BTW, if you want to avoid fakes, Tubeshunter sells bare PCB pairs for USD 20. These accept T03 or plastic power as output transistors. Fit your own original spec. or as you wish. I'll try this next - after the 20 other projects I hope to do...
Thanks Ian,
I was thinking to re-work my existing 140 clone with all the mods that I found worthy, so last year I bought a pair of those boards, but still haven't populated them.
I guess, because I'm satisfied and my amp works fine. Someday though ... may be.
You say NCC200 is not a Naim? That's what I suspected, but never had the opportunity to compare. Some people claim to be better, but it's a matter of taste I think. I expect it to sound on the "mellow" side and "slower" in the bass compared to original Naim circuit. To me it's to much modified to keep the "Naim sound". Good amp, but different.
I have spectrum analyser at work, but it's an RF one and unfortunately not useful for audio. So, I can not check the distortion spectrum, but would like very much. Then I'll know exactly what each modification does. I have the feeling that's what Naim engineers do when they change components. That's why they can always preserve the signature sound through the whole range of their products.
lt cdr data,
I think the Naim circuit is just the right amount sound vs. complexity. And fast transistors with high gain everywhere.
I wouldn't dare to ask Naim technical info
I've read their forum and have good idea. But, hey, they have to sell, I understand! I am sure that they read us, though.Naim is a very basic amplifier that sounds surprisingly good. Self or Bob Cordell's books, they both practically start with this circuit as a base for their theory explanations.
Do you know for sure NAP-500 is bridged version, and not parallel? Or you just think it should be bridged because of the higher power?
I'm not sure that right, I believe they use slow outputs and drivers. Perhaps someone else can confirm.
Hi Luke
Yeah, the MJE243/53 drivers would be considered average (Ft 40 MHz) even in the 1980s but the outputs (BDY58) are Ft 7Mhz and pretty slick for the time. The later Sankens are, of course, much higher again. The VAS transistors (ZTX653/753) may not be fast/low Cob by today's standards but quite fast at Ft 140 MHz, compared to what was typically used in BJT amps by other manufacturers.
Though not a concern for speed, the small signal types were typically Motorola MPSA06/56 types, IIRC.
Yeah, the MJE243/53 drivers would be considered average (Ft 40 MHz) even in the 1980s but the outputs (BDY58) are Ft 7Mhz and pretty slick for the time. The later Sankens are, of course, much higher again. The VAS transistors (ZTX653/753) may not be fast/low Cob by today's standards but quite fast at Ft 140 MHz, compared to what was typically used in BJT amps by other manufacturers.
Though not a concern for speed, the small signal types were typically Motorola MPSA06/56 types, IIRC.
Hi Luke,
I think they are fast if you compare as a function of their current rating. I couldn't find higher bandwidth transistors from a major manufacturer and ones that have higher gain in the same time.
Take for example the Semelab type, that I hear Naim are using in their new amps. I saw on their site 100V/50Acont. device at 40MHz. Quite impressive!
Low bandwidth is bad for this circuit, because the compensation capacitor is small - only 39pF originally, and the open loop gain is high. Any "slow" transistor will cause premature phase shift and oscillation. May be one of the secrets of the Naim sound lies in the borderline stability of their earlier circuits. They tend to use any available bandwidth in order to decrease the high freq. distortions. If you remember they even used to recommend their own specific cables to guarantee proper operation. As per their user's manual:
"Using alternative loudspeaker cable will degrade performance, and may even damage your amplifier".
As alternative I understand highly capacitive.
That's interesting that these transistors were fast or are fast as the best sounding clone (ncc200) uses mj15003 which is quite slow.
I like the Naim sound, but I think it's a little over rated. Ive heard alot of midfi gear that can give naim a good run. To each his own, as Nelson says, "were in the entertainment business"
I like the Naim sound, but I think it's a little over rated. Ive heard alot of midfi gear that can give naim a good run. To each his own, as Nelson says, "were in the entertainment business"
That's interesting that these transistors were fast or are fast as the best sounding clone (ncc200) uses mj15003 which is quite slow.
I like the Naim sound, but I think it's a little over rated. Ive heard alot of midfi gear that can give naim a good run. To each his own, as Nelson says, "were in the entertainment business"
Totally agree with all that.
Just have in mind that NCC200 is way more stable than the original Naim circuit due to all the mods. I think that makes it less dependant of specific transistors. In addition, IMO, drivers are the more important part there (the thing which input capacitance VAS sees first).
Vinyl sound
Yes, agree on the over-rating also since the NAP140 sound applies to a a time long gone - It was vinyl era when it was at it's height and turntables were the only commercial way to get good sound. The combination is still great today but as many find, typical high quality digital sources seem to sound much better through newer systems generally.
Regarding power output transistors, Semelab gear really is outstanding - with a matching cost too! Have others used and evaluated more affordable parts like the earlier clones which used genuine 2SC5200? To me. a matched pair of these should be the economical way forward but my clones (unmatched) were not really Naim-sounding. Any further comments?
Yes, agree on the over-rating also since the NAP140 sound applies to a a time long gone - It was vinyl era when it was at it's height and turntables were the only commercial way to get good sound. The combination is still great today but as many find, typical high quality digital sources seem to sound much better through newer systems generally.
Regarding power output transistors, Semelab gear really is outstanding - with a matching cost too! Have others used and evaluated more affordable parts like the earlier clones which used genuine 2SC5200? To me. a matched pair of these should be the economical way forward but my clones (unmatched) were not really Naim-sounding. Any further comments?
@Mr-Dave & Ruwe
Hi,
does exist a pcb for schematic in #612 or below?
_______________________
regards
Hi,
does exist a pcb for schematic in #612 or below?
An externally hosted image should be here but it was not working when we last tested it.
_______________________
regards
Hi Softon,
I think any of the kits in sale on ebay are based on this schematic. May be the transistor choice and some capacitors values to be different, but the circuit is the same.
Somewhere on the earlier posts you could find the ebay schematic and compare it with yours. IMO they are identical as circuit diagram.
I think any of the kits in sale on ebay are based on this schematic. May be the transistor choice and some capacitors values to be different, but the circuit is the same.
Somewhere on the earlier posts you could find the ebay schematic and compare it with yours. IMO they are identical as circuit diagram.
Yes, some only have the VI limiter parts erased but otherwise - same graphic even. The boards now are sometimes branded by the designer/manufacturer LJM, who is a DIY member too. The parts more correctly match those on the overlay now on his kits or finished boards. There should be less mistakes for unwary builders on his products but fakes still abound.
I agree with the points made about hype. I can see very little reason to build a clone of a Naim 140 or 250, and I own one of the latter. The circuit was never state of the art, even when it first came out. Those compensating caps in the signal path look just terrible in this day and age, but back in the day they were sorely needed for HF stability. Naim built their amps well, with decent power supplies and they became the stuff of legend. I know this since I fell for it.
It would be hard to build an exact clone of the 250, as the BDY58 is long gone. The only source for direct replacements seem to Naim, who get them custom made by a semi-secret factory.
Just picking a modern replacement and leaving the rest of the circuit unchanged could be a recipe for disaster. From playing around with LTspice it seems that modern power transistors with higher fT in that circuit are just itching to oscillate. Reworking the circuit to cope with this would alter the sound to something that is different from the original, so why bother?
Building an amplifier is an expensive business. Transformer, heatsink, case, it all adds up. Might as well go for a modern design. Unless you really, really want a Naim clone, of course. To each his own.
It would be hard to build an exact clone of the 250, as the BDY58 is long gone. The only source for direct replacements seem to Naim, who get them custom made by a semi-secret factory.
Just picking a modern replacement and leaving the rest of the circuit unchanged could be a recipe for disaster. From playing around with LTspice it seems that modern power transistors with higher fT in that circuit are just itching to oscillate. Reworking the circuit to cope with this would alter the sound to something that is different from the original, so why bother?
Building an amplifier is an expensive business. Transformer, heatsink, case, it all adds up. Might as well go for a modern design. Unless you really, really want a Naim clone, of course. To each his own.
.....Unless you really, really want a Naim clone, of course. To each his own.
That is exactly the hook with the very low price for all the electronics, even finished boards...even the PSU and preamp! Pretty hard to get near that with buying individual parts for a DIY of any quality, modern or nostalgic tastes or whatever. It's good for Newbs who are uncertain about what a working unit should be like.
I would not be too mesmerised by BDY58 Magic. Naim swapped to Sanken M200s mid-stream with the NAP 140 and 250 - no big issues there as Ft was well up to the 7MHz mark. Have a look at the current clones on Ebay - though if they are supplying genuine Sankens, I'll eat my hat!
I agree with the points made about hype. I can see very little reason to build a clone of a Naim 140 or 250, and I own one of the latter. The circuit was never state of the art, even when it first came out. Those compensating caps in the signal path look just terrible in this day and age, but back in the day they were sorely needed for HF stability. Naim built their amps well, with decent power supplies and they became the stuff of legend. I know this since I fell for it.
It would be hard to build an exact clone of the 250, as the BDY58 is long gone. The only source for direct replacements seem to Naim, who get them custom made by a semi-secret factory.
Just picking a modern replacement and leaving the rest of the circuit unchanged could be a recipe for disaster. From playing around with LTspice it seems that modern power transistors with higher fT in that circuit are just itching to oscillate. Reworking the circuit to cope with this would alter the sound to something that is different from the original, so why bother?
Building an amplifier is an expensive business. Transformer, heatsink, case, it all adds up. Might as well go for a modern design. Unless you really, really want a Naim clone, of course. To each his own.
Hi ingenious
Did you know naim still build the 250, according to a member on another forum Im involved with not much has changed except part changes. When I at revievs of this newer amp they are all positive and amoung the best at their price range. Im still trying to get hold of schematics to see what changes were made to the new model. Whatever one may think of the design, I agree it looks primitive but yet many still seem to love the sound of this amp. I cannot comment as I havent heard one yet, old or new.
Ian Finch, you're quite right about the prices of those boards - they do look very tempting. With a clone, at least you know what you're getting.
I assume that you refer to the MT-200 case, which seem to be offered only by Sanken.
Do you happen to know which model Naim uses?
I assume that you refer to the MT-200 case, which seem to be offered only by Sanken.
An externally hosted image should be here but it was not working when we last tested it.
Do you happen to know which model Naim uses?
If something worked well, had a broad following, and sold well and performed well, why change it at all. Because of their simplistic approach Naim captured the heart of many audiophile and still remains a very pleasing amplifier regardless of its age.
It goes without saying, it will be cloned because there remains a demand to own one, even if it is not the real thing.
It goes without saying, it will be cloned because there remains a demand to own one, even if it is not the real thing.
Absolutely - such Linn/Naim vinyl combos remain great IMO. Many claim newer, higher-spec. gear at even higher cost is better but really, it comes down to taste in sound quality. Once you achieve an adequate low noise figure, stereo image and tonal qualities that suit you, extra gloss is not always appreciated.
I have not looked in recent releases of the 250 either but I have worked on a span of about 15 years of 250s and they changed the case (obviously), output transistors, ss transistors, transformer, passive part brands to name a few things. Part value changes are rare and minor.
Over such a long period, it is not possible to maintain supply of all components identical to originals. Put a spin like "ongoing development" or "refinement" to this and a hundred guesses as to what really is little different will pop up.There is a lot of waffling and guesswork on some forums discussing Naim gear, so it must suit the sponsors who seem happy to let confusion reign.
Yes, Ingenieus and apologies all - the case style "MT200'' is what I intended but somehow have a problem typing. The other Sanken power transistor case, MT100, is similar to TO3P.
I have not looked in recent releases of the 250 either but I have worked on a span of about 15 years of 250s and they changed the case (obviously), output transistors, ss transistors, transformer, passive part brands to name a few things. Part value changes are rare and minor.
Over such a long period, it is not possible to maintain supply of all components identical to originals. Put a spin like "ongoing development" or "refinement" to this and a hundred guesses as to what really is little different will pop up.There is a lot of waffling and guesswork on some forums discussing Naim gear, so it must suit the sponsors who seem happy to let confusion reign.
Yes, Ingenieus and apologies all - the case style "MT200'' is what I intended but somehow have a problem typing. The other Sanken power transistor case, MT100, is similar to TO3P.