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Neutrik NA2F-D2B-TX Miniature transformer balancing adapter quick measurement

polmuaddib

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Hello,
Since I have ground loop in my system which isn't fully balanced yet, I bought Neutrik RCA to XLR adapter with small transformer inside.
It does a good job of eliminating a ground loop.
908-na2m-d2b-tx-hinten.jpg

There is also a NA2M-D2B-TX version which is essentially the same but with male XLR.
So I wanted to measure it and used my RME ADI 2 Pro FS. Here is the loopback of RME just to have the base level.
RME loop 19dbu vol -5 3.86v procenat.jpg

I may have gotten a better loopback measurement, but this is good enough for what I need. REW generator of 1kHz is at 0 dbfs, RME vol is -5db, 3.86V and REF level is +19dBu input and output.
And here is Neutrik measured from unbalanced output of RME into balanced input:
NEutrik procenat.jpg


So, the good thing is that it introduces very little noise, almost none, which is important. But it introduces a lot of distortion at 0.016%
On the other hand, there are amplifiers with the same amount of distortion and for this small transformer this isn't so bad IMHO.

The price is little less then 50 euros and I don't think you can find cheaper product for this purpose, unless DIY. Which I am thinking of doing, since it is just Neutrik NTE1 transformer inside which costs about 10 euros. Add to it XLR and RCA connector, some cable and housing, the time to do it...

I don't know how to make other measurements, like frequency response, which would also be important. But when I learn how to measure more and have time, I will.

It's just a quick measurement, but I hope you find it somewhat useful.
 

pma

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I appreciate that you have measured this adapter. I would suggest to measure also at lower frequencies, like 50Hz, 200Hz, at different voltage level and to mention at which voltage the measurement was done. Transformer distortion heavily depends on frequency and level, it gets worse at lower frequencies and higher amplitudes.
 
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polmuaddib

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50 Hz at 1V
50hz 1V.jpg

50 Hz at 2V
50hz 2V.jpg

50 Hz at 3.86V
50hz 3.86V.jpg

100 Hz at 1V
100hz 1V.jpg

100 Hz at 2V
100hz 2V.jpg

100 Hz at 3.86V
100hz 3.86V.jpg

250 Hz at 1V
250hz 1V.jpg

250 Hz at 2V
250hz 2V.jpg

250 Hz at 3.86V
250Hz 3.86V.jpg

500 Hz at 1V
500hz 1V.jpg

500 Hz at 2V
500hz 2V.jpg

500 Hz at 3.86V
500hz 3.86V.jpg

5000 Hz at 1V
5000hz 1V.jpg

5000 Hz at 2V
5000hz 2V.jpg

5000 Hz at 3.86V
5000hz 3.86V.jpg

10 kHz at 3.87V
10000Hz 3.87V.jpg
 
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polmuaddib

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I appreciate that you have measured this adapter. I would suggest to measure also at lower frequencies, like 50Hz, 200Hz, at different voltage level and to mention at which voltage the measurement was done. Transformer distortion heavily depends on frequency and level, it gets worse at lower frequencies and higher amplitudes.
You were right. It is awful at low frequencies.
 
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pma

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You were right. It is awful at low frequencies.

It is worse than I would expect. Please also check that there is no permanent DC offset at the output of the DAC that drives the trafo, distortion accelerates as a rocket with the DC occurence.

P.S.: We might also ask @MC_RME what he thinks about driving the transformer directly from ADI2 output. Not always are the opamps happy when driving the transformer load. In my experience it is good to use a higher power buffer, with low output impedance.
 
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0mega0

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I tried a couple of these on the XLR outs of the Pegasus DAC. Unfortunately the lower frequencies sound horrible.
 

Lambda

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@polmuaddib

Thanks for the measurement. unfortunately the result is verry bad.
Maybe driving it from a low impedance headphone output with low levels 0,3Vrms or so would result in better performance.
I would also recommend using die seep measurement funktion to show THD and frequency response vs frequency

The price is little less then 50 euros and I don't think you can find cheaper
 
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