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Neutrik NA2F-D0B-TX XLR to RCA Adapter Review

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  • 1. Poor (headless panther)

    Votes: 121 82.3%
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    Votes: 9 6.1%
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amirm

amirm

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Can anyone explain to me why so many of you want this to be a hifi audio device, when it's clearly (to me) a troubleshooting tool for pro/live audio contexts?
Because there a number of good amplifiers that only take XLR input and folks want to interface them with RCA. These things are sold for seemingly that purpose. Without my testing, you could easily believe that it absolutely serves that purpose.
 

Sokel

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Because there a number of good amplifiers that only take XLR input and folks want to interface them with RCA. These things are sold for seemingly that purpose. Without my testing, you could easily believe that it absolutely serves that purpose.
I think it's other way around.
Most of the nice balanced amps don't have a problem connecting them with an RCA to XRL cable (properly wired),they don't need a converter (ok,some strange may do).
The main problem who absolutely needs a converter is when we have an XLR source (like a lot of the new DACs) that needs to connect to an unbalanced amp.

That's what folks are after.
 

PeteL

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I think it's other way around.
Most of the nice balanced amps don't have a problem connecting them with an RCA to XRL cable (properly wired),they don't need a converter (ok,some strange may do).
The main problem who absolutely needs a converter is when we have an XLR source (like a lot of the new DACs) that needs to connect to an unbalanced amp.

That's what folks are after.
Especially since the XLR is a female.
 

pma

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Looking forward to @pma's experiments.

Here they go:


I have to say I have measured very different frequency response and quite different distortion than @amirm , most certainly for the reason that I have used my headphone amplifier with Zout = 0.056 ohm / 250mA current capability to drive the adapter. It is all about laws of physics and electrical circuits. The Neutrik adapter has excellent CMRR and wide, flat frequency response when driven from low impedance. I think it has its areas of use, though usually not at the home system. Still, if someone has huge ground loop hum/buzz, it will certainly help a lot.

Last, I highly recommend this book, to those who might be interested in real audio engineering: Bill Whitlock, Audio Transformers

 

Porter

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Because there a number of good amplifiers that only take XLR input and folks want to interface them with RCA. These things are sold for seemingly that purpose. Without my testing, you could easily believe that it absolutely serves that purpose.
Sure, but that's not the market that this product is designed for. This is a professional audio connector tool with very specific applicability, not a hifi dac-to-amp or pre-to-amp interface.

I think the "standards"-based interconnection assumptions that home/hifi users have become accustomed to are doing us a disservice here. Not all uses of a balanced XLR cable are equivalent.

For example, I can attach a TON of different things with an XLR jack, including a pretty surprising range of non-audio scientific sensors in a research/lab context, but that doesn't make those devices appropriate to attach to a home hifi system.


If the point you're trying to make is that this product isn't appropriate for home hi-fi use, then just say that. Instead you seem to have made a value judgment about quality, and are expressing the results as a blanket engineering criticism. That doesn't seem to match your stated intent.
 

torgeirs

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Driving this gadget with a high impedance sourse is like driving a dynamic loudspeaker with a high output impedance tubeamp and expecting flat frequency responce.
In real world it works great for connecting a computer via headphone out to a xlr PA without the buzz and the big BUMP.
 

sarumbear

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Sure, but that's not the market that this product is designed for. This is a professional audio connector tool with very specific applicability, not a hifi dac-to-amp or pre-to-amp interface.
Can you tell us what “specific” cases the unit is designed for?
 

Gruesome

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Can you tell us what “specific” cases the unit is designed for?
Ground separation for microphone level signals, about -30 dBu, for example from a microphone or a direct injection box (with suitable pad to adjust the level). It was explained earlier in the thread, but there is so much noise it's easy to overlook.
PMA's test shows the device is ok (< 1% THD) up to about -3 dBu, but the optimum voltage range seems to be around 50 mV.
 
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sarumbear

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Ground separation for microphone level signals, about -30 dBu, for example from a microphone or a direct injection box (with suitable pad to adjust the level). It was explained earlier in the thread, but there is so much noise it's easy to overlook.
PMA's test shows the device is ok (< 1% THD) up to about -3 dBu, but the optimum voltage range seems to be around 100 mV.
Why would you use an RCA socket if you are going to use a microphone? Have you ever seen a microphone input on a RCA connector? What use scenario is there that requires an inherently balanced microphone to an unbalanced RCA microphone input of any professional device?

Similarly, have you seen RCA connectors used for line level input on mixers, etc. so that the DI use case requires an RCA connector? In fact how often do you use RCA connectors on a professional device, other than interfacing with Hi-Fi equipment, like 2-track inputs on a mixer?
 

Gruesome

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Why would you use an RCA socket if you are going to use a microphone? Have you ever seen a microphone input on a RCA connector? What use scenario is there that requires an inherently balanced microphone to an unbalanced RCA microphone input of any professional device?

Similarly, have you seen RCA connectors used for line level input on mixers, etc. so that the DI use case requires an RCA connector? In fact how often do you use RCA connectors on a professional device, other than interfacing with Hi-Fi equipment, like 2-track inputs on a mixer?
Sarumbear, where is this going to go? Is this another 'this device can't possibly be what it is' argument?
 

Porter

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Can you tell us what “specific” cases the unit is designed for?
In my own experience, this would be super useful for quickly testing different runs to find the source of a ground loop in a large scale live audio production scenario, without getting out a multimeter and unprofessionally jumpering and alligator-clipping a bunch of things together to get a testable scenario.

Ground loops can be really, really difficult to track down when you have dozens (or more) mic and instrument runs coming to and from different systems via long stage snake XLR bundles, sometimes involving multiple stages of performers with radically different equipment being attached to the other end of the snake, sometimes at a great distance where you have to coordinate with the staff at the other end entirely over radio. Imagine a stage changeover situation at a large music festival or other multi-performer production context, where performers are arriving with just an hour or so to spare and there's only a 30min or so reset interval between performances on a single stage. Sometimes those performers show up with really strange instrumentation, unusual boutique microphones, or situations where they have highly customized or finicky pickup situations on unusual instruments, sometimes that are also connected to mains AC power in ways that can get really weird.

I've personally seen a thing like this involving a vibraphone player with a neat little array of acoustic pickups on his vibes, and a ground loop that would start whenever the motor was plugged in to run the discs in his resonator tubes. Damn thing had shorted to the metal of the housing during transport. This stuff happens, and is really hard to diagnose on the fly when you have 20-ish minutes to make it perfect before a group takes the stage in front of 10k people. Not running the vibe motor is not an option, it doesn't sound like a vibraphone if it's not running, there's no vibrato. So you have to figure out how to make it work in a hurry. And that's just a simple case of a short. Imagine a case where a ground loop only exists when two different unrelated instruments are plugged in at the same time, and they only "touch" electrically through your board, or occasionally through the interaction of those instruments and some kind of other equipment in your rack.

A bag with a few of these things in different input/output connector formats (XLR to XLR being the most common) would be invaluable in helping to rapidly track down the source of a ground loop problem. I wouldn't leave one in the signal path except in an emergency, but WOW would it be a time saver when you suddenly have some kind of crazy hum and it's not obvious exactly where it's coming from. And for a lot of the cases where this would be used, you don't have any signal below 100hz anyway, so it doesn't matter if it distorts at 50hz because the instrument doesn't play in that range. People certainly don't sing that low, in the case of a microphone.

The design of this thing seems obvious to me... figure out how to make a really simple and effective isolation transformer that can be inserted in a signal path quickly, and make it small enough to make a "kit" out of them in somebody's gig bag without adding an insane amount of weight. It doesn't have to be the last word in audio quality, it just needs to be effective, and "good enough" to be used in the signal path in an absolute emergency if there's no way to kill a ground loop at the actual source because of some weird situational constraint.

Hope that helps... I know it's a wall of text but those are my thoughts on this. It's simply not a device that I would try to use in a hifi context, it seems to me to not be what it's designed or intended to do.
 

sarumbear

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Sarumbear, where is this going to go? Is this another 'this device can't possibly be what it is' argument?
I asked what real life cases where this unit can be used in the pro world? You said interfacing microphones or used as DI unit’s. I explained that your examples are illogical. If you don’t agree with my explanation, correct me why?
 

sarumbear

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In my own experience, this would be super useful for quickly testing different runs to find the source of a ground loop in a large scale live audio production scenario…
Any examples please. Your answer is not specific.
 

sarumbear

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Removing hums.
I asked for a “specific” case. Not specific “use”. What device will be connected to what device?
 

sarumbear

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I don't know what you're asking for. Is my wall of text describing some pretty specific scenarios not enough?
You are stipulating. I’m asking specific cases as in the way the word “specific” is used for. There are not a huge number of different type of devices that a professional use in a live environment. Give me please examples how/where this unit maybe used?

It was suggested it will be used on microphones. I explained why that can not be the case. It was also suggested that this is DI unit. I then asked what mixer has an input on a RCA connector?
 

Porter

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You are stipulating. I’m asking specific cases as in the way the word “specific” is used for. There are not a huge number of devices that a professional use in a live environment. Give me please examples o scenario where this unit maybe used?

It was suggested it will be used on microphones. I explained why that can not be the case. It was also suggested that this is DI unit. I then asked what mixer has an input on RCA connector?

I see, maybe you're asking for more context. In that case... where I would use these is directly off the back of the sound board, or to the input racks connected to the board on a big system. Possibly quickly plugging and replugging it to different signal cables coming in from instruments and microphones, usually from the send of a DI box but not always. Sometimes the instrument that's "humming" with a 60hz (or 50hz) tone isn't the source of the ground loop, but is the one affected by it. So a bit of process-of-elimination is often warranted. That's possible with something this small in ways that it wouldn't be with a larger device, because you can hang this thing off a short cable on the back of your board without worrying about the weight damaging the input.

FYI almost all modern mixers have a few RCA inputs in addition to XLR. Typically they're used for AUX (line level) input, but I've seen them used in some pretty weird scenarios, so I think there are applications where this could be useful.
 
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sarumbear

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FYI almost all modern mixers have a few RCA inputs in addition to XLR. Typically they're used for AUX (line level) input, but I've seen them used in some pretty weird scenarios, so I think there are applications where this could be useful.
I had said on my post that RCA connector is used on aux inputs.

You are now telling me that this device is designed to connect a balanced feed to the mixer aux inputs, which are designed to connect local equipment, and as expected, it hums. Irrespective of the fact that, those aux inputs are almost always non-routable and hence useless for feeding the signal to the audience during the live event.

It is indeed a “pretty weird scenario.” I wonder how often that happens? :)
 

Rja4000

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Ok, now some comparison points:

I measured a Radial Catapult TX4L

This is a Cat 5 "Stage box" with transformer Isolation.

It's the only 1:1 transformer-based device I have at hand.
(Picture from Radial web site)

catapult_3-hirez-768x764.jpg

Measurements were performed with my RME ADI-2/4 Pro SE as DAC and ADC
Software is Virtins Multi Instrument 3.9.8.1

I measured from XLR input to ISO output, so not through the Cat5 cable.


SINAD Dashboard at 4V

Catapult Dashboard 997Hz 4V_crop..png


SINAD Dashboard at 4V 40Hz

Catapult Dashboard 40Hz 4V_crop..png


Multitone


Catapult MT 192kHz 1.9V_crop..png

NB: This is the same level setting in the software than for 4V dashboard.
But the multitone has a very different crest factor and, as the software is targetting the same peak level, it then gives a lower RMS voltage.


Frequency response (384kHz BW)

Catapult FR 768kHz 5dB.png



To compare with Radial's published measurements, I re-ran the same @0dBu

SINAD Dashboard at 0dBu


Catapult Dashboard 997Hz 0dBu_crop..png


SINAD Dashboard at 0dBu 40Hz

Catapult Dashboard 40Hz 0dBu_crop..png


We are performing worse than their measurements at 40Hz.
At 40Hz 0dBu, I read 0 003% THD from their graph.
(Picture copied from the Graph section of Radial web page.)
To be fair, at 1kHz, my measurements are a bit better than what they publish.

catapult-tx4l-rx4l-graph-distortion-v-frequency (1).jpg


By curiosity, I also ran the

Dashboard at 24dBu (12V)

Catapult Dashboard 997Hz 24dBu_crop..png


At least, that gives us a comparison point.
 

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