Thanks Nickgreek for posting all those schematics.
From where did you get it ? Were you in naim service (like me a bit) in those old and brave days ?
We should beware that this this is mostly 80ies and earlier stuff.
But I personally like the single ended topology of the Naim pre stages very much. I listen to a (mod) Naim-Preamp every day.
I think they still use this technique now, but with the newest preamp they seem to have changed to a symmetrical +/-12V power supply - to get rid of the caps, I suppose.
Klaus
ps:
artnyos: please take a long close look /the rest has been cut out/
From where did you get it ? Were you in naim service (like me a bit) in those old and brave days ?
We should beware that this this is mostly 80ies and earlier stuff.
But I personally like the single ended topology of the Naim pre stages very much. I listen to a (mod) Naim-Preamp every day.
I think they still use this technique now, but with the newest preamp they seem to have changed to a symmetrical +/-12V power supply - to get rid of the caps, I suppose.
Klaus
ps:
artnyos: please take a long close look /the rest has been cut out/
lohk said:
lohk,
the 80ies Naim stuff is that which sounds best. I listened to 90ies Naim stuff several times, did even home demonstrations, but I did not like the sound. Even the latest series 5 and the new NAP500 is not my taste.
I have 32.5-Snaps2 (that is a modified Snaps power supply to work in Hicap mode, that is two power rails are used for the preamp) NAP140 (with Sanken output bipolars, slightly modified as described in another post in this thread before), NAT101+Snaps (a wonderful tuner, better than the tube Macs and all the Sansui/Kenwood/Yamaha hi-end tuners I had before), and it is more sounding like tube, giving the full Naim virtues of rythm and drive. Current Naim stuff lost that tube magic.
re the new 552 preamp with split rails: Well, I also suspected that they eliminated some coupling caps, when I saw the frequency plot in current German Stereoplay/Audio issue. Though I think the main reason for using the split rails was that considerably less power supply currents go through the ground line.
I dared to think they had something like a diamond configuration follower (see the input stage of a Hiraga Class A), when I saw the thermal coupling of transistors, but knowing that they never changed the circuits, they surely won't. Though I read somewhere they introduced a new output buffer design for one of their CD players, and used that design later in their NAP500 (I guess for driving the inverting channel through the feedback ground resistor ;-)). Do you have more information on that ?
regards,
Hartmut, who does really like Naim (at least the old stuff)
Re: substitutes
Ced,
Zetex ceased production of these to the beginning of the year, but Naim always got their transistors from another supplier respective second source (someone mentioned it on the Naim forum, but I cannot remember the brand).
Have in mind that the Naim stuff was designed in the 70ies, and the choice of transistors simply reflects the standard of that time. Of course you can use BC384 or BC214 which are the generic numbers for said Zetex variants. Or even more modern devices, like BC550C, BC550C. Or even more standard hi-end transistors like the common Hitachi 2SC1775/2SA872 or Toshiba 2SC2240/2SA940.
Almost any small signal NPN and PNP transistors will work in a Naim preamp circuit.
Neil McBride did use the Toshiba 2SC2547A for the NPN small signal transistor, but I do not like that choice.
I prefer 2SC2240 for the NPNs and 2SA872 for the VAS.
regards,
Hartmut
ced said:
Ced,
Zetex ceased production of these to the beginning of the year, but Naim always got their transistors from another supplier respective second source (someone mentioned it on the Naim forum, but I cannot remember the brand).
Have in mind that the Naim stuff was designed in the 70ies, and the choice of transistors simply reflects the standard of that time. Of course you can use BC384 or BC214 which are the generic numbers for said Zetex variants. Or even more modern devices, like BC550C, BC550C. Or even more standard hi-end transistors like the common Hitachi 2SC1775/2SA872 or Toshiba 2SC2240/2SA940.
Almost any small signal NPN and PNP transistors will work in a Naim preamp circuit.
Neil McBride did use the Toshiba 2SC2547A for the NPN small signal transistor, but I do not like that choice.
I prefer 2SC2240 for the NPNs and 2SA872 for the VAS.
regards,
Hartmut
NAC 32
Hello people!
Who has interested for Naim32C can get my information by e-mail.
nickgreek@gmx.de
Hello people!
Who has interested for Naim32C can get my information by e-mail.
nickgreek@gmx.de
729 boards
Jim,
I wouldn't worry unduly about pics of the 729's (unless you're a Naim-spotter!), the schematic I've posted is all you need to make your own.
Many of Naim's PCB layouts on earlier designs are far from optimal loads of shared current paths, long signal paths etc. - have a go yourself, and do it better!
Andy.
Jim,
I wouldn't worry unduly about pics of the 729's (unless you're a Naim-spotter!), the schematic I've posted is all you need to make your own.
Many of Naim's PCB layouts on earlier designs are far from optimal loads of shared current paths, long signal paths etc. - have a go yourself, and do it better!
Andy.
Hi Andy,
Yup, I'd tend to agree with you - I'm a firm believer that everything can be improved, and am quite happy to have a go.
The schematic you posted was on my harddrive within about five minutes of you posting it - cheers!
However, it's often usefull to have an existing design to refer to.
Certainly not essential, but usefull for lazy guys like me ;-)
Jim.
Yup, I'd tend to agree with you - I'm a firm believer that everything can be improved, and am quite happy to have a go.
The schematic you posted was on my harddrive within about five minutes of you posting it - cheers!
However, it's often usefull to have an existing design to refer to.
Certainly not essential, but usefull for lazy guys like me ;-)
Jim.
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