Upgrade to vintage NAP 250

Hi-Fi Corner
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My first naim system was 32.5/snaps/250.

The 32.5 had (still has since I have it in the attic) 2 sets of BNC inputs (one set for MM and one for for MC). I only ever used MM (Shure M75ED). Eventually I moved to NAC82 and MC.

I think if you have both MC and MM cards in your 72 you can swap them around so that you have either the MC or MM card attached to the BNC sockets.

However, before you try this, check with the forum.

Unless you are using two decks or have a detachable headshell you really only need one phono input.

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Better get the whole thing checked and serviced by Darran before having all the fun.

Given Darran’s current lead time I know it’s painful but really worth it.

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I recall the early Nac 72 had two pair BNC phono inputs, possible with MM & MC cards as standard.?

Then came CD medie and Naim released CDS/CDi.

The later Nac 72 had one BNC phono input and one DIN5 AUX/CD input, mine had the variable output cards for this input.

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Hi Richard

Thanks for this advice.

Long story short my 72/140 system is working perfectly now.

Long story -

I tried all the inputs again and found that I could hear audio albeit with background “machine gun pop pop pop noise”. With no audio input the noise increased with the Volume knob turning louder when the CD input was selected , but not on any of the other inputs.

I opened up the 72 and removed the MC cards from their slots and all feedback noise ceased. Hurrah !!

I then replaced the MM cards feeding the BNC phono inputs with MC phono cards and hey presto that worked as well.

I reckon the MC boards were stored in those “CD ?” slots for safe keeping as the unit had been stored for some time. Those slots are now empty (as you can see : every thing works so I don’t know what purpose they are used for).

See a picture of the empty slots

FWIW I still get a hum when the machine turns on and then after three seconds there are a couple of clicks and the hum disappears. It seems to happen when I turn the machine off, a thump then a hum , a couple of clicks . Can anyone explain this ?

Anyway - now the fun starts

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Great news - music at last!

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Nice to hear it’s up and running. Free tweak - if you’re not using a tape player for recording, you can pull out the NA324 tape buffer boards. I find the sound is more focused, though some prefer to leave them in.

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This is normal when powered from the power amp. @NeilS can probably explain why better than I can…

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Glad to hear you’re up and running.

The CD input will work as next to the input wires (yellow/black & red/black) are the links that bypass any fitted board. What could be fitted there (with the links cut) was a variable input board which was designed to attenuate and filter the signal from early CD players but the general consensus is they are detrimental to the sound.

Hums and clicks are perfectly normal - the 72 has a mute relay which disconnects the 140 during power up and subsequently disconnects during power down. If you added a Hicap and kept the 72 powered on then you could turn the 140 on and off with no noises.

The hum can be reduced if you tie the signal ground to mains earth. Traditionally this would be achieved by connecting a naim source. (CD player, streamer). The other way to do it is an earth wire from the ground post on the back of the 72 to the earth pin of a mains outlet.

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I recall I preferred them in - its been ages though.

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As said above - when you switch on, the main thump is from the power amp, followed by light hum as the power amp input is floating. The next couple of pops are each channel of the double pole output relay in the preamp closing.
When you switch off, the main thump comes from the preamp losing power, followed by the floating input hum, then the next couple of pops are each channel of the power amp discharging.
I’ve always viewed direct pre to power amp like this, as a bit of a stop-gap solution to get you up & running before adding a power supply.

Regards
Neil.

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You need to cut these two links if cards are fitted to these slots… The wire links, not the cables.. :slightly_smiling_face:

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Thanks Neil, that’s very helpful - it’s reassuring to learn that the 140 is behaving itself and acting as should be expected, of which I wasn’t sure.

I do realise that at some point I need to get her serviced but I would like to enjoy her first.

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Thanks Darran.

I think I will just keep those slots empty for now.

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I have now had a chance to listen to the 72/140 combination and the 323/5 MC phono boards.

The Amplifiers provide an excellent sound - rock solid image and control; a real depth of bass; an ability to deal with multiple instruments with ease and they are able to drive my Yamaha NS1000m without difficulty.

I have thrown Yes , Pink Floyd , The Who , Van Halen, McLaughin/DiMeola Friday Night, Brahms & Bach’s Cello concertos at them and they all sound good both with very very loud and also at minimum listening volumes.

With regard to the latter, what impresses me particularly is how at very low volumes the depth of sound and also the bass remains there. I realise the Amps don’t have a loudness button in any case but if they did there would be no need to use it.

Using the Naim amps in such a way and not at high volumes actually
makes you appreciate the music more , as you are able to listen to the intricacy of the players whilst still hearing the whole depth of sound.

The phono stage has surprised me as to how good it is and how it stands up to the Rega Fono 4. I have an old Quad 303 and it’s phono stage whilst sounding organic is actually quite muffled compared to the detail from modern phono stages, so I was expecting a little of the same from the Naim MC. Well I was blown away, the Naim 323/5 boards are very very good and I have no need to use my Rega Fono stage, although it’s always fun to switch units and compare.

Listing to Friday Night - the Naim’s strong PRAT capabilities are really in evidence : the system handles the speed of the three players with consummate ease.

So no upgrade to the NAP 250, but I don’t feel like I have missed out, as I feel all your help has got me this classic combo and it feels right.

I was within a whisker of giving up and sending both units back when nothing was working but thanks for the advice which helped me persevere.

I realise I will need to get the Amp serviced ant some point and then consider get a serviced HiCap but for now I will sit back and enjoy this experience cos it’s great….

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Congrats! Very happy for you

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Great ! :+1:,the Naim 323/5 also outperformed the Naim Stageline when I compared.

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Yep, the 72 is pretty fab isn’t it :grin:

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I see you have gone down the 180 & HiCap route with your 72. Have you always had that combination with your 72?

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Started out with a NAP 110 with the NAC72 + HC (previously having a NAC42.5). Moved up to the NAP 180 - not a lot of difference, more power, more control, a bit more feisty. Both 110 and 180, along with the 140, are excellent.

I’m one of those strange people who prefer the 180 to the 250.

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I think it is easy to adopt the herd mentality. This hobby is very subjective and based on lots of factors unknown to others ie how the the listening room affects the sound.

There is often no right answer even though people tend to be definitive about their listening experience.

Maybe I will stop at the 140 myself and not get to the 250 …

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