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NAP-140 Clone Amp Kit on Ebay
NAP-140 Clone Amp Kit on Ebay
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Old Yesterday, 10:02 AM   #3231
Bigun is offline Bigun  Canada
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NAP-140 Clone Amp Kit on Ebay
My 2c....As a commercial product the output protection has some merit but I bet th3 modern versions are far better and hence less intrusive. For the old NAP I see no need for DIY to include it. Good idea to include the phase networks.


With the different kinds of hf hash on mains supply these days I wonder if subtle differences in clone design are going to be worthwhile worrying over ?
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Old Yesterday, 03:31 PM   #3232
maxfrister is offline maxfrister
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Default Bare ebay PCB reviews

After looking at the options further, here is my uniformed review of the choices:


Light green. Poor quality pcb material. Layout is similar but the the same as the original (see the extra ground connection on the input). Traces are drawn with modern cad tools. Footprint for MT-200 output devices.


Dark green. Good quality pcb materials with, perhaps, ENIG flash. Layout is similar but the the same as the original (see the extra ground connection on the input). Modern cad-drawn traces. Some of the footprints have been modernized (e.g., trimmer pot). Footprint to TO-3 output devices.


Blue. Actually now black in the description. Small boards with a layout emphasis on size not sound.


Red. Good quality pcb material. Layout is the closest to the original but still not the same. Modern cad-drawn traces. Footprints for either MT-200 or TO-3 outputs. Sold for 3x the price of the other options.


I've gone ahead and ordered the dark green boards.


I intended to include the SOAR circuitry. I can't think of a good reason to omit it.


I understand that for a myriad of reasons my efforts will result in a poor copy and in no way a "clone" of the original but I'd like to try to stay true to the original. Just because you can't step in the same river twice doesn't mean you don't like to swim.
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Old Yesterday, 04:47 PM   #3233
huggygood is offline huggygood  France
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just a tip.
take a NAC 42.5 and repopulate it with the right components and a good power supply.
I have never worked my clone as well as with a clone of nac.
you will pay less than $ 25 and frankly it's worth it if you do what it takes to get closer to the original
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Old Yesterday, 05:18 PM   #3234
Ian Finch is offline Ian Finch  Australia
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You'll probably find the differences between those particular NAP boards isn't a big deal but the semis you use probably will be. The original parts were often close matched pairs/complements (and some were intentionally mis-matched too). Several times in the thread, It's been found that you really should use the original semis and grades where possible. Exceptions are the output transistors which have gone through several big changes without issues over the decades in production and I guess the general purpose MPSA types used for the current source and limiters could be substituted with BC546B/56B without drama too.

The input LTP are BC239C or possibly 2N5089 because of their higher than usual hFE. I have found it to be ≥ 450 in some original Naim amps, which may not be possible to do from small quantities of recommended types like BC550C or whatever else you can buy in low-noise transistors. Types I can buy now seem to fit a spec of only about 300-450. Sure, they should work OK but Naim were fussy about the numbers and known to reject batches that didn't meet their spec.
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Old Yesterday, 09:46 PM   #3235
traderbam is offline traderbam  Europe
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The BC550 datasheet says that the C types have hfe 420 to 800.
https://www.mouser.com/ds/2/149/BC550-888526.pdf
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