Connecting Naim Pre-amp and/or Power Supply to ATC Active Speakers

I may be new to this forum but not Naim Audio equipment. I’ve been an owner since the mid 90’s starting with the ‘slim’ olive products of NAP 90 & NAC 92 then, like many, moving up through the range but never quite reaching the summit. For me, a degree of pragmatism and the law of diminishing returns applies here.

My reason for breaking with tradition and writing this post is simple. During a recent search for my ‘end game’ speakers I listened to and very much liked, the ATC SCM50 active stand-mounts and therefore wanted to find out the best way to connect them to both my Naim system and a pair of REL S/510 subwoofers. I was given lots of advice through dealers near and far as well as forums such as this one. The problem was that the majority of advice I gathered was contradictory. Everyone had their own ‘correct’ advice and I became a little confused. However, my determined streak took over and to that end I went back to first principles and contacted ATC, Naim Audio, Design-a-cable, Canford Audio and Orso Audio in search of the ‘real’ correct answer.

Forgive me if I am being too simple here but the ‘problem’ I encountered stems from the Naim NAC252 and Supercap producing an unbalanced output signal. The potential difficulty lies in the detail as the ATC active speakers ‘require’ a balanced input signal. There are two main schools of thought here in regards to a solution. One is to use a ‘pseudo’ balanced cables from the Supercap directly to the active speakers (such as this one) whilst the other suggests using a transformer/converter provided by such companies as Canford Audio (here) or Orso Audio (here). Digging further there are also active and passive options of the converter route. Confused yet? I was!
To cut a very long story short, the answer is to connect directly from the pre-amp/power supply combo to the active ATC speakers using a pseudo ‘balanced cable’. A simple search for “four pin din to xlr’ will reveal a suitable offering from Design-a-Cable for less than £100. The cables are supplied as a stereo pair and are designed for just this kind of scenario. As it turns out, the very source of the issue (NAC 252 & Supercap) also aids the solution: the relatively high output voltage of the 252 is more than enough to ‘drive’ the speakers (ATCs words not my own).
During my quest I did find that the design Engineers at ATC don’t exactly all agree with this school of thought but the majority won my vote. I think this might be where the two different schools of thought might have originated. However, they were actually brilliant in answering my ‘noddy’ questions and did state that the majority of their customers who also own Naim equipment use ‘pseudo’ balanced cables.
Some however do go down the transformer/converter route. Why? In the words of ATC and Naim, a transformer/converter would come into play if a system issue (such as interference) was encountered. ATC said that an active transformer would be best (they strongly recommended Lundhal) but if not really required it would simply act as a weak link in the signal chain. In my trek down this road I found a small audio company called Orso Audio which are one of their distributors in the UK and were recommended to me by Lundahl themselves. If required they can make a custom box with converter/transformer inside with DIN inputs and XLR outputs so that no custom cables would be required.

Furnished with this information some might remain hesitant in using a ‘pseudo balanced’ cable for fear of causing unwanted damage to the Naim equipment. To quell my own fears I contacted Naim again, they said…
“No, this should put no strain on the pre amplifier or power supply. All the cables are doing is presenting your speakers with line level for the internal amplifier to amplify.”

And when asked about how to connect they also said…
“To make this setup work you will simply need to get two 4 pin DIN to XLR cables, which will run out of the Supercap directly into the two speakers. It is not possible to make your system balanced as the preamplifier is only able to supply unbalanced signal, so it is important to not run your cables alongside any power cables as unbalanced cables are far more susceptible to picking up noise.”

As it turns out, I was (as usual) digging too deep into a subject and got caught up in minor detail. The correct answer was unusually the most simple (and cheapest) solution. Before signing off may I just say that (for anyone who has any doubts about me) I absolutely do not work for any of the companies previously mentioned. I, like you, am just an average ‘Joe’. I have saved all emails from the likes of Naim and ATC just in case someone needs a little more reassurance as I once did. May I also say that I was a little disappointed in the ATC dealers I visited. All were more than one hundred miles apart and all never knew the answer or had suitable cables at hand to offer for a home demo. I found this absolutely astounding. Knowing that Naim go rather well with ATC I expected better from shops who sell high end products. The cables are not expensive and take up little space in a stock room so I therefore fail to see a good reason for this shortfall.

And for the final piece of evidence, well, it’s my ears. I am currently sitting in front of my system with a pair of active ATC SCM50s and they do sound rather good. It’s strange… the infamous Naim ‘hum’ is no more. First time in thirty years I’ve not had that.

In my journey I cannot applaud enough the efforts of ATC and Naim for their answers and efforts. At one point ATC contacted Naim directly to make sure the information they were giving me was 100% correct. This, for me, is the ‘gold standard’ in customer service. So for Tom and Charlie at ATC, Alex at Naim and Rob at REL Acoustics… I owe you at least one beer for the time spent and countless emails sent in reply to me. If only all customer service was this good.

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Or - buy a New Classic preamp with balanced outputs… :wink:

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It was a few yars back I tried active ATC but I first used fthe cable arrangement to connect an unbalanced preamp as is described in the ATC-speakers handbook. It sounded perfectly fine with a vanDen Hul wire. So no transformer in that arrangement but I was worried about the earthing having the speakers mains connected to a different wall socket in the other end of the room.

So, to be safe, instead I talked to Lundahl (1 hour by car from here) and then built my own unbalanced → balanced (XLR) box. Nothing active, just a few resistors and caps. When I asked Lundahl for a suitable circuit for wiring it up (requires soldering and a bit of knowledge) they referred me to a page on their site. This kept the Supercap galvanically isolated from the speakers in addition to giving a balanced connection. The Lundahls sound amazing and is used in studio equipment as well as the Linn Klimax DSM:s (the old smaller ones). It was very simple but you need to keep the earthing under control. I built my box to connect with one cable to the stereo DIN output on the supercap, the earthing on that one should be the single reference point). I also earthed the box from that one via a switch to diconnect it. Be sure to ask a dealer or someone who knows this to do this stuff (dont rely on my ramblings here). But my Lundahl arrangement was balanced from the Lundahls to the ATC:s. Just the 20cm wire from the supercap to the Lundahl-box was unbalanced.

If the pseudo arrangement sound fine to you - I wouldnt bother with a transformer. The less stuff you use the better it tend to sound :slight_smile:

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I went with the advice of ATC and my dealer and use a simple connector from the supercap (hicap previously) to let and right inputs on the ATCs. ATC provided the cable with the speakers.

Pseudo balanced outputs in fact :upside_down_face:

When I reviewed the SCM50A with my NAC82/Hicap and a 252/Supercap on both occasions I used a VanDamme Din-XLR cable supplied by ATC and tapped off I think the third output socket on the Hicap and a similar output on the Supercap.

No hum, no probs, sounded stunning!!

Enjoy!

JonathanG

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Can you point me to where you found that please?

Hi Andy. At 3:00 minutes in Jason Kennedy’s video on Naim New Classic at https://www.youtube.com/watch?v=60oB83vJMkk .

He sounds bored almost to tears…

I think there’s scope for people to get confused with this, although in practise it might be moot.

The specifications on the Naim website are different for the streamer/pre (described as balanced impedance, 7V rms max) and the pre (described as balanced, 10V rms max). I think I’d need to see a circuit diagram to understand the marketing…

Where/how was the REL connected when active ATC’s are connected pseudo balanced from the Supercap?

When I last looked into this (Rel subs with ATC actives) I seem to recall that the only method would be to connect from the preamp using the low-level arrangement. With passive mains you have two additional options which are to connect the high level input of the Rel to either the binding posts on the speakers or the speaker binding post on the back of the amp. There is no difference between either of these two high-level methods. There is a difference between low-level and high level connections with Rel recommending the high level method. That’s because the high-level input of the Rel is “measuring” the signal within the amp/speaker circuit and they claim this helps integration.

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