Compensation does change the sound. And why VAS? It is the major location affecting the response. Compensation also has something to do with stability. When there is a hint of instability, the sound changes for the worse. Sometimes it can be 'dull' tho it is probably different with the 'dull' sound you mentioned if the Cob is low. But we can't just reduce the Cob in a working circuit without changing everything else. Otherwise, ultima legione wouldn't be happy with his clone.
If we need to reduce the miller cap (I think I see two different values in Naim schematics), we can do it by adding compensation somewhere else. But it is hard to remove it entirely as the VAS is the major location where you can easily add compensation (that's why 'miller cap' is so familiar).
BTW, I'm curious with ultima legione result, as it is so different with Naim circuit. Of course, we can make better (in general term) amplifier than Naim, but there is that specific quality that I don't believe can be achieved by changing the VAS transistor to his part of choice.
Yes, ultima legione's findings are somewhat different to other's but it is his to prefer and he is entitled to compare sound qualities like timbre as the equal of the original. Strange indeed, that his adaptation using H140 kit boards has many significant changes, affecting all sound qualities, I think.
I didn't particularly like the sound resulting from fitting low Cob VAS transistors, with or without the necessary increase in Cdom (Miller compensation capacitor). Sound quality was certainly different to me but each to his own
I didn't particularly like the sound resulting from fitting low Cob VAS transistors, with or without the necessary increase in Cdom (Miller compensation capacitor). Sound quality was certainly different to me but each to his own
Yes, I fully confirm your assumptions.
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And given that I also consider the structure of the VAS fundamental for the total sound of any power amplifier, actually being able to say that I know very well the sound NAIM, in the realization of its clones, more than the search for the same musicality, I had the ambition to experiment and even go beyond, where possible, already being the excellent design circuit with very low harmonic distortion (very few other electronics even current can boast distortion rates equal to or less than 0.017% THD!!!). .
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And honestly I can say, with the latest releases built, that the musicality largely satisfies both me and my friends owners.
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And given that I also consider the structure of the VAS fundamental for the total sound of any power amplifier, actually being able to say that I know very well the sound NAIM, in the realization of its clones, more than the search for the same musicality, I had the ambition to experiment and even go beyond, where possible, already being the excellent design circuit with very low harmonic distortion (very few other electronics even current can boast distortion rates equal to or less than 0.017% THD!!!). .
.
And honestly I can say, with the latest releases built, that the musicality largely satisfies both me and my friends owners.
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i have skimmed through the whole post and still cannot decide which board to use and what is the secret recipe for naim like sound. Caowei, boards are not available, allegedly they are the best. H140 by Hifidiy is also not available. Would some one be kind enough to guide me in the right direction please ?
I want PCB and will use digikey or mouser for components. Please help!
Many Thanks
I want PCB and will use digikey or mouser for components. Please help!
Many Thanks
this one :
Septembre magasin DIY kit NOUVEAU 140 amplificateur kit + alimentation kit base sur NAIM NAP140 dans Amplificateur de Electronique sur AliExpress.com | Alibaba Group
or this one :
Aiyima NAIM NAP140 AMP CLONE KIT 2SC2922 Amplificateur conseil Kits Pour DIY 2 canaux J163 dans Amplificateur de Electronique sur AliExpress.com | Alibaba Group
Septembre magasin DIY kit NOUVEAU 140 amplificateur kit + alimentation kit base sur NAIM NAP140 dans Amplificateur de Electronique sur AliExpress.com | Alibaba Group
or this one :
Aiyima NAIM NAP140 AMP CLONE KIT 2SC2922 Amplificateur conseil Kits Pour DIY 2 canaux J163 dans Amplificateur de Electronique sur AliExpress.com | Alibaba Group
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I'm not in the business of selling kits or promoting clones, but if you are looking for something that needs a bit more 'DIY' and want to learn about NAIM sound etc. rather than taking what you can find on eBay I have this: TGM10 - based on NAIM by Julian Vereker which is more or less a NAP clone with better engineered thermal control and I still have a spare pair of un-built PCBs.
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Take care with PCBs marked GLZOZONE or similar. Resistor values marked on the PCB are incorrect in the VAS section. i.e. those resistors associated with the bias adjustment potentiometer, some of which, are also incorrect values.
The problem is, you cannot set correct bias current with the values marked. Check the resistor values of the bias setting pot. and other fixed resistors associated with it. Compare to the original NAP 250 schematic (also wrongly assumed to be NAP140 schematic which you find posted here occasionally and is found everywhere on the net).
You can buy the same PCBS without components here:
One pair Clone NAIM NAP140 amplifier bare PCB amp PCB | eBay
I am sorry to be a pain but which schematic is correct one?
this very thread says that original schematic is for 140 and it has been soled as 160, 180 and 250. Is this correct?
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The difference between many of these amps is the power supply, it’s voltage, size and number of transformers etc., but the amplifier schematic is more or less unchanged so I wouldn’t worry too much. In my case I reverse engineered a NAP from detailed photos but I didn’t follow it slavishly because I wanted proper thermal control rather than rely on the original scheme.
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The original 250 has a regulated psu for each channel as well as the best components. The less powerful models have smaller supplies and worse components in certain places.
You might as well go for a NAP250 and seek best performance, either with or without the regulated psu.
The amp boards are at the bottom in the attached image of an old style 250. You don't have to have regulators. You don't have to use TO-3 can style power transistors. But notice all the amplifier capacitors are either tantalum or polystyrene. Oh, except for the zobel capacitor.
You might as well go for a NAP250 and seek best performance, either with or without the regulated psu.
The amp boards are at the bottom in the attached image of an old style 250. You don't have to have regulators. You don't have to use TO-3 can style power transistors. But notice all the amplifier capacitors are either tantalum or polystyrene. Oh, except for the zobel capacitor.
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I've read mixed reviews about the regulators, some folk saying they thought it improved things, others saying they like the amps without regulators. The trouble with regulators is that that they have to be better than the amplifier they are controlling, they are a technical challenge that you don't see being addressed for power amplifiers on this forum too often. Naim now have a more modern design for their power rail regulator, I've taken a pretty close look at it and believe they've done a really nice job of it. The detailed schematics are not available although you can work out what most of it looks like.
A good regulator allows you to be a bit lazy with the PSRR of your amplifier - the basic NAP doesn't have brilliant PSRR due to poor rail decoupling of the front-end which makes the sound of the amplifier more sensitive to power supply design and hence reports of differences between the 140, 160, etc. Rail decoupling is important for sound, the AKSA amplifier has some secret sauce that most folk never understood but is related to the use of bootstrapped VAS load. Anyhow, I believe the earlier NAP models do respond to power rail regulation but it will change the sound and in my opinion the jury is still out on whether to use it or not. And if I were to add a regulator, I would forgo the historical accuracy and design something with better performance.
Note: I didn't incorporate the outputs stage protection circuit either - I consider them necessary for my DIY use as well as reducing the risk of adverse affect on the sonics (perhaps a dual slope limiter would be better but the only design I liked so far I reverse engineered from a Bryston amplifier).
A good regulator allows you to be a bit lazy with the PSRR of your amplifier - the basic NAP doesn't have brilliant PSRR due to poor rail decoupling of the front-end which makes the sound of the amplifier more sensitive to power supply design and hence reports of differences between the 140, 160, etc. Rail decoupling is important for sound, the AKSA amplifier has some secret sauce that most folk never understood but is related to the use of bootstrapped VAS load. Anyhow, I believe the earlier NAP models do respond to power rail regulation but it will change the sound and in my opinion the jury is still out on whether to use it or not. And if I were to add a regulator, I would forgo the historical accuracy and design something with better performance.
Note: I didn't incorporate the outputs stage protection circuit either - I consider them necessary for my DIY use as well as reducing the risk of adverse affect on the sonics (perhaps a dual slope limiter would be better but the only design I liked so far I reverse engineered from a Bryston amplifier).
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Please excuse my ignorance, which capacitor is zobel ? as I see Tant or Polystyrene only? I have made 250 clone using NCC 200 clone boards by zerozone. It sounds no way near to my Original Nap 200. Reading this whole thread gave me an impression 140 sounds better, hence I opted for that. Would you recommend otherwise?
I agree, amplifier sounds better without regulators. I have tried both multi VBE and HCR type. Without regulator sound is definitely better.
No excuses needed. The zobel cap is the pale rectangle between the blue and green wire connectors.
The problem you have is that clones sound worse. It may be a 140 clone happens to sound worse in a more pleasing way than the 200 clone? I have never made a clone so I can't advise. It may just be the particular parts you used at the time or the psu or some other difference. They are all pretty similar so you could swap cap types around until it sounds best, I suppose.
The problem you have is that clones sound worse. It may be a 140 clone happens to sound worse in a more pleasing way than the 200 clone? I have never made a clone so I can't advise. It may just be the particular parts you used at the time or the psu or some other difference. They are all pretty similar so you could swap cap types around until it sounds best, I suppose.
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One thing that has changed a lot over time - the technology and quality of parts has improved a lot. Speakers have also improved a lot. If you want to be sure you have the original sound or if you're going to lose sleep because people you never met say your clone can't possibly sound like the real unit then it's best to go and find and buy an original amplifier - they are around and even if they look pricey you can resell them (DIY amps don't keep their resale !) so it's not a bad option. My clone has not been compared with an original (I don't lose sleep) but I've found subjective descriptions of the old Naim sound to 'ring true' with my own subjective impressions which includes both the good, especially from trade mags (e.g. PRAT and sound stage) and the bad, mostly from users - usually around it sounding a bit tense in the treble - which is system dependent and leading to all sorts of pre-amp and cable discussions... a big topic by itself.
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No, this thread or at least my oft repeated posts here, have said that there is only one schematic originating from Naim that is on the 'net and is traceable to any of the NAP models. That model is the regulated NAP250, probably at the time of the first revision which preceded the Chrome-bumper series and a significant change of power transistor type. Some models differ in their supply rail voltages and consequently, the resistors in the first 2 stages are slightly different too.
Clone builders and sellers have been using that schematic for as long as I can remember so it isn't surprising that it turns up everywhere titled as whatever model the seller is promoting. The actual circuits are indeed similar but not so close as to call the same. If you want the genuine NAP 140 schematic and voltages for example, you'll have to reverse-engineer it from a real amplifier for yourself.
When you use Google etc. to find the schematic, try terms like NAP 250 schematic, circuit diagram etc. then NAP 140 and so on. Notice what diagram comes up most then compare with the version that appears on Neil McBride's archive site, marked with his own parts ID numbers at: Modifying Naim Audio power amplifiers Simple logic will tell you which schematic is Naim's and which are drawn by the clone designers with, mods, simplified circuits, will likely be supplied with inferior substitute or unsuitable parts etc.
If you want to tinker with clones, you'll find that site to be a good resource for identifying many older models and the very few reference schematics make a reasonable starting point, even if the suggested parts changes are rather dated now.
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