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Power supply rails for NAC 282 & 252?

Discussion in 'audio' started by Paul McDonough, Feb 13, 2020 at 9:41 AM.

  1. Paul McDonough

    Paul McDonough Active Member

    I think that I understand the Naim hierarchy for Naim Pre's and PSUs, but reading the specs for the PSUs doesn't tell you what supply rails are actually utilised by the 282 and the 252 in each pre/PSU combination.

    Can anyone point to work or investigations carried out which identify the supply rail requirements of the Nac 282 and the 252?

    I'd just like to understand what is actually going on.

    Many thanks
     
  2. MJS

    MJS Trade: Consultant at WH Audio

    The 282 can use 4 rails from 2 hicaps or a supercap. We can unlock that to 10 for use on the supercap (likewise with NAC 82 and 102)

    ISTR that the 252 uses 8 of the supercap rails and passes two more through for the external phono stage.

    Basically each audio stage - phono, filter/buffer, gain, and tape buffer all run from their own supply. Multiply by 2 for stereo. The filter circuit (aka 729) in later preamps is split into two sections with their own power supply. Our mod does this for the older preamp too.
     
  3. Paul McDonough

    Paul McDonough Active Member

    Thank you very much for your reply MJS. I wonder if I may read back to you my understanding of what you have said?

    The 282 requires either 2 or 4 regulated 24V DC supplies and from you say the use of a Supercap would mean that a lot of its power rails would not be utilised.

    Similarly, even with a 252, I am guessing this still just makes use of 24V DC rails, just more of them (8 No.) and that this is because the 252 is normally wired to take advantage of 8 No. separately regulated 24V DC rails generally derived from the Supercap?

    So the pre-amps only use 24V DC supplies?

    From your description, you seem to be saying that you have found a way of breaking into the power rails inside the 282? This is very interesting as I had a suspicion that this was a significant part of the difference between a 282 and a 252. Can I ask, is this 'unlocking' process reversible?
     
  4. MJS

    MJS Trade: Consultant at WH Audio

    The short answer to all of your questions is yes!

    The modification to allow more rails from a supercap is called the SuperLink and was designed for the NAC82. It also works for the 282 and 102 (and 32,42,62,72 by eliminating the 4 pin power socket).

    The usual Naim link plug that sets 2 or 4 rails for 82/282 is removed and a 10 pin plug is put in instead. This allows us to use it as a link plug or to insert more power rails (all 24v). It is supplied with link plugs so you can still run the 82/282 from a single amp, 1 Hicap, 2 Hicaps, or a Supercap. It's entirely backwards compatible or reversible.

    https://witchhatservicing.co.uk/82-superlink-mod/#howitworks
    There are pictures in the drop down FAQs at the bottom of the page.
     
  5. Paul McDonough

    Paul McDonough Active Member

    Thank you MJS, perhaps for once I was paying attention!

    your modification sounds very interesting, I think that you may have convinced me to go for a 282!
     
  6. Rosewind

    Rosewind Lost in Translation

    Did you ever compare the Superlinked 282 to a 252?

    I am curious, as once upon a time, I owned a Naim Nac 252.
     
  7. Jonn

    Jonn Tons of Trouble

    I had the Superlink 282 mod done around 18 months ago and it did not make it more 252 like. I've owned a 252 in the past and didn't find it to be an overall improvement on the 282. Gains in refinement but losses in rhythm and timing.

    This is what I wrote following the 282 mod:

    "I've had the Superlink mod done on my 282 so that it can benefit from ten rails from a Supercap rather than just four. A couple of link plugs are supplied so the amp can still be powered by a Hicap for example so no change in connectivity.

    There is a significant improvement in clarity and differentiation. For example, vocal inflections are more evident and it is much easier to distinguish between singers in a group. Words in a song that had previously been difficult to discern are now much clearer. Overall you can hear "deeper into the mix" and the sound remains very engaging.

    So a worthwhile upgrade in my view at reasonable cost."
     
    Rosewind likes this.
  8. Paul McDonough

    Paul McDonough Active Member

    Thank you Jonn, that's great feedback.
     

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