Naim Nap135 Monoblocks (Homemade)

This is really for all those folks that think hifi is over priced and that the price you pay is built purely on reputation.

My friend and I are going to build a pair of Naim 135 style Monoblocks with a suitably large power supply. I've just completed the parts list and it comes to to £300 for the lot. Someone please tell me the list price

Now, I'm not saying that Naim pay £300 for the compents in each pair of 135s, because they will buy in bulk and get a big discount, but I've costed the parts and that's what it's going to cost to build a pair of these monoblocks.

Some of the individual components, for example are( Output transistors £5 alone) (Heatsink £25), Toroidal transformer (550VA £26). Luckily, I'm an electronic engineer, so I can see where the performance benefits are gained in every component used , versus lower grade components.

I was surprised at how high the value of the components was for a pair of 135s, but my friend and I are going to build 2 pairs of these monoblocks and be damned. I'm looking to Bi-amp with a NAD 370 doing the bass duties, cos that sounded sweet when we did it with my NADC370 (Bass) and his Naim Nait5 (Treble) a while back

I suppose if you're speptical then buy a service manual and cost the parts yourself. Personally, I'm happy with the price I paid for my own kit, but I wonder if the same would aply to very high end kit like Krell etc.....?

Anyway I'll let you guys know how the project goes, but I suspect for £300 a pair it's got to be good.


P.S. I do my own beer (full mash), and that's about a million times better than most stuff you buy in almost all pubs. I Expect the same with this project.


P.P.S Feel free to ask what a "full mash" is.




DEX

 

I don't doubt your brewing or engineeering skills. However, a pair of 135s - home made or otherwise should sound better alone than if a NAD amp came anywhere near the system. No disrespect to NAD but notwithstanding the gain issues, there will surely be some timing issues too if you use a NAD amp to power the bass/mid and the Naim clones to power the treble?

Hang on, troll alert!

 

The parts sound very cheap to me.

The transformer replacement for my Border Patrol amp cost just shy of 150 (part only). Are the components the same quality that Naim use in their 135s?

Chris

 

Indeed, I think in the interests of fairness you need to use the parts from the same manufacturer.

Then factor in the cost of designing and building the case work, R 'n' D, dealer profit margins, promotion, consistant product, staffing, building rental, magazine advirtising, hifi shows, and of course your own profit

Commerce is a difficult thing.

 

Chris, i imagine your Border Patrol Tx's will have multiple secondary windings, whereas for a SS amp it is most likely just 1 center tapped secondary. I also think that valve supply TX's will sell a lot less that the others. It may go some way to explain the price differences?

 

yeah, mine is a super-duper custom made slippery shiny no holes bared wonder-winder jobby.



http://www.borderpatrol.co.uk/transind.htm


Still though, 25 notes looks too cheap to be what Naim would use, surely?

 

Naim transformers are wound for Naim (this isn't a big deal, I'm sure the manufacturers will wind exactly what you want, but maybe not in twos) and have (IIRC) two centre-tapped secondaries.

The output transistors are 'custom' made by Semelec, again I'm sure they'd do that for you too.

I suspect the most expensive part of a NAP135 is the casework.

As a crude estimate if a NAP135 retailed at £2000 then it left the factory at about £1000 and should have cost less than £500 to make, so about £250 or less in parts?

Paul

 

Absolutely right Paul,

The case is the most expensive item in a solid state amplifier. I'm always told that the best toroids are the Antrim ones but if you can't find one off the shelf, Maplin keep some, that is just right then you have to have them made up and they need a minimum order.

I have always been told that Naim's expertise lies largely in the layout of the boards and wiring of the amp, so it would be sensible to stick as closely as possible to the original. They also throw away a hell of a lot of substandard caps and resistors retaining only the selected ones for use in the amps.

 

Most electronics are made for between 18-25% of RRP, the dealers are the ones that make the money
any way for £600 why bother with naim, just buy a Evo 200.2 for £600 shipped in from the US, easy voltage swop, bomb proof & will comfortably take apart a pair of nap 135's, with dynamics speed and bass control that nap 500 owners aspire too ( as james says do they admit to owning one? ) sorry just board before I go out

 

I should have said that the £300 price is only for the electronic components, not for any of the case work required. My mate is going to do this as he owns a sword making company that has loads of machinery that we can use to build nice hefty custom made aluminium cases.

I also should have included all the various chassis connectors and sockets etc.

As for the Toroidal transformer heres the spec from the Farnell electronic components company "TRANSFORMER 500VA 2X55V Regulation 5 % Current rating 4.55 A Diameter, external 136 mm Length / Height, external 59 mm Power, AC 500 VA Voltage, output 55 V" £26.45. I'm really not too sure what Naim use in their power supplies, maybe they use massively over-specced transformer, but even then you're looking at £40-50.

Anyway we should have fun building them and listening to them, hopefully we won't blow anything up.

Here the link to the site where we got the design and idea from. http://www.neilmcbride.co.uk/jknamps.html



Dex

 

hmm

is that Blue's swords?

 

55v seems excessive?

Anyway a Naim amp would have 4x55v due to the way they configure their rectifiers. I don't know how important this is to the sound of the end result.

Have fun... You might find some useful experience and links to pictures of McBride derived '135s' on the Pink Fish forum.

Paul

 

Hello Penance,

My mates company is called Armour Class. Webpage at http://www.armourclass.co.uk/. Very high quality stuff. Hope our amp is as good as his swords and my beer.

 

Hi Dex

I see he does re-enactment swords, similar to one i had.
Shame i dont do it anymore

 

That depends on volume purchased. At these quantities you'd be closer with about double that price, especially for 'audio grade' spec.

Anyway, that's of little significance here, there's a lot more to that circuit than meets the eye, for one you can't buy the same output devices as Naim and these are a pretty crucial part of the performance.

You'll also need to take care in matching certain components (and I don't mean only the input diff. pair!). Bear in mind (and I know Neil won't mind me saying this) he does not understand the circuit in detail; this is obvious from the schematics, which have copied the Naim component values in some areas where they will need to change because of changes elsewhere in component choice.

In fact, Neil himself no longer uses these amps, but uses something much more akin to the evo suggestion!

Before you ask, I'm not going to offer any more than this, it wouldn't be fair to Naim.

I have no doubt you will build a good sounding amp, given enough care, but it cannot be a Naim.

Personally I agree with WM, this is a difficult, ill-understood circuit and you could get far better results via another means, just as cheaply. It just looks simple, on paper

Andy.