Referance earth from 4 pin DIN to 3 PIN XLR balanced cable

I have naim nac n 272 and have purchased ATC SCM 40 active speaker. I want to connect through 4 PIN DIN of 272( left and right) to ATC 40 active by 3 PIN XLR balanced cable. What should be reference earth connection ie at DIN end or at XLR end or at both end. ATC have balanced 3 PIN XLR connection only. I As my wire manufacturer is asking the same for termination of cable

It’s not really ‘reference’ earth it’s how to connect the DIN to XLR cable(s) screen. The important thing is to not connect at both ends thereby interconnecting the Naim -ve and ATC ground.
I connected the screen at the ATC end and left the screen open at the Naim end.

Thanks for reply so , I understand that at DIN there will be Signal(+) and return(-) and at XLR end it will be hot(+) at Pin 2, Return (-) at Pin 3 and Screen at Pin 1. No screen at DIN

Exactly right ksanjeev9

I received this reply from Naim in connection with the RCA to DIN Superlumina source IC. The same principles apply.

The website has this description of the superlumina interconnect cable:

“The fundamental cable design consists of several individually-insulated multi-strand silver-plated copper conductors of varying diameters enclosed in a tin-plated copper shield. This is all enclosed in a soft outer jacket which facilitates easy installation whilst minimising microphonic interference. Each signal, return, ground and shield conductor is individually manufactured for its specific function.”

As is obvious from inspection of the cable the screen (referred to as a shield above) is separate for each channel.

In the case of a naim system the “preamp chassis earth” is connected to the “signal earth” inside the preamp. Since our preamps have external power supplies the signal ground is used as the preamp chassis screen. Note that in the following description “ground” or “system ground” is the negative or 0V reference of the system and “mains earth” is the earth connection supplied by the mains lead and plug.

In this customer’s case (of an RCA to DIN lead) the RCA connectors will have the signal and ground connections using the individual conductors soldered together. The white sleeved cables are the ground and the red or black sleeved cables are the signal. In addition (since the RCA’s are the source end) the screen will also be connected to the ground via a padding resistor. The resistor is there to control the characteristic of the screen “seen” by the ground.

The overall screen in a cable is there to "protect the signal”. It has to have a connection to the system ground at some point, or it won’t work as needed. Note that system ground is not the same as mains earth, ideally they should be connected together at one point (usually at the most often used source), but in most cases a system will work without problems “floating” from (as in not connected to) mains earth. We would always recommend that a system has its system ground connected to mains earth for best sound quality.

There is always an earth loop when using RCA connectors in a stereo system; as long as the two channel’s cables are kept close together it will not cause a problem. If they are split and are routed far away from each other there may be some mains hum picked up. In the case of most audio cables the two channel’s cables will be joined together by their overall sleeve and so will be kept close together. This is one (of many) reasons we prefer to use din connectors for signals between parts of the system.

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The manual explains how to connect balanced or unbalanced inputs.

And dont just look at the pictures, read the text under section 4 which has important additional info on this!!

@ Mike -B . As guided above got 4 PIN DIN with source(+) and (-) only and at XOR end connected (+) to pin 2, (-) to pin 3 and screen at pin 1. Not connected screen at DIN end . But Hum is coming from speakers. Also noted that when I switch off 272 , at the time of switching off no sound coming from speaker but when I am switching off speaker irrespective 272 is on or not loud noise ( like electrical spark) coming from speaker. Otherwise sound from ATC 40 a is very good . What to do

It’s impossible for me to say for sure what the problem could be, I can only guess.

I made the cables for a friend with 272 - SMC19A, the system worked perfectly with no hum other than a very quiet noise when the room is silent & ears are about 0.5m away.
I deliberately did not connect the screen at the DIN ends simply because the 272 was on a different power supply to the speaker power & wanted to avoid connecting across. Also the Naim (-ve) is not actually earth, it is (-) negative signal, so connecting that to a power circuit earth is potentially a bad idea & that is another reason I did not connect the screen at the DIN end.
You can try disconnecting the screen at the XLR end so that no screen is connected,
an open screen can effective in a ‘quiet’ environment.

Regarding the loud switch off noise, I suggest you ask ATC (e-mail) I suspect its normal but they might have some advise on it.

I was not aware that Naim have balanced output to a poweramp. Balanced uses signal and inverted signal to eliminate noise. The signal return presumably acts as the signal ground. Naim use a resistor in their Super Lumina IC screen BNC plugs presumably to handle the noise originating screen. The don’t say what value. They just advise keeping the two channels close together to avoid hum.

I posted above about this.


You are right, Naim pre out is always unbalanced. However, ATC provide instructions on how to wire the pins for either balanced or unbalanced use in the manual. There may be some confusion around grounding though, and the ATC instructions show how to connect to an unbalanced RCA, not DIN.

Further As Hum was coming from original DIN to XLR so removed it. I also had Superlumina DIN to XLR and audioquest Wind XLR-XLR( 3 mtrs). So connected superlumina DIN in 272 , XLR male end of Superlumina to the Female XLR of audioquest and Male end of Audioquest to ATC 40 active as speakers are 8 ft apart and superlumina is 3 ft only). No Hum at all. Full sonic sound, awsome sound. Fist time i heard such sound from ATC 40 Active. But in left speaker observed less sound in comparison to Right speaker so adjusted output balance in 272( less power in left speaker than right, however when i connect through RCA-XLR both speaker output is proper).
After that i opened Superlumina DIN to XLR wire and observed that the Source (+) is connected at proper place in, DIN and return(-) is connected in DIN as shown in NAC 272 back side and no screen is connected at DIN. While in XLR end source(+) is connected at Pin no.2, Return(-) is not connected in any PIN of XLR and screen is connected at Pin no.3.
How to balance the output of both side

Fwiw, we’ve only ever used Van Damme Pro Grade Classic XKE 1 pair install cable blue for SINGLE 4 pin din > 2 x XLR’s for connection to power amplifiers or active speakers.

Our SINGLE 4 pin din > 2 x XLR’s are configured as -

At the Din end:

Pin1: Ch1 left (white core)

Pin2: no connection

Pin3: signal ground ( two blue cores)

Pin4: Ch2 right (white core)

Note: drain wires are not connected at the din end.

At the male XLR end:

Pin 1: drain wire

Pin 2: signal high (white core)

Pin3: signal low (blue core)

Note: link XLR pins 1 and 3 with 20 gauge wire

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