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Courtiestown - Naim Amplifier (Avondale) Upgrade Project

Discussion in 'd.i.y.' started by Richard Lines, Dec 7, 2021.

  1. Richard Lines

    Richard Lines pfm Member

    Honestly not sure, possibly just pre Diodes Inc. if the manufacturing process was unchanged. I have just heard that the earlier devices are 'better' sonically.

    The devices which Silicon Ark were selling are definitely 'old' - you can tell by the 'leg' material it has that lead like look to it rather than the shiny thin stuff you get with modern components.

    Regards

    Richard
     
  2. Richard Lines

    Richard Lines pfm Member

    Good Morning All,

    As per my Wanted advert I'm looking for the one 300uF wet tantalum capacitor as this seems to hit a 'sweet spot'. Worst case is I'll need to resort to - https://www.ebay.co.uk/itm/19140169...d=link&campid=5338728743&toolid=20001&mkevt=1 and the absolute worst case would be https://www.ebay.co.uk/itm/25295696...d=link&campid=5338728743&toolid=20001&mkevt=1

    They are both identical to the ones Mike P. was selling.

    Very busy at the moment and still got to cobble a PSU together for the NAXO. I've not heard back from Naim despite two EM's in the last fortnight.

    Regards

    Richard
     
  3. Richard Lines

    Richard Lines pfm Member

    Good Afternoon All,

    Today I have received a delivery via Parcel2go/ Yodel of 2off HackerNap PCB's with no indication who they are from. I'm not aware I have sought these in recent times and certainly wasn't expecting them (dementia setting in??) - I'm assuming it is somebody on this forum???

    Regards

    Richard
     
    Last edited: May 17, 2022
  4. Richard Lines

    Richard Lines pfm Member

    Good Afternoon All,

    This posted from the Mercure Hotel in Le Havre pending joining a boatie tomorrow to assist in laying the main cables for the Calvados Wind Farm off Ouistreham (Sword Beach as it was known in 1944).

    I'm still none the wiser as to the mysterious benefactor of the two HackerNap PCB's but have now ordered the components I don't have to hand. I cannot see any difference between MJW21194 or MJL21194 devices in electrical terms. The former is described as Obsolete on the Digi-Key site. I have quite a large amount of the MJL devices to hand.

    One question is R30/ 34 a 1M or 2M resistor?

    [​IMG]

    Regards

    Richard
     
  5. gavreid

    gavreid pfm Member

  6. Richard Lines

    Richard Lines pfm Member

    Good Morning All,

    In my quest to look at/ audition a range of older (sonically superior?) components I'm currently looking into sourcing some old Roederstein (ROE) EK capacitors ("maroons"). Clearly these are in limited supply nowadays but I note some differences of opinion in the past over their sonic benefits. Clearly Naim, and other high end manufacturers, fitted them as their capacitor of choice when they were more readily available.

    I have found a source of 22uF/ 63V and 220uF/ 63V devices so far.

    Anybody out there with thoughts on these devices? Equally is there anybody out there with any of these sitting in the back of their spare parts drawer who would be willing to part with them?

    Regards

    Richard
     
    Last edited: May 27, 2022
  7. Pete MB&D

    Pete MB&D Pete Maddex, the one and only!

    I think you will find naim selected them for price v performance not the other way round.

    Old caps are just old caps no magic just old dried out components, even ones that have sat on a shelf unused for years.

    I much prefered film caps, you don't get as much of the naim sound but to me that was a good thing.

    Pete
     
  8. Richard Lines

    Richard Lines pfm Member

    Good Afternoon All,

    Cable burying activities on the boatie I'm on at the moment are going very slowly so plenty of time to sort out bits for building a dual mono HackerNap.

    I've just bought a pair of 68uF AVX capacitors on eBay from someone who I suspect might be @bennyboyph on here? I have other parts to fit in this location but am aiming to emulate Carl's original build as closely as possible.

    I'm now looking at the parts required to build up four HackerCap boards.

    I intend to use my 2off already bought RS EI 75VA and 100VA 50 - 0 - 50V transformers for the FE.

    I'll need to order another ModuShop case.................

    As we're heading to Portland (Dorset) for tomorrow afternoon I'll be ringing Stephen at Tiger Toroids on Monday to enquire about having 2off 500VA toroids made.

    I have bought some of the old Roederstein EK maroons from Canada and Turkey to carry out trials.

    I am still looking for genuine Ferranti period ZTX653's. It is looking increasingly like needing to buy old Naim amplifiers just to remove the ZTX653/ ZTX753, replace them with a modern equivalent and sell on :rolleyes:

    Regards

    Richard
     
  9. Avon

    Avon Well-Known Member

    In my opinion, the ROEs work best in the feedback bypass position. That’s in the pre-amp gain stage / phono stage / possibly also in the power amp too. They give that bass thwack. The only capacitor I know of that beats them for thwack would be WET tantalum, though these are crazy expensive. ROEs have a resin-sealed end, which might prevent them from drying out (check for cracks therefore).
     
  10. Richard Lines

    Richard Lines pfm Member

    I bought a few to play with based on some people expressing a preference, I have no fixed idea as to what I'm going to do with them.

    I also bought the last 12off 300uF/ 30V M39006 wet tantalums that goldenopportunities1 was selling on eBay, these cost me £16.20 each (having said that he appears to be selling just the one now). I bought the last 5 that Mike P. of this parish was selling. These are performing very well in the latest boards I've been building. One Israeli seller wants over £80 for just the one.

    Following on from my last post the cost of building a fully fledged HackerNap is slowly building. The FETlington modifications are OK but if you go the route of the pre-regulated ALWSR with all the John Luckins modifications..........:-

    [​IMG]

    and

    [​IMG]

    then it becomes less straightforward.

    I'll also need to expand the title to include HackerNap??????

    Regards

    Richard
     
  11. Richard Lines

    Richard Lines pfm Member

    Good Morning All,

    I'm messaging an eBay supplier who advises that they can supply genuine Ferranti ZTX752's, brilliant I thought and they supplied this as evidence it they were genuine Ferranti parts:-

    [​IMG]

    So apart from the fact that the box has Zetex on it and a manufacturing date of 1996 (Ferranti Electronics demise being 1989) then yes they are genuine.............

    Regards

    Richard
     
  12. Richard Lines

    Richard Lines pfm Member

    Good Morning All,

    I did finally hear back from thoe awfully nice people at Naim.

    My unit was originally aimed at SBL's, it will cost a mere £399 to have the unit serviced with a turn around time of 8weeks. Apparently it has to be sent to them via a dealer - really????????

    I'll need to see if I can get Kate to drop it off a Holborn Hi-Fi.........

    Regards

    Richard
     
  13. Richard Lines

    Richard Lines pfm Member

    Good Evening All,

    That's 6 weeks away from home on this boatie now..............

    The Naxo finally found its way to Holborn Hi Fi on Saturday

    Been doing lots of reading (there being plenty of time......).

    Just been reading the 1980 Audio magazine article by Walt Jung and Richard Marsh on capacitors.

    Given the enthusiasm expressed for 47uF MMK polyester devices being used to substitute in the feedback position in place of such as tantalums in the Avondale and HackerNap devices where this article has:-

    “Polyester types are the most widely available for all the films and are already widely used in many audio circuits. There is no doubt that this is due to the generally low cost of these capacitors, but convenience and low cost should not be primary selection criteria to a critical audiophile. Polyester capacitors can be readily heard in good systems, with defects similar to those described for tantalum but, of course, reduced in magnitude.”

    and

    “In our opinion, polyester capacitors should be very carefully applied in an audiophile’s system and any system using them in the signal path may, potentially, benefit by the substitution of (equal value, voltage and tolerance) polyproplenes or polycarbonates. We have done this ourselves on different items of equipment, tube and transistor, with always the same result, a stunning upgrade in sound quality”

    I have a pair of the AVX 68uF/ 75V polyester jobbies to try in the HackerNap so will be able to form my own opinion.

    The only thing outstanding to enable me to build a HackerNap now is a ModuShop (other manufacturers area available) case - oh and being at home.

    Regards

    Richard
     
  14. chiily

    chiily PFM Special Builder

    I have used polyester cap in the feedback loop of NCC200 and 220s, I didn't like them personally. Much preferred a wet tant there.

    I was surprised to see WIMA MKS polyester caps in the signal path of the STA15 I restored, built way back in 1963. It has polystyrene caps in the feedback loop I think.
     
  15. martin clark

    martin clark pinko bodger

    In valve amps like the STA 15 the impedances are so high you can do nice things like that!

    There are other ways around, but it leads to different trade-offs elsewhere of course.
     
  16. S-Man

    S-Man Kinkless Tetrode Admirer


    I have had poor subjective results using Walt's circuits, even though they appear rather cunning. This makes me cautious of his opinions.
    Another well respected audio designer told me that polyprops have a "squeaky" character and should be used sparingly.
    Who actually knows?

    Your approach of finding out for yourself the is the only/right one!!!
     
  17. martin clark

    martin clark pinko bodger

    Big polyester in feedback and certain-other other uses where teh signal across it varies, certainly has a bright/squeaky quality IME.

    Polypropylene in preference, everytime.

    +1 to 'try for yourself' ..!
     
  18. Richard Lines

    Richard Lines pfm Member

    Good Afternoon All,

    They say a little knowledge is a dangerous thing......... so on that basis......

    Whilst "reading" Doug Self's "Audio Power Amplifier Design Handbook" I was intrigued to see mention of a 1000uF feedback capacitor.

    Acknowledging this as being from said book above:-

    [​IMG]

    I'm currently at 300uF which seems some way up on LesW's original proposed value of 47uF.

    Is this something that needs to be tried?? I was surprised to see the back to back diodes, DS notes that there are four to counter the increase in distortion caused by just the two?

    Could somebody explain this in simple terms and also comment on heading upwards from a 300uF capacitor in the feedback position?

    Regards

    Richard
     
  19. S-Man

    S-Man Kinkless Tetrode Admirer

    The diodes are to protect C2 from DC above the rating of the cap i.e. +6.3V and approx -1V.

    WRT to the capacitance value, you need to consider the time-constant of the filter formed by C2 and the 110R resistor.
    Dougie's use of low value feedback resistors, I assume in an attempt to achive vanishingly low distortion figures, means he needs a large (e.g. X10) value for the cap to achieve a similar LF bandwidth of the amp.

    https://electronics.stackexchange.c...value-of-each-component-in-an-audio-amplifier
     
  20. Richard Lines

    Richard Lines pfm Member

    Good Morning All,

    Work on cable burying on this boat has ground to a complete halt currently.

    The next question as I try and read Doug Self's book is to snub or not to snub - Quasimodo anybody? A thread running to 116 pages......:(

    Regards

    Richard
     

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