While trolling the bay I found this:
http://cgi.ebay.com/2-X-NAIM-CLONE-...ryZ12050QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
Would this be a worthwhile first project for a kit newbie? Not much published on it, though I did find this:
http://hk.myblog.yahoo.com/ricky_t7/article?mid=338&prev=340&next=335
Highly suspect source, references to Kenny G and such...
http://cgi.ebay.com/2-X-NAIM-CLONE-...ryZ12050QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
Would this be a worthwhile first project for a kit newbie? Not much published on it, though I did find this:
http://hk.myblog.yahoo.com/ricky_t7/article?mid=338&prev=340&next=335
Highly suspect source, references to Kenny G and such...
Please Sparkle, inform the Croatian forum link, for us to visit
People told me the forum uses a lot of nice images and good resolution pictures too.
Despite language barriers, schematic can be read around the world, also images can be understood...smilies informs things too.
regards,
Carlos
People told me the forum uses a lot of nice images and good resolution pictures too.
Despite language barriers, schematic can be read around the world, also images can be understood...smilies informs things too.
regards,
Carlos
The good thing about the Naim circuits, in general, is that they use relatively few parts and so are easy to build and get working. At US$50 for two boards and all parts it is at a reasonable price.
Just a couple of things. The design is not the same as a real NAP140 so it won't sound the same. Looking at the photo, the output transistor over-current protection circuit is missing so you'll need to be careful never to accidentally short the speaker outputs or the transistors will be destroyed.
Brian
Just a couple of things. The design is not the same as a real NAP140 so it won't sound the same. Looking at the photo, the output transistor over-current protection circuit is missing so you'll need to be careful never to accidentally short the speaker outputs or the transistors will be destroyed.
Brian
Re: I think Aeon is our forum member...not sure...he can tell us something about
Funny, i think it looks like a wooden cooler underneath the output trannies in post #8. Or is it copper maybe 😕
destroyer X said:
Funny, i think it looks like a wooden cooler underneath the output trannies in post #8. Or is it copper maybe 😕
It seems to be some finishment applied over the aluminium heatsink dear Ebbe
Those anodising results, that transforms silver aluminium in something that remembers copper or gold.
The one is not very clean, not very polished, not very new....some heatsink he captured from dismounted amplifiers.
regards,
Carlos
Those anodising results, that transforms silver aluminium in something that remembers copper or gold.
The one is not very clean, not very polished, not very new....some heatsink he captured from dismounted amplifiers.
regards,
Carlos
Attachments
Hi Carlos,
That schematic looks like it matches the photo. Note that the 10uF and 68uF capacitors are shown the wrong way around: they are reversed biased in the schematic.
Brian
That schematic looks like it matches the photo. Note that the 10uF and 68uF capacitors are shown the wrong way around: they are reversed biased in the schematic.
Brian
I'd say You're right about the 10uF, but the 68uF over the c-e at the 2sd786 looks right to my eyes.
best regards
Ebbe
best regards
Ebbe
Is this topology Class A? Can it be biased into Class A if not?
I am familiar with Naim, but never had/heard one...from a few posts I have read, and pics I have seen, I have never seen one with monster heatsinks, so my guess is they are not Class A amps...
I am familiar with Naim, but never had/heard one...from a few posts I have read, and pics I have seen, I have never seen one with monster heatsinks, so my guess is they are not Class A amps...
John,
You are right. The Naim's are class AB - with output transistor bias current set in the 30mA to 50mA region (as far as I recall). Very good for the environment. I see no technical reason not to bias it higher if you wish. In a real Naim circuit the extra bias doesn't affect the sound much. They are also what would usually be called high NFB designs.
The circuit is deceptively simple, based on an RCA design from the 1970s. But it is not simple at all. To get them to sound as good as Naim does requires a lot of careful selection and matching of parts. The parts these clone circuits use are not all the same ones as Naim uses.
Brian
You are right. The Naim's are class AB - with output transistor bias current set in the 30mA to 50mA region (as far as I recall). Very good for the environment. I see no technical reason not to bias it higher if you wish. In a real Naim circuit the extra bias doesn't affect the sound much. They are also what would usually be called high NFB designs.
The circuit is deceptively simple, based on an RCA design from the 1970s. But it is not simple at all. To get them to sound as good as Naim does requires a lot of careful selection and matching of parts. The parts these clone circuits use are not all the same ones as Naim uses.
Brian
Hello
Yes, Naim amp do used selected parts and the LTP input pairs transistors was matched for HFE and VBE , and take a fast transistor for the VAS.
In the NAP 250 schematic you can see a 10 uf cap in the protection circuit, it's to do a small delay so the protection will get in after that small delay and will do less interferences in the normal high level output signal.
Bye
Gaetan
Here's the NAP 250 schematic;
Yes, Naim amp do used selected parts and the LTP input pairs transistors was matched for HFE and VBE , and take a fast transistor for the VAS.
In the NAP 250 schematic you can see a 10 uf cap in the protection circuit, it's to do a small delay so the protection will get in after that small delay and will do less interferences in the normal high level output signal.
Bye
Gaetan
Here's the NAP 250 schematic;
An externally hosted image should be here but it was not working when we last tested it.
I did end up purchasing that kit and I'm providing the schematic that came with it. There is also another sheet included in Chinese. The boards are very nicely constructed with gold traces. The parts are as described in the listing.
I compared this schematic with the one posted by Carlos, some slightly different values, those are highlighted with an asterisk.
I have never built a kit and this looked to be a good first one, not sure when I'll get to it, though. If anyone wants any additional information on what I received, just ask.
There is some writing on the board:
AEON copy NAP140 2007 and hifidiy.net.
I do have one question at this point: I have two power supplies from the Accurian receiver that recently was going for $15. The toroid is a 28-0-28 2A. Would I be able to use these for a dual mono arrangement? If not, what are the power supply needs, they are not indicated in the schematic.
I compared this schematic with the one posted by Carlos, some slightly different values, those are highlighted with an asterisk.
I have never built a kit and this looked to be a good first one, not sure when I'll get to it, though. If anyone wants any additional information on what I received, just ask.
There is some writing on the board:
AEON copy NAP140 2007 and hifidiy.net.
I do have one question at this point: I have two power supplies from the Accurian receiver that recently was going for $15. The toroid is a 28-0-28 2A. Would I be able to use these for a dual mono arrangement? If not, what are the power supply needs, they are not indicated in the schematic.
Attachments
Here is a link to some photos of the same kit I received:
http://bbs.hifidiy.net/viewthread.php?tid=78276
http://bbs.hifidiy.net/viewthread.php?tid=78276
