Counterfeiting is a real problem in electronics, which is why I order almost everything from mouser, or almost from RS component or farnell. In principle, with these suppliers, the origin is guaranteed. Honestly I did some tests with other suppliers on the internet and each time it was counterfeit...
That's why for me I strongly recommend to buy only from these big suppliers (Farnell / RS comonents / mouser / digikey)
That's why for me I strongly recommend to buy only from these big suppliers (Farnell / RS comonents / mouser / digikey)
Now, I did as feedback 1k+39p and 27/33 ohm & 560/390ohm version, like original nap140. but, my psu is 40v. And for idle current I used proper BC239's and changed MPSA06's emittor resistor. I think I finished. My advice, first finish the proper and easy nap140 original device (Because you can find orginal power transistor 2sc2922). After then if you want you can change the power transistors (and feedback and phase compensation resistors) for extra power and bass extention. Use NAP140 as reference.
For Nap140 I used the original circuit and values. 47uf feedback tantal Phillips 6v and 470pf's Kemet's double sided PP/250v. And NAC42.5 pre. from chinese with different PSU from NAP and only changed 47uf cap with ELNA silmic-> must be. Result is really good. I'm using with Hi-res player of FIIO.
For Nap140 I used the original circuit and values. 47uf feedback tantal Phillips 6v and 470pf's Kemet's double sided PP/250v. And NAC42.5 pre. from chinese with different PSU from NAP and only changed 47uf cap with ELNA silmic-> must be. Result is really good. I'm using with Hi-res player of FIIO.
Where do you find original 2sc2922 ? I think they are no longer manufactured but on the other hand it seems to me that there is a more recent equivalent reference I will try to find that.
For example in https://octopart.com / Newyork. also, https://www.digipart.com/
Somebody wrote in that forum, 2SC3263 is the same chip, different case. I don't know.
Somebody wrote in that forum, 2SC3263 is the same chip, different case. I don't know.
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Here a LAPT equivalent of the 2sc2922 on Digikey it's very close
https://www.semicon.sanken-ele.co.jp/sk_content/2sc3519a_ds_en.pdf
https://www.semicon.sanken-ele.co.jp/sk_content/2sc3519a_ds_en.pdf
Like the NAP 500! I had thought about this implantation for a while, but I gave up afterwards.
The elements are well placed the space is well occupied, how much are the transformers? how do you do double mono? The third trasnfo is to feed protection cards?
The elements are well placed the space is well occupied, how much are the transformers? how do you do double mono? The third trasnfo is to feed protection cards?
The big transformers are 500VA each, the small one has 2 windings which go into the CRC boards for the front end. The bigger cap boards are for the power stage. So basically two complete mono amps in one case, only the front end has both transformers wound onto the same core. The case is too tightly stuffed, I hope I don't get interferences or hum. A second case (not in the pictures) will contain the Naim boards, I will post more pictures as I progress. Cases are 2U dissipate 400mm by Modushop, I ordered extra top and bottom covers without air slots...
I plan a Naim amp with the original amp and regulator boards and 2 vintage Holden+Fisher transformers. This amp will be like two NAP135s in one case.
The second amp is my own clone amp as shown in the picture with two Toroidy transformers and the extra transformer for the front end super regulators.
I am curious if the Naim amp sounds better than my clone with separately regulated front ends and power stages...
The second amp is my own clone amp as shown in the picture with two Toroidy transformers and the extra transformer for the front end super regulators.
I am curious if the Naim amp sounds better than my clone with separately regulated front ends and power stages...
I would use the big ones as chokes.
Not the "super-regulators" I would use. And certainly not channel separated, double mono! Also same components sound differently, and also same power supplies from same components modulate the sound channel-unequal, which leads to a more unclean sound: cloudy, noisy, flat, undynamic.
;-)
Did you try it? I tried it. Separate PSUs for the channels sound far better with this amp. And even with a shared PSU you will have different parts in each amp channel, so it never can sound absolutely equal. Also my ears sound considerably different: nobody has exact same ears left and right. So the PSU seems to be the smallest problem in this regard. But please explain how to use the transformers as chokes! I would love to see your suggested schematic.
😢
If it sounds better, then your speakers, sources and so on are not good enough. And the construction of the amps too has many problems. For example, all the sockets and plugs that connect power supplies and boards and connectors... All that sounds like scrap metal. This is countered by a grey, flat, noisy character through, for example, channel-separated and active power supplies.
Use the secondary windings of the trafos. In series. One trafo for + and one for -. The primary winding you could use, per shorting, to test the difference C-C-C and C-R-C.
If it sounds better, then your speakers, sources and so on are not good enough. And the construction of the amps too has many problems. For example, all the sockets and plugs that connect power supplies and boards and connectors... All that sounds like scrap metal. This is countered by a grey, flat, noisy character through, for example, channel-separated and active power supplies.
Use the secondary windings of the trafos. In series. One trafo for + and one for -. The primary winding you could use, per shorting, to test the difference C-C-C and C-R-C.
I don't quite understand the origin of your review. The dual mono architecture is widely used in a lot of amplifiers, while I'm not sure it offers a gain in sound quality I don't think it diminishes the quality. On the other hand, it is heavier to manufacture and for the wiring.
For the additional regulation stage it is the choice made by NAIM with its DR system, having never made a direct comparison between a NAIM NAP 250 and a DR version myself I do not know but I think that if NAIM fact is that it still brings a plus.