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Naim Tri-amp system setup and servicing options

Discussion in 'audio' started by cctaylor, Jul 11, 2019.

  1. cctaylor

    cctaylor pfm Member

    I have inherited my father's Naim Tri-amp system. This is a very early one with the Isobariks serial numbers 13 &14.

    I have the following items,

    NAC 32
    SNAPS (2 off)
    NAP 250 (3 off)

    All are original bolt down, the 250s were serviced about 10 - 15 years ago. The other items are untouched. The there is hum on the MC input, this is present with turntable unplugged. There is also a faint burbling in the background present with and without the preamp. (Need to eliminate the WiFi router as a possible cause.)

    I also have an olive NAC62.

    My questions:

    32 or 62 as preamp?
    Is there a sensible way to use the second SNAPS?
    Any advantage in dual railing the preamp?
    What regulator upgrades options for the SNAPS?
    Anyone tried the Witch Hat upgrade on the 250?

  2. Paul R

    Paul R pfm Member

    The second SNAPS powers the NAXO. Lots of wires, from NAC32 to SNAPS, from SNAPS to SNAPS, from SNAPS to NAXO, from NAXO to NAPs.

    I'd be inclined to leave well alone as much as possible, although putting a 5 pin output on to a SNAPS is non-destructive and would improve matters with the NAC62.

    I think we need some photos. Are the Isobariks the original wide side forward style?
  3. divedeepdog

    divedeepdog pfm Member

    If its in good cosmetic condition I'd be inclined towards sympathetic service, straight early gear is becoming rare. Class A in Sheffield will maintain its Naim credentials and authenticity.

    For background I'm an Avondale fanboi and would normally recommend modding Naim, but for minty (historical) set, original is nice.

    *Options also alter depending if you want to keep or resell gear.
    Strictly Stereo likes this.
  4. cctaylor

    cctaylor pfm Member

    The Isobariks are 2nd generation, as I understand it all PMS were that style. Dad did have a set of the original Isobariks with the slab sides driven initially with Sugden P50s set up as mono amps. Then a single 250 which occasionally would cut on over temp!
  5. Woodface

    Woodface pfm Member

    Lovely system, keep it as original as possible, probably some sympathetic mods to the pre-amp? The nap250s will only go up in value & give a sound unavailable elsewhere.
  6. Bob McC

    Bob McC Living the life of Riley

    I’d keep it as is apart from splashing out on a full service then enjoy it until it is inherited by your kids...
  7. Stemcor

    Stemcor I should be listening to music

    This is a bit of a “time capsule” system and of it were mine, I’d look to get the 32 and both snaps serviced and probably leave everything else alone.
  8. Woodface

    Woodface pfm Member

    Can the 32 be turned into 32.5 to accept a high cap? That would give a lovely symmetry.
  9. nobeone

    nobeone pfm Member

    I have to agree, service, then enjoy ...

    ... then if you want to, start with non-intrusive upgrades ...

    ... how about about RSL cards to drop in replace the 32 card? I have not owned a 32 but own a 72 and recently tried the RSL cards and really liked them. It would turn the 32 into a giant killer, the onboard regulation in the RSL cards may make your desire to tweak the SNAPS deminish too. Plus you could go backward to original status very easily. When you have got to the point of wanting to try modifications then contact Kit on PFM and try the loan cards, see if you agree. Nothing lost?

    Try Avondale style separation of power and signal cabling and replacement cables from NAXO to 250.
  10. cctaylor

    cctaylor pfm Member

    Hi thanks for the suggestions, especially the RSL card options. I have Witch Hat SNAICs on order and they separate the power from the signal in a different way from Avondale.
  11. peterm

    peterm pfm Member

    I agree with above comments regarding maintaining originality of these collectable items from Naim's early days, don't mess around with them if you want to retain their desirability and value.

    Having said that the "burbling" sound is almost certainly the 250s (or one of them) telling you it needs a service. 250s have a weak point in the power supply regulator boards in the form of some small electrolytic capacitors that fail at regular intervals, after 10 - 15 years it's probably one of the 250s (you could try switching them off one at a time to see which one it is!). The capacitors are cheap as chips but a professional service to replace them isn't!

    The hum from the phono input probably indicates the SNAPS powering it needs a service.

    I don't think a bolt down 32 should be modified to "32.5" dual railed form, losing originality again. Your 62 is dual rail of course, are your SNAPS dual or single output (I believe there were both). If they're single rail I'd be inclined to buy a HiCap (you can sell it on and get your money back!) and try that with the 62 against the single rail 32/SNAPS and see which you prefer.

    If I were in your shoes I think I'd have a conversation with Darren at class A and explain what you've got, how you'd like to keep it original, but don't want to spend a fortune on servicing items that don't need it (I don't think pre amps need servicing unless they're faulty, I've no experience of SNAXOs) and ask for an all in price to do the minimum required to maintain originality whilst ensuring it's all working properly.

    I'm another fan of Avondale Audio, and Les can certainly improve the SNAPS (and I believe convert a single rail version to a HiCap beating dual rail version) but with this "vintage" system I'd be inclined not to mess around with it!
    divedeepdog likes this.
  12. MJS

    MJS Trade: Consultant at WH Audio

    Hum on phono inputs with nothing connected could be quite normal, they're picking up stray mains hum. The 32 probably has MM and MC boards fitted and it's worse on the MC inputs.
    Even if you want to keep it original I'd still dual-rail the SNAPS and the 32 and get a nice upgrade for minimal effort. Use the 32 over the 62 but pull the boards you don't need e.g. tape buffers and unused phono input.

    The 250s almost certainly need a service, although RF pickup through the NAXO can also cause these sort of issues with bubbling/hiss/distortion. As they're bolt-up 250s there are no upgrade options available that fit so they can be kept original. You may want to upgrade the power supply boards in the SNAPS. We have our own board that does that and makes a huge difference.

    In short, if I had to chose an order to service them get the 250s done first - they definitely need it by now. Then get the SNAPS done and later the pre-amp and NAXO. Alternatively get it all done at once and wonder how a 40 year old system can still amaze.
  13. suzywong

    suzywong Shifting 0s & 1s since 1968

    I’m genuinely* curious about these “original wide side forward style Isobariks” that Paul mentions, as all the Briks I’ve seen are deeper than they are wide. Do you have any links or pictures?

    *as joint owner of two sets of Briks over a 35 year period :)
  14. cctaylor

    cctaylor pfm Member

    IIRC The first Isobariks my father owned had what I call slab sides. The foam on the front started at bottom and finished at back of the top. The only visible woodwork was the side panels.
  15. suzywong

    suzywong Shifting 0s & 1s since 1968

    Thanks, And there I was, thinking I knew “all” about Briks :rolleyes::D:D.

    Both of our pairs were/are DMS with the fluted panel on the top front face. The first set were bought in ‘84. We gave them to friends when we got the second set in the late ‘90’s. The latter had been converted to “active”, running off Kairn, Aktiv Isobarik & LK280s. They are still in use in the conservatory.
    Last edited: Jul 12, 2019
  16. Paul R

    Paul R pfm Member

    I think the original Isobarik was proportioned in plan differently, wider than it was deep as opposed to the cabinet style we all know and love. I clearly recall seeing one, but not in full working order, and the foam was long gone. Mick Seymour's revision guide says the current cabinet style was adopted in 1976, so we're into the deep past.
  17. cctaylor

    cctaylor pfm Member

    I have been unable to find any pictures of the original Isobariks. My speakers date from 1977, dad had the original Isobariks bought from Hi-fi Corner in Leith Walk Edinburgh. The salesman was a certain Russ Andrews.

    The amps were a pair of Sugden P51s running in bridge mode. I still have the Q51 he used in a quadrophonic set up with the C51.

    The Isobariks I have now will date from 1977 when the Tri-amp system was introduced.
  18. mikemusic

    mikemusic pfm Member

    I have seen a very old pair of Isobariks many years ago.
    They were different. Think I would recognise them if I saw them
  19. Martin M

    Martin M Crueller than April

    Original Isobariks (courtesy of Kuma)
  20. cctaylor

    cctaylor pfm Member

    Thanks Martin

    My memory is pretty vague, after all it was over 40 years ago. I don't recall the wood across the top of the front. I am prepared admit my memory may be faulty. I do remember the narrow edges at either side on the top. This is where my description "slab sided" comes from. Most of time dad had them I was in Edinburgh at Heriot Watt University so was away from home a lot.

    The bass drivers and tweeters are obviously different from the ones I have. The Isobariks were obviously work in progress at this time. My tweeters were updated at the factory, dad dropped them off at the factory while he attended a course at Auchincruive near Ayr.

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