not.
Yet you keep posting measurements from near zero source. No line level audio device has near zero output impedance on purpose (otherwise you could short it and damage the output buffers). Typical load impedances are 100 Ohm which is far, far more than 0.05 ohm headphone amp you are using as the source. These are all highly misleading measurements.
 
I'm strictly a layman when it comes to electronics and I find myself pretty confused when it comes to what the appropriated application of this device is supposed to be. Ashamedly though @pma clearly know what he is talking about, I mostly do not. What I would like is a simple, add-on device that will convert an ordinary audio line-level SE signal to a differential balanced signal with near-zero distortion -- I come away uncertain whether this Neutrix device can effectively do that.
This device is completely useless in any performant audio system. It is made to be tiny and inexpensive and that hugely limits its capability and performance as I showed in the original review. I can't figure out the fascination with bending to what it can do and showing that. It is simply the wrong device for the job. Kind of like buying a 0.5 watt amplifier and wanting to power a typical bookshelf speaker with it.
 
Yet you keep posting measurements from near zero source. No line level audio device has near zero output impedance on purpose (otherwise you could short it and damage the output buffers). Typical load impedances are 100 Ohm which is far, far more than 0.05 ohm headphone amp you are using as the source. These are all highly misleading measurements.

You are joking, right?

@pma has done much more than you to test under a variety of conditions to give us a better understanding of performance including these measurements at 200 ohm output impedance -> https://www.audiosciencereview.com/...rmer-adapter-review.45759/page-3#post-1631785.

Michael
 
YoYou are joking, right?
@pma has done much more than you to test under a variety of conditions to give us a better understanding of performance including these measurements at 200 ohm output impedance -> https://www.audiosciencereview.com/...rmer-adapter-review.45759/page-3#post-1631785.

Michael
Nonsense. My testing fit precisely how people in our domain would be using the device: nominal 4 volts on XLR with > 0 source impedance. The device is total failure for that application. The story ended there. Period.

His OP tests were fine and I promoted the thread for it. But not when it keeps going on and on with 0.05 ohm source impedance which simply does not exist in any application we may have for the device. I actually don't know any application for this device in audio where the source impedance is 0.05 ohm. It is now leading to confusion among the less technical members.

You have a technical counter, let's see it. Otherwise, I don't appreciate the rude protest.
 
Yet you keep posting measurements from near zero source. No line level audio device has near zero output impedance on purpose (otherwise you could short it and damage the output buffers). Typical load impedances are 100 Ohm which is far, far more than 0.05 ohm headphone amp you are using as the source. These are all highly misleading measurements.

Well.. there is the 200ohm source measurement.
There we see (assuming 0dB = no attenuation) a 2.5dB drop in level, probably due to the transformer being used in the 'wrong direction', and when driven from a source of 200ohm we see an additional 1dB.
In any case the difference in output level (due to voltage division) between 0ohm and 200ohm is 1dB.
This means 0.11V fell over the 200ohm and 0.89V fell over the load. We know the source R and that one is 8.1x higher than the source R (200ohm) so around 1.6k, which makes perfect sense as the load is also 1.6k.
This is also what's expected from a 1:1 ratio transformer. 1:1 voltage and 1:1 impedance ratio (which I suspect it only is in 1 direction and slightly different in the other direction).
Also what is observed is that for the lowest frequencies (when not saturating the core) the impedance at the lowest audio frequencies does not deviate much.
I am quite sure when you load the transformer with 10k the 'input load' will probably also be in that range (but lower because of the mystery value resistor).

My testing fit precisely how people in our domain would be using the device: nominal 4 volts on XLR with > 0 source impedance. The device is total failure for that application. The story ended there. Period.
Yes, for that application I agree. But it would be the same as expecting a phone to be able to drive the DCA Stealth to reach 120dB SPL. Both aren't made for that purpose.
 
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there is the 200ohm source measurement.
For which results are very much in line with Amir's measurements, if I'm not mistaken.

I agree with Amir: making a point of somehow better results with an headphones output as a source is misleasing.
Nobody will use it this way.

The Audioprecision's 40 ohm source impedance is much more representative of real life.

The only relevant questions, IMO, were level (this is obviously not designed for 4V or even 2V - but Amir had it covered) and the direction the device is meant to be used - if it matters or not (and Pma answered by showing no difference between the 2 directions).

So Amir's conclusion remains, IMO.

This is a live sound inforcement secundary problem mitigator. Not a device you'd include in your Front-of-house chain nor in your home Hi-Fi.
 
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Amir's measurement differs in the fact that the transformer inside is actually used 'in the right direction' so the output is not attenuated 2.5dB.
You see I assume that the difference in winding DC resistance in the NTE-1 is why it is marked as having a primary and secondary to ensure it is 1:1 in one direction.
I suspect in 'reverse' the ratio is not 1:1 anymore but has some losses (2.5dB seems a LOT ?).
At least I assume Amir used 4V as input, 100k as a load (parallel to 47k/4k7) and Pavel also used the 0dB as being the input level.
If one of them did not do this all bets are off.
As Amir did not measure it with another source resistance we have no indication of the actual load and as Amir drove it in saturation the 'impedance' transfer will have been very different than when it were measured at the expected level.
So. yes, near 0Hz the load will be close to the DC resistance. Near 100Hz the load 'seen' by the source will likely have been around a few kohm and at 1kHz around 30kohm or so.
As this hasn't been measured we don't know.

All we can do at this point is ask @pma to do some 'impedance measurements' of the load seen by the source at the expected levels and at 4V (saturated) over a frequency range starting from say... 10Hz.

Until this is measured we don't know and it is all 'my' theorizing.
We would need an 'input load' measurement (preferably with both a 1.6k load and higher) and maybe check the transfer ratio in both directions (or explanation of the -2.5dB level)

Measurements are simply incomplete to draw conclusions. The only conclusion that can be drawn now is that there is a max. input level that has an influence on FR and distortion and that it can be used (break ground loops) in both 'directions' and that difference in both directions are negligible in FR.
 
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Not just similar,they look identical.And there's two versions,RCA > XLR and XLR > RCA.

RCA to XLR.PNG XLR to RCA.PNG

Maybe measure them with the conditions they describe?
 
  • Neutrik XLR to RCA Connectors
  • Gain/Loss: 0dB In To 0dB Out
  • Single Channel
  • Frequency Response: Line level 20hz to 20khz
  • Interface Unbalanced Equipment to Balanced 600 Ohm Systems
There is no mention of cutoff points, there is no mention of levels, there is no documentation. They might as well be rebranded Neutriks.
 
  • Neutrik XLR to RCA Connectors
  • Gain/Loss: 0dB In To 0dB Out
  • Single Channel
  • Frequency Response: Line level 20hz to 20khz
  • Interface Unbalanced Equipment to Balanced 600 Ohm Systems
There is no mention of cutoff points, there is no mention of levels, there is no documentation. They might as well be rebranded Neutriks.
pma's version is the male one,so it's RCA to XLR.
 
All we can do at this point is ask @pma to do some 'impedance measurements' of the load seen by the source

1) As a coincidence, I have just been doing such measurements, because I can see, from many posts of many posters here, that the transformer input impedance concept is not well understood, in general. I do not criticize it, just noting it. I will try to stay as much technical only as possible. Transformers are a kind of "steam loco" engineering, it is basic electrical engineering and nowadays generation is not much in contact with such things.

So, this is the NA2M input impedance when loaded with 10kohm
NA2M-D2B-TX 10kohm input impedance.png

Please note that 47kohm terminating resistor inside NA2M and 10kohm load makes a parallel resulting resistance seen at the upper end.


and this is when loaded with 1.6kohm, as in case of my Cosmos ADC
NA2M-D2B-TX 1.6kohm input impedance.png

1.6kohm above 1kHz, below the L1 = 1.94H influence.

2) Why @amirm has measured the LF roll-off below 80Hz or so? Because the adapter was overloaded, saturated core and the LF shape then is not sinusoidal and rms value falls down.
At -3dBu (550mV approx.), I measure LF roll-off starting at 40Hz (still flat) and reaching -4dB at 20Hz. At lower level like 200mV there is no roll off and 20Hz is still flat.

3) NA2M and NA2F adapters are basically identical, with small distinctions mentioned several times. The different results of the 2 reviews are fir the reasons of different test conditions used, namely source impedance and test level.


Please everyone, try to thing scientifically, with your brains, less emotions and heart involved ;). Listen to the facts and make your own studies on the subjects discussed.

 
pma's version is the male one,so it's RCA to XLR.

Yes but per the documentation the transformer and internal load resistor are not changed in 'direction' so it appears as though only the XLR is different which would determine the direction in which it would logically be used.
Of course 1:1 transformers themselves are not directional, at least when the number of windings is the same. This also depends on how the actual windings are made.
On top of each other or next to each other. It would appear as though the windings lie on top of each other and thus they may be of different length.
 
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1) As a coincidence, I have just been doing such measurements, because I can see, from many posts of many posters here, that the transformer input impedance concept is not well understood, in general. I do not criticize it, just noting it. I will try to stay as much technical only as possible. Transformers are a kind of "steam loco" engineering, it is basic electrical engineering and nowadays generation is not much in contact with such things.

So, this is the NA2M input impedance when loaded with 10kohm
View attachment 294126
Please note that 47kohm terminating resistor inside NA2M and 10kohm load makes a parallel resulting resistance seen at the upper end.


and this is when loaded with 1.6kohm, as in case of my Cosmos ADC
View attachment 294127
1.6kohm above 1kHz, below the L1 = 1.94H influence.

2) Why @amirm has measured the LF roll-off below 80Hz or so? Because the adapter was overloaded, saturated core and the LF shape then is not sinusoidal and rms value falls down.
At -3dBu (550mV approx.), I measure LF roll-off starting at 40Hz (still flat) and reaching -4dB at 20Hz. At lower level like 200mV there is no roll off and 20Hz is still flat.


Please everyone, try to thing scientifically, with your brains, less emotions and heart involved ;). Listen to the facts and make your own studies on the subjects discussed.


As expected... How does it measure when saturated (4V) and what is the transfer ratio in both 'directions' (as to explain the 2.5dB level) ?
 
As expected... How does it measure when saturated (4V) and what is the transfer ratio in both 'directions' (as to explain the 2.5dB level) ?

1kHz almost 4V
1kHz_THD_0.056R.png

It is of course unusable at low frequencies/4V. Very sorry but I am not to make a setup again and measure at 4V. Never use this adapter above 1V, better stay at or below 550mV.

The 2.5dB level difference (you probably point at some comparison plot of FR) was due to my too fast, indicative only measurement wit input level unintentionally changed. The adapter works as it should and according to simplest laws of physics. Fortunately.
 
pma's version is the male one,so it's RCA to XLR.
Same, already explained questions are repeated. Inside is the same circuitry, FR and distortion are same in both directions. Only the terminating resistor 47k placement makes no sense in XLR==>RCA version, though it will change unloaded HF response above 20kHz only. No change in posted measurements, NA2F and NA2M will measure same under same test conditions, regardless the difference in I/O direction. Everything explained in post 1 of this thread, together with schematics and comparison measurements.
 
1kHz almost 4V
View attachment 294128
It is of course unusable at low frequencies/4V. Very sorry but I am not to make a setup again and measure at 4V. Never use this adapter above 1V, better stay at or below 550mV.

The 2.5dB level difference (you probably point at some comparison plot of FR) was due to my too fast, indicative only measurement wit input level unintentionally changed. The adapter works as it should and according to simplest laws of physics. Fortunately.
2.5dB explained which was not entirely clear from the measurements.

I was wondering more about the impedance transfer when measured at 4V. I would expect the impedance to drop more in the lowest frequencies at 4V but, of course, never reach the DC resistance which was the whole point of the 'load' debate.

Multitone at 0.3V and 4V could have been fun to see, but we can't have everything in life.:)

Transformers are weird in that aspect and not very intuitive like transducers (DC resistance vs transferred impedance).

Yep, not to be used at 2V and most certainly not at 4V. Fine for mic to -10dBV levels when a groundloop has to be broken (problem solver).
Amirs point, because of this, is also valid in that it performs lousy when used with home hifi at these levels.
Also the documentation on it is really poor from a 'consumer hifi equipment' user standpoint and even for professionals. Neutrik could have certainly done better here.
 
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Amirs point, because of this, is also valid in that it performs lousy when used with home hifi at these levels.

Sure. It needs a qualified operator and should not be used by the user who does not have the exact idea about the function of the adapter and has not defined his issue exactly. Neutrik is for Pro or Semi-Pro use, like Rane, Roland, you name it. It is not originally intended for home consumer audio use by a non-qualified person. The adapter can be used at home after a qualified problem analysis and then a recommendation by a qualified person. It works as expected and as it should within its circuit limits. I agree that the technical documentation should have been much more detailed. However, for a qualified person it is still sufficient. Maximum level definition at defined low frequency and defined THD is a standard for link transformers. NA2M adapter fullfills the specs.
 
2.5dB explained which was not entirely clear from the measurements.

If you speak about the difference in transfer ratio between the 2 I/O directions (XLR=>RCA, RCA=>XLR), it exists but is negligible, like 0.1dB, and is shown (I suppose it actually was already shown) below:

NA2M_adapter_FR_2directions.png
 
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