Need to identify Phono and AUX Board for NAC 72


I am new about knowledge of Naim Phono / AUX board, have NAC 72 with 2 labels :

  1. Phono BNC with K label
  2. AUX BNC with V label

What do they mean ? Do the Phono labelled K for MM or MC cartridges ?
Also the meaning of AUX input labelled V

please help to explain

Many Thanks

Info on Phono boards can be found here;

K, would indicate that when new this NAC72 had NA323K MC boards fitted for Phono.

V, likely indicates that when new this NAC72 originally had NA328 variable sensitivity boards fitted for AUX.


thank you

K label have little information printout on backpanel 100 uV or 2 mV, does it means this input can connect to MC or MM cartridge? do the board inside NAC 72 have selector switch ?

K is specific to MC, N I think equals MM (at least it does with the stageline, K/E/S are for MC).
@Richard.Dane what’s your opinion on 62 vs 72? Primavera has a 62/140 and his friend is offering a 72. No info on servicing history for any of these.

No and no. With the appropriate Boards fitted - either 522 (N) or 523 (S or K) - the input can deal with MM or MC carts, respectively.

Please - read the link @Richard.Dane has posted above. All will be clear then - or it should be.

72 is better than 62. Simples.

PS. The Phono boards are the same in the 62 & 72. You could swap between them, if that would help.


Oh I see, it’s clear.
That K label notify that This Phono BNC is just for MC Cartridges, no option for MM
and now for variable input boards ( V label ), can this AUX BNC connected to CD Player, or what is the best input in NAC 72 that best suite for CD Player?

thank you

Yes and No.

You need first to know what Boards are actually fitted - as they might have been swapped.

A K board is specifically matched with Linn MC’s. An S board is the general purpose MC board. The N board is MM. The V board is a variable, line level board, intended for CD use - but not generally preferred, these days.

Am sure most of this is in the link you were sent…? Please - read it.

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Yes, instead of the NA328 variable boards you should instead fit link boards (NA326) for a modern CD player, or else just use one of the DIN line inputs.

I believe NaimLore © says the Tuner DIN input is the most favoured input for CD use, on an early type 72, with 2 sets of BNC’s… :sunglasses:

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Good luck finding 326 boards.
Has the 72 been serviced recently?
If not, remove the 328 boards and have the original links remade. Then sell the 328 boards. They have little use now. One use was for early cd players to allow you to " tune" the high pass filter, to make early cdps sound better. And if doing that, think about replacing the bncs for phonos.

I wonder if there is any market for 328 V boards…? They are variable gain - any filters are fixed. I had them in my first 72. If they were fully turned ‘down’, the gain of CD wasn’t far off that of Phono.

BNC’s are better (than Phono’s), according to NaimLore ©…

My dealer did try to sell me a pair of 328 boards when I enquired about 326’s. Not by mistake, he was trying to help.
My 72 ( both my 72s) are slightly late versions with just one set of bncs.
I had them both swapped to RCAs. For convenience really. But no complaints.
One 72 has the RCA input links remade and I use an external phono stage.
The other has 322? MM boards and my Rega 25 goes direct into that.

Might be a stretch of forum rules but I’ve put a pair of 528 boards in a box that takes the record out from my SN3 and acts as a buffer to drive a long audio line to the other side of the house and into the mu-so Qb in the kitchen. Works incredibly well!

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I guess you cannot explain how these are powered… Or you may have to censor yourself… :thinking:

Yes, NA322’s are the N boards, for MM or ‘normal’ carts (or low output MC’s, such as my DV10X…)

Don’t mention the NA323 E boards… Mentioned them once, but got away with it… :laughing:

With an iSupply so keeping it “in the family” :smile:

Mk1/prove-out of this actually used a headline to drive the signal which also worked but seemed like overkill

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If the NAC-72 is labeled with “K” and “V” stickers like the photo above, is it possible if the NAC-72 does not have a module in it?

Do you mean only the BNC connector is there, but it can’t be used specifically according to the sticker label attached?
or do I call it dummy?

So the module inside the NAC-72 is we have to buy it again?

You need to look inside for the boards. When I bought my NAC62 from the original owners, it had no boards and they had owned since new/never used a turntable so assume the dealer may have removed the cards and sold them for a discount when new.

I bought fully serviced and boxed boards for mine from Darran at Class A for less than a set on eBay.


thank you
But my question is, why are stickers “K” and “V” attached if indeed there is no corresponding board on the NAC-72 itself?

Doesn’t the sticking of the sticker correspond to the board installed in the NAC-72?

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Someone could have removed the boards, you need to look inside.