naim clones

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Naim Clones

Hello All 😉

First of all I would like to thank everyone for such an interesting subject (if this is what it is).
I'am new to all of this but still find the whole thing of naim clone's very very interesting indeed. :idea: So intersted that I would like to build a naim clone HIFi and would be very greatfull for any advice and information the people in this forum could post or e-mail me.
Please don't let this get out of hand and keep up the interesting subject.


Thanking One & All of you kind people.

Les Atkinson
 
Yes, Andy, can you reveal some facts about the all-new naim amp circuits ?
In the smaller amps this means a different frontend and biasing, I suppose. Did you lift one of these black caps, which clamps together the input diff stage ?

very curious,
Klaus
 
In a somewhat closer inspection of an image of the NAP150 (low res only, printed in the german mag AudioPhile 3/2002) I found a few more details (?) about the new amp version:

The main circuit (in comparison the NAP140) seems basically unchanged, besides changes in the overload protection section (which interests me not that much) I think the main changes are (not in the order of importance):

All the tantal pearl caps are gone (well almost, see below). I spot two polarized caps for bias smoothing(?) and feedback highpass, and another one, probably bipolar, at the input, all from Panasonic I think (dark blue).

The CCS for the input stage changed from a simple (one transistor/two diodes) version to the naim typical CCS they use in the preamp output stages (two npn trannies/two resistors, full voltage supply). This seems a good thing, but the connection of the second driver transistor to the new CCS is yet unclear to me (maybe unchanged from the base of the main transistor of the CCS via the 1k resistor).

The bias transistor is now thermically connected, not directly to the heatsink, but to the bottom of the case. After all the case is a part of the heatsink anyway.

The input difference amp pair is hidden under a thermal coupling cap, and has probably changed to a (so the text suggests) four transistor version. There is a new small styroflex cap from + , maybe bypassing one of the collector resistors (?). The stability and tolerance here is a part of the Naim sound I suppose.

The psu has not changed (one bridge for each channel with two 10000yF caps, running from the the same secondary windings of the transformer). The preamp psu section has its own secondaries now, again two windings running into two diodes for one output voltage (like in the bigger preamp psus. This is followed by the usual LM317 section (individually heat sinked), where I can spot the last remaining tantal caps. The LEDs illuminating the front name display are running from the unregulated line of the preamp psu supply line.

Input is still via a DIN socket, but this is a plastic PCB soldered version here, as far as can see.

Probably there is a small resistor now connecting the power star ground to the input star ground, but this section of the image is quite dark and unreadable.

All resistors are still pretty basic metal film 5%, except the feedback resistors with 1% tolerance. These guys at Nain are pretty self confident, I must say.

All for the moment.
Klaus
 
Hello .. and some tips ...

Hi,

first post here so don't be to hard on me. I noticed my name mentioned a few times in this thread and thought I ought to conribute myself. Below is a post I put up on the Pink Fish Media forum regarding Naim preamp power supply tips. I have found all of these help a bit to get you beyond Hicap performance. Add to this some of ALW's fatastic regulators and you will be a very happy camper indeed!


Cheers

Jason Hector

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I found the biggest upgrades I made to my supplies were:

Moving to a pre-regulator (so I have reg 1 which regulates the voltage off of the smoothing caps to 29V, then reg 2 which regulates this line to 24V). I still use a standard LM317 circuit just careful implementation.

Using multiple decreasing paralleled capacitors on the inputs to the second regulator - 10uF 1uF and 0.1uF.

Being **cking careful about the wiring and ensuring I have a really good star ground point, including wiring each pre regulator and post regulator individually back to the same point. So in a two rail device I have four ground wires just for the 4 regulator grounds and anothr two for the signal in and out individually. Also I take the star point at the end of the wire that links the smoothing caps. This seems to act like a benificial RC circuit. The input to the pre reg also has a couple of paralleled capacitors on its input which appear in parallel with the main smoothing cap bank.

Cases are all aluminium and I am of the big toroid and cap school - 500VA + 40000 to 50000uF of smoothing in the physically largest caps I can afford at the time. Also I spread things out. So my power supplies are full width. Toroid on one side, then the cap bank down the middle in a line, and regulators and socketry as far from the toroid as possibe. + Use high current (low R) wire.


All of these things are pretty subtle and that is why I am up to iteration 7!
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And lastly here is a report on ALW's visit to my abode ...

A visit by the master tweaker pt 1 ...
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Last Friday Andrew Weekes he of tweaking the hell out of Snaps' fame visited the Hector residence bearing a multitude of small boxes partly filled with some pretty special electronics ...

Now many of you will be aware that Andrew has been tinkering around with the boxes in his syetm to try to build better power supplies (he has done other stuff but that is a discussion for another day). As a homebuilder myself I was intrigued to talk to him and after seeing the circuit for his super regulators I had to have a listen.

My own power supplies are dead simple but seem to get the job done after numerous failures along the developement path (including an interesting experience connecting 30000microF of electrolytics the wrong way, they didn't go bang but teh dielectric boiled!). In my system I think they work pretty damned well as they are balanced to the rest of the boxes.

Andrew brought the following devices:
Dual rail SNAPS using two super regs and two SNAPS' with a single rail super reg. He also brought a 42.5 which had a superreg on board and some other tweaks to up its performance.

So after a cup of tea we set the SNPAS a warming and played some tunes in the hope that Andrew could adjust from IBL's to Shahinian Obelisks ...

The first supply we tried was to replace my dual rail Prefix supply with a single railed Snaps. Immediately it was obvious that the noise floor dropped a long way, shite a hole opened under it and I think it is still falling. The backgound electronic noise all but disappeared, result! The music that then issued forth was as enthralling as before but the upper bass seemed to have lost something. The Te-Kaitora cart I use has a fantastic ability to just get out of the way and its bass performance is exquisite so this was for me a little disappointing. That said the rest of the frequency band was clearly benifitting from the super reg. Vocals in particular were cleaned up and seemd to give a little more emotion although I thought there was some masking in the midband and because of the bass issue I lost some of my connectionto the music. This could have been just because it was different in a system I am more than used to. The next step however was to replace the single rail Snaps with a dual rail device. Now that was more like it. The bass was back in its proper place and we seemed to have removed a ludicrous amount of crap from teh signal. Bass was tighter, treble had real texture and the system just boogied beautifully. To be honest I was shocked that this little box was sounding sooo good. The raw passion in voices was a joy, cymbals were palpable, they sounded like a large disc of metal being whacked by a stick.

Suffice to say I will be including a pair of superregs in my next power supply project ... actually I am only starting a new project because I have heard how good the super regs are!

The other Snaps were similarily impressive replacing my 4 rail supply to the 82. Again the most obvious change was a driop in the noise floor and again the lusicality of the system just grabbed you from the moment the stylus hit groove modulation. Again though we both felt that the dual rail power supply had the edge in the upper bass. Andrew will now be dual railing everything!

Last into the system was the modded 42.5. Once upon a time I modded a 42 to Niel McBrides specs and ended up with 6 regulators inside of it each feeding a small part of the circuit. Andrews singly regulated Snaps strongly reminded me of that pre amp. Basically when you locally regulate a 42 or similar you just make huge gains in the important areas and the thing, to quote our FE guru "times like a bastard". Andrews did this, yes the four railed 82 was more detailed but in isolation the little pre was just such good fun that you ignored the missing bits ... I can't really imagine how good it would be with 4 reg boards but I intend to find out ... anybody got a 42, 32, 62 .. .they don't want.

Sorry for posting such a ludicrously long post but I thought it would be interesting to many of you.
 
I expect it. I dont no know what power use (in Va)

If others have feedback...
It's a very basic Naim preamp circuit with 5 TO92 small signal transistors per channel, powered by an onboard 24V 3 terminal regulator. The stated current requirement is 10 mA per channel, total 20 mA. By VA, I assume you are referring to a suitable transformer and even the smallest types commonly available (around 5VA) with 12+12 or even 9+9 VAC windings should be fine for the sniff of current required from the single +24VDC supply after regulation.
 
It may be useful....
 

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