Jeff Young
pfm Member
Three large capacitors and 16 regulators supply power to the NAC 552's various sections.
Jun sent me some more stuff on the 552, and I think Stereophile's description is a bit misleading. A bunch of those regulated supplies are eaten up by other stuff: a couple for the DAC TTL level stuff, a couple for the clock, one for the volume/balance control motors, one for the front panel illumination, one for the source relays, etc.
Near as I can tell on the audio side there's just one set for the TA filter stage and one set for the gain stage. Interestingly, it does *not* appear to separate the left and right channels.
This would suggest a single pair (+/-) of rails for 1 & 2 in the schematic in the first post, and a second set for 3 & 4, for a total of 4 rails.
If one wanted to improve on that, I'd separate left and right (for a total of 8 rails) before separating 1/2 and 3/4. But my guess is that Naim did their homework and 4 hits the sweet spot.
On another note, we *have* to use the TO-3 cased regulators. It's just so much of the Naim "look".