An original clone?
January 10, 2021 Leave a comment
Something of an oxymoron perhaps, but this NCC-200 amp from Avondale Audio probably qualifies as “the original” Naim amplifier clone.
Naim clone amplifiers are plentiful these days but somehow nearly all of them seem to reference the Avondale schematics. Some people also started tweaking the design (with varying degrees of success it must be said…) and the NCC200 also inspired the “HackerNAP” design – although in this case you have to look a bit harder to even see the similarities 😉
To be honest it’s not hard to see why these amps would be a popular subject for DIY clones. The older Naim amplifiers are fairly simple discrete designs, they sound good and they fit a DIY’ers “modular mindset” quite well. Many of the different commercial Naim amplifiers were not actually different amplifiers, just the same amplifier board with a few tweaks and then different rail voltages and PSU/chassis combinations to make both mono and stereo amps in various power and quality levels.
Before Xmas I spotted that Les (the man behind Avondale Audio) was selling his last NCC200 boards on ebay and after a bit of consideration (I don’t really need more amps after all) I decided to buy some boards. With such a variety of clones there are obviously numerous cheaper ebay options available for boards but that wasn’t really the point here – I wanted to try “the originals”.
I was honestly planning to show this build in slightly more completed form, but gave up on that when I suddenly realised that I didn’t have the MJ15003 output transistors in stock anyway (they are now in the mail somewhere). The NCC200 has what’s called a “quasi-complementary” output stage, meaning it uses two NPN output transistors per side rather than an NPN/PNP pair. Which obviously means you need four (4!) transistors for a stereo amplifier and that is apparently more than I can count to at the moment…
For the power supply I think I’ll go with a “barebones” configuration of just a single PSU for the whole amplifier instead of separate PSUs for the front end and output stage. I have a few PSU board designs already – not least my “HackerCAP”-clone – that could be used, so that part I am not too concerned about.
In the stock form this is quite a low-bias amp and so it can get by with limited heatsinking. As I have a pair of small boxes from ebay already I plan to make these into a pair of small mono blocks. Apart from missing some suitable transformers I just need to shoehorn all the parts into the boxes. It looks doable though, so once the missing parts arrive I can start working out how to do that 🙂