It's a great post, Ruwe, honest opinion and informative.
I also found with 3 clone pairs built and tweaked, that parts were the issue and though using fast stuff can certainly "improve" performance (lower THD etc) it does not get closer to Naim sound which is surely the signature distortion and general characteristics of the amplifier in a system.
The only fakes I have found with about a dozen Ebay kits have been these M-200 Sankens, which we could guess with the low price. I agree about the quality of the NCC200, it does sound good, but is way overvalued for a simple module and does not, IMO, sound quite like a NAP 140, even swapped in an original amp, as I have been fortunate to test with Linn Saras.
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...
BEWARE!!! I had a bad experience with Tubeshunter. He sold me wrong type and even fake diodes...
Maybe so, Bassivus, It does seem standard practice for all difficult and expensive semis in Asian Ebay kits and similar sources to be fake. Just look at and compare the total price of the kit with trusted suppliers prices for the special parts it is claimed to contain - if they are indeed obtainable. Often the parts are as expensive as the kit, so common sense tells you what you are buying.
However, in the case of buying blank PCBs as I suggest, it is kinda hard to fake your own design! That then, is my solution.
However, in the case of buying blank PCBs as I suggest, it is kinda hard to fake your own design! That then, is my solution.
After reading Ruwe's update on parts he liked MJL3281 which I can get at Mouser with my other parts. For drivers I got MJE243 & MJE253... I was given an old Bogen mono 125w rack mount power amp. It's a great chassis and heatsink. The power transformer is too high of voltage unforunately. A good amount of room & heavy steel construction. I was thinking of a 2 Antek 200va 25-0-25 torids? What did you use for the 10uf 10v input cap? Finding a film one is imposible. I did read the thread several times consuming huge amounts of time trying to figure what's good. We have snow here & this is a great hobby for the winter time. I like to find another old amp and build the DX Blame HX MKIII Supercharged if the boards become availible. But for now I better focus on 1 project at a time or nothing will get done....
Power transistors
That's fine too - perhaps too fine to get that Naim sound but there aren't a lot of options as the Sanken Parts are expensive but I'm sure you could use the same die in the TO247 pack there, which is what the cheaper Sankens are. I haven't done it yet, but I have them on order (Newark in the US has them) so I might get to try this some time. The supplied kit parts (see ljm-ljm post above) are not any power transistor at all - more like a TIP31 or less.
The VAS transistors were Zetex ZTX 653/753 which are borderline hot running. In recent kits they also supply Renesas 2SC2547 + complement which are mighty low noise transistors - wasted here, but if they work...
If they fitted, I would use decent Video drivers like TO126 Fairchild KSC3503/A1381. There you have near the cheapest but still best, without concerns of ratings.
The rails will need to be up above 35V to get decent power and the originals had 40V rails which is a twin 27 or 28V max. secondary windings transformer. Here they are a stock item at manufacturers or resellers specialising in audio applications. 160VA or 300VA should be plenty and are common sizes for use with each or both channels respectively.
Interesting, the Tantalum caps on Naims. I fitted huge polypropylene caps that I thought would be superb but it lost the sound a bit and I had to fit earthed sleeves to them to eliminate hum and noise pickup, so I went back to the original spec. and they do sound right if you are careful to get adequate voltage spec. and quality, like anything. I used 15V rating - still overkill but I'm paranoid about damage, even though I have 30 year old gear full of 'em that are still fine and the sound has changed but not necessarily been improved by substituting electrolytic caps.
If you just want the best sound possible, go with polypropylene, but lead them off-board to the input sockets and well away from power leads. Use decent standard electrolytics like Panasonic or Rubycon etc. elsewhere. If you like it, revisit and fit boutique gold plated terminal stuff later.
Good luck with the DX projects. Anything based on the DX blame ST or ES like those supercharged versions should be fine as a powerhouse. They sound good in original form too, with bog-standard parts. That's all Carlos uses.
That's fine too - perhaps too fine to get that Naim sound but there aren't a lot of options as the Sanken Parts are expensive but I'm sure you could use the same die in the TO247 pack there, which is what the cheaper Sankens are. I haven't done it yet, but I have them on order (Newark in the US has them) so I might get to try this some time. The supplied kit parts (see ljm-ljm post above) are not any power transistor at all - more like a TIP31 or less.
The VAS transistors were Zetex ZTX 653/753 which are borderline hot running. In recent kits they also supply Renesas 2SC2547 + complement which are mighty low noise transistors - wasted here, but if they work...
If they fitted, I would use decent Video drivers like TO126 Fairchild KSC3503/A1381. There you have near the cheapest but still best, without concerns of ratings.
The rails will need to be up above 35V to get decent power and the originals had 40V rails which is a twin 27 or 28V max. secondary windings transformer. Here they are a stock item at manufacturers or resellers specialising in audio applications. 160VA or 300VA should be plenty and are common sizes for use with each or both channels respectively.
Interesting, the Tantalum caps on Naims. I fitted huge polypropylene caps that I thought would be superb but it lost the sound a bit and I had to fit earthed sleeves to them to eliminate hum and noise pickup, so I went back to the original spec. and they do sound right if you are careful to get adequate voltage spec. and quality, like anything. I used 15V rating - still overkill but I'm paranoid about damage, even though I have 30 year old gear full of 'em that are still fine and the sound has changed but not necessarily been improved by substituting electrolytic caps.
If you just want the best sound possible, go with polypropylene, but lead them off-board to the input sockets and well away from power leads. Use decent standard electrolytics like Panasonic or Rubycon etc. elsewhere. If you like it, revisit and fit boutique gold plated terminal stuff later.
Good luck with the DX projects. Anything based on the DX blame ST or ES like those supercharged versions should be fine as a powerhouse. They sound good in original form too, with bog-standard parts. That's all Carlos uses
.Now. The NAP140 will provide the LJM adopts excellent B649 D669.
Replace the original MJE340 NAIM MJE350. It has a high frequency and linear.
And Japan produced SANKEN 2SC3858.
Please note. Don't let a transistor has static current.
Because no temperature compensation circuit.
It is suitable only for work in CLASS B
AND 2SC3858 VBE< 450MV
Replace the original MJE340 NAIM MJE350. It has a high frequency and linear.
And Japan produced SANKEN 2SC3858.
Please note. Don't let a transistor has static current.
Because no temperature compensation circuit.
It is suitable only for work in CLASS B
AND 2SC3858 VBE< 450MV
Hi
You are aware, I guess, these Renesas types are not manufactured for a long time so how can your suppliers offer this NOS that is unobtanium, for next to nothing? Or 4 x Japanese Sanken 2SC3858 that will cost $20 to you, not including profit, shipping etc. Having tested recent pre-assembled NAP140 modules and paid only $37/pr, I know I got only what I paid for but it is not using genuine parts as quoted. Not even the printing is correct, straight and the tinning is brand new on minimum 12 year old worn parts that are described as "pulls" from scrapped amplifiers.!!!
Customers are at yours and similar Ebay suppliers' mercy as to what is in those parts but whatever you quote as your design specified parts means nothing if the silicon is only a cheap substitute, as mine were (output transistors failed at 22W sinewave power). If you take a random sample from production and demonstrate it produces 70W RMS/8R then we may have more confidence in your claims. So, if the suppliers don't follow your declared specification, who can we believe? No-one!
It is a great pity that our pastime is plagued with faked components that attract keen buyers thinking they have a bargain in their kit purchases. What they have is something that will work in a basic way as long as you don't use it anywhere near the original specified rating. Customers would be better off to use a small chipamp like LM1875 and still have better sound with a chance of it surviving normal use, too.
To be fair, most inexpensive and current manufactured parts appear genuine and that is reasonable since there is little point in faking cheap parts. So substituting MJE340/50 with long obsolete parts would seem a good idea, if they were real RENESAS parts. Certainly, I have bought NAP 140 kits that use cheap but good parts like 2SC5200 transistors. These worked near to spec. but cost more as kits.
Had that sales policy remained, we might have happier customers returning for more products. Ian, Thx for sharing your experience with the NAP 140s. You are correct in stating selling kits with real parts that would work to spec would encourage repeat sales and happy customers. If these Ebay sellers had their own forum for customer input and updates AND gave the customers what they wanted, they would triple their sales. Selling faulty/fake circuits and parts leaves you with a bad feeling of being ripped off thus no return customer. There's plenty of room for improvement.... However, hobbyists like us take a chance searching for something decent, then share the experience so others can benefit. I wish DIY would be more open to letting circuit boards be sold for profit or take over popular approved projects sales. Any profit could go towards promoting the website. I rather buy a board from this forum than China. Ok, I'm done.......
Iv'e almost completed my tubeshunter nap clones. I have a few questions if anyone can help. Should I send a wire from my signal ground to my star ground?, my input phono sockets are insulated. Do I check accross R29 to adjust the pot, and should I read about 4mv or less? Merry Xmas and a Happy New Year to all. Regards Barry
Hi Barry
Run a substantial earth lead from Input ground connector to star ground on the PSU or from an adjacent connector provided for it.
I also find it worthwhile to place a 10 or 12R resistor between the signal lead braid and the input ground terminal to lower Hum quite measurably in domestic amplifiers.
I guess you are checking offset voltage there and not bias (I hope). You measure offset across the output terminals to the speaker (without it being connected) and 4mV is as good as it gets. Few amps are this good and 25-40 mV is still OK.
Thanks for your good wishes. Season's greetings also to you and yours.
Run a substantial earth lead from Input ground connector to star ground on the PSU or from an adjacent connector provided for it.
I also find it worthwhile to place a 10 or 12R resistor between the signal lead braid and the input ground terminal to lower Hum quite measurably in domestic amplifiers.
I guess you are checking offset voltage there and not bias (I hope). You measure offset across the output terminals to the speaker (without it being connected) and 4mV is as good as it gets. Few amps are this good and 25-40 mV is still OK.
Thanks for your good wishes. Season's greetings also to you and yours.
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Ok, After finding the tubeshunter o/p trannies are real and the ones I bought to replace them are fakes I have fitted the originals and apart from two joints unsoldered (oops) and one duff resistor, I now get a reading of 2.2mv accross R29 and 11.5mv and 16.5mv accross the speaker terminals. I don't know why they are different but I assume it is OK. Next I will plug in the pre-amp and speakers and see if there is any life. Regards Barry