Neutrik NA2M-D2B-Tx balancing transformer adapter review

[solderdude]

There are two types of the adapter where just the XLR sex is different. Why it makes no sense to you to feed XLR in? Besides, you are confusing us by making a different test to @amirm’s who fed signal to the XLR socket while presenting your test to be the same as his.

PMA tested it the way it should be used, at least acc. to the schematic which has a load resistor on the secondary side.
The output being F or M is a bit weird but science says the XLR is output.

 

[voodooless]

The output being F or M is a bit weird but science says the XLR is output.

So does the product page for that matter

 

[sarumbear]

The output being F or M is a bit weird but science says the XLR is output.

Did you just said “science”?

 

[solderdude]

What would be the technical reason for paralleling an input with a 4k7 (or even 47k) resistor ?
That only makes sense on the output of an audio transformer to prevent peaking by ensuring a miminum load resistance.
Both the XLR F and M seem to have a parallel resistor.
If one of them would be XLR-RCA that resistor would have been on the RCA side.
At least that is what the 'science' behind the transformers says.

Besides... what would explain the existence of XLR F-F adapters and XLR M-M adapters and cables ?

 

[pma]

Yes. This adapter, NA2M, M stands for male, has RCA CINCH input and XLR output. Amir tested NA2F version, female, XLR in and RCA out. It is absolutely clear and there can be no doubts. But, the placement of resistor in the NA2F adapter is strange.

BTW, frequency response also depends on signal level, I made another measurement at 280mV and FR is flat from 20Hz. Of course again in case of generator impedance close to zero. At -3dBu, the transformer starts to get saturated below 40Hz, thus the roll off here in post #1.

 

[sarumbear]

Yes. This adapter, NA2M, M stands for male, has RCA CINCH input and XLR output. Amir tested NA2F version, female, XLR in and RCA out. It is absolutely clear and there can be no doubts.

Tell that to @solderdude His science disagrees.

 

[solderdude]

Not 'my' science though.
Transformer loading 'science'.
It may have something to do with the existence of M-M and F-F XLR cables.

 

[voodooless]

Yes. This adapter, NA2M, M stands for male, has RCA CINCH input and XLR output. Amir tested NA2F version, female, XLR in and RCA out. It is absolutely clear and there can be no doubts.

There certainly are doubts. The product page of both products states RCA to XLR:

Low cost solution for unbalanced / balanced line conversion and passive
DI applications, where no earth or gain switching is required.

 

[voodooless]

just for prosperity
In the attached data sheet the resistor is shown as well.

Where is that attached datasheet?

 

[solderdude]

Given the fact that the input and output of the transformer are color coded and not have the exact same DC resistance and the M and F version both have the red/black lead to RCA tells me the signal direction is always from RCA to XLR but.... normally one draws the input side on the left and output on the right so the drawing is confusing to say the least.
Weird is that the used transformer is the NTE-1 and this specifies the output as being red+black so that would mean RCA is always out which is contrary to the science that says the output should have a mimimum load.

Then again... the 47k resistor does not make much sense (and seems to be just that) but looking at the picture the resistor appears to be between pin 1 and 2 (so hot and common) which @pma could easily verify.

Needless to say contradictions everywhere
One thing is clear though.... do not feed it with signal levels above 300mV (SE nor balanced) and it won't improve signal fidelity, it is limited in usage but can provide galvanic separation and turn SE to balanced.

 

[Sokel]

Given the fact that the input and output of the transformer are color coded and not have the exact same DC resistance and the M and F version both have the red/black lead to RCA tells me the signal direction is always from RCA to XLR but.... normally one draws the input side on the left and output on the right so the drawing is confusing to say the least.
Weird is that the used transformer is the NTE-1 and this specifies the output as being red+black so that would mean RCA is always out which is contrary to the science that says the output should have a mimimum load.

Needless to say contradictions everywhere

Common sense says that the sorted cold-ground pins on the XLR side (both F and M) on the drawning are intended to be output to go to an unbalanced input.
It's strange,yes.

 

[amirm]

Nice work. Promoted to home page.

 

[SIY]

Some of us may have issues with ground loops in subs, and clearly these kind of products are not usable for that. What kind of transformer may work well in that case for a decent budget?

Cinemag CMLI-15:15. Not cheap, but significantly less than Jensen or Lundahl. Edcor WSM 10k/10k is cheaper and almost as good.

 

[Multicore]

It has to be driven from low impedance, 5 ohm or less at best.

What does this mean in practice? It sounds very low to me. Can you describe the kind of gear that would be compatible?

 

[PeteL]

Besides... what would explain the existence of XLR F-F adapters and XLR M-M adapters and cables ?

Most of the time those are used because you run one big bundled snake of cables from the stage to the board, this snake can be all in the same direction or a mix, but you may need to turn some around if you have an extra out and missing an in or vice versa. but it would not be designed specifically to need to have a coupler to function as intended. OK Honestly I think they can both work both ways. The resistor is a bit mysterious yes, me on the schematic you posted I see it between 2 and 3 so hot and cold hence very large, and I think on the picture My bet would that it’s an optical illusion that they appear between 1 and 2. Nothing on Amir’s measurment show that it’s a non working adapter that way, the measurments are not that different than what we have here if we rescale.

 

[dualazmak]

I have read the ASR review on the almost same product, with the only difference that it had female XLR and black CINCH, though my adapter has male XLR and red CINCH, otherwise they are same.

We (at least I) need clarifications:

Amirm tested on his thread NA2F-D0B-TX (female XLR & RCA).
PMA tested on this thread NA2M-D0B-TX (male XLR & RCA).

My naive understanding is that;

NA2F-D0B-TX (amirm tested) is designed for balanced-XLR into unbalanced-RCA conversion,
and
NA2M-D0B-TX (PMA tested) is designed for unbalanced-RCA into balanced-XLR conversion.

If my understanding is correct, the two threads are quite different stories with each other, as I pointed and shared here and here on amirm's thread.

 

[Rja4000]

NA2F-D0B-TX (amirm tested) is designed for balanced-XLR into unbalanced-RCA conversion,

It doesn't seem so.

Neutrik describes it as "Miniature transformer balancing adapter", which makes sense only if the input is the RCA in both cases.

Also, as @pma said, the purpose is to prevent ground loops, which only makes sense if the source is unbalanced.

On top of this, -3dBu is not the kind of level you expect on a balanced output, where +4dBu is usually the standard.
But -10dBV (-7.8dBu) is a standard level often seen on RCA.

The Female plug seems just to be for convenience, for use cases like @PeteL was describing above.

 

[thecheapseats]

Not 'my' science though.
Transformer loading 'science'.
It may have something to do with the existence of M-M and F-F XLR cables.

cables existence? - very unusual, typically no... you can buy a pre-made cable (rare) with the same gender on each end, but if used incorrectly/wrong, it may destroy some devices and doesn't have a common use - it's an accident waiting to happen as a 'cable'... in real world usage (you know this) an xlr-m is an output always - an xlr-f is an input always...

I have no idea why Neutrik built two skus with the different xlr genders...

.m-m/f-f xlr adapters? - yes... XLR M-M and XLR F-F barrel 'adapters' are used in pairs (always) for sound reinforcement (one of each gender on each end) to turn XLRs in a sound-reinforcement multi-connector snake installation from a send-to-receive/or a receive-to-send... it's a common trick used because it's the only way to get the job done sometimes - and in pairs (m-m and f-f) stops an inadvertent 'patching mistake'...

occasionally I use a single m-m barrel adapter to get a send from a control room TT patch bay from the xlr-f patchbays in the studio for the same purpose (as a send) - or to patch a line xfmr on that same send - but that's rare...

 

[Rja4000]

XLR M-M and XLR F-F barrel 'adapters' are used in pairs (always) for sound reinforcement

Same here, except you replace the F-F one by this adapter (XLR F - RCA F)

 

[dualazmak]

It doesn't seem so.

Neutrik describes it as "Miniature transformer balancing adapter", which makes sense only if the input is the RCA in both cases.

I still have some doubt for bi-directional use (or RCA only input) of these two transformer-included adaptors.

When I went into audio enjoyment hobby world in my young era, my audio-advisory guy, who was in pro-audio world, taught me in non-elegant wordings;
"You need to remember in this way. Male XLR should only output/ejaculate signals, Female XLR should only accept the signals, in any setup of audio gears."