NAP 300 DR labelling confusion

Just idly pondering and noticed that with the NAP 300 the DR sticker is situated on the rear of the amp unit and not the 300PS.
Prices for the DR upgrade (and service) only list the 300PS.
I’m confused - is direct regulation only applicable to the amp, the PSU or both?
If just the PSU, why is the sticker placed on the amp? If they are split and a non-DR PS paired with a DR labelled amp how would you know?

Just checked my worksheet from NAIM in Feb 2018, both the 300 AMP & PSU time spent 1.45 hours on AMP and 15 mins on PSU

parts changed in both, would imagine the 300 AMP has the most internals to change for DR

from memory the DR label is only on 300 AMP, but paperwork comfirms the DR upgrade was carried out on both units

Thanks for this. Does the paperwork indicate which unit was ‘DR’d’ and which was serviced?

The DR upgrade price list only specifies the PSU and not the amp for both the 300 and 500 - hence my confusion when the sticker is on the amp.

I find that hard to believe as an accurate reflection of time spent. Get the box to workstation, open the case, remove unneeded components and fit new, followed by test & reassembly, all in 15 mins? And at the price Naim charge for a service? Something doesn’t tally, and I wouldn’t be impressed if my PS was rushed through in 15 minutes.

here are the work sheets, I am only going from these

AFAIK, most all of the DR work is on the amp itself, not the power supply (not to be confused with very different DR work on pre-amp power supplies). Perhaps @NeilS can clarify.

Antz, I’d imagine the 15 minutes on the PSU was probably for the Logo replacement?

I wasn’t doubting your numbers, more doubting the veracity of the times input by the service guy. And to repeat, if I ship £8k’s worth of amp off for a service I’d hope the PS gets more than a 15 minute rush job.

The PSU now has a NAP500 block mount too.

That’s news. I understood the point of DR was that it provides much regulation of power and would therefore belong in the PS to create smooth clean power for distribution into the amp.

what ever time they spent, it was well spent the DR upgrade is outstanding, took an already superb AMP on to another level

Remember that the 300 is effectively a 250 in two boxes. The DR bits have to go somewhere and it doesn’t really matter which box. It’s completely different to something like a 555PS that can power many things.

Yes, on the big Naim amps, they are regulated designs, essentially two amps in one, where one “amp” regulates the other; which is why in the old big Naim amps the regulation boards looks so similar to the power amp boards and use the same output devices; in the NAP300 they’re in the power amp case.

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Hi Guys,

In the case of the 300 & 500, the PS contains the transformer smoothing caps & discharge circuitry, the regulated power supplies are in the head unit - that’s where the DR bit is.
The two examples of paperwork above look to have been transposed - the work carried out on the PS has been entered against the head unit. At the time, the labour charge was included in the upgrade part number, so the labour you see on the p/work is for work over & above the standard upgrade.


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Sorry about this @NeilS, I am going to collect a 300 DR in the next few days and my stacking order plans might now be questionable.

I was going to treat the 300 head unit as a “brains” component under a 252. If the power supplies are in the head unit is this OK or is it best on a shelf above the 300 PSU and under the Supercap?

I know you must be fed up of this type of question by now but your advice would be very much appreciated.

Judging by the name (not Naim), one of the devices was serviced by a female employee!

AJK, it’s the transformer that’s the brawn bit here, so treating the head unit as a “brain” is just fine.

It is brains. The power supplies are in the power supply. The regulators are in the head unit.

Thanks Richard, I am getting over excited here, its like a second Christmas day.

Jodie is male!

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HH, re PS in the PS that explains it well, obvious really.