Naim NA3xx and NA5xx Pre-amplifier daughter boards

Earlier Naim pre-amplifiers used interchangeable daughter boards. While the very earliest NAC12s did not use daughter boards, most were updated, and the early versions of the NAC12 and NAC22 used NA1xx and NA2xx boards that used knife edge connectors but were superseded by pin mounted NA3xx boards.

The NA3xx boards that can be found and used in later NAC12s are;

NA325 - Switching Relay, switch-on output delay x 1
NA321 - Main gain, output drive x 2
NA324 - Input Buffers x 2
NA322 - MM cartridge input x 2
NA323S - Low Output MC Cartridge input (standard) x 2
NA323K - Low Output MC Cartridge input (for higher spec carts) x 2
NA323E - Medium Output MC Cartridge input (also seen as 323R) x 2
NA326 - Link Boards for line level input x 2
NA328 - Variable sensitivity boards with high frequency filtering x 2

The NA3xx boards that can be found and used in the NAC32, NAC32.5, and NAC72;

NA325 - Switching Relay, switch-on output delay x 1
NA321 - Main gain, output drive x 2
NA324 - Input Buffers x 4
NA329 - Time-aligned input buffer boards (similar to NA729), retrofittable for upgrade by replacing the input pair of NA324s x 2
NA729 - Time-aligned input buffer boards (standard in NAC72 - can be used to upgrade NAC32) x 2
NA322 - MM cartridge input x 2
NA323S - Low Output MC Cartridge input (standard) x 2
NA323K - Low Output MC Cartridge input (for higher spec carts) x 2
NA323E - Medium Output MC Cartridge input (also seen as 323R) x 2
NA326 - Link Boards for line level input x 2
NA328 - Variable sensitivity boards with high frequency filtering x 2

The NA3xx boards that can be found and used in the NAC42, NAC42.5, and NAC62 (most circuitry is on the main board);

NA322 - MM cartridge input x 2
NA323S - Low Output MC Cartridge input (standard) x 2
NA323K - Low Output MC Cartridge input (for higher spec carts) x 2
NA323E - Medium Output MC Cartridge input (also seen as 323R) x 2
NA326 - Link Boards for line level input x 2
NA328 - Variable sensitivity boards with high frequency filtering x 2

Olive ‘big-box’ pre-amps had most circuitry on the main mother board and used NA5xx boards for plug-in source matching and, in the case of the early NAC52, tape levels. The main difference between NA3xx boards and NA5xx boards is in the way they fit - NA3xx boards sit upright with connectors on one edge, whereas NA5xx boards fit flat with connectors underneath.

The NA5xx boards that can be found and used in the NAC52 are;

NA522 - MM cartridge input x 2
NA523S - Low Output MC Cartridge input (standard) x 2
NA523K - Low Output MC Cartridge input (for higher spec carts) x 2
NA523E - Medium Output MC Cartridge input (also seen as 323R) x 2
NA526 - Link Boards for line level input x 2
NA528 - Variable sensitivity boards with high frequency filtering. Can also be used to increase or decrease output levels on inputs 5 & 6 for use with tape machines of differing sensitivities x 2 per input/output

The NA5xx boards that can be found and used in the NAC82, NAC92, NAC102 and NAIT3* are;

NA322 - MM cartridge input x 2
NA323S - Low Output MC Cartridge input (standard) x 2
NA323K - Low Output MC Cartridge input (for higher spec carts) x 2
NA323E - Medium Output MC Cartridge input (also seen as 323R) x 2
NA326 - Link Boards for line level input x 2
NA328 - Variable sensitivity boards with high frequency filtering x 2

  • A special shielding kit is required to be fitted to the NAIT 3 if MC boards are used
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