NAP-140 Clone Amp Kit on eBay

They are excelent!... do not loose a minute more to buy them

regards,

Carlos
 

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The good thing about the Naim circuits, in general, is that they use relatively few parts and so are easy to build and get working. At US$50 for two boards and all parts it is at a reasonable price.

Just a couple of things. The design is not the same as a real NAP140 so it won't sound the same. Looking at the photo, the output transistor over-current protection circuit is missing so you'll need to be careful never to accidentally short the speaker outputs or the transistors will be destroyed.

Brian
 
It seems to be some finishment applied over the aluminium heatsink dear Ebbe

Those anodising results, that transforms silver aluminium in something that remembers copper or gold.

The one is not very clean, not very polished, not very new....some heatsink he captured from dismounted amplifiers.

regards,

Carlos
 

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Is this topology Class A? Can it be biased into Class A if not?

I am familiar with Naim, but never had/heard one...from a few posts I have read, and pics I have seen, I have never seen one with monster heatsinks, so my guess is they are not Class A amps...
 
John,
You are right. The Naim's are class AB - with output transistor bias current set in the 30mA to 50mA region (as far as I recall). Very good for the environment. I see no technical reason not to bias it higher if you wish. In a real Naim circuit the extra bias doesn't affect the sound much. They are also what would usually be called high NFB designs.

The circuit is deceptively simple, based on an RCA design from the 1970s. But it is not simple at all. To get them to sound as good as Naim does requires a lot of careful selection and matching of parts. The parts these clone circuits use are not all the same ones as Naim uses.
Brian
 
Hello

Yes, Naim amp do used selected parts and the LTP input pairs transistors was matched for HFE and VBE , and take a fast transistor for the VAS.

In the NAP 250 schematic you can see a 10 uf cap in the protection circuit, it's to do a small delay so the protection will get in after that small delay and will do less interferences in the normal high level output signal.

Bye

Gaetan

Here's the NAP 250 schematic;

An externally hosted image should be here but it was not working when we last tested it.
 
I did end up purchasing that kit and I'm providing the schematic that came with it. There is also another sheet included in Chinese. The boards are very nicely constructed with gold traces. The parts are as described in the listing.

I compared this schematic with the one posted by Carlos, some slightly different values, those are highlighted with an asterisk.

I have never built a kit and this looked to be a good first one, not sure when I'll get to it, though. If anyone wants any additional information on what I received, just ask.

There is some writing on the board:

AEON copy NAP140 2007 and hifidiy.net.

I do have one question at this point: I have two power supplies from the Accurian receiver that recently was going for $15. The toroid is a 28-0-28 2A. Would I be able to use these for a dual mono arrangement? If not, what are the power supply needs, they are not indicated in the schematic.
 

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