I think this amp is best enjoyed with its limitations. The original amp is just 45Wpc after all.
I find it sweetest if listened to at moderate volume and sitting no more than 2m (about 7ft) from the speakers. Living in an apartment, that's about all I can afford anyway😅
Should I decide that I need more power, I think it'll make more economic sense for me to buy another unit and use them as mono block. It doesn't even matter if I rip out the extra channel coz its QI is so low
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I see this is a finished retail product rather than a DIY kit of parts, so you have only the product to discuss and compare with what? Perhaps the NAP250 it's derived from or the appropriately smaller NAP140? This won't sound much like either or anything Naim produced since though.
45W is plenty of power in a typical apartment dwelling or small home. I'm happy with just 10. Loudness really, is a matter of speaker sensitivity, the room size and the tolerance of any other family members to the program. We often forget that perceived volume has a logarithmic scale and 100W is only twice as loud as 10W etc. Accordingly, most people will have the volume on their 80W amplifier at or below about 10 a.m. - perhaps only 5W peak. The most popular and best known Naim model is Nait2 and its only rated 20W/channel - still plenty of power for personal entertainment though.
45W is plenty of power in a typical apartment dwelling or small home. I'm happy with just 10. Loudness really, is a matter of speaker sensitivity, the room size and the tolerance of any other family members to the program. We often forget that perceived volume has a logarithmic scale and 100W is only twice as loud as 10W etc. Accordingly, most people will have the volume on their 80W amplifier at or below about 10 a.m. - perhaps only 5W peak. The most popular and best known Naim model is Nait2 and its only rated 20W/channel - still plenty of power for personal entertainment though.
Under $100 for a complete amplifier. That’s amazing to me. Probably explains the high debt and inflation in the West…but that’s another story.
If you could post some close-ups we may spot some improvements.
The TIP41/42 have been fitted on Ebay clone kits since day #1 here. It's a tradition of its own from the kit originators at Hifidiy. Check destroyer X's pics at post #2.
Coincidentally, Traderbam was there too in 2007. Yep, 14 years ago! Anyway, I agree in that I think the original MJE243/253 drivers perform and sound significantly better than typical TIP41/42 examples but an Ebay clone is about cheapest possible in cash terms. Such is the price for cheap - probably the most significant one.
Coincidentally, Traderbam was there too in 2007. Yep, 14 years ago! Anyway, I agree in that I think the original MJE243/253 drivers perform and sound significantly better than typical TIP41/42 examples but an Ebay clone is about cheapest possible in cash terms. Such is the price for cheap - probably the most significant one.
Lol
Is this chat still active ?
Is this our sound and harmonics?
https://thumbs.dreamstime.com/z/bun...ngs-bunch-various-ferrite-rings-230773155.jpg
https://ae01.alicdn.com/kf/HTB1.hAq...0A-1W-10V-1N4740-Single-5-2-Pin-DO-41-T-R.jpg
Two most important components overlooked.
By combination ---- we can make thousand of exiting sounds with this stuff, all kinds of harmonics. Stay blessed.
As reminder, wires also, theyr corners, sharpened corners in various shapes.
Is this chat still active ?
Is this our sound and harmonics?
https://thumbs.dreamstime.com/z/bun...ngs-bunch-various-ferrite-rings-230773155.jpg
https://ae01.alicdn.com/kf/HTB1.hAq...0A-1W-10V-1N4740-Single-5-2-Pin-DO-41-T-R.jpg
Two most important components overlooked.
By combination ---- we can make thousand of exiting sounds with this stuff, all kinds of harmonics. Stay blessed.
As reminder, wires also, theyr corners, sharpened corners in various shapes.
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Maybe our AC wiring is done wrong ?? AC wiring should be done carefully ? What are we fixing with amplifiers anywayz ? Fix the mistakes done by electricians ? lol... How close LIVE, neutral&ground should be and those coupling effects... is twisting them a good idea ? 
EDIT> forgot to tell, i have listened to various batterys also, they all sound dead to me somehow... done that through various opamps as preamps and as headphone amplifiers. But all batteries are dead, just dead. Its like there is no harmonics at all ... dead.
EDIT> forgot to tell, i have listened to various batterys also, they all sound dead to me somehow... done that through various opamps as preamps and as headphone amplifiers.
But all batteries are dead, just dead. Its like there is no harmonics at all ... dead.
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The shaping of wires and PCB traces in the copper foil plane, has no effect on circuits or sound quality until you reach radio frequencies - VHF usually, where other effects resulting from the necessarily long, parallel traces, become quite apparent. That simply means features like sharp corners in themselves, are irrelevant.
However, parallel conductors have significant capacitive and inductive coupling between them, so there likely will be problems or at least effects that may influence the audio output. Audible effects can sound better, worse or don't matter but just to be clear, that still has nothing to do with the geometry or sharpness of corners in conductors.
Otherwise, it's pretty obvious from what you say, that you like lots of distortion and probably, with low order, declining harmonics, as in 2nd >3rd> 4th >5th and so on. That also tells me you should be reading the Pass Labs Forum or, for a high end approach, AKSA and XRK's thread co-operations in recent times. Also good and cheap, try Hiraga's simple and popular class A designs like "le monstre" (mind that they're class A and very hot,hot,hot! so you'll need real heatsinks.) There are plenty of threads and opinions there - some informative and some confused. Enjoy!
However, parallel conductors have significant capacitive and inductive coupling between them, so there likely will be problems or at least effects that may influence the audio output. Audible effects can sound better, worse or don't matter but just to be clear, that still has nothing to do with the geometry or sharpness of corners in conductors.
Otherwise, it's pretty obvious from what you say, that you like lots of distortion and probably, with low order, declining harmonics, as in 2nd >3rd> 4th >5th and so on. That also tells me you should be reading the Pass Labs Forum or, for a high end approach, AKSA and XRK's thread co-operations in recent times. Also good and cheap, try Hiraga's simple and popular class A designs like "le monstre" (mind that they're class A and very hot,hot,hot! so you'll need real heatsinks.) There are plenty of threads and opinions there - some informative and some confused. Enjoy!
Hi, I'm trying some Nap140, 250 kits. changing the elements ect.
lastly, I bought a kit nap200 from aliexpress. I didn't modified or change any part. It's nearly good as my old old kits. If someone here tried, please comment did you like? I will not write any link. I will post a pic. from the side.
Kit has some little changes like added two more caps. 2X100n&uf caps. Other all elements are the same as pic.. And no cooler. Note that, offset nearly 1mv, Bais total 11mv. Perhaps all but, I see Power transistors matched.
lastly, I bought a kit nap200 from aliexpress. I didn't modified or change any part. It's nearly good as my old old kits. If someone here tried, please comment did you like? I will not write any link. I will post a pic. from the side.
Kit has some little changes like added two more caps. 2X100n&uf caps. Other all elements are the same as pic.. And no cooler. Note that, offset nearly 1mv, Bais total 11mv. Perhaps all but, I see Power transistors matched.
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After nearly 2 hours run, power transistors are getting hot. My NCC200 is very cool at the same time. Perhaps need bigger cooler or it oscillate? VAS cap is very big as 80pf on this nap200.
NAP200 is rated 100W/channel at 4R speaker loads. So yes, it will get hot and will burn without some form of heatsink and (originally) a thick heat spreader bar because the relatively thin case itself is the sink. The case is minimum 3 mm thick aluminium sheet in the form of a standard 2-unit rack size box. All NAP models use their case as the heatsink so you won't find any separate finned cooler in genuine product.
It's becomes obvious that
the cheap kits all leave the case design to you and whatever images of the original product are available on the internet. They are probably all you have as a guide for matching the cooling required with the power that needs to be dissipated for any particular model. It also appears that that this kit is nothing like NAP200 anyway. It's way too simplified, has no VI limiters, so its probably best to consider assembly and use as a smaller amp like NAP140 which, with +/- 35V supplies, will run cooler given the same bias current setting, reduced power and dissipation. The attached image is how NAP200 needs to be constructed for proper bias tracking too. Though your kit is tiny by comparison, you may find the ideas in the NAP140 kit thread helpful.
It's becomes obvious that
Attachments
As a late edit, I should have said that the kit does appear to have a heat spreader plate attached to the output transistors but this also needs to have heatsink grease applied to the lower surface and then be fastened down to a thick, as in 3mm minimum aluminium case which can then dissipate the heat effectively. That's how all the Nait/NAP models are designed to work.
Hi Ian, I want to say thank you for your answer,
Nap200 left channal & NCC right channal. Nap200 output transistors, connected with heatsink grease on the L shape 3mm aluminium heatsink. And heatsink connected to 400gr aluminium another heatsink with NCC200. Connections made like your image.
NCC200 has been tested more than continuous 24 hours. But, Nap200 getting hot after 2 hours. This is one channal of amp.. Volume is not full, it's very quiet (or no input). MJ15003 is 250w and 2SC2922 is 200w transistors. Both, drive by 41.7V ( transformer nearly 30v). I don't expect that much heat
Assuming no wiring errors, have you measured and adjusted the quiescent (bias) current correctly? Bias current is what generates heat so that needs to be set correctly and the Vbe multiplier transistor (marked 2N5089) located underneath the PCB) needs to be right next to the heatsink to regulate it properly. The bias test points TP1,TP2 may actually be across both emitter resistors in series, in which case the 1k potentiometer should be adjusted for about 12-15 mV voltage measurement. If TP1 and TP2 are across only one of those large, white resistors, a voltage of only half that (6-8) mV should be set. Don't confuse those 3 resistors - one of them is simply in series with the output connection and has nothing to do with bias setting but you should first check and note what the voltage (mV) reading is before adjustment. You can use the NCC200 schematic for guidance as this will be virtually the same as NAP designs at the output stage.
Your power supply voltages of about +/- 42V will normally be this high with no output or load, so no problem, as long as your electrolytic capacitor ratings are at least 50V.
Your power supply voltages of about +/- 42V will normally be this high with no output or load, so no problem, as long as your electrolytic capacitor ratings are at least 50V.
I drop the bias as 3.5mv x 2. Now it's better. Before, I measured the bias from the wrong points (TP1, TP2.. on my picture).
It's good that it was just the bias setting which, in your terms, would be specified as ~7mV x 2 but this is not critical with a quasi-complementary design like this one. It just needs to be enough bias to sound like a good compromise between say, harsh and sweet sounding. I assume you bought the kit of parts version so it would always be necessary to make that adjustment yourself, after assembly.
Chinese kits are often parts only - seldom are there any assembly instructions. Occasionally, some instructions are shown at the seller's offer pages but they may just be copy/pasted from similar offers. Beware of errors with that practice because there are often differences between kits that may not apply to your product and could end in disaster.
Chinese kits are often parts only - seldom are there any assembly instructions. Occasionally, some instructions are shown at the seller's offer pages but they may just be copy/pasted from similar offers. Beware of errors with that practice because there are often differences between kits that may not apply to your product and could end in disaster.
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I think, bias increase with time (not stabilized after 30 min.), because Vbe multiplier transistor doesn't sense the environment temp. ? Is it related with located underneath the PCB? Do I change the place on top? Or ZTX108 can sense better than 2N5089? I don't want to mount it on the power tr's heatsink.
Bias settling and stability depends on heat from the case warming the air that flows up to the 2N5089 transistor which as said, is mounted on the underside of the PCB to minimise the thermal settling (warm-up time) and hence reach a relatively stable bias level within a reasonable time of a few minutes. Just be sure to use a transistor with the correct pinout if you substitute or use fakes for some reason.
The pictures of the full-sized clone and real NAP200 show you that the thermal design is all very simple and requires no special parts at all but the closed box case is an integral and important part of the NAP design. Just assemble the kits and mount them inside a case as shown but don't assume you can just couple the transistors on a common heatsink to solve the thermal delay problem. That generally does not work at all for quasi-complementary designs because the increased heat transfer over-compensates and reduces bias too much and the amp may also become unstable. The original design using air as the transfer medium works more or less correctly and safely as it has for more than 50 years - and as long as the components are arranged much as they are in the original NAP200 design examples.
There will always be a few minutes delay before the amplifier settles to its optimum bias level and operating temperature but that won't be too obvious a problem. You may notice small improvements as it warms up more and your own hearing also adjusts to suit the program.
The pictures of the full-sized clone and real NAP200 show you that the thermal design is all very simple and requires no special parts at all but the closed box case is an integral and important part of the NAP design. Just assemble the kits and mount them inside a case as shown but don't assume you can just couple the transistors on a common heatsink to solve the thermal delay problem. That generally does not work at all for quasi-complementary designs because the increased heat transfer over-compensates and reduces bias too much and the amp may also become unstable. The original design using air as the transfer medium works more or less correctly and safely as it has for more than 50 years - and as long as the components are arranged much as they are in the original NAP200 design examples.
There will always be a few minutes delay before the amplifier settles to its optimum bias level and operating temperature but that won't be too obvious a problem. You may notice small improvements as it warms up more and your own hearing also adjusts to suit the program.
The great thing about the Naim is that it is relatively eco-friendly, with 30 or 40mA bias through the bipolar power transistors. JV said that above this it doesn't make much sonic difference.
The NAP internal air temperature thermal feedback is a simple, low-cost way to keep the amps fairly temperature stable. To do the job better I suppose you could plot a graph of bias voltage vs heatsink temperature and design a custom bias compensator that is attached to the heatsink. The faster the thermal feedback the more stable the bias should be.
Thermal runaway isn’t normally a problem if using a big enough heat sink. Like Ian says, the whole Naim case is a heat sink (5mm aluminium?). Of course the masters of heat removal are gaming PCs: fans and water-cooling. If fan whir isn’t a problem these methods would work great for an amplifier.
The NAP internal air temperature thermal feedback is a simple, low-cost way to keep the amps fairly temperature stable. To do the job better I suppose you could plot a graph of bias voltage vs heatsink temperature and design a custom bias compensator that is attached to the heatsink. The faster the thermal feedback the more stable the bias should be.
Thermal runaway isn’t normally a problem if using a big enough heat sink. Like Ian says, the whole Naim case is a heat sink (5mm aluminium?). Of course the masters of heat removal are gaming PCs: fans and water-cooling. If fan whir isn’t a problem these methods would work great for an amplifier.
Some years ago, I was helping some local schoolkids with checking parts and getting their Ebay kits working, making the bias setting correctly, stable and so on. The case was the last and generally most expensive part they considered (if at all) so some had watched as their builds overheated, burnt or even if everything survived the first power-ups, the sound quality was awful with the board and power supply just lying apart on the desk. They figured something must be wrong with Naim styled kits or blamed the semis because typical emitter-follower designs seemed to work and bias could be adjusted with only a small heatsink or adaptor plate in use for testing.
Schoolteachers didn't seem to understand or even recognize that Naim's QC design was a valid topology either so it came down to doing a demo with references to Rod Elliott's articles on output stage topology at his ESP site. Maybe others here will gain some insight from reading the main article too: https://sound-au.com/articles/cmpd-vs-darl.htm
Schoolteachers didn't seem to understand or even recognize that Naim's QC design was a valid topology either so it came down to doing a demo with references to Rod Elliott's articles on output stage topology at his ESP site. Maybe others here will gain some insight from reading the main article too: https://sound-au.com/articles/cmpd-vs-darl.htm