Early Ebay Clone kits came with all the semis substituted with anything cheap that would work reliably. This was a bad idea because it gave the kits and by association, the original Naim product, a reputation for sounding relatively flat and lifeless, like a generic style amp intended for beginners. Not bad for the money but not at all what you were hoping to hear when it was assembled. See the H140 kit at #2 for example. It works, sounds a little better now and is still around but.....
The main offenders were the driver and VAS transistors which were not easy or cheap to buy so naturally they were subbed with low frequency parts like the TIP41/42 which have poor linearity. Fitting the original Diodes inc. ZTX transistors makes the most significant improvement to the VAS, even if they are specified quite contrary to modern design practice. They do wonders with sound quality and the PRT effect in this design though.
Only now do we find some kits that include the critical, original spec. components. Beware though, some of these critical parts are fakes or poor copies. A recent kit I saw had ZTX653/753 supplied in TO92 packages which is not original and they don't even measure like the originals. You can buy these parts quite cheaply in large quantities too, which tells you something about their origin.
The main offenders were the driver and VAS transistors which were not easy or cheap to buy so naturally they were subbed with low frequency parts like the TIP41/42 which have poor linearity. Fitting the original Diodes inc. ZTX transistors makes the most significant improvement to the VAS, even if they are specified quite contrary to modern design practice. They do wonders with sound quality and the PRT effect in this design though.
Only now do we find some kits that include the critical, original spec. components. Beware though, some of these critical parts are fakes or poor copies. A recent kit I saw had ZTX653/753 supplied in TO92 packages which is not original and they don't even measure like the originals. You can buy these parts quite cheaply in large quantities too, which tells you something about their origin.
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@Giuseppe, I also have Magnepans (0.7s, because those are the biggest my wife will accept in the library). But I'm feeding them with a 100wpc tube amp (Rogue Audio Cronus Magnum II).
I'm not sure what I'm going to pair my NAP250 clone with yet. I do have a pair of Isobariks in the attic, but while I adored their bass I remember not being terribly satisfied with their mids/highs and imaging....
I'm not sure what I'm going to pair my NAP250 clone with yet. I do have a pair of Isobariks in the attic, but while I adored their bass I remember not being terribly satisfied with their mids/highs and imaging....
Stylish build.
It appears from the photo that zobel and input grounds are connected together on each amp board?
a friend of me will buy this NAP 140 PCB units:
NEW LJM NAIM NAP140 AMP CLONE Board 2SC2922 Amplifier Board | eBay
Very cheap. But what about the risc concerning the BjT power output devices, not getting genuine parts from Sanken, but rather counterfeits from anywhere ?
The supplier do not send a reply after asking this question.
NEW LJM NAIM NAP140 AMP CLONE Board 2SC2922 Amplifier Board | eBay
Very cheap. But what about the risc concerning the BjT power output devices, not getting genuine parts from Sanken, but rather counterfeits from anywhere ?
The supplier do not send a reply after asking this question.
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Early Ebay Clone kits came with all the semis substituted with anything cheap that would work reliably. This was a bad idea because it gave the kits and by association, the original Naim product, a reputation for sounding relatively flat and lifeless, like a generic style amp intended for beginners. Not bad for the money but not at all what you were hoping to hear when it was assembled. See the H140 kit at #2 for example. It works, sounds a little better now and is still around but.....
The main offenders were the driver and VAS transistors which were not easy or cheap to buy so naturally they were subbed with low frequency parts like the TIP41/42 which have poor linearity. Fitting the original Diodes inc. ZTX transistors makes the most significant improvement to the VAS, even if they are specified quite contrary to modern design practice. They do wonders with sound quality and the PRT effect in this design though.
Only now do we find some kits that include the critical, original spec. components. Beware though, some of these critical parts are fakes or poor copies. A recent kit I saw had ZTX653/753 supplied in TO92 packages which is not original and they don't even measure like the originals. You can buy these parts quite cheaply in large quantities too, which tells you something about their origin.
Hi Ian,
I totally agree on everything.
After about ten years of tests, refinements, modifications, measurements and listening with at least 6 different versions made over time where, among the many valuable suggestions of this thread, your suggestions and those of @tradebarm were among the most essential,
today I finally have a final that already sounds exactly as I want and that is literally able to "give the dust" to the most famous brands at a cost of several thousand euros both in Europe and overseas.And I'm sure I'll surprise more than one person by saying that when a dear colleague and friend of mine, less than two months ago, parked at my house for a week a brand new NAIM NAP 300DR, for controlled comparisons with the NAP clone and various speakers, when he took it back home he brought it back to the shop and started making the shopping list to have an exact copy of my clone made.
As for the ZTX653/753 transistors, after experimenting with a couple of different versions of the clone, I confirm that they are an extremely peculiar and characteristic premise of this circuit layout.
And it is no coincidence that together with my rarest and most precious thermionic tubes, I jealously keep a handful of these complements, obviously original DIODES Inc.
After I've finished other upgrades on my valve preamp, I think it will be the last tweak I'll do on this amazing amplifier.
Great amp really the Rogue Audio Cronus Magnum II.
I keep the memory of an extremely "fast" and detailed sound, almost like a solid state, with the refined timbre and musical nuance of a tube!
As long as I owned a pair of MAGNEPAN SMG-C's, I always had great fun driving them with valves, or to be more precise with the OTL-OCL valves that I enjoy making.
But after my stay with the MG 1.6QR, I had to migrate to the solid state and from here the need to "hit the nose" for almost 10 years with an amp able to really unite in symbiosis with them without sacrificing timbre, speed, control and musical seduction.
Stylish build.
It appears from the photo that zobel and input grounds are connected together on each amp board?
Thank you for your words of appreciation.
In fact, in the latest versions, I have completely eliminated the original network of Zobel, never having found any kind of instability and / or oscillation with any type of speaker, cable connection or condition of use.
The kits and assembled boards are extremely cheap and all too easy to buy - a lazy person's way to DIY which is what most of us are until we're really inspired by some rare, sure-fire certainty that sounds great, whoever builds it.
I buy the occasional kit or preassembled boards now but I only change out the critical semis and caps as necessary. I've never noticed any problem with the supplied MF resistors. However, repeatedly moving and refitting them can cause the endcaps to break away. I treat film resistors as one-trip ponies - cut the leads and quickly drop the tails out without force, to avoid damaging the PCB. The parts just aren't worth dickering about with but the PCB certainly is.
@huggygood, Wow, you've had a 300DR delivered and compared to your clone! What a buzz when you found your NAP clone to sound better. I guess that was always going to be the case when the engineers got hold of the Naim sound quality and de-tuned it for "detailed sound". Sure, people now like to marvel over details, some that aren't even desirable if it's the music performance you wanted to hear rather than studio sounds, player breathing and movement, audience coughing etc. That build of yours must be sublime - congratulations
I'll have to have a listen to some more recent models myself. I had a feeling, perhaps confirmed by traderbam's auditions elsewhere, that Naim were continuing on a trend to mainstream sound quality. Personally, I wouldn't like to be marketing a product like this which on the one hand, relies on JV's much-respected legacy of the 20th century Naim brand but on the other, seems to diverge back toward the competition with a price disadvantage.
I'd also like to know what current budget models sound like by comparison with earlier models like Naits, NAP 140,160, 250 etc?...I mean with real amplifiers and speaker systems and I don't mean what you hear for background music in their promotional YouTube videos.
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Sorry about that, Huggygood and Ultima Legione, I've just confused you and given the honour of building a clone that was better sounding than the 300DR model to the wrong guy. Again, sincere apologies but maybe you both have clones that do that?
Dear Ian,
no problem or "Injured Majesty"!
Thanks to the suggestions of this thread, which is certainly one of the oldest with its almost 12 years of life and the almost 1 million visits, which I have read and consulted hundreds of times, I was able to get the satisfaction that no other commercial amplifier (over the years I spent almost the same money with which I could buy my BMW Coupe) had ever managed to give me in almost 40 years of unbridled passion.
And I'm equally certain that I, like our French friend @huggygood or anyone else who takes advantage of these tips would be able to achieve an amplification capable of giving extraordinary satisfaction, in my personal opinion directly if not quite superior to the original NAIM.
And this apart from the pride of a unique and self-made object.
And this (here I apologize to everyone for the sin of vanity
) of having dressed these extraordinary electronics, an aspect that quite differently from the severe black aesthetics of the NAIM, with a style that we Italians do not miss is able to give an aesthetics that does justice to the great Sound of NAIM.
Observe that ultima legione is not even following the Naim BOM. But he could make his amp subjectively better than the real Naim. So good ears are what we need, as no measurement tools can substitute what it can do.
Regarding Naim engineers couldn't make better sound, I think that's because they don't use ears or they don't have that capability. Following measurement alone will not do it imo. There is no clear measurement objectives regarding PRAT or musicality.
If you believe that ultima legione could get such a good result without the high-capacitance ZTX then you should believe that you could possibly design an amp that is very detailed yet sound musical by your own standard. But you must start with using theoretically proper device for that purpose. I have made a few amps with resolution which seem to be even better than my headphone direct. All i need is video transistors for VAS and/or drivers.
I am not as good as you for all that is to do simulation and calculation of operation, I have a lot of delay to catch because I have focused on troubleshooting during these last twenty years.
However, I trust my ears because in the end, what matters is to make an amp that I like to me.
The jlh and naim were revealing for me, it is thanks to them that I became aware of the right component in the right place.
for now I'm doing a little pose with the transistors because I had the good idea to interest myself to the tubes and there, I am right in it.
finally, a few weeks ago, I bought an amp Isem AP250 (late 80s) and I think, not in fact I'm sure this amp is one of the best I've In my life and it would be worth it to be cloned and as the brand ISEM died in 2015, it no longer poses a legal problem.
However, I trust my ears because in the end, what matters is to make an amp that I like to me.
The jlh and naim were revealing for me, it is thanks to them that I became aware of the right component in the right place.
for now I'm doing a little pose with the transistors because I had the good idea to interest myself to the tubes and there, I am right in it.
finally, a few weeks ago, I bought an amp Isem AP250 (late 80s) and I think, not in fact I'm sure this amp is one of the best I've In my life and it would be worth it to be cloned and as the brand ISEM died in 2015, it no longer poses a legal problem.
So here's a thought:
The e-line package was designed for higher operating temps: the case is made of a more heat-resistant silicone polymer, and it's thinner allowing a lower Rth (20 - 30% better than a TO-92).
This is good for the 653/753 which, as we know, run a bit hot in the NAP design.
But hang on here. Rth doesn't have an arrow; it works both ways. So a Vbe bias spreader in an e-line package (ie: the original-spec ZTX108 or McBride's ZTX384) will track ambient thermal characteristics 20 - 30% faster than something like a 2N5551, 2N5089, BC546, BC550, or 2SC2240 as used in HackerNAP, Avondale and the clones.
Which begs the question: does the NAP200-clone's TO-92 on the back of the board work better than an e-line on the front? For that matter, what does Naim use in their NAP200? Did they stick with a ZTX e-line or move to TO-92?
The e-line package was designed for higher operating temps: the case is made of a more heat-resistant silicone polymer, and it's thinner allowing a lower Rth (20 - 30% better than a TO-92).
This is good for the 653/753 which, as we know, run a bit hot in the NAP design.
But hang on here. Rth doesn't have an arrow; it works both ways. So a Vbe bias spreader in an e-line package (ie: the original-spec ZTX108 or McBride's ZTX384) will track ambient thermal characteristics 20 - 30% faster than something like a 2N5551, 2N5089, BC546, BC550, or 2SC2240 as used in HackerNAP, Avondale and the clones.
Which begs the question: does the NAP200-clone's TO-92 on the back of the board work better than an e-line on the front? For that matter, what does Naim use in their NAP200? Did they stick with a ZTX e-line or move to TO-92?
Considering how painfully slow the Vbe multiplier in earlier NAP designs responds to temperature changes in the output stage, any transistor used in the NAP200, from a TO18 can to a TO92 will respond much faster than the way the various small NPNs used by Naim in early designs based on the familiar small NAP PCBs, as you find in better clone kits. Here though, with the transistor in close proximity to the heatsink, the transistor package will be less important than the thermal resistance of the heatsink (i.e. the thick aluminium baseplate).
It has also been mentioned here and at other forums, that it takes some 20-30mins for early NAP140 models to reach a stable bias level where the sound quality could be considered optimum. It seems that it took Naim decades to get around to improving the thermal design of their amplifiers so that they settled faster and you didn't really need to leave the fool things on 24/7 just to get them to sound right. I think that's an absurd condition for the full enjoyment of any entertainment system, particularly where it also means that safety aspects are simply ignored.
It has also been mentioned here and at other forums, that it takes some 20-30mins for early NAP140 models to reach a stable bias level where the sound quality could be considered optimum. It seems that it took Naim decades to get around to improving the thermal design of their amplifiers so that they settled faster and you didn't really need to leave the fool things on 24/7 just to get them to sound right. I think that's an absurd condition for the full enjoyment of any entertainment system, particularly where it also means that safety aspects are simply ignored.