NAC 42XO - what do I have?

Hello all - first post!

About 15 years ago, I picked up this NAC 42. I’m missing the power amp, so I never have powered it up.

I recently decided to take a look at this and figure it out. The rear tag lists the model as “NAC XO”. It also appears there the is a sticker over the original connection chart. Wondering if this was upgraded at some point? Here’s some pics - I think it has MM phono boards.




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It may well have started out as a NAC42XO but it must have been converted back to a regular NAC42 (actually looks like a NAC42.5) at some point, with a new main board too by the looks of it.

Here’s what a NAC42XO would have looked like inside;

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I’m assuming this would have been partnered with a pair of 110s / 140s at the time (which would also provide power to the 42XO) ? Any ideas on typical speaker partnering combinations at the time - Naim, ARC, Linn etc ?

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Yes, typically a pair of 110s. Speakers would most likely have been active KANs, or SARAs.

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Ah ok - thanks Richard. I take it not too many of these were made ?

I don’t know the numbers, but I don’t think there were that many. And of course a good number would have been converted to regular NAC42/42.5s in later years.

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I had a NAC42, bought 1982. Think it had a spare DIN socket, which was for potential conversion to 42XO…?

On its conversion from 42 to 42.5 (main PCB changed), that spare socket became the 5 way HiCap socket, I think… :thinking:

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Yes, the extra DIN socket for the 42XO was convenient for the 42.5 conversion.

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Interesting info - thanks both.

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Thanks for the helpful replies!

Any thoughts on the phono boards? I couldn’t decode the numbers beyond the 322 for MM.

NA322 MM boards. Is there an issue number on the PCB? Final version was NA322/4.

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I have a set of those, from a 1995 build NAC72.

Making some progress. Hooked up a laboratory power supply and various jumpers to get signal in and out. Changed the BNC on the phono inputs to RCA.

Did some testing with CD and vinyl. Sounded pretty darn good with cd. Vinyl was OK, but I’m using a new cart which I don’t have a handle on. The Vintage Sony amp is also a bit of a wildcard. Late 80s vintage (recapped). I haven’t used it in a system before. Thinking about moving this system downstairs and giving the Marantz a break.

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