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NAPSC Voltage & Polarity

M

Mus

pfm Member
I want to put together a NAPSC replacement for a friend's 102 but I need a bit more info:

i) The NAPSC output voltage is 18.5V but the 102 has internal regulators so what voltage range can I get away with, would 24V be OK?

ii) If I use a wall wart will it need to be regulated, any recommendations as to make/model?

iii) What is the polarity of the NAPSC plug, looking at the end of the plug with the cut-out to the right is the top or bottom pin 18.5V (see attached image)?

TIA

Regards,

Mus
 
"i) The NAPSC output voltage is 18.5V but the 102 has internal regulators so what voltage range can I get away with, would 24V be OK"

24V is fine - that is what is applied when the link plug is in place.

"ii) If I use a wall wart will it need to be regulated, any recommendations as to make/model?"

Yes you'd need to use a reg'd one, rated at approx 250mA minimum. Hot tip -The telecomms industry is awash with wall warts of suitable ratings.

"iii) What is the polarity of the NAPSC plug, looking at the end of the plug with the cut-out to the right is the top or bottom pin 18.5V (see attached image)?"

I should know this but can't remember. Open up the pre and the answer will be revealed!

Mr Tibbs
 
Originally posted by Mr Tibbs
I should know this but can't remember. Open up the pre and the answer will be revealed!
Click to expand...

Mr T,

Thanks for the info much appreciated. As my friend is a considerable trek away, and not able to open up a plug let alone a 102, the polarity would still be useful if anyone knows.

Regards,

Mus
 
Mus,

I can tell you the polarity tonight, I'll check my Headline for you.

Otherwise the rest of the info is fine and despite the manufacturers advice to the contrary, the NAPSC supply doesn't appear to be too critical, from those that have tried various options.

Definitely get a regulated one, if you want to build something nice looking, take a peek at the FAQ section here.

Andy.
 
I'm running an 18V unregulated supply (IOW, just a transformer, some diodes, and a smoothing capacitor). It's rated @ 1A, and it sounds just fine. What benefits might I experience by doing a larger supply and adding regulation down to 18V?

BTW, pin #is positive.

-=> Mike Hanson <=-
 
Hi Andy,

Thanks, much appreciated. I had a look at your "battery charger" NAPSC when you first posted it; it's very nice but we will be going for the skinflint option :)

Hi Mike

"BTW, pin #is positive."

That was an unfortunate place to have a typo, thanks anyway.

Regards,

Mus
 
I run my Headline from a, heresy, heresy, generic 12 V supply. Looking at the bits and pieces inside I would say it's switched to. Sound nice.

JohanR
 
as you look at the socket the 'BOTTOM. pin is the 0v. IIRC or better still get the sleeve off (go on you know you want to) you will see the 0v pin connected to the 0v track (all 0v are top side of the PCB).

Graham
 
Originally posted by Mus
"BTW, pin #is positive."

That was an unfortunate place to have a typo, thanks anyway.
Click to expand...
:eek: Sorry about that. It's #1 that's positive.

-=> Mike Hanson <=-
 
Have you tried 'better' supplies for the NAPSC side of things?

If so, what did you find?

I'm running an 18V unregulated supply (IOW, just a transformer, some diodes, and a smoothing capacitor). It's rated @ 1A, and it sounds just fine. What benefits might I experience by doing a larger supply and adding regulation down to 18V?
Click to expand...

There may not be any, I don't know to be honest. The possible advantage of regulation may just potential stability (no pun intended!).

Andy.
 
Andy and others

Originally posted by Andrew L Weekes
Have you tried 'better' supplies for the NAPSC side of things?
If so, what did you find?
Andy.
Click to expand...

I've tried various here but found little improvements, if any. As far as I can see it ONLY supplies the switching and motorised pot circuits. If you power the NAPSC before any external audio supply
you will only see the switching LED's elluminate.

In thery then it has nothing to do with the audio side of things. or does it???

The LED's on the Naim 'logo' are supplied from the audio supplies and not from the NAPSC, you would of thought that they would of utilised the NAPSC for this.

In the end I use the one you put together Andy, as found in the FAQ here.

Graham
 
Thanks Graham,

The big advantage of the NAPSC is removal of the digital currents from the analogue supplies, but there can be more subtle effects elsewhere (for example within relays - big coil next to signal path, could couple from PSU rails to audio path, depending upon impedances etc.).

Pinout info for the NAPSC is now in the FAQ project, at the bottom of the page.

Andy.
 
"The LED's on the Naim 'logo' are supplied from the audio supplies and not from the NAPSC, you would of thought that they would of utilised the NAPSC for this."

Yeah, I remember changing that so my DIYPSC powers the logo as well. Every little helps....

Mr Tibbs
 
but there can be more subtle effects elsewhere (for example within relays - big coil next to signal path, could couple from PSU rails to audio path, depending upon impedances etc.).
Click to expand...

I knew that all along, did I bollocks.

But makes sence now, I could hear something, but oh so 'subtle' as to what I could not say and so I dismissed it.

Strange thpough how I ended up with ALW/Farnell special NAPSC over a few others inc. the Naim

As always Thanks Andy

Graham
 
Originally posted by Mr Tibbs
[BYeah, I remember changing that so my DIYPSC powers the logo as well. Every little helps.... [/B]
Click to expand...

A lesson learnt here by me ........its hard enough getting every last drop of music out of a system so why give it up to an Elluminating Sign.

Graham
 
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