Naim NAC-42 233 MC Card The Color of Preamps

Click all  pics to enlarge: lower left corner; the red and black wires are my addition, the + and -ve of 24V DC. The vertical boards are MC Phono Boards. Pic immediately below shows the Jameco on the power bar.

Review: Naim NAC-42 Preamp with 233 MC Card 
Naim Nait 1, 2, 3

Revised 3/14/22: A few corrections after a reader pointed them out.

If not for the lockdown, I'd never have acquired this piece of equipment. It was quite a bit of work to get it going, just to prove on the cheap whether a hunch is correct or not. As Naim is well documented on the net, I'll not cite much for background.

My Unit The Serial Number of my recently acquired very reasonably priced but mint US 120V Naim NAC-42 (1979-85) Preamp is 7416, which Naim's Website tells me is from 1983. My unit came with the 233 MC Card but without power supply, which is usually derived from its matching 110 Amp. In terms of looks, those large knobs are kind of whacky - I prefer the looks of the Nait 1 and 2 that I had before. I was also surprised by the size of the shoebox, a little larger than I remember of the Nait 1 and 2 (but my recollection could be faulty). At the bottom of this article is an old review.

Why This Project? Sit tight, for this will be heresy to some: I wanted to show that the magic of the earlier Naim's (which many prefer to later ones) come mostly from the Preamp Section than from the Amp Section. Let me tell how this came about. It started with the NAD 3020 I have always loved this iconic NAD integrated amp and have written a lot on it. Around 2014 I acquired a 220V unit and tested it in NYC before bringing it back to HK. I didn't write about it then but one of the things I did was to evaluate the preamp section (3020 has preamp out-amp in jumpers which can be removed to facilitate the use of either section). Used with my other amps, the sonic signature remained very similar. I concluded that the NAD sonic signature largely comes from the preamp section. This was corroborated by my friend Hoi when I visited him (here). On to Nait 1,2,3  Back in HK I then got to use all 3 generations of Nait's, but not their power amps, which are overpriced. I particularly admire their rhythm and pace. My first was the Nait 2 which truly astonished me. As I wrote in my Special Integrated Amp Article: "...These are excellent but not as neutral as the Cyrus. The sound is bolder and Naim's famed "Rhythm and Pace" is very much in evidence (more than its modern counterparts), but there are things to watch out for: (1) the vital vocal midrange is a little recessed; (2) Lower midrange to upper bass is a little emphasized; (3) Treble is just that little bit reticent. Its primary strength is in its portrayal of the leading edge, an area I have not heard its equal. It is best partnered with its own CD players, which shall yield a sound that is uniquely rhythmic and pacey, not neutral but a paradigm in what it excels in. In a complete set, it can lay claim to a unique sound not heard with other brands, and here I tip my hat. An example is my Nait II and CD2 (TDA1541A) combo. With it, the ATTACK of a single plugged string (like guitar), or drumming, is phenomenally live. Even more surprisingly, the "rhythm and pace" benefits tremendously a slow instrument like the organ. With Bach's organ work, you can literally feel the different degree of attack that the organists applied on the keyboard, and it's a revelation. For a good read click for this TNT audio article. Note that the phonostages are either MM or MC, and they are excellent..." My first was the excellent Nait 2 but some reason I didn't write it up individually. Then came Nait 3 (here) and last, the Nait 1, which I only let go when I left HK (here). Of the 3, in terms of the most prized Naim rhythm and pace, I'd say it's a toss up between the 1 and 2 (the 2 is from memory a little airier), but either is significantly better than the 3. Incidentally, I have heard the later 5(i) and it is not even close to even the 3, not to mention the 1 and 2. So! Given the unique early Naim sound which I know so well and love, I wanted to investigate whether the Naim Preamp is responsible for the sonic signature. This project is on the cheap and I'd not have to get a Naim amp, which are expensive. Nait 1 was produced from 1983-88; Nait 2, 1988-93; Nait 3 1993-2000, so my 1983 NAC-42 likely most corresponds to the Nait 1. Does it have the magic?

Power Supply One can power the Preamp from a Naim Amp of the period, or one can use one of Naim's Power Supplies (or an aftermarket one). This ecoustics forum thread gives a run down on which ones to use and how to connect. Basically, what is needed is a 24V DC power supply, easy enough, right? But we shall see. As this Naim project is just a diversion I was not about to go all the way to build, not to mention buying, a serious power supply. I toyed with the idea of using one of those cheap Chinese DIY 24V kits but that's still too much work so I resolved to use Wall Warts. Online discussions mentioned the preamp uses very little power, estimated to be 0.5 A or less.

Connectivity Except for the Phono Inputs of some units (others even use BNC), the Naim's of this era all use various DIN connectors, which they claim are superior sounding (actually many UK manufacturers like Meridian and Quad also used DIN connection early on). The Preamp Output is the most interesting, utilizing a 4-pin DIN that sends both the signals to the amp and 24V DC power supply back from the amp to the preamp (signal and power supply grounds are common). Tuner Input uses a 180 degree 5-pin DIN, as does the Tape In and Out.

A Lot of Work! First, I had to gather some parts. I have leftover quality 5-pin Rean DIN male connectors but for 4-pin it seems only generic ones are available, so I ordered a 5-pack. I also ordered the appropriate 2.5mm male socket for mating with wall wart. The extra unlabeled 4-pin DIN is supposed to be used for the SNAPS Power Supply, but it is not even connected to the circuit board. As seen in the top pic, I decided to avail myself of this socket by soldering a red wire (for 24V+) and black wire (for 0V) to the appropriate points on the circuit board (red wire and green star ground). I constructed a 4-pin DIN to Male 2.5mm DC plug socket adaptor (rightmost grey cable) for mating with the wall wart. Thus I did not have to connect the power supply to the preamp out cable (less soldering difficulty). The 4-pin DIN is connected to 2 runs of the slim but sonically good Belden 8451 (my go-to hookup wire, used also in my TU-8150 bypass). For Tuner Input I divided up the 4-conductor Mogami 4534 for both channels and connected it to the 5-pin DIN. Boy, soldering those tiny and close-together DIN pins was a royal pain, especially with the lower-quality 4-pin connectors (I ruined one)! Finally I was ready to go!

Turntable: Technics SL-1200 Mk II with Denon DL-103
Bluetooth Receiver: Dayton Audio BTR-01 Digital Out with Belden 1694A
DAC: Micromega MyDAC
Amp: Akitika GT-102 with Gotham 50025
Loudspeaker: Audiomaster LS3/5A 15 ohms

Comments and Sound

• Power There is no on-off switch on the preamp (it is on the 110 amp). When the power is plugged in, the light stays on. To turn off, I had to unplug the wall wart.

• Interference First I used a Switch-Mode Power Supply and, sorry, that was no go. I heard a high-pitched frequency sound and knew that was interference. So I ordered a 24V regulated Linear (transformer) DC Wall Wart, made by Jameco in Taiwan (Part # 174879, here), a really high quality unit. Despite the heft, its rating is only 0.5 A. I have had it on for many days and it only gets lukewarm, so I deem it sufficient (I do unplug when signing off). The background was totally quiet. I highly recommend Jameco Linear DC power supplies if you are looking to upgrade your Switch Mode DC supplies and your current requirement is not high (more current of course available for lower output voltages).

• Scratchy Pots Initially occasionally one channel or both would cut out. Rocking the selector back and forth would restore sound and with time the problem disappeared, even without cleaning.

• Cables Before I forget I shall say that, in contrast to most Flat-Earthers, I have always disliked the stock Naim interconnect cables (which are made by Chord, whose cables I don't like because of their subtractive nature). Yes, I have compared before and I prefer my Gotham, Mogami, Belden. And, for loudspeaker cables I never used NACA either; I have use Gotham  (50025 and 50150) and Belden 9497 to great effect.

• Sound - Line I knew exactly what I was in for. Coming off the Artemis, I felt the top lacked a little air but the ear soon adjusted. The sound was exactly like what I wrote about the Nait's (shaded text above). Very good rhythm and pace, more apparent on jazz. As I was just streaming I did not even try the CD.

• Sound-Phono Wunderbar! I played the Hank Jones Happenings (Impulse, shown in next to top pic) was swinging hard! And, with the keyboard, that famous Naim quality was again evident - we can virtually feel (and hear) how Jones touched the keyboard (again, see shaded text above). This was the first time I used a Naim MC card and I have to say I think it is superior to my experience with the MM Cards (well, I prefer MC).

Conclusion My write up is short, but actually I listened to the Naim endlessly for at least three weeks. I am convinced, like the NAD 3020, The Naim Preamp, or Preamp Section of the Nait's, is largely responsible for the Naim Sound.

I hear you. This is not "neutral"; this is a "color". Well, if "colors" make music sound real, I want more colors. If colors make me feel and hear how Hank Jones touches the keyboard, I want more colors. I am glad vintage Naim is so "colorful". And perhaps Western Electric is colored too?

I'd gladly have continued using the NAC-42 in this baking hot weather (I only use a fan). But then by chance I got a Yamamoto Preamp, which beckoned me away...I told you, no relationship is forever, but a fling now and then is rejuvenating...who wants to be tethered to something that is always "correct" - meaning you are always wrong in your desires?

Pic above from 7/89 Streophile; review below from tomtomclub page