As there are some Naim experts (mr. Ian) here i wanted to ask somethings about a project i'm wanne start. I can get some original power boards for free. I want to put them in a nice Modus case with nice styling (Naim knobs and fonts etc). As you can see there is some work on it. I wil rebuild them. For a PSU i am thinking of a simple bridge with 20.000uf per rail just like the 140. For a transformer i think i can use something from 25vac to max. 27vac?
I'm also going to apply some acoustica.org mods like remove current protection circuit and coupling cap and maybe some Welwyn resistors in the signal and feedback.
But can you tell me something about these boards and if i'm overlooking something about this PSU or project?
My second ask within this build is the pre. After reading a lot about this i'm have my mind set on a NAC72 witch i also have. I'm gonne use a Sjöström reg on it. And maybe leave the buffer out. The relay i'm gonne leave out for sure.
But looking at the circuit i see a lot of coupling caps. I have caps in my sources. So are there any objection about leaving some out as you can see in my drawing?
I'm also going to apply some acoustica.org mods like remove current protection circuit and coupling cap and maybe some Welwyn resistors in the signal and feedback.
But can you tell me something about these boards and if i'm overlooking something about this PSU or project?
My second ask within this build is the pre. After reading a lot about this i'm have my mind set on a NAC72 witch i also have. I'm gonne use a Sjöström reg on it. And maybe leave the buffer out. The relay i'm gonne leave out for sure.
But looking at the circuit i see a lot of coupling caps. I have caps in my sources. So are there any objection about leaving some out as you can see in my drawing?
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Good day Arnolddev
Please give more information about yours original boards
Boards is not working? Or need repair ?
Also I have questions about your preamp
you need build new ?
or you have work NAC preamp ?
I have clean boards of NAP140 maybe you need relocate original parts from damage old boards to new ?
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I'm need to check and rebuild the boards. Resistors are missing and transistors. Do you have a blue print with resistors numbers and transistors of the pcb? I can find the sceme's but not the pcb layout with parts.
The pre amp i think i'm gonne make new ones based on nac72 with time align and gain stage. I have a NAC72.
Nice boards you have.
The pre amp i think i'm gonne make new ones based on nac72 with time align and gain stage. I have a NAC72.
Nice boards you have.
In attachment Chinese clone of NAP140 boards with silk print parts nominals
Maybe this help to you
And schematic for yours boards with NA001 output transistors
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I living in Rus and if you have friends in Rus who send to you boards I send boards to friends
Cost for two clean boards 8$ without shipping
photo of ready boards after building in attachment
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Also photo of original boards (NA001 output transistors) in Amp
I think this help you for repair
Nominals of all resistors great watching on this photo (colour rings)
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Nice. I had the same idee. But a slighly modified lay-out. I want to leave room for different film coupling caps in stead of the tantalum. Also the relay on the Nac, what is the function. A delay for powering after the NAP has powered first?
I do not have any friends or connections in that part of the word. Did you you not want to populate the boards with the original Philips resistors and orgininal transistors? I think the pcb is a upgrade. What kind of copper (um) did you use?
I have many diy boards
In all boards I use original transistors but I have few boards with not original resistors and original resistors
Sound is different if you use different resistors and I testing both 🙂) sound with original resistors little soft but not original resistors little strong I like both variants
For preamps I make both variants PCBs resistors
also I make nac boards with ZTX and 2N50xx transistors
This is very interesting experience🙂)
in attachment both variants NAC boards (orig and not orig resistors) and NAP boards with original resistors
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The big question with any clone build is, how original it must be in sound quality, power, size and appearance etc. NAP140 is actually only a shoebox size amplifier of 45W per channel/8Ω but arguably, the best sounding of all the original models. 'Problem is, the earlier clone kits were based on only the NAP250 power amplifier board, then simplified to a Chinese DIY forum's H140 design and fitted with whatever semis would work and were cheaply available. The result has an acceptable sound but nothing like the original and sought-after Naim sound quality with it's PR&T effect (see the OP of the long NAP140 thread). Perhaps if you never heard the original, that wouldn't matter so much.
Recent Chinese clones and PCBs are now supplying something closer to the NAP250 schematic with a similar PCB appearance from the topside but the copper side traces may be quite different and some include its phase correction networks, others don't. Some have also had circuit errors or just don't look like good layouts to me. It pays to thoroughly check what you buy because the finished amp may work fine but not sound anything like you assumed it would.
Don't forget to also use appropriate supply voltages and approx. original transformer power ratings (or regulation in the NAP250 case) either. Power supplies do make a difference.
Recent Chinese clones and PCBs are now supplying something closer to the NAP250 schematic with a similar PCB appearance from the topside but the copper side traces may be quite different and some include its phase correction networks, others don't. Some have also had circuit errors or just don't look like good layouts to me. It pays to thoroughly check what you buy because the finished amp may work fine but not sound anything like you assumed it would.
Don't forget to also use appropriate supply voltages and approx. original transformer power ratings (or regulation in the NAP250 case) either. Power supplies do make a difference.
I get all boards from Factory
When I create order I see FR4 raw material
I think this one standard thin 70um but I not sure 🙂)
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Correct 0.22 is emitter resistors and output resistor.
8.2 ohms and 12 ohms this is zobel circuit (need for hi frequency cut in output for stability amp working with many loads)
8.2 Ohms use in old Naim amps
12 ohms use in new Naim amps
Naim actually use a very mild form of Zobel network and older designs that most clone kits are based on, up to the olive series, had none at all. Standard Zobel values are more usually 4.7R + 0.1µF though it's not critical for the purpose of stabilising the amplifier when driving some of the nastier 4-8R loudspeakers.
New NAIM NAP500 have 4.7 Ohms but this amp is BTL design
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New Nap 300 have 12 ohms and NAP250.2 too
but I not have information about zobel resistor nominal in DR version 🙂
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I dare say the precise C, R values are unimportant because of the low Q of Zobels. So whether its 8 or 12 ohms may not be significant, as long as the time constants are roughly similar. In other words, if you want a precise time constant for some reason, you could compensate the smaller resistance with a larger capacitance and vice-versa according to T = CR where T is the time constant in seconds, C is the capacitance in Farads and R is total resistance in Ohms (not forgetting that some, not all, wire-wound resistors can also have considerable parallel inductance).